PVI Mechanism — EECC MCQ
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Correct answer: D — Pulmonary veins contain sleeves of myocardial tissue that generate rapid electrical firing (triggers) initiating AF — PVI electrically isolates these sleeves from the left atrium, eliminating the triggers; the antral tissue also harbours AF-sustaining rotors/drivers
The seminal work of Haïssaguerre (1998) demonstrated that ectopic foci in the pulmonary veins (PVs) trigger the majority of paroxysmal AF. The PVs contain sleeves of atrial myocardium extending 1-3 cm from the LA-PV junction, which have distinct electrophysiological properties: shorter refractory periods, triggered automaticity, and complex fibre orientation promoting micro-re-entry. PVI creates circumferential lesions around each PV ostium (or pairs of PVs — wide-area circumferential ablation), electrically disconnecting the PV sleeves from the LA. This eliminates: (1) PV triggers; (2) PV-based rotors/drivers that sustain AF. For persistent AF, additional substrate modification (LA roof line, mitral isthmus line, posterior wall isolation) may be performed. PFA technology achieves PVI with potentially more durable isolation and fewer complications.
Reference: ESC (2024): AF Guidelines; Haïssaguerre et al. NEJM 1998