NHA EKG Technician (CET) — All Questions

A technician measures the distance from the beginning of the P wave to the beginning of the QRS complex on a strip and counts four small boxes. What is the PR interval, and is it normal?

• a.0.04 second, which is shorter than normal
• b.0.16 second, which is normal✓
• c.0.08 second, which is normal
• d.0.40 second, which is longer than normal

Each small box equals 0.04 second at the standard paper speed of 25 mm/sec, so four small boxes equal 0.16 second. The normal PR interval is 0.12 to 0.20 second, so 0.16 second falls in range. The 0.04 and 0.08 answers miscount the boxes, and 0.40 second would require ten small boxes and would indicate a first-degree AV block.

What is the normal duration of the QRS complex in an adult?

• a.0.20 to 0.36 second
• b.Greater than 0.44 second
• c.0.12 to 0.20 second
• d.Less than 0.12 second✓

A normal QRS is under 0.12 second (fewer than three small boxes) because the ventricles depolarize rapidly through the bundle branches and Purkinje fibers. The 0.12 to 0.20 second range describes the PR interval, not the QRS. Values of 0.20 second or more suggest a bundle branch block or a beat that started in the ventricles, and 0.44 second is a QT-interval reference, not a QRS value.

Using the 300 method on a regular rhythm, a technician counts four large boxes between two consecutive R waves. What is the heart rate?

• a.150 beats per minute
• b.75 beats per minute✓
• c.100 beats per minute
• d.60 beats per minute

The 300 method divides 300 by the number of large boxes between R waves, so 300 divided by 4 equals 75 beats per minute. Sixty would require five large boxes, 100 would require three, and 150 would require two. The method only works when the rhythm is regular, because it assumes every R-R interval is the same.

A patient has an irregular rhythm. The technician counts 11 QRS complexes in a six-second strip. What is the approximate heart rate?

• a.11 beats per minute
• b.110 beats per minute✓
• c.66 beats per minute
• d.22 beats per minute

The six-second method multiplies the number of QRS complexes in six seconds by 10, giving 11 times 10, or about 110 beats per minute. This estimate is the preferred method for irregular rhythms because the 300 and 1500 methods assume equal R-R intervals. Multiplying by 2 or 6 instead of 10 gives the wrong scaling, since six seconds is one tenth of a minute.

What electrical event does the P wave represent on an EKG tracing?

• a.Atrial repolarization
• b.Atrial depolarization✓
• c.Ventricular depolarization
• d.Ventricular repolarization

The P wave is the small rounded deflection produced when the impulse from the SA node spreads across both atria and depolarizes them, which triggers atrial contraction. Ventricular depolarization produces the QRS complex, and ventricular repolarization produces the T wave. Atrial repolarization does occur, but it is buried inside the much larger QRS complex and is not normally visible.

A technician is explaining a tracing to a student and points to the rounded wave that follows each QRS complex. What does this wave represent?

• a.Depolarization of the ventricles
• b.Conduction delay at the AV node
• c.Repolarization of the ventricles✓
• d.Contraction of the atria

The T wave follows the QRS and represents ventricular repolarization, the recovery phase in which the ventricular cells return to their resting electrical state. Ventricular depolarization is the QRS itself. The AV node delay is represented by the flat segment within the PR interval, and atrial contraction follows the P wave.

Using the 1500 method, a technician counts 20 small boxes between two consecutive R waves on a regular strip. What is the heart rate?

• a.50 beats per minute
• b.75 beats per minute✓
• c.300 beats per minute
• d.100 beats per minute

The 1500 method divides 1500 by the number of small boxes between R waves: 1500 divided by 20 equals 75 beats per minute. The number 1500 is used because there are 1500 small boxes in one minute at 25 mm/sec. This method is the most precise of the calculation methods, but like the 300 method it requires a regular rhythm.

Which set of findings meets the criteria for normal sinus rhythm?

• a.Rate 80, irregularly irregular, no P waves, QRS 0.08 second
• b.Rate 80, regular, upright P before each QRS, PR 0.16, QRS 0.08 second✓
• c.Rate 112, regular, upright P before each QRS, PR 0.16, QRS 0.08 second
• d.Rate 52, regular, inverted P after each QRS, PR not measurable

Normal sinus rhythm requires a rate of 60 to 100, a regular rhythm, one upright P wave in front of every QRS, a PR interval of 0.12 to 0.20 second, and a QRS under 0.12 second. The choice at 112 meets every one of those criteria except the rate, which makes it sinus tachycardia rather than normal sinus rhythm. Absent P waves with an irregularly irregular ventricular response describes atrial fibrillation. A rate of 52 with P waves inverted after the QRS points to a junctional rhythm, in which the impulse starts below the atria and travels backward through them.

A sleeping athlete on telemetry shows a regular rhythm at 52 beats per minute with an upright P wave before each narrow QRS and a PR interval of 0.16 second. How should this rhythm be identified?

• a.Normal sinus rhythm
• b.Sinus bradycardia✓
• c.Junctional escape rhythm
• d.Second-degree AV block

Every measurement is normal except the rate, which is below 60, so the rhythm is sinus bradycardia. Normal sinus rhythm requires a rate of at least 60. A junctional escape rhythm would show absent or inverted P waves, and a second-degree AV block would show P waves that are not all followed by a QRS complex.

A patient with a fever of 103 degrees Fahrenheit has a regular rhythm at 124 beats per minute with an upright P wave before every narrow QRS. What is this rhythm?

• a.Sinus tachycardia✓
• b.Ventricular tachycardia
• c.Atrial flutter
• d.Supraventricular tachycardia

Sinus tachycardia is a sinus rhythm faster than 100 beats per minute, and it is a normal response to fever, pain, exercise, anxiety, or dehydration. Supraventricular tachycardia is usually faster than 150 and the P waves are hidden. Atrial flutter shows sawtooth flutter waves, and ventricular tachycardia produces wide QRS complexes with no P waves.

A pediatric strip shows upright P waves before every narrow QRS, a PR interval of 0.14 second, and R-R intervals that shorten with inhalation and lengthen with exhalation. What is this rhythm?

• a.Wandering atrial pacemaker
• b.Sinus arrhythmia✓
• c.Second-degree AV block, Mobitz I
• d.Atrial fibrillation

Sinus arrhythmia is a sinus rhythm whose only abnormality is an irregularity that varies with the breathing cycle, and it is a normal finding in children and young adults. Atrial fibrillation would have no identifiable P waves and an irregularly irregular rhythm. Wandering atrial pacemaker shows at least three different P wave shapes, and Mobitz I shows progressively lengthening PR intervals with a dropped QRS.

A strip shows no identifiable P waves, a wavy chaotic baseline, narrow QRS complexes, and R-R intervals that vary from beat to beat with no pattern. What is this rhythm?

• a.Atrial flutter
• b.Ventricular fibrillation
• c.Sinus arrhythmia
• d.Atrial fibrillation✓

Atrial fibrillation is described as irregularly irregular with no discernible P waves and a fibrillatory baseline, while the QRS stays narrow because conduction below the AV node is normal. Sinus arrhythmia still has clear P waves. Atrial flutter has organized sawtooth waves, and ventricular fibrillation has no QRS complexes at all.

A monitor strip shows a sawtooth baseline with regular atrial waves at about 300 per minute and a QRS after every fourth sawtooth wave. What is this rhythm?

• a.Atrial flutter with 4:1 conduction✓
• b.Coarse atrial fibrillation
• c.Sinus tachycardia with artifact
• d.Second-degree AV block, 4:1

Atrial flutter produces uniform sawtooth flutter waves, classically at 250 to 350 per minute, and the AV node blocks most of them so only every second, third, or fourth impulse reaches the ventricles. That physiologic filtering is normal protection and is not called second-degree AV block, which is a conduction defect occurring at ordinary atrial rates. Coarse atrial fibrillation has a chaotic, constantly changing baseline instead of identical repeating waves, and sinus tachycardia shows discrete P waves that stop at the QRS rather than marching straight through it.

An otherwise regular sinus strip contains one early beat with a P wave shaped differently from the others, followed by a normal narrow QRS and then a pause. What is the early beat?

• a.Escape beat
• b.Premature atrial contraction✓
• c.Premature ventricular contraction
• d.Premature junctional contraction

A premature atrial contraction arrives early and comes from an irritable site in the atria, so its P wave looks different from the sinus P waves but the QRS remains narrow because conduction to the ventricles is normal. A premature ventricular contraction would be wide and bizarre with no P wave. A junctional premature beat has an inverted or absent P wave, and an escape beat arrives late rather than early.

A patient reports sudden palpitations. The strip shows a perfectly regular narrow-complex rhythm at 180 beats per minute with P waves that cannot be identified. What is the most likely rhythm?

• a.Accelerated junctional rhythm
• b.Ventricular tachycardia
• c.Supraventricular tachycardia✓
• d.Sinus tachycardia

Supraventricular tachycardia is a regular narrow-complex rhythm, usually 150 to 250 beats per minute, in which the P waves are buried in the preceding T waves and cannot be seen. Sinus tachycardia usually stays under 160 and has visible P waves that speed up gradually. Ventricular tachycardia has wide QRS complexes, and an accelerated junctional rhythm runs about 60 to 100.

A strip shows a regular rhythm at 45 beats per minute with narrow QRS complexes and inverted P waves appearing immediately after each QRS. What is this rhythm?

• a.Junctional escape rhythm✓
• b.Idioventricular rhythm
• c.First-degree AV block
• d.Sinus bradycardia

When the junction takes over as pacemaker, the atria depolarize backward, so the P wave is inverted and may fall before, during, or after the QRS; at 40 to 60 beats per minute this is a junctional escape rhythm. Sinus bradycardia has upright P waves before the QRS. An idioventricular rhythm has wide QRS complexes at 20 to 40, and first-degree AV block has upright P waves with a long PR interval.

What is the inherent rate range of the AV junction when it functions as the heart's pacemaker?

• a.40 to 60 beats per minute✓
• b.20 to 40 beats per minute
• c.60 to 100 beats per minute
• d.100 to 150 beats per minute

The AV junction fires at an inherent rate of 40 to 60 beats per minute and takes over when the SA node fails or slows. The SA node is the primary pacemaker at 60 to 100, and the ventricular Purkinje network is the last-resort pacemaker at 20 to 40. A junctional rhythm faster than 60 is called accelerated junctional, and above 100 it is junctional tachycardia.

A sinus rhythm strip contains a single early beat that is wide and bizarre, has no preceding P wave, and has a T wave that points opposite to the QRS. What is the beat?

