ACSM-EP Electrocardiography 2 — Questions and Answers
Question 1: During exercise stress testing, which ECG change is considered the most significant indicator of myocardial ischemia?
- T-wave inversion only
- Horizontal or downsloping ST-segment depression ≥1 mm (Correct answer)
- Upsloping ST-segment depression ≥0.5 mm
- Prolonged PR interval
Correct answer: Horizontal or downsloping ST-segment depression ≥1 mm
Horizontal or downsloping ST-segment depression ≥1 mm at 80 ms past the J-point is the classic ECG criterion for exercise-induced myocardial ischemia.
Question 2: What does the QT interval on an ECG represent?
- Atrial depolarization duration
- Total ventricular electrical activity from depolarization through repolarization (Correct answer)
- Time for the SA node to fire
- Duration of the P-R segment only
Correct answer: Total ventricular electrical activity from depolarization through repolarization
The QT interval encompasses both ventricular depolarization (QRS) and repolarization (T wave), representing total ventricular electrical activity.
Question 3: A patient's ECG shows a ventricular rate of 150 bpm with narrow QRS complexes and no visible P waves. Which arrhythmia is most likely?
- Ventricular tachycardia
- Atrial flutter with 2:1 block (Correct answer)
- Sinus tachycardia
- Third-degree heart block
Correct answer: Atrial flutter with 2:1 block
Atrial flutter typically presents at 150 bpm ventricular rate due to 2:1 AV conduction of the 300 bpm atrial flutter rate, often with sawtooth flutter waves hidden in QRS complexes.
Question 4: On a standard ECG at normal paper speed, how many small squares represent 1 second?
- 10
- 15
- 25 (Correct answer)
- 30
Correct answer: 25
At the standard paper speed of 25 mm/sec, each small square (1 mm) = 0.04 seconds, so 25 small squares = 1 second.
Question 5: Which lead configuration is best for monitoring ST-segment changes in the inferior wall of the left ventricle?
- V1 and V2
- aVR and aVL
- II, III, and aVF (Correct answer)
- V4 and V5
Correct answer: II, III, and aVF
Leads II, III, and aVF are inferior leads that face the inferior wall of the left ventricle, making them optimal for detecting inferior wall ischemia.
Question 6: What is the normal duration of the QRS complex on an ECG?
- 0.04–0.08 seconds
- 0.06–0.10 seconds (Correct answer)
- 0.12–0.20 seconds
- 0.20–0.24 seconds
Correct answer: 0.06–0.10 seconds
A normal QRS complex duration is 0.06–0.10 seconds (1.5–2.5 small squares); values ≥0.12 seconds suggest a bundle branch block or ventricular origin.
Question 7: During a graded exercise test, ST-segment elevation in a non-Q-wave lead is most concerning for which condition?
- Benign early repolarization
- Vasospastic (Prinzmetal) angina or severe transmural ischemia (Correct answer)
- Left ventricular hypertrophy
- Electrolyte imbalance
Correct answer: Vasospastic (Prinzmetal) angina or severe transmural ischemia
Exercise-induced ST elevation in a non-infarct lead strongly suggests transmural ischemia or vasospastic angina due to severe coronary artery narrowing or spasm.
ACSM-EP Electrocardiography 2
During exercise stress testing, which ECG change is considered the most significant indicator of myocardial ischemia?