CVT Electrophysiology Studies & Catheter Ablation 2 — Questions and Answers
Question 1: During programmed electrical stimulation (PES), what is the purpose of delivering extrastimuli (S2, S3)?
- To measure sinus node recovery time
- To induce tachyarrhythmias by scanning through refractory periods (Correct answer)
- To quantify His-Purkinje conduction velocity
- To assess left ventricular systolic function
Correct answer: To induce tachyarrhythmias by scanning through refractory periods
Extrastimuli are delivered at progressively shorter coupling intervals to identify tissue refractory periods and initiate reentrant arrhythmias.
Question 2: What is the normal range for the AH interval in an EP study?
- 10–30 ms
- 55–125 ms (Correct answer)
- 150–200 ms
- 200–300 ms
Correct answer: 55–125 ms
The AH interval (atrial-to-His, representing AV nodal conduction) normally measures 55–125 ms and prolongates with vagal tone or AV nodal disease.
Question 3: On a 3D electroanatomical bipolar voltage map, purple/blue color typically represents:
- Normal myocardium with high bipolar voltage (>1.5 mV)
- Scar tissue with low bipolar voltage (<0.5 mV) (Correct answer)
- Areas of earliest activation during tachycardia
- Catheter contact pressure points
Correct answer: Scar tissue with low bipolar voltage (<0.5 mV)
Purple/blue on bipolar voltage maps indicates dense scar (<0.5 mV), which commonly serves as the substrate for reentrant ventricular tachycardia.
Question 4: Pulmonary vein isolation (PVI) during atrial fibrillation ablation targets pulmonary vein ostia located in the:
- Right ventricle
- Left atrium (Correct answer)
- Coronary sinus
- Superior vena cava
Correct answer: Left atrium
AF triggers originate predominantly from the pulmonary vein ostia, which connect to the left atrium; PVI electrically isolates these veins.
Question 5: During RF ablation, what is the primary reason to limit catheter tip temperature to approximately 50–60°C?
- To maximize lesion depth without surface charring
- To prevent steam pops that can cause cardiac perforation (Correct answer)
- To ensure adequate anticoagulation efficacy
- To avoid damage to the fluoroscopy equipment
Correct answer: To prevent steam pops that can cause cardiac perforation
Excessive temperature (>60°C) causes rapid tissue vaporization, producing steam pops (microexplosions) that risk cardiac perforation or thrombus.
Question 6: Which conduction property is characteristic of the AV node and describes slowing of conduction with increasing pacing rates?
- Automaticity
- Triggered activity
- Decremental conduction (Correct answer)
- Supernormal conduction
Correct answer: Decremental conduction
Decremental conduction means conduction velocity slows as the stimulation rate increases — a hallmark property of the AV node.
Question 7: Which two major complications are most feared during left-sided catheter ablation procedures requiring transseptal access?
- Complete heart block and pulmonary hypertension
- Renal failure and pneumothorax
- Cardiac tamponade and thromboembolic stroke (Correct answer)
- Ventricular fibrillation and aortic dissection
Correct answer: Cardiac tamponade and thromboembolic stroke
Transseptal left heart access carries risks of cardiac tamponade (from perforation) and stroke (from thrombus or air embolism in the left-sided circulation).
CVT Electrophysiology Studies & Catheter Ablation 2
During programmed electrical stimulation (PES), what is the purpose of delivering extrastimuli (S2, S3)?