• a.Somatic tremor artifact in one lead
• b.Premature ventricular contraction✓
• c.Ventricular paced beat with capture
• d.Premature atrial contraction with aberrancy

A premature ventricular contraction originates below the bundle of His, so the impulse spreads muscle cell to muscle cell rather than through the fast conduction system, producing a wide bizarre QRS with no preceding P wave and a T wave that points opposite the QRS. A premature atrial contraction conducted with aberrancy is the genuinely competing answer: it is also early and wide, but it is preceded by its own early P wave, which this beat lacks. A paced beat carries a sharp pacing spike immediately in front of it, and tremor artifact rides on top of the baseline without replacing a beat or resetting the cycle.

A monitor alarms and the strip shows a regular wide-complex rhythm at 170 beats per minute with no visible P waves. The patient is unresponsive. What rhythm is displayed?

• a.Supraventricular tachycardia
• b.Sinus tachycardia with a bundle branch block
• c.Ventricular tachycardia✓
• d.Atrial flutter

Ventricular tachycardia is three or more consecutive PVCs at a rate above 100, appearing as a regular run of wide, uniform complexes without P waves, and it is a lethal rhythm when the patient has no pulse. Supraventricular tachycardia is narrow. Atrial flutter shows sawtooth waves, and while a rate-related bundle branch block can widen a sinus tachycardia, an unresponsive patient with this tracing must be treated as ventricular tachycardia and help summoned at once.

A telemetry strip suddenly shows chaotic, irregular waves of varying height with no identifiable P waves, QRS complexes, or T waves. What should the technician do first?

• a.Reposition the electrodes and print a new strip
• b.Immediately check the patient and call for emergency help✓
• c.Ask the patient to lie still and stop talking
• d.Chart the finding and continue monitoring

That description is ventricular fibrillation, a lethal rhythm in which the ventricles quiver and produce no cardiac output, so the technician must verify the patient at the bedside and activate the emergency response without delay. Documenting and waiting wastes the minutes that determine survival. Repositioning electrodes or asking the patient to hold still is the response to suspected artifact, and artifact is ruled out the moment the patient is found unresponsive and pulseless.

A monitor shows a nearly flat line with no waveforms in two different leads and the patient is unresponsive with no pulse. What is this rhythm?

• a.Loose lead artifact
• b.Ventricular fibrillation
• c.Idioventricular rhythm
• d.Asystole✓

Asystole is the absence of all electrical activity, appearing as a flat or nearly flat line, and it must be confirmed in more than one lead before it is accepted as true. Ventricular fibrillation still shows chaotic deflections, and an idioventricular rhythm shows wide slow complexes. A loose lead can mimic a flat line, which is exactly why the finding is confirmed in a second lead and at the bedside.

A strip shows wide QRS complexes at a regular rate of 32 beats per minute with no P waves. What is this rhythm called?

• a.Agonal artifact
• b.Junctional escape rhythm
• c.Idioventricular rhythm✓
• d.Sinus bradycardia

When the ventricles become the pacemaker of last resort, they fire at their inherent rate of 20 to 40 beats per minute and produce wide complexes without P waves, which is an idioventricular rhythm. A junctional escape rhythm runs 40 to 60 with narrow complexes. Sinus bradycardia has upright P waves and narrow QRS complexes, and this tracing is an organized rhythm rather than artifact.

A regular strip at 68 beats per minute has one upright P wave before every narrow QRS, and every PR interval measures 0.28 second. What is this rhythm?

• a.Normal sinus rhythm at a rate of 68
• b.Second-degree AV block, Mobitz type II
• c.Third-degree AV block with a junctional escape
• d.Sinus rhythm with a first-degree AV block✓

A PR interval that is constant but longer than 0.20 second defines first-degree AV block, in which every impulse still reaches the ventricles but is delayed. Normal sinus rhythm requires a PR of 0.12 to 0.20 second, so 0.28 second rules it out. Mobitz II drops beats without lengthening the PR, and this strip drops nothing. In third-degree block with a junctional escape, the P waves and QRS complexes march at independent rates, so no PR interval would measure the same value twice, let alone every time.

A strip shows PR intervals of 0.18, 0.24, 0.32 second, then a P wave with no QRS after it, and the pattern repeats. What is this rhythm?

• a.First-degree AV block with a sinus pause
• b.Second-degree AV block, Mobitz type II
• c.Second-degree AV block, Mobitz I (Wenckebach)✓
• d.Third-degree AV block with variable PR intervals

Mobitz I, also called Wenckebach, shows the PR interval getting progressively longer until one P wave is not conducted and a QRS is dropped, after which the cycle starts over. Mobitz II also drops beats, but the conducted PR intervals stay constant, which is the single feature that separates the two here. First-degree block never drops a beat at all, so pairing it with a pause misreads the dropped QRS as a sinus problem. In third-degree block the PR intervals vary randomly because the atria and ventricles are unrelated, rather than lengthening in an orderly sequence.

A strip shows a constant PR interval of 0.20 second on conducted beats, but every third P wave is suddenly not followed by a QRS complex. What is this rhythm?

• a.Premature atrial contractions that are not conducted
• b.Second-degree AV block, Mobitz II✓
• c.Second-degree AV block, Mobitz I
• d.Sinus arrhythmia

Mobitz II is identified by dropped QRS complexes with no warning and PR intervals that remain constant on the beats that do conduct. Mobitz I would show the PR lengthening before the drop. Sinus arrhythmia never drops a QRS, and non-conducted premature atrial contractions arrive early with abnormal P waves rather than on schedule.

A strip shows a regular ventricular rhythm at 40 beats per minute with wide QRS complexes, regular P waves at 80 per minute, and no consistent relationship between the P waves and the QRS complexes. What is this rhythm?

• a.Sinus bradycardia with premature atrial contractions
• b.Second-degree AV block, Mobitz I
• c.Junctional escape rhythm
• d.Third-degree (complete) AV block✓

In third-degree AV block nothing crosses the AV node, so the atria and ventricles beat independently: the P-P interval is regular, the R-R interval is regular, and the PR interval constantly changes. Mobitz I still conducts most beats with a lengthening PR. Sinus bradycardia keeps one P wave tied to each QRS, and a pure junctional escape rhythm would not show a separate faster atrial rate marching through the tracing.

A strip shows a sharp, narrow vertical spike immediately before each wide QRS complex at a regular rate of 70. What does this indicate?

• a.Sixty-cycle AC interference
• b.A ventricular paced rhythm✓
• c.Somatic tremor artifact
• d.A premature ventricular contraction pattern

A pacemaker spike is a thin vertical line marking the electrical impulse delivered by the device; a spike followed by a wide QRS indicates ventricular capture. AC interference appears as a uniform fuzzy band across the whole tracing rather than a single spike per beat. Premature ventricular contractions occur early and irregularly without spikes, and somatic tremor causes erratic jagged baseline movement.

A monitor alarms for ventricular fibrillation, but the technician finds the patient sitting up, alert, and brushing her teeth, and a regular narrow-complex rhythm is visible between the chaotic sections. What is the most likely explanation?

• a.Pacemaker malfunction
• b.Intermittent true ventricular fibrillation
• c.Third-degree AV block
• d.Muscle movement artifact✓

An alert, talking patient cannot be in ventricular fibrillation, and the presence of underlying normal complexes marching through the chaos identifies the tracing as motion artifact. True ventricular fibrillation has no organized QRS complexes anywhere and produces immediate unresponsiveness. AV block and pacemaker failure both produce organized, measurable patterns rather than chaotic noise tied to the patient's activity.

Which group of rhythms is considered immediately life-threatening and requires the technician to summon help right away?

• a.Sinus bradycardia, sinus tachycardia, and sinus arrhythmia
• b.First-degree AV block, atrial flutter, and premature atrial contractions
• c.Junctional rhythm, wandering atrial pacemaker, and paced rhythm
• d.Ventricular fibrillation, pulseless ventricular tachycardia, and asystole✓

Ventricular fibrillation, pulseless ventricular tachycardia, and asystole produce no effective cardiac output, so survival depends on immediate recognition and activation of the emergency response. The sinus rhythms in the first choice are common and often benign. First-degree block, flutter, and premature atrial beats need reporting but not emergency action, and junctional or paced rhythms usually maintain perfusion.

What does the QT interval measure on an EKG tracing?

• a.The delay of the impulse at the AV node
• b.The time between two consecutive R waves
• c.Atrial depolarization plus repolarization
• d.Ventricular depolarization plus repolarization✓

The QT interval is measured from the start of the QRS complex to the end of the T wave and represents the full cycle of ventricular depolarization and recovery; it normally occupies less than half of the R-R interval and generally measures under about 0.44 second at normal rates. Atrial depolarization is the P wave, and atrial repolarization is buried inside the QRS and is not measured. The AV nodal delay lies inside the PR interval, and the R-R interval measures rate and regularity.

A strip shows a normal sinus beat followed by a wide bizarre beat, then another sinus beat followed by another wide bizarre beat, repeating throughout the strip. What is this pattern called?

• a.Ventricular bigeminy✓
• b.Ventricular tachycardia
• c.Ventricular trigeminy
• d.A couplet

Bigeminy means every other beat is a premature ventricular contraction, alternating one normal beat and one PVC. Trigeminy is a PVC every third beat. A couplet is two PVCs in a row, and three or more consecutive PVCs at a rate above 100 constitute ventricular tachycardia.

Which premature ventricular contraction pattern is considered most dangerous because it can trigger ventricular tachycardia or fibrillation?

• a.An interpolated PVC between two normal beats
• b.A unifocal PVC that is late in the cycle
• c.A PVC followed by a full compensatory pause
• d.A PVC that lands on the T wave of the preceding beat✓

A PVC falling on the T wave, called the R-on-T phenomenon, arrives during the vulnerable relative refractory period of repolarization and can precipitate ventricular tachycardia or fibrillation. Unifocal PVCs that arrive later in the cycle are the least worrisome type. An interpolated PVC does not disturb the underlying rhythm, and a compensatory pause is a normal feature of most PVCs rather than a warning sign.

An otherwise normal sinus strip contains one early narrow beat with an inverted P wave right in front of it and a PR interval of 0.08 second. What is this beat?

• a.Premature atrial contraction
• b.Premature ventricular contraction
• c.Sinus escape beat
• d.Premature junctional contraction✓

A premature junctional contraction comes from the AV junction, so the atria depolarize retrograde and produce an inverted P wave with a short PR of less than 0.12 second, while the QRS stays narrow. A premature atrial contraction has an upright though differently shaped P wave with a normal PR. A PVC is wide with no P wave, and an escape beat comes late, not early.

What is the correct way to determine whether a ventricular rhythm is regular?

