Pacemaker induced ventricular fibrillation in coronary care units

doi:10.1136/bmj.328.7450.1249

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Andrew A McLeod, consultant cardiologist (heartdoc@tcp.co.uk)1,
Percy P Jokhi, specialist registrar in cardiology1

¹ Cardiac Department, Poole Hospital NHS Trust, Poole BH15 2JB

Correspondence to: A A McLeod

Accepted 18 November 2003

Introduction

Temporary transvenous pacing is an established treatment for many bradyarrhythmias associated with haemodynamic compromise in patients who have had acute myocardial infarction. Procedural complications associated with insertion of temporary pacing electrodes are well recognised and documented, as is subsequent loss of capture due to rising stimulation threshold or electrode displacement.1 Temporary transvenous pacing, if not applied correctly, may also directly provoke ventricular arrhythmias. Here we report two cases of ventricular fibrillation that were caused by a temporary pacemaker in a coronary care unit.

Case reports

Case 1

A 64 year old man was admitted to the coronary care unit with acute inferior myocardial infarction. He was noted to be hypotensive and have a nodal rhythm with no atrial activity at 30 beats/min. There was no response to atropine. A temporary pacing electrode was inserted and connected to an external ventricular demand pacemaker. During the following two days, at least 15 episodes of ventricular fibrillation and many sustained episodes of ventricular tachycardia occurred. Review of the electrocardiograms showed occasional failure of pacing and sensing and of pacing impulses delivered into the ST segment and the T wave of spontaneous beats causing ventricular fibrillation (fig 1). The pacemaker was turned off. A bradycardia with first degree atrioventricular block was noted, but the episodes of ventricular fibrillation stopped immediately and did not recur.

Fig 1

Case 1. Top: Apparently satisfactory pacing (first QRS complex) is followed by fusion beats, but failure to sense becomes apparent when the pacemaker spike (narrow artefact) discharges into the ST segment. The first captured premature complex leads to ventricular tachycardia, which