AMCA EKG / Electrocardiography

Question 1

How many leads are recorded in a standard 12-lead ECG?

Accepted Answer

12

Answer

A 12-lead ECG records 12 electrical views of the heart (I, II, III, aVR, aVL, aVF, and V1–V6), even though only 10 electrodes are physically placed on the patient.

Question 2

Which ECG lead is placed on the fourth intercostal space at the RIGHT sternal border?

Accepted Answer

V1

Answer

V1 is placed at the fourth intercostal space to the right of the sternum. V2 mirrors it on the left side, and the remaining precordial leads continue across the chest.

Question 3

A patient's ECG shows a sawtooth pattern at approximately 300 bpm with no discernible P waves. This finding is most consistent with:

Accepted Answer

Atrial flutter

Answer

Atrial flutter characteristically produces a sawtooth (flutter wave) baseline at ~250–350 bpm. Atrial fibrillation produces an irregularly irregular baseline, while ventricular fibrillation is a chaotic, life-threatening rhythm.

Question 4

Somatic tremor artifact on an ECG tracing is MOST likely caused by:

Accepted Answer

Patient movement or muscle activity

Answer

Somatic tremor artifact results from skeletal muscle movement — the patient shivering, trembling, or moving during recording. Asking the patient to lie still and relax resolves this artifact.

Question 5

Which interval on an ECG represents the total time for ventricular depolarization AND repolarization?

Accepted Answer

QT interval

Answer

The QT interval spans from the start of ventricular depolarization (Q wave) through the end of repolarization (T wave). A prolonged QT interval raises the risk of dangerous arrhythmias such as Torsades de Pointes.

(AMCA) American Medical Certification Association Practice Test

(AMCA) American Medical Certification Association Practice Test

AMCA EKG / Electrocardiography