• a.March out the R-to-R intervals and check that they stay equal✓
• b.Compare the height of each R wave from one beat to the next
• c.March out the P-to-P intervals, since the atria govern the rate
• d.Check that every PR interval measures less than 0.20 second

Ventricular regularity is judged by marching out the R-to-R intervals with calipers or a paper edge and checking whether they stay the same. Marching out P-to-P intervals is a real measurement, but it reports ATRIAL regularity, and the two differ whenever conduction fails: in complete heart block the P-to-P intervals can be perfectly regular while the ventricles are not. R wave height reflects voltage and lead placement rather than timing, and measuring PR intervals evaluates AV conduction.

On standard EKG paper running at 25 mm/sec, how far apart are the vertical time markers printed at the top of the strip used for the six-second method?

• a.One second apart, so six intervals equal six seconds
• b.Six seconds apart, so one interval equals six seconds
• c.Half a second apart, so twelve intervals equal six seconds
• d.Three seconds apart, so two intervals equal six seconds✓

EKG paper is marked at three-second intervals, which equals 15 large boxes, so a six-second strip spans two marked intervals or 30 large boxes. Each large box is 0.20 second and each small box is 0.04 second at the standard 25 mm/sec speed. The other spacings do not correspond to how standard EKG paper is printed.

A technician is asked to point out the PR segment on a 12-lead tracing. Which portion of the tracing is the PR segment?

• a.The stretch from the beginning of the P wave to the beginning of the QRS complex
• b.The stretch from the end of the QRS to the beginning of the T wave
• c.The flat stretch from the end of the P wave to the beginning of the QRS✓
• d.The flat stretch from the end of the T wave to the next P wave

The PR segment is the flat piece of baseline that begins where the P wave ends and stops where the QRS begins; it corresponds to the conduction delay in the AV node and bundle of His. Measuring from the start of the P wave instead gives the PR interval, which includes the P wave and normally runs 0.12 to 0.20 second, so that answer describes an interval rather than a segment. The stretch from the end of the QRS to the start of the T wave is the ST segment, and the flat piece from the end of the T wave to the next P wave is the TP segment.

On a 12-lead tracing, which landmark marks the end of the QRS complex and the start of the ST segment?

• a.The J point, evaluated in each of the twelve leads✓
• b.The peak of the R wave, the tallest upward deflection
• c.The isoelectric baseline between two consecutive beats
• d.The end of the PR interval, just before the QRS

The J point is the junction where the last deflection of the QRS ends and the ST segment begins, and ST elevation or depression is judged at or just after it. The peak of the R wave sits in the middle of ventricular depolarization, not at its end. The isoelectric baseline is the flat reference line the tracing rests on between beats, not a landmark on the complex itself. The end of the PR interval is a real landmark, but it marks the onset of the QRS rather than its offset.

A technician needs a reference line to judge whether an ST segment sits above or below baseline. Which part of the tracing supplies that isoelectric reference?

• a.The peak of the T wave that follows the segment being measured
• b.The top of the tallest R wave recorded anywhere on the strip
• c.The PR interval, measured from the start of the P wave to the QRS
• d.The TP segment, the flat line from the end of the T wave to the next P wave✓

The TP segment is electrically silent, so it is the flat baseline against which ST deviation is measured. The PR interval is not a reference line at all, because it spans the P wave and the PR segment together and is measured as a duration; the flat PR segment alone can substitute as a baseline when a fast rate leaves almost no TP segment. The peak of the T wave and the top of an R wave are deflections away from baseline, so neither can define where the isoelectric line lies.

Which description states correctly where a QT interval starts and where it ends?

• a.From the beginning of the P wave to the end of the T wave
• b.From the end of the P wave to the point where the T wave ends
• c.From the beginning of the QRS complex to the end of the T wave✓
• d.From the first deflection of the QRS to the point where the T wave peaks

The QT interval runs from the earliest onset of the QRS complex, whether that first deflection is a Q wave or an R wave, to the point where the T wave returns to the isoelectric line, and it is read in the lead where the end of the T wave is clearest, often lead II or V5. Starting at the onset of the P wave adds the whole PR interval and overstates the measurement. Starting at the end of the P wave still includes the PR segment, so it also runs long. Stopping at the peak of the T wave cuts the measurement short, because repolarization is not finished until the T wave has come back to the baseline.

On a regular strip, one R wave falls on a heavy line and the next R wave falls midway between the fourth and fifth heavy lines after it. What is the approximate ventricular rate?

• a.Exactly 75 beats per minute, the value at the fourth heavy line
• b.About 67 beats per minute, between the 75 and 60 values✓
• c.Exactly 60 beats per minute, the value at the fifth line
• d.About 45 beats per minute, since the boxes are wide

The sequence method assigns 300, 150, 100, 75, 60, 50 to successive heavy lines, so an R wave landing between the fourth and fifth lines falls between 75 and 60 beats per minute. Dividing 300 by the 4.5 large boxes actually measured gives 66.7, which rounds to about 67. Reading the fourth line as 75 or the fifth line as 60 forces the R wave onto a line it did not reach. A rate near 45 would require more than six large boxes between R waves.

During a 12-lead acquisition the baseline drifts slowly up and down across the paper in the limb leads while the patient breathes deeply and shifts on the table. What should the technician do first?

• a.Report the drifting baseline to the supervisor before repeating the tracing
• b.Secure the limb electrodes on flat skin, ask the patient to lie still, and repeat✓
• c.Record the tracing anyway and note that the patient was breathing deeply
• d.Switch the machine to the 50 mm/sec setting to flatten the baseline

A slow, rolling baseline is wandering-baseline artifact, and it comes from patient motion, deep respiration, or electrodes that are loose, dried out, or sitting over skin that was not prepared. Correcting the cause and repeating the tracing is inside the technician's own scope and takes seconds, so raising it with a supervisor first delays the study without fixing anything. Submitting a drifting tracing with a note leaves an uninterpretable ST segment for the reader. Doubling the paper speed stretches the complexes horizontally but does nothing to the drift and makes the tracing nonstandard.

A technician analyzes every strip the same way, beginning with the rate and then the regularity. In a standard five-step analysis, what is examined next?

• a.The width of the QRS complexes, measured in small boxes
• b.Whether a uniform P wave precedes each QRS complex✓
• c.The PR interval, counted in small boxes
• d.The shape of the T wave in that same lead

The usual five steps are rate, regularity, P waves, PR interval, and QRS duration, so the P waves come third. Looking at the P waves first is what makes the PR interval meaningful, because a PR interval cannot be measured until an atrial wave has been identified and shown to be uniform and upright. QRS duration is the fifth step and separates supraventricular from ventricular complexes. T wave shape is part of a physician's interpretation and is not one of the five measured steps.

A strip shows P waves marching out at their own regular rate and QRS complexes at a slower regular rate. How should the technician determine the atrial rate?

• a.Count the QRS complexes in a six-second strip and multiply the total by ten
• b.Divide 1500 by the number of small boxes between a P wave and the QRS after it
• c.Subtract the ventricular rate from 300 to get the rate of the atria
• d.Measure from one P wave to the next and apply a rate method✓

When the atria and the ventricles are firing independently, two rates exist and each is measured from its own waves: the atrial rate from P-P intervals and the ventricular rate from R-R intervals. Counting QRS complexes gives only the ventricular rate and says nothing about how fast the atria are firing. Measuring from a P wave to the following QRS measures the PR interval, which is a conduction time and not a cycle length. Subtracting from 300 has no basis; the 300 is a count of large boxes per minute, not a rate that can be split between chambers.

Every lead of a 12-lead tracing shows a thick, fuzzy baseline of fine, perfectly regular oscillations. The patient is comfortable and lying still, and the complexes are still visible through the fuzz. What should the technician do first?

• a.Report the fuzzy baseline to the supervisor and wait for further direction
• b.Ask the patient to hold still and breathe quietly during the repeat
• c.Move nearby electrical equipment away and untangle the lead wires✓
• d.Raise the calibration to 20 mm/mV so the complexes stand out

A uniform, perfectly regular fuzz in every lead of a still patient is alternating-current interference picked up from nearby powered equipment or from lead wires running alongside power cords. Separating the wires from power cords, unplugging or moving the offending device, and confirming the cable connections is the technician's own first step. Asking a patient who is already lying still to hold still addresses somatic tremor artifact instead, which is coarse and irregular rather than uniform. Doubling the calibration magnifies the interference along with the complexes and makes the tracing nonstandard, and handing the problem to a supervisor delays a fix the technician can make.

A telemetry strip on a patient with a low potassium level and a heart rate of 52 shows an extra small, rounded, upright deflection in every cardiac cycle, most prominent in leads V2 and V3. What is this deflection called?

• a.An early P wave from the next beat
• b.A U wave following the T wave✓
• c.A biphasic T wave with two peaks
• d.A J point elevated above baseline

A small rounded wave that comes after the T wave and shares its direction is a U wave, best seen in leads V2 and V3, and it becomes prominent with a low potassium level and with slow heart rates. A premature P wave would fall early in the cycle and would be followed by its own QRS complex rather than appearing once in every cycle. A biphasic T wave has one positive and one negative component within a single wave rather than a separate rounded deflection after the T wave returns to baseline. The J point lies at the far end of the QRS, well before the T wave.

A ventricular complex on a strip is entirely negative: it begins with a downward deflection and no upward deflection appears anywhere in it. How is this complex named?

• a.A Q wave followed immediately by an S wave
• b.An R wave inverted below baseline
• c.A QS complex, with no R wave present✓
• d.A deep S wave without a Q wave

Naming depends on the R wave: a Q wave is a negative deflection before the first R wave and an S wave is a negative deflection after an R wave, so with no R wave at all there is nothing to place a Q before or an S after, and the whole complex is called a QS complex. Calling it a Q followed by an S is the common trap, because it would require an R wave between them. An R wave is positive by definition, so there is no such thing as an inverted R wave. Calling it an S wave alone has the same problem in reverse, since an S wave must follow an R wave.

In lead V1 a complex shows a small upward deflection, then a downward deflection, then a second upward deflection. How is that second upward deflection labeled?

• a.An S wave, because it follows the first negative deflection
• b.A J point elevation on the tail end of the complex
• c.An R prime wave, the second positive deflection✓
• d.A U wave riding on the end of the complex

Any positive deflection after the first one is labeled R prime, so this complex is written as rSR prime, the pattern often seen in V1. An S wave is negative by definition and cannot name an upward deflection. J point elevation is a shift of the baseline where the QRS ends, not an added wave inside the complex. A U wave appears after the T wave has finished, separated from the QRS by the ST segment and the T wave.

