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.