Transcoronary cardiac pacing during myocardial ischemia

Severe bradyarrhythmias are a rare but potentially life threatening complication of percutaneous transluminal coronary angioplasty (PTCA). Previous work has outlined a technique for coronary pacing using the angioplasty guidewire. To examine the effectiveness of this technique during severe ischemia, seven swine underwent placement of an unmodified 0.014 inch angioplasty guidewire and 3.0 mm balloon catheter in the left anterior descending (LAD) artery. Baseline pacing thresholds were obtained. Pacing was begun at twice diastolic threshold and ischemia was produced by balloon inflation. Repeat capture thresholds were obtained after 1 and 8 minutes of ischemia. Transcoronary pacing was successfully performed in all seven animals and was continued for a mean of 13.8 +/- 1.5 minutes. The baseline capture threshold was 4.0 +/- 0.5 mA. The mean capture threshold was 3.3 +/- 0.3 mA and 4.5 +/- 0.9 mA at 1 and 8 minutes of ischemia, respectively. We conclude that transcoronary pacing using the angioplasty guidewire can be successfully performed during myocardial ischemia and may serve as a reliable backup system during interventional procedures complicated by bradyarrhythmias.