In a normally conducted sinus rhythm, how should the P wave appear in lead II and in lead aVR?

• a.Inverted in lead II, upright in aVR
• b.Upright in lead II and inverted in lead aVR✓
• c.Upright in both lead II and lead aVR
• d.Flat in lead II and biphasic in aVR

A sinus impulse starts high in the right atrium and spreads downward and to the left, toward the positive electrode of lead II and away from the positive electrode of aVR, so the sinus P wave is upright in lead II and inverted in aVR. An inverted P wave in lead II means the atria were depolarized from below, as happens when the pacemaker site sits low in the atria or in the junction. An upright P wave in aVR is a separate warning sign and most often means limb electrodes have been reversed, so it should send the technician back to check the arm and leg placements before the tracing is submitted. A flat P wave in lead II usually means the atrial activity is too small to see in that lead rather than that conduction is normal.

Across an entire strip the R-R intervals repeat the same pattern of two short intervals followed by one long interval. How is this regularity described?

• a.Regularly irregular✓
• b.Irregularly irregular
• c.Occasionally irregular
• d.Regular with a pause

An irregular rhythm whose irregularity repeats in a predictable cycle is called regularly irregular, and grouped beating like this is the reason a technician measures several R-R intervals across the whole strip rather than one pair. Irregularly irregular describes R-R intervals that vary with no repeating pattern, which is not what a repeating two-short-one-long sequence does. Occasionally irregular fits a rhythm that is regular except for isolated ectopic beats. Calling it regular with a pause would require the underlying R-R intervals to be constant, and here they are not.

A woman started on a new antiarrhythmic has a regular sinus rhythm at 60 beats per minute, and her QT interval measures 0.48 second. What should the technician do with this measurement?

• a.Report the long QT to the supervisor and document it✓
• b.Tell the patient the new medication is unsafe for her
• c.Record the QT from the lead where the T wave ends first
• d.Repeat the tracing at 50 mm/sec so the QT measures shorter

At 60 beats per minute the R-R interval is exactly one second, and the square root of one is one, so the corrected QT equals the measured 0.48 second, above the roughly 0.46-second upper limit used for women. A prolonged QT on a patient starting an antiarrhythmic is a finding the technician reports promptly through the chain of command and documents, since a CET acquires and reports but does not diagnose or advise on therapy. Telling the patient the drug is unsafe is interpreting for the patient and is outside the technician's scope. Choosing the lead with the earliest T wave ending hides the longest QT, and doubling the paper speed only widens the tracing; the measured duration in seconds does not change.

A monitored patient who is awake and talking has a sinus rhythm at 68 beats per minute interrupted by a 4-second stretch with no P wave and no QRS complex, after which sinus rhythm resumes. What should the technician do?

• a.Print the strip and report the pause to the supervisor at once✓
• b.Raise the low-rate alarm limit so the monitor stops alarming
• c.Wait to see whether the pause repeats before telling anyone
• d.Chart the pause as artifact from the patient turning over in bed

A pause with no atrial and no ventricular activity is a sinus arrest, and under typical monitoring policy a pause beyond about three seconds is printed, documented, and reported to the nurse or supervisor without waiting, even in a patient who currently feels well. Waiting for a second event trades away the time a longer pause would cost. Raising the alarm limit suppresses the very event the monitor exists to catch. Calling it artifact does not fit, because motion artifact leaves a noisy baseline rather than a clean flat line that ends with the sinus rhythm resuming.

A sinus rhythm at 75 beats per minute is interrupted by one missing P-QRS pair, and the pause measures exactly twice the underlying P-P interval before the sinus rhythm resumes on schedule. What does this pattern suggest?

• a.A sinoatrial exit block dropped one P-QRS cycle✓
• b.Sinus arrest, with the sinus node failing to fire
• c.An atrial beat that arrived early and did not conduct
• d.A dropped beat from a second-degree AV block

In sinoatrial exit block the sinus node keeps firing on time but one impulse fails to leave the node, so the pause equals an exact multiple of the underlying P-P interval and the next P wave lands right where the caliper predicts. In sinus arrest the node itself stops, and the pause has no arithmetic relationship to the P-P interval, so the rhythm usually resumes off schedule. A nonconducted early atrial beat would show a premature P wave, often hidden in the preceding T wave, before the pause. A dropped beat from AV block would leave a P wave standing alone with no QRS after it, whereas here the P wave is missing along with the QRS.

A tracing was recorded at a paper speed of 50 mm/sec. On a regular rhythm the R waves are five large boxes apart. What is the patient's actual heart rate?

• a.60 beats per minute, read the way a 25 mm/sec strip is read
• b.About 30 beats per minute, because the paper ran twice as fast
• c.150 beats per minute, using the sequence method on this strip
• d.120 beats per minute, because each large box here is 0.10 second✓

Doubling the paper speed halves the time each box represents, so at 50 mm/sec a small box is 0.02 second and a large box is 0.10 second. Five large boxes is therefore 0.50 second, and 60 divided by 0.50 gives 120 beats per minute. Reading the strip as though it ran at 25 mm/sec yields 60 and halves the true rate, which is the error this speed most often causes. Halving again to 30 compounds that mistake, and the memorized sequence values apply only at 25 mm/sec.

A patient with a resting hand tremor produces a strip whose limb leads carry a fine, jagged, irregular baseline. The chest leads are clean, the R-R intervals are regular, and an upright P wave precedes every QRS. What is the most likely explanation?

• a.Atrial fibrillation with a fine fibrillatory baseline
• b.Atrial flutter at a rate the monitor cannot count
• c.Muscle tremor artifact from the patient's hand✓
• d.Interference from nearby electrical equipment

Somatic tremor artifact produces an irregular, spiky baseline that appears in the leads sharing the trembling limb and spares leads that do not, and the underlying rhythm shows through it unchanged. Regular R-R intervals with an upright P wave before each QRS rule out atrial fibrillation, which is irregularly irregular and has no P waves. Flutter waves are uniform sawtooth deflections at a regular atrial rate near 300 per minute, not the ragged tracing described. Alternating-current interference would be uniform and perfectly regular and would appear in every lead rather than in the limb leads alone.

A technician wants to know whether the P waves continue on schedule through a pause on a strip. How are calipers used to check that?

• a.Set the points on a P wave and the QRS that follows it, then step across
• b.Set the points on two consecutive P waves, then step that width across the pause✓
• c.Set the points on the tallest R waves and compare that width to the pause
• d.Set the points on the width of one P wave and count how many fit

Marching out the atrial rhythm means fixing the calipers on the P-P interval of two conducted beats and then stepping that same distance forward, which shows whether the next P wave arrives where the sinus node would have placed it. Setting the points on a P wave and the QRS after it measures the PR interval, a conduction time that says nothing about atrial timing. Using R waves marches out the ventricular rhythm, which is a separate measurement and can stay regular while the atrial rhythm does not. The width of a single P wave is its duration, not a cycle length, so counting how many fit in a pause measures nothing useful.

During tracheal suctioning a monitored patient's rate falls from 74 to 46 beats per minute. Upright P waves still precede every narrow QRS with a PR interval of 0.16 second, and the rate returns to 74 once suctioning stops. What best explains the slowing?

• a.A junctional escape rhythm took over during suctioning
• b.Vagal stimulation slowed the rate of the sinus node✓
• c.The sinus node stopped and an atrial focus took over
• d.A second-degree block dropped every other beat

Suctioning, vomiting, gagging, and bearing down all stimulate the vagus nerve, which slows the sinus node and produces a transient sinus bradycardia that resolves when the stimulus ends. The P waves stayed upright with a normal PR interval, so the sinus node is still the pacemaker, which rules out a junctional escape rhythm and an ectopic atrial focus; both would change the shape of the P wave or its timing relative to the QRS. A second-degree block dropping alternate beats would leave P waves standing alone with no QRS after them, and none are described. The technician documents the episode and the intervention that provoked it.

A strip's R-R intervals range from 0.68 second to 1.12 second. A technician measures one pair of R waves, counts four large boxes, and charts a rate of 75 beats per minute. Why is that number unreliable?

• a.The 300 method may be used only when the first R wave falls on a heavy line
• b.The 300 method assumes all R-R intervals match the pair measured, which they do not✓
• c.The 300 method works only on strips that run longer than six seconds
• d.The 300 method cannot be used when the QRS complexes are narrow

Dividing 300 by the large boxes between two R waves converts one cycle length into a rate, which describes the whole strip only if every cycle is the same length. Here the intervals run from 0.68 to 1.12 second, so the measured pair yields 75 while other pairs would yield about 88 and about 54. On an irregular rhythm the technician counts the complexes in a six-second strip and multiplies by ten, which averages the variation. Starting on a heavy line is a convenience of the sequence method rather than a requirement of the 300 method, and neither strip length nor QRS width restricts it.

Why is a measured QT interval corrected for heart rate before it is compared with a normal limit?

• a.Because the QT interval lengthens as the heart rate rises
• b.Because paper speed changes the measured QT at fast rates
• c.Because T wave height varies with electrode position
• d.Because the QT interval shortens as the rate rises✓

Repolarization takes less time when the heart beats faster, so the raw QT shortens as the rate rises and lengthens as it falls, and a single normal range cannot fit both. Correction, most often by dividing the QT by the square root of the R-R interval in seconds, restates the value as the QT that rate would produce at 60 beats per minute, where the upper limits are about 0.44 second for men and about 0.46 second for women. The relationship runs the opposite way from the answer that has the QT lengthening with rate. Paper speed changes how wide the interval looks but not how many seconds it lasts, and T wave amplitude is not part of the measurement.

A febrile adult on telemetry has a regular narrow-complex rhythm at 148 beats per minute. A small upright deflection distorts the front of each T wave, and the rate has climbed gradually from 110 over the past hour. What is the most likely rhythm?

• a.Paroxysmal supraventricular tachycardia, a reentrant rhythm
• b.Atrial flutter with two-to-one AV conduction
• c.An accelerated rhythm from the AV junction
• d.Sinus tachycardia arising in the sinoatrial node✓

A rate that climbs gradually over an hour, with one upright atrial wave for every QRS partly buried in the preceding T wave, is sinus tachycardia; the sinus node speeds up and slows down over minutes rather than switching on and off. Paroxysmal supraventricular tachycardia starts and stops abruptly and usually parks at a fixed rate without visible atrial waves. Atrial flutter is the serious alternative here, but 2:1 conduction from an atrial rate near 300 holds the ventricular rate close to 150 whatever the patient's temperature, and it produces sawtooth waves best seen in leads II, III, and aVF, including a second atrial wave near the QRS. An accelerated junctional rhythm would run slower than this and would show an inverted P wave close to the QRS or none at all.

