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A 74 year old woman presented with cardiogenic shock and a ventricular septal defect (VSD), four days after an undiagnosed inferior myocardial infarction. An infero-apical VSD was repaired using a 4 × 3 cm Dacron patch during emergency cardiopulmonary bypass. Despite postoperative ventilation, balloon pump, and inotropic support she remained hypotensive and oliguric on the third postoperative day. In addition, inappropriate sinus bradycardia resulted in frequent ectopy and eight episodes of ventricular tachycardia/fibrillation, requiring DC cardioversion.
Ventricular demand (VVI) pacing via epicardial temporary pacing leads increased heart rate, but did not improve blood pressure or urine output. Neither VVI pacing, nor intravenous loading with amiodarone, suppressed the ventricular arrhythmia.
Dual chamber (DDD) temporary pacing was achieved using a single lead balloon flotation catheter (panel A: the two ventricular, three atrial and single indifferent superior vena cava (SVC) electrode positions are marked. Inset: 1.0 ml air filled balloon to facilitate “flow directed” catheter positioning.) This electrode catheter allows atrial pacing in DDD mode by overlapping biphasic impulses (OLBI, Biotronik) via a pair of non-contact atrial electrodes. Fluoroscopic screening was used to optimise electrode position (panel B). Reliable DDD pacing using an external generator (Eikos SLD, Biotronik) was maintained at 100 beats per minute for five days with dramatic clinical improvement. There was a 24 mm Hg rise in mean arterial pressure (panel C) enabling withdrawal of inotropic support, recovery of renal function, and a steady clinical improvement. In addition, the ventricular arrhythmia was completely suppressed apart from two further episodes of ventricular tachycardia provoked by testing ventricular thresholds in VVI mode.