NHA EKG Technician (CET)

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?

1. A0.04 second, which is shorter than normal
2. B0.16 second, which is normalĐúng
3. C0.08 second, which is normal
4. D0.40 second, which is longer than normal

Vì sao: 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.

Where is the V1 electrode placed for a 12-lead EKG?

1. AFifth intercostal space, right sternal border
2. BFourth intercostal space, right sternal borderĐúng
3. CFifth intercostal space, left midclavicular line
4. DFourth intercostal space, left sternal border

Vì sao: V1 sits in the fourth intercostal space at the right sternal border, and it is located by walking down from the sternal angle to the second rib, then counting the second, third, and fourth spaces. The fourth space at the left sternal border is V2. The fifth space at the left midclavicular line is V4, and there is no standard chest lead at the fifth space on the right sternal border.