On a tracing recorded at 25 mm/sec, what is the normal upper limit for the width of the P wave, and in which lead is it usually assessed?

• a.0.12 second, or three small boxes, measured in lead II✓
• b.0.20 second, or one large box, measured in lead aVR
• c.0.08 second, or two small boxes, seen best in lead V6
• d.0.04 second, one small box, in any of the limb leads

A normal P wave is no wider than about 0.12 second, which is three small boxes at 25 mm/sec, and lead II is the conventional lead for judging it because the sinus P wave is upright and best formed there. The 0.20-second answer is the upper limit of the PR interval, not of the P wave itself, and aVR is the lead where a sinus P wave is inverted. Two small boxes would be 0.08 second, which is a common P wave duration but not the upper limit. One small box is 0.04 second, far narrower than a normal P wave.

A monitor strip shows regular sinus beats interrupted by one unexpected pause. The T wave immediately before the pause is taller and more pointed than every other T wave on the strip, and the sinus P waves resume on schedule after the pause. What most likely produced the pause?

• a.A second-degree AV block, type II, that dropped one conducted beat
• b.A sinus arrest in which the sinus node failed to fire
• c.An early atrial beat buried in the T wave that did not conduct✓
• d.A junctional escape beat that appeared before the next sinus beat

A deformed T wave just before an unexplained pause is the classic footprint of a nonconducted premature atrial contraction: the early P wave lands on the T wave and finds the AV node still refractory, so no QRS follows. Because the early P wave also resets the sinus node, the following P waves march out from the new timing, which fits the strip described. Second-degree type II block is ruled out by the extra deflection on the T wave, since in that block the P waves stay perfectly on time and no premature P wave appears. Sinus arrest would leave the baseline flat with no P wave at all during the pause, and an escape beat would fill the pause rather than create one.

A strip shows a regular narrow-complex rhythm at 190 beats per minute. Small P waves are visible in front of each QRS, but they are pointed and shaped differently from the same patient's sinus P waves recorded an hour earlier. Which rhythm best fits this tracing?

• a.Sinus tachycardia driven by fever, pain, or exertion
• b.Junctional tachycardia arising in the AV node
• c.Atrial flutter conducting two waves per QRS
• d.Atrial tachycardia from an ectopic atrial focus✓

P waves that are present but shaped unlike the patient's own sinus P waves point to an atrial focus outside the sinus node, and atrial tachycardia typically runs about 150 to 250 beats per minute, which brackets this rate. Sinus tachycardia would carry P waves identical in shape to the earlier baseline tracing. A junctional focus depolarizes the atria backward, so its P waves would be inverted in lead II or absent, not merely differently shaped. Atrial flutter conducting two atrial waves for each QRS would give a ventricular rate near 150, with sawtooth waves rather than discrete P waves.

A patient with severe emphysema has an irregular narrow-complex rhythm at 130 beats per minute. A P wave precedes every QRS, but at least three clearly different P wave shapes appear on the strip and the PR intervals vary along with them. What is this rhythm?

• a.Multifocal atrial tachycardia✓
• b.Coarse atrial fibrillation
• c.Wandering atrial pacemaker
• d.Atrial flutter with variable block

Three or more distinct P wave morphologies with varying PR intervals and a rate above 100 beats per minute define multifocal atrial tachycardia, which is strongly associated with chronic lung disease such as emphysema. Atrial fibrillation is excluded because organized P waves precede each QRS; coarse fibrillatory waves are not true P waves and do not carry measurable PR intervals. Wandering atrial pacemaker has the same shifting P wave pattern but by definition runs at 100 beats per minute or slower, so the rate of 130 rules it out. Atrial flutter would show identical sawtooth waves at roughly 250 to 350 per minute rather than several different P wave shapes.

A strip shows a slightly irregular rhythm at 78 beats per minute in which the P waves change shape from beat to beat, showing at least three different forms, and the PR intervals vary with them. What is this rhythm?

• a.Multifocal atrial tachycardia
• b.Wandering atrial pacemaker✓
• c.Atrial fibrillation, fine type
• d.Sinus arrhythmia with ectopy

Shifting P wave shapes with varying PR intervals at a rate of 100 beats per minute or slower is wandering atrial pacemaker, in which the dominant pacemaker site drifts among the sinus node, other atrial sites, and the AV junction. The rate is the only feature separating it from multifocal atrial tachycardia, which shows the identical pattern faster than 100 beats per minute; at 78 the slower label applies. Fine atrial fibrillation would have no organized P waves at all and no measurable PR interval. Sinus arrhythmia varies in rate with respiration but keeps one consistent P wave shape and a constant PR interval.

A regular narrow-complex rhythm at 150 beats per minute could be sinus tachycardia or atrial flutter conducting two atrial waves for each QRS. Which finding on the strip best separates the two?

• a.A ventricular rate that stays perfectly regular
• b.Narrow QRS complexes across the whole strip
• c.An upright deflection right before every QRS complex
• d.A second atrial wave hidden in each T wave✓

At an atrial rate near 300 per minute with two-to-one conduction, one flutter wave falls on the T wave of the preceding beat, so finding that extra buried deflection is the finding that identifies flutter; lead II and V1 usually show it best. A perfectly regular ventricular rate does not help, because sinus tachycardia and flutter with a fixed conduction ratio are both regular. Narrow QRS complexes only establish that the rhythm is supraventricular, which is true of both. An upright deflection before each QRS is the weakest discriminator of all, since a flutter wave arriving just ahead of the QRS is routinely mistaken for a sinus P wave.

In typical atrial flutter, what is the usual range of the atrial rate?

• a.Roughly 100 to 150 beats per minute
• b.Roughly 175 to 240 beats per minute
• c.About 250 to 350 beats per minute✓
• d.More than 400 beats per minute at rest

Typical atrial flutter arises from a reentry circuit in the right atrium that turns at about 250 to 350 atrial cycles per minute, most often near 300, producing the sawtooth flutter waves. The ventricular rate is much slower because the AV node blocks most of those impulses, which is why a flutter patient may show a pulse of 150, 100, or 75. A rate of 100 to 150 describes the ventricular response in flutter rather than the atrial rate itself, and 175 to 240 is closer to the range quoted for atrial tachycardia. Rates faster than 400 belong to atrial fibrillation, whose fibrillatory waves are chaotic and never form an organized sawtooth.

A strip shows uniform sawtooth atrial waves marching out regularly at about 300 per minute, but the R-R intervals are irregular and the ventricular rate wanders between 75 and 150 beats per minute. How should this rhythm be identified?

• a.Atrial fibrillation with a rapid ventricular response
• b.Atrial flutter conducting at a changing ratio at the AV node✓
• c.Multifocal atrial tachycardia with changing P wave shapes
• d.Sinus rhythm with frequent nonconducted atrial ectopy

Regular, identical sawtooth waves at about 300 per minute establish atrial flutter; when the AV node lets through a different number of those waves from beat to beat, the ventricular response becomes irregular, which is called flutter with variable conduction. Atrial fibrillation is the common misread here because the R-R intervals are irregular, but fibrillation has a chaotic baseline with no two atrial waves alike, whereas these waves are uniform and regular. Multifocal atrial tachycardia requires three or more different P wave shapes, not one repeating sawtooth. Frequent nonconducted atrial ectopy would show premature P waves of varying shape interrupting an otherwise sinus rhythm, not a continuous sawtooth baseline.

On a routine telemetry round a technician sees that a comfortable, stable patient whose rhythm was sinus earlier in the shift now has an irregularly irregular narrow-complex rhythm at 96 beats per minute with no identifiable P waves. What should the technician do?

• a.Tell the patient he has developed atrial fibrillation
• b.Notify the supervisor and save the strip✓
• c.Wait until the end of the shift to log the change
• d.Take the electrodes off and reapply them in an hour

A new irregularly irregular rhythm without P waves is a change in the patient's condition, and the technician's role is to recognize it, preserve the documentation, and pass it up promptly so a licensed clinician can evaluate it. Waiting until the end of the shift delays care for a rhythm change that may need same-day treatment, even though the rate is controlled and the patient feels well. Telling the patient his rhythm is atrial fibrillation is interpreting for the patient, which is outside the technician's scope. Removing and reapplying the electrodes discards the tracing that documents the change, and the finding here is a genuine rhythm, not an artifact pattern.

A patient watching the bedside monitor asks the technician what his irregular rhythm means and whether it is dangerous. What is the technician's most appropriate response?

• a.Explain that the rhythm is atrial fibrillation but is not serious
• b.Point out the missing P waves on the screen for the patient
• c.Say the tracing looks normal so the patient will not worry
• d.Refer the question to the nurse or the supervisor✓

A certified EKG technician acquires and monitors tracings and reports findings to licensed staff, but does not diagnose or interpret a rhythm for the patient, so the question belongs to the nurse or provider caring for him. Naming the rhythm as atrial fibrillation and calling it not serious is both a diagnosis and a prognosis, two things outside the technician's scope. Walking the patient through the missing P waves is interpretation in everything but name. Telling him the tracing looks normal is false reassurance and puts a false statement into the encounter.

A telemetry patient's rhythm changes to atrial fibrillation at 168 beats per minute, and the patient becomes pale and sweaty and says his chest feels tight. What should the technician do first?

• a.Report the rhythm change to the supervisor at the end of the round
• b.Print the strip and file it in the patient's chart
• c.Reposition the chest electrodes to confirm the rhythm
• d.Bring the nurse to the bedside now and stay with the patient✓

A rapid ventricular response with pallor, sweating, and chest tightness is a symptomatic rhythm change, and the technician's first duty is to get licensed help to the bedside immediately and keep the patient under observation. Finishing the round and reporting later is the wrong pace for a patient who is symptomatic right now, even though routine rhythm changes are handled that way. Printing and filing the strip is necessary documentation but does not bring anyone to the patient. Repositioning electrodes to confirm the rhythm wastes time and would be reasonable only if the tracing suggested artifact, which pallor, sweating, and chest tightness do not.

An early narrow beat with an abnormally shaped P wave is followed by a pause. The technician measures from the sinus beat before the early beat to the sinus beat after it and finds that distance is shorter than two normal R-R intervals. What does that measurement indicate?

