PCP Cardiac Care and ECG 1 — Questions and Answers
Question 1: On a 12-lead ECG, ST-segment elevation in leads II, III, and aVF suggests an infarction in which territory?
- Anterior wall
- Lateral wall
- Inferior wall (Correct answer)
- Posterior wall
Correct answer: Inferior wall
Leads II, III, and aVF are the inferior leads; ST elevation in these leads indicates an inferior STEMI, typically from RCA occlusion.
Question 2: Ventricular fibrillation (VF) on an ECG appears as:
- Regular narrow QRS complexes at 150 bpm
- Completely chaotic, irregular waveforms with no identifiable QRS (Correct answer)
- Wide-complex regular tachycardia at 180 bpm
- Saw-tooth flutter waves at 300 bpm
Correct answer: Completely chaotic, irregular waveforms with no identifiable QRS
VF produces chaotic, disorganized electrical activity with no identifiable QRS complexes, P waves, or T waves.
Question 3: Which rhythm is characterized by a regular narrow-complex tachycardia at 150–250 bpm with no visible P waves?
- Atrial flutter
- Sinus tachycardia
- Supraventricular tachycardia (SVT) (Correct answer)
- Ventricular tachycardia
Correct answer: Supraventricular tachycardia (SVT)
SVT presents as a regular narrow-complex tachycardia at 150–250 bpm; P waves are often buried in the preceding T wave.
Question 4: The first-line treatment for stable narrow-complex SVT is:
- Synchronized cardioversion at 100 J
- Valsalva maneuver or carotid sinus massage (Correct answer)
- Amiodarone IV
- Defibrillation at 200 J
Correct answer: Valsalva maneuver or carotid sinus massage
Vagal maneuvers (Valsalva, carotid sinus massage) are the first-line treatment for stable SVT to slow conduction through the AV node.
Question 5: A patient in third-degree (complete) heart block will show:
- Progressively lengthening PR interval then a dropped beat
- Consistent PR prolongation >0.20 seconds
- Complete dissociation of P waves and QRS complexes (Correct answer)
- Absent P waves with irregular QRS
Correct answer: Complete dissociation of P waves and QRS complexes
Third-degree AV block shows complete dissociation — P waves and QRS complexes march independently at different rates.
Question 6: Which of the following is the correct joule setting for synchronized cardioversion of an unstable narrow-complex tachycardia?
- 50–100 J biphasic (Correct answer)
- 200 J biphasic
- 360 J monophasic only
- 1 J/kg
Correct answer: 50–100 J biphasic
Synchronized cardioversion for narrow-complex tachycardia begins at 50–100 J biphasic and is escalated as needed.
PCP Cardiac Care and ECG 1
On a 12-lead ECG, ST-segment elevation in leads II, III, and aVF suggests an infarction in which territory?