Electrophysiology Studies & Catheter Ablation Flashcards

What is the primary purpose of an electrophysiology (EP) study?

Answer: To map electrical pathways and identify arrhythmia mechanisms

EP studies use intracardiac catheters to map electrical conduction and identify the origin and mechanism of arrhythmias.

Which catheter position is used to record His bundle electrograms during an EP study?

Answer: Tricuspid valve region

The His bundle catheter is positioned at the tricuspid valve region to record activation of the AV node and His bundle.

What does the HV interval measure in an electrophysiology study?

Answer: Time from His bundle activation to ventricular depolarization

The HV interval (normally 35–55 ms) measures conduction time from the His bundle through the His-Purkinje system to ventricular activation.

Radiofrequency (RF) catheter ablation destroys arrhythmogenic tissue primarily by:

Answer: Applying thermal energy to cause localized tissue necrosis

RF ablation delivers resistive heating (typically 50–60°C) through the catheter tip to create a focal lesion of coagulative necrosis.

In Wolff-Parkinson-White (WPW) syndrome, which EP study finding confirms the presence of an accessory pathway?

Answer: Short or negative HV interval with ventricular pre-excitation

WPW produces a short or negative HV interval because the ventricles are pre-excited via the accessory pathway before normal His-Purkinje conduction.

Why is cryoablation often preferred over RF ablation for AVNRT located close to the AV node?

Answer: It allows reversible testing (cryomapping) before creating a permanent lesion

Cryoablation permits cryomapping at –30°C; if AV block occurs, the effect is reversible, reducing the risk of permanent AV nodal damage.

During a standard EP study, where is the atrial pacing catheter most commonly placed?

Answer: Right atrium or coronary sinus

Atrial pacing to evaluate AV nodal function and induce supraventricular arrhythmias is performed from the right atrium or coronary sinus.