• a.The early beat reset the sinus node, so the pause is noncompensatory✓
• b.The early beat started in the ventricles and gave a full compensatory pause
• c.The sinus node failed to fire for one full cycle, producing a sinus arrest
• d.The AV node blocked one sinus impulse, so a whole beat was dropped

A premature atrial contraction usually depolarizes the sinus node early and restarts its timing cycle, so the sinus beat after the ectopic arrives sooner than expected and the pause is called noncompensatory. Measured across the early beat, that shortfall is exactly what a distance of less than two normal R-R intervals shows. A premature ventricular contraction typically leaves the sinus node undisturbed, so its pause is fully compensatory and the same measurement equals two R-R intervals; the narrow QRS and the visible early P wave also place this beat above the ventricles. Sinus arrest and a dropped conducted beat both leave a pause without any premature beat in front of it, and here an early beat clearly precedes the pause.

In an otherwise sinus rhythm the monitor shows a pause of about 1.6 seconds, which is ended by a single narrow beat carrying an inverted P wave immediately after its QRS. How should the technician label this beat?

• a.A junctional escape beat✓
• b.A premature junctional contraction
• c.A nonconducted atrial beat
• d.A ventricular escape beat

A beat that ends a pause has arrived late, and timing is what separates an escape beat from a premature one: the escape beat appears only after the higher pacemaker has failed to deliver on time, making it a protective backup rather than an irritable focus. The inverted P wave following a narrow QRS places the origin in the AV junction, so this late beat is a junctional escape beat. A premature junctional contraction looks similar in shape but comes early, interrupting the underlying rhythm instead of rescuing it. A ventricular escape beat would be wide and bizarre because it bypasses the normal conduction pathway, and a nonconducted atrial beat produces no QRS at all.

A technician reads a report describing a patient's rhythm as supraventricular. What does that term indicate about the origin of the impulse?

• a.It started in the Purkinje fibers of the ventricular walls
• b.It started above the ventricles, in the atria or junction✓
• c.It started above the AV node, in the atria or sinus node
• d.It started in the left bundle branch and spread down

Supraventricular means the impulse formed anywhere above the ventricles, which includes the sinus node, any atrial focus, and the AV junction itself. Because such an impulse still reaches the ventricles through the normal His-Purkinje pathway, it depolarizes them quickly and produces a narrow QRS of less than 0.12 second, which is why a narrow QRS points above the ventricles. Restricting the term to sites above the AV node is the common error, since junctional rhythms are supraventricular too, which is why junctional tachycardia belongs to the supraventricular family. The Purkinje fibers and the bundle branches lie inside the ventricular conduction system, so a beat starting there spreads partly through muscle and widens the QRS.

A monitor shows a regular wide-complex tachycardia at 165 beats per minute in a patient who has a pulse. The rhythm could be ventricular tachycardia or a supraventricular tachycardia conducted with aberrancy. What is the safest working assumption while licensed staff evaluate the patient?

• a.Assume aberrant conduction because the rate is under 180
• b.Assume the rhythm is benign while a pulse is present
• c.Regard the rhythm as ventricular tachycardia✓
• d.Assume atrial flutter conducting one wave per QRS

The standard teaching for any wide-complex tachycardia of uncertain origin is to regard it as ventricular tachycardia until a qualified clinician proves otherwise, because that assumption is the one that fails safely. Rate does not distinguish the two, since ventricular tachycardia and supraventricular tachycardia with aberrancy overlap heavily in the range around 165. The presence of a pulse says only that the rhythm is perfusing at this moment; ventricular tachycardia commonly has a pulse before it deteriorates. Assuming flutter conducting one atrial wave per QRS is a guess the technician cannot support and would set the urgency far too low.

A junctional rhythm is labeled junctional tachycardia rather than accelerated junctional rhythm once the rate exceeds what value?

• a.Faster than 60 beats per minute
• b.Faster than 100 beats per minute✓
• c.Faster than 140 beats per minute in adults
• d.Faster than 120 beats per minute at rest

Junctional rhythms are named by how far the junctional focus has been driven above its inherent 40 to 60 beats per minute: 60 to 100 is an accelerated junctional rhythm, and above 100 the rhythm is called junctional tachycardia. Passing 60 marks the boundary between junctional escape rhythm and accelerated junctional rhythm, not the tachycardia threshold. The figures of 120 and 140 are simply higher rates within junctional tachycardia and do not mark any naming boundary. The morphology stays the same across all three labels, with a narrow QRS and an inverted or absent P wave, so the rate is what determines the name.

A strip shows a regular narrow-complex rhythm at 82 beats per minute. Lead II shows no upright P waves; instead a small inverted deflection sits just ahead of each QRS with a PR interval of 0.08 second. How should this rhythm be identified?

• a.Sinus rhythm, since a P wave precedes each QRS
• b.Junctional escape rhythm, the junction's inherent rate
• c.Accelerated junctional rhythm from the AV junction✓
• d.Junctional tachycardia from an irritable focus

An inverted P wave in lead II with a PR interval shorter than 0.12 second marks a junctional origin, and a sustained junctional rhythm at 82 beats per minute sits in the 60 to 100 window that defines an accelerated junctional rhythm. A junctional escape rhythm would run at the junction's inherent 40 to 60 beats per minute, so 82 is too fast for that label. Junctional tachycardia requires a rate above 100, so 82 is too slow for it. Sinus rhythm is excluded because a sinus impulse depolarizes the atria downward and produces an upright P wave in lead II with a PR interval of at least 0.12 second.

In a beat that originates in the AV junction, why does the P wave appear inverted in lead II?

• a.The sinus impulse travels to the atria through an accessory pathway
• b.The atria depolarize backward, away from the positive electrode✓
• c.The ventricles depolarize before the atria have finished
• d.The left leg electrode has been reversed with the right arm

Lead II looks from the right arm toward the left leg, so its positive electrode sits low on the left; a sinus impulse traveling downward toward that electrode writes an upright P wave. A junctional impulse instead spreads retrograde, upward from the junction into the atria and away from the positive electrode of lead II, which inverts the P wave. Whether that inverted P wave lands before the QRS, inside it, or after it depends only on how fast the impulse reaches the atria relative to the ventricles, not on the direction. Timing is also why saying the ventricles fire before the atria explains a P wave that follows the QRS but not the inversion itself, and a limb lead reversal would distort several leads at once rather than produce this consistent junctional pattern.

While recording a routine 12-lead, a technician notices several early beats whose P waves are shaped differently from the sinus P waves and which are followed by narrow QRS complexes. The patient is comfortable and has no complaints. What should the technician do?

• a.Stop the recording and notify the supervisor before continuing
• b.Finish the 12-lead and note the early beats on it✓
• c.Repeat the tracing until a strip with no early beats prints
• d.Delete the tracing and record it after the beats settle down

Early beats with an abnormal P wave and a narrow QRS are premature atrial contractions, which are common, are frequently seen in healthy people, and are not an emergency in a comfortable patient; the technician completes the tracing and notes the ectopy so the interpreting clinician sees it. Stopping a routine tracing on a stable patient to escalate delays the study without changing anything about the patient's care. Repeating the tracing until no early beats appear discards real diagnostic information, which is the opposite of what the recording is for. Deleting the tracing destroys documentation of a finding the provider should see.

Two strips both show atrial fibrillation. On the first, the baseline between QRS complexes carries tall, easily seen fibrillatory waves; on the second the baseline is nearly flat with only a slight ragged quiver. How are these two tracings described?

• a.The first is atrial flutter and the second is fibrillation
• b.The first has a faster ventricular rate than the second
• c.The first is coarse and the second is fine atrial fibrillation✓
• d.The first is untreated and the second has been converted

Fibrillatory waves are described by their amplitude: prominent, easily visible waves are called coarse atrial fibrillation, and a nearly flat, barely undulating baseline is called fine atrial fibrillation. Both remain atrial fibrillation, and both show the same defining features of absent P waves and irregularly irregular R-R intervals. Wave amplitude does not set the ventricular rate, which depends on how many impulses the AV node conducts, so either pattern can appear with a fast or a controlled rate. Neither pattern is flutter, whose waves are uniform and organized into a sawtooth, and a converted patient would be back in an organized rhythm with real P waves rather than a quivering baseline.

Atrial fibrillation is described as having a rapid ventricular response when the ventricular rate rises above what value?

• a.Above 100 beats per minute✓
• b.Above 120 beats per minute in adults
• c.Above 150 beats per minute at rest
• d.Above 80 beats per minute when awake

The ventricular rate in atrial fibrillation is judged against the ordinary adult range, so a rate over 100 beats per minute is a rapid ventricular response and a rate under 100 is described as controlled. The threshold has nothing to do with symptoms, which is why a patient at 110 with no complaints is still charted as having a rapid ventricular response. The figures of 120 and 150 are faster rates that certainly qualify but are not the boundary, and using them would mislabel a patient at 110 as controlled. A rate above 80 is within the normal adult range and would not be called rapid in any patient.

Why is atrial fibrillation associated with an increased risk of stroke?

• a.The fast ventricular rate injures the lining of the coronary arteries
• b.The atria quiver rather than contract, so blood pools and clots✓
• c.The irregular rhythm raises blood pressure inside the skull
• d.Clots form in the ventricles because they fill irregularly

In atrial fibrillation the atrial muscle quivers instead of contracting as a unit, so the atria do not empty completely; blood stagnates, particularly in the left atrial appendage, and can form a clot that later travels to the brain. That loss of coordinated atrial contraction is also why cardiac output falls even when the ventricular rate is controlled. The stagnation is atrial rather than ventricular, since the ventricles still contract fully with every beat and eject their contents even though the intervals between beats are uneven. Coronary artery injury describes atherosclerotic disease rather than anything fibrillation does to a vessel wall, and pressure inside the skull has no relationship to the atrial rhythm.

An early beat on a sinus strip has a wide, unusual QRS. Close inspection shows a premature P wave distorting the T wave of the preceding beat, and the pause after the early beat is not fully compensatory. How is this beat best classified?

• a.A premature ventricular contraction with a retrograde P wave
• b.A ventricular escape beat arriving after a dropped sinus beat
• c.A premature atrial beat conducted aberrantly down a bundle branch✓
• d.A fusion beat formed by two impulses meeting in the ventricle

The premature P wave riding on the preceding T wave shows the impulse began in the atria, and the noncompensatory pause confirms that the ectopic reset the sinus node, both of which mark an atrial origin. The QRS is wide only because the early impulse reached a bundle branch that had not yet recovered, so it conducted with aberrancy; a supraventricular beat with aberrancy is the classic imitator of a ventricular beat. A premature ventricular contraction would have no P wave in front of it and would usually leave a full compensatory pause. An escape beat comes late rather than early, and a fusion beat requires a ventricular impulse and a supraventricular impulse to reach the ventricles at the same moment, producing a hybrid shape rather than the sequence described.

Telemetry captures a regular narrow-complex tachycardia at 130 beats per minute that speeds up gradually over several beats, with inverted P waves following each QRS. Which rhythm best fits this tracing?

• a.Junctional tachycardia from a fast junctional focus✓
• b.Paroxysmal supraventricular tachycardia with a sudden onset
• c.Atrial tachycardia from an ectopic focus high in the atrium
• d.Accelerated junctional rhythm that has sped up a little

Inverted P waves after each QRS place the pacemaker in the AV junction, and a junctional rate above 100 beats per minute is junctional tachycardia; its onset is characteristically gradual, warming up over several beats. Paroxysmal supraventricular tachycardia is the close call here because it is also narrow and regular, but it begins and ends abruptly, often from one beat to the next, and its rate usually runs higher than 130. An accelerated junctional rhythm has the same P wave pattern and the same gradual onset but is defined as 60 to 100 beats per minute, so 130 is above its ceiling. Atrial tachycardia would show upright ectopic P waves ahead of the QRS rather than inverted ones behind it.

A telemetry monitor records a narrow-complex tachycardia at 200 beats per minute that starts abruptly, runs for 40 seconds, and stops on its own. The patient felt a flutter in his chest and is now comfortable. What should the technician do with the tracing?

• a.Print the strip and record the times the fast rhythm began and ended✓
• b.Discard the strip, since the rhythm corrected itself and the patient is well
• c.Silence the alarm and reset the monitor so the same episode is not recounted
• d.Wait for a second episode before printing anything from the monitor

A self-terminating run of a paroxysmal supraventricular tachycardia is exactly the evidence a provider needs, and it exists only if the technician preserves it; the printed strip plus the onset and termination times documents how fast the rhythm ran and how long it lasted. The abrupt start and stop are themselves diagnostic features worth capturing on paper. Discarding the strip because the patient feels well erases the only record of the episode, and the fact that a rhythm self-terminated does not make it unimportant. Silencing the alarm and resetting the monitor addresses the noise rather than the finding, and waiting for a second episode gambles that another one will occur while the patient is still monitored.

A strip shows uniform sawtooth atrial waves at 300 per minute with one QRS complex after every third sawtooth wave. What is the ventricular rate, and how is the conduction described?

• a.About 75 beats per minute, four-to-one conduction
• b.About 150 beats per minute, two-to-one block
• c.About 300 beats per minute, one-to-one block
• d.About 100 beats per minute, three-to-one conduction✓

Dividing the atrial rate by the conduction ratio gives the ventricular rate, so 300 divided by 3 is 100 beats per minute, described as atrial flutter with three-to-one conduction. Two-to-one conduction from the same atrial rate would yield 300 divided by 2, or 150, and four-to-one would yield 300 divided by 4, or 75; both are common flutter presentations but neither matches a QRS after every third wave. One-to-one conduction would drive the ventricles at 300, which the AV node rarely permits and which would be a medical emergency. Counting the sawtooth waves between QRS complexes is the reliable way to establish the ratio.

A six-second strip recorded in one lead contains five premature wide beats, and those beats have two clearly different shapes. What does the difference in shape indicate?

• a.The premature beats are unifocal and come from a single site
• b.The premature beats are fusion beats formed in the AV junction
• c.The premature beats are multifocal and come from separate sites✓
• d.The premature beats are supraventricular beats conducted aberrantly

Premature ventricular complexes that arise from different ventricular sites depolarize the ventricles along different paths, so their QRS shapes differ within the same lead; identical shapes in one lead describe unifocal ectopy. Multifocal ectopy is reported promptly because it points to more widespread ventricular irritability. A fusion beat is a single hybrid complex created when a supraventricular impulse and a ventricular impulse activate the ventricles at the same time, not a set of beats with two repeating shapes. Supraventricular beats conducted aberrantly are preceded by a premature P wave, which these beats lack.

An otherwise sinus strip contains two wide, bizarre complexes occurring back to back, arriving earlier than the next expected sinus beat, and neither one is preceded by a P wave. What is this pattern called?

• a.A ventricular triplet, also described as a short salvo
• b.A short run of nonsustained ventricular tachycardia
• c.A pair of ventricular escape beats from the Purkinje fibers
• d.A ventricular couplet, which may be uniform or multiform✓

Two premature ventricular complexes in a row are a couplet; three in a row are a triplet or salvo, and three or more consecutive ventricular beats at a rate above 100 beats per minute are commonly reported as a run of ventricular tachycardia. Counting the consecutive ectopic beats is what separates these terms. Escape beats are late rather than early: they appear after a pause when the higher pacemakers fail, while these complexes interrupt the underlying rhythm ahead of the next expected beat. The two complexes may look alike or differ in shape, and either way the technician documents the pattern and its frequency and leaves the significance to the provider.

A patient with a permanent pacemaker is on telemetry. Sharp pacing spikes appear at a regular rate of 60, but many of the spikes are followed by no QRS complex at all, and the patient's own rate is 42 beats per minute. What is this malfunction called, and what should the technician do?

• a.Failure to capture; notify the supervisor and save the strip✓
• b.Undersensing of intrinsic beats; notify the supervisor and save the strip
• c.Pacemaker oversensing; notify the supervisor and save the strip
• d.Loss of pacer output; notify the supervisor and save the strip

A pacing spike that produces no complex is failure to capture: the generator delivers its impulse on schedule, but the impulse does not depolarize the myocardium, so the patient is left with an underlying rate of 42 beats per minute. Undersensing is the opposite fault, in which the generator does not recognize the patient's own beats and fires into them, sometimes onto a T wave. Oversensing is the generator mistaking other signals, such as muscle activity, for intrinsic beats and withholding pacing that it should have delivered. Loss of output means no spikes reach the tracing at all, while here the spikes are present and regular. Naming the malfunction does not change what the technician does, since reporting it promptly and keeping the tracing is the response to any of them; adjusting the device belongs to the provider or the device clinic.

During continuous monitoring, a strip shows a nine-beat run of regular wide complexes at 180 beats per minute that stops on its own. The patient is awake and reports that she felt lightheaded during the run. What should the technician do?

• a.Report the run to the supervisor immediately and save the labeled strip✓
• b.Wait for a second run before mentioning the episode to the care team
• c.Delete the section as artifact, since the rhythm corrected by itself
• d.Chart the run at the end of the shift because it needed no treatment

A run of wide complexes at 180 beats per minute that ends on its own is nonsustained ventricular tachycardia, and symptoms during the run make it a finding the care team needs while the strip is still available. The technician's job is to recognize, report, and preserve the tracing, not to decide whether the run matters. Waiting for a recurrence or charting at the end of the shift delays information that may change monitoring or treatment within minutes. The run is not artifact: artifact does not produce uniform complexes at a steady rate, and the patient's symptoms fit the tracing.

Two strips both show chaotic, irregular waveforms with no identifiable QRS complexes. On the first the deflections are tall and coarse; on the second they are low and fine. What does the difference between the two tracings most likely reflect?

• a.The fine tracing indicates a slower ventricular rate than the coarse one
• b.The coarse tracing is muscle artifact and the fine tracing is true arrest
• c.The fine tracing means an electrode has loosened and weakened the signal
• d.Fibrillation has usually been present longer when the waves are fine✓

Coarse ventricular fibrillation, with taller deflections, is typically seen soon after onset, while the waveform becomes fine as the myocardium is deprived of oxygen and its energy stores fall, so fine fibrillation usually means more time has passed. Both are pulseless, both are handled as cardiac arrest, and the technician's response does not change with the amplitude. Rate cannot be measured in fibrillation because there are no organized complexes to measure between. A loose electrode produces a wandering or flat baseline rather than continuous chaotic deflections, and muscle artifact leaves recognizable QRS complexes marching through it.

A patient who is unresponsive and has no palpable pulse shows occasional wide, misshapen complexes at about 8 beats per minute on the monitor, with no P waves. How is this tracing best described?

• a.Fine ventricular fibrillation with a few conducted wide beats
• b.An agonal rhythm that slows progressively toward asystole✓
• c.An accelerated idioventricular rhythm near its lowest rate
• d.A complete heart block with a ventricular escape focus

An agonal rhythm shows a few widely spaced, wide and irregular complexes, usually well under 20 beats per minute, with no pulse; it is handled as cardiac arrest rather than as a perfusing rhythm, and it commonly deteriorates into asystole. Ventricular fibrillation has no discrete complexes at all, only a chaotic baseline, so recognizable complexes rule it out. An accelerated idioventricular rhythm runs between 40 and 100 beats per minute, far faster than this tracing. Complete heart block requires visible P waves marching at their own rate, and none are present here.

A monitor displays an organized rhythm at 70 beats per minute with narrow QRS complexes and upright P waves, but the patient is unresponsive and no pulse can be felt. How is this situation described?

• a.Ventricular tachycardia hidden by the monitor's filter setting
• b.Sinus rhythm with a broken cable between patient and monitor
• c.Artifact created by the chest compressions that are being delivered
• d.Pulseless electrical activity, which is managed as cardiac arrest✓

Pulseless electrical activity is organized electrical activity on the monitor without a mechanical pulse; the tracing shows depolarization, not the ejection of blood, which is why the patient rather than the monitor decides what is happening. The finding is treated as cardiac arrest, and the technician calls for help immediately and stays with the patient. A cable fault or filter problem would distort or lose the tracing, not produce clean narrow complexes with P waves in an unresponsive patient. Compression artifact appears as broad regular waves at the compression rate superimposed on the baseline, and compressions have not been started here.

A strip shows a regular rhythm at 65 beats per minute with wide QRS complexes, no P waves, and T waves pointing opposite to the QRS complexes. What is this rhythm?

• a.An accelerated idioventricular rhythm✓
• b.Slow monomorphic ventricular tachycardia
• c.An idioventricular escape rhythm
• d.A junctional rhythm with bundle branch block

A ventricular focus firing faster than its inherent 20 to 40 beats per minute but slower than 100 produces an accelerated idioventricular rhythm, and 65 beats per minute falls squarely in that 40 to 100 range. Ventricular tachycardia is used for ventricular rhythms above 100 beats per minute, so the rate here excludes it. An idioventricular escape rhythm runs at that inherent 20 to 40 beats per minute, well below this rate. A junctional rhythm carrying a bundle branch block is the closest competing answer, since it also produces wide complexes, but the junctional inherent rate is 40 to 60 beats per minute and inverted P waves are often visible just before or just after the QRS complexes.

A telemetry monitor alarms for asystole. The first displayed lead shows a flat line, the second displayed lead shows a normal rhythm at 76 beats per minute, and the patient is sitting up talking with a visitor. What should the technician do first?

• a.Silence the alarm and note that the asystole limit is set too high
• b.Check the electrode and lead wire for the flat lead and replace them✓
• c.Report the asystole to the supervisor before touching any of the leads
• d.Print a strip from the flat lead and place it in the patient's record

A flat line in one lead while another lead shows an organized rhythm in a patient who is awake and talking is a lead problem: a dried, loose, or disconnected electrode, or a broken lead wire. True asystole is confirmed in two or more leads in a patient who is unresponsive and pulseless, and neither condition is met here. Escalating a rhythm the patient plainly is not in wastes time when the fix is at the electrode, and silencing the alarm without repairing the lead leaves the monitor unable to detect a real event. Filing a tracing of an artifact documents the wrong thing.

Within each group of conducted beats in a second-degree AV block, type I, what happens to the R-R intervals as the group progresses toward the dropped beat?

• a.They stay exactly equal, because only the PR interval is changing
• b.They shorten slightly with each successive beat✓
• c.They lengthen from beat to beat as each PR interval lengthens
• d.They vary at random, with no repeating pattern across the group

In type I block the PR interval lengthens by a smaller amount with each successive beat, so each R-R interval is slightly shorter than the one before it until a P wave is not conducted. The pause that contains the dropped beat is less than twice the shortest R-R interval in the group, which is the other classic clue. Assuming the R-R must lengthen because the PR lengthens is the usual error and reverses the actual pattern. The rhythm is not random: the repeating cluster of beats followed by a pause is the grouped beating that makes the block recognizable at a glance.

A patient with a demand ventricular pacemaker has an underlying rhythm at 68 beats per minute. Pacing spikes appear without regard to the patient's own beats, and one spike lands on a T wave. What should the technician do?

• a.Document normal demand pacing and continue routine monitoring
• b.Print the strip, note the spikes, and pass it along at the end of the shift
• c.Notify the supervisor promptly and save the tracing that was recorded✓
• d.Reposition the patient, since the spikes are movement artifact

A demand pacemaker is supposed to sense the patient's own beats and withhold its output; spikes that ignore intrinsic beats are failure to sense, and a spike landing on a T wave falls in the vulnerable period and can provoke ventricular tachycardia or fibrillation. That combination is reported without delay and the tracing is kept as evidence for the provider and the device clinic. Printing the strip and noting the spikes is proper work in itself, but holding the finding until the shift ends delays a report on a malfunction that can cause an arrest in the meantime. Calling it normal demand pacing misses that the generator is competing with the patient's own rhythm, and pacer spikes are sharp and evenly sized within a lead, unlike the irregular deflections of movement artifact.

A strip shows exactly two P waves for every QRS complex throughout, and the PR interval of every conducted beat measures 0.24 second. How should the technician describe this rhythm?

• a.Second-degree AV block, type II, from the constant PR interval
• b.Second-degree AV block, type I, because a P wave is regularly dropped
• c.Complete heart block, because two P waves appear for each QRS complex
• d.Second-degree AV block with 2:1 conduction, type not classified✓

With 2:1 conduction there are never two conducted beats in a row, so there is no sequence of PR intervals in which lengthening could be seen, and the strip cannot be sorted into type I or type II from the ratio alone; it is reported as 2:1 AV block. A constant PR interval does not settle the question, because in 2:1 conduction every conducted beat is the first beat of its group and would have the same PR in either type. Regularly dropped P waves occur in both types and do not identify type I. Complete heart block is excluded because the conducted P waves hold a fixed relationship to the QRS complexes.

Compared with a second-degree AV block, type I, why is a second-degree AV block, type II, generally treated as the more serious finding?

• a.Type II drops a larger share of the P waves in most patients
• b.Type II is the only second-degree block that leaves a pause
• c.Type II lies below the AV node and may progress to complete block✓
• d.Type II responds to atropine, while type I usually does not respond

Type I block is usually located within the AV node and is often transient, while type II usually arises in the His-Purkinje system below the node, frequently shows a wide QRS, and can progress without warning to complete heart block, which is why it is reported promptly. The number of dropped beats does not determine the type; a type I block can drop as many beats as a type II block. Both types produce pauses on the strip, so a pause identifies neither. The atropine claim is reversed as well as outside the technician's scope, since atropine acts on the AV node and is the nodal block that may respond.

A monitored patient's QRS complexes measure 0.14 second. What is it about a bundle branch block that widens the QRS complex?

• a.The atria and the ventricles depolarize together through the AV node
• b.One ventricle depolarizes late because the impulse spreads muscle to muscle✓
• c.The impulse turns back through the AV node and depolarizes the atria
• d.The ventricles repolarize more slowly, which stretches the QRS complex

When one bundle branch is blocked, the ventricle it serves is not activated through the fast Purkinje network; the impulse reaches it by slower cell-to-cell spread from the other ventricle, so the two ventricles depolarize one after the other instead of together and the QRS reaches 0.12 second or more. Repolarization of the ventricles is represented by the T wave, so slowing it would not widen the QRS. Conduction turning back toward the atria produces an inverted P wave near the QRS, as in junctional beats, rather than a wide complex. Simultaneous atrial and ventricular depolarization is not what normal conduction does at all.

A technician records a single-lead rhythm strip that shows wide QRS complexes with an rSR' pattern. What is the appropriate way to report this finding?

• a.As a right bundle branch block, which the rSR' pattern shows
• b.As wide QRS complexes, noting that a 12-lead is needed to say more✓
• c.As a left bundle branch block, since the QRS exceeds 0.12 second
• d.As ventricular beats, since the complexes are wide and misshapen

An rSR' pattern is associated with right bundle branch block, but naming the side depends on the QRS shape in V1 and V6 on a 12-lead, and a monitoring lead is not V1 unless it was deliberately set up as a modified chest lead. The technician measures and describes what is on the strip, including QRS duration and morphology, and leaves the interpretation to the provider. Width alone identifies neither branch, since both blocks widen the QRS past 0.12 second. Wide complexes that follow P waves with a consistent PR interval are conducted beats rather than ventricular ectopic beats.

A patient with a demand pacemaker programmed to 60 beats per minute is on telemetry. The strip shows long pauses with no pacing spikes at all during them, and each pause follows a burst of muscle noise on the baseline. What is the most likely explanation?

• a.Oversensing, in which noise is read as beats and output is withheld✓
• b.Failure to capture, since the paced impulses produce no complexes
• c.Failure to sense, since the generator fires without regard to the beats
• d.Battery depletion, to be reported to the supervisor as a failed device

A demand pacemaker withholds its output whenever it senses electrical activity, so when it counts muscle tremor or other electrical noise as ventricular beats it stops pacing and the rate falls below the programmed 60 beats per minute; the pauses tracking the noise bursts are the giveaway. Failure to capture shows spikes that produce no complex, yet during these pauses there are no spikes at all. Failure to sense produces the opposite picture, extra spikes competing with the patient's own beats. Battery status is determined by device interrogation rather than from a rhythm strip, and declaring a device failed is not the technician's call.

A strip shows a regular wide-complex tachycardia at 160 beats per minute. Which additional finding on that strip would most support ventricular tachycardia rather than a supraventricular rhythm conducted with aberrancy?

• a.QRS complexes that measure more than 0.12 second across the strip
• b.T waves that point in the same direction as the QRS complexes
• c.P waves marching through at an unrelated rate of 80 per minute✓
• d.An R-R interval that stays regular from the first to the last beat

Independent P waves continuing at their own slower rate through the tachycardia show AV dissociation, which strongly favors a ventricular origin; capture beats and fusion beats point the same way. A QRS wider than 0.12 second is present in both possibilities, since aberrant conduction widens the complex too, so width alone separates nothing. Regularity is likewise shared by both. T waves in wide-complex beats usually point opposite the QRS, so concordant T waves are not a feature that favors either. Whatever the strip suggests, the technician reports a wide-complex tachycardia and gets help rather than naming the mechanism.

A monitored patient's rhythm changes to a ventricular rate of 34 beats per minute with wide QRS complexes and P waves bearing no relationship to them. The patient says he feels faint and looks pale. What should the technician do?

• a.Recheck the electrodes, since a rate that low is usually a lead problem
• b.Report the strip to the supervisor at the end of the current monitoring round
• c.Ask the patient to sit upright so his ventricular rate will come up
• d.Stay with the patient and alert the nurse at once, per facility policy✓

A new complete heart block at 34 beats per minute in a patient with symptoms is an emergency finding, so the technician stays with the patient, summons the nurse or the emergency response as facility policy directs, and keeps the strip running for the team. Holding the tracing until the end of the round delays care that is needed now. Clean, regular wide complexes with independent P waves are a real rhythm and not a lead problem, so troubleshooting electrodes first wastes time. Sitting a lightheaded patient upright does not restore conduction through a blocked pathway and adds a fall risk.

A sinus strip at 70 beats per minute contains one wide, bizarre beat sandwiched between two consecutive sinus beats, and the surrounding sinus P-P and R-R intervals are undisturbed. What is the wide beat called?

• a.A ventricular escape beat, since no pause follows it
• b.A fusion beat formed by two impulses meeting in the ventricle
• c.An interpolated premature ventricular contraction✓
• d.A junctional premature beat with aberration

An interpolated premature ventricular contraction falls between two normally timed sinus beats without resetting the sinus node, so no compensatory pause follows it and the underlying cycle continues undisturbed. A ventricular escape beat is late rather than early and appears after a pause when the higher pacemakers have failed, which does not fit a beat squeezed into an intact sinus cycle. A fusion beat is a single hybrid complex whose shape lies between that of a sinus beat and that of a ventricular beat. A junctional premature beat is narrow unless it is conducted aberrantly, comes early with an inverted P wave near the complex, and usually resets the underlying rhythm.

A strip shows a rapid wide-complex rhythm whose QRS complexes change amplitude gradually and appear to twist around the baseline. Which measurement from the same patient's earlier tracing is most closely related to this rhythm?

• a.A PR interval of 0.22 second measured on the earlier tracing
• b.A QRS duration of 0.10 second measured on the earlier tracing
• c.A corrected QT interval of 0.52 second measured on the earlier tracing✓
• d.An R-R interval that varied with breathing on the earlier tracing

The twisting pattern is torsades de pointes, a polymorphic ventricular tachycardia that arises when the QT interval is prolonged, and a corrected QT of 0.52 second is well beyond the usual upper limits of about 0.44 second in men and 0.46 second in women. A PR interval of 0.22 second is a first-degree AV block, a delay in conduction into the ventricles that does not set up this rhythm. A QRS of 0.10 second is within the normal range of less than 0.12 second. R-R intervals that vary with breathing describe sinus arrhythmia, a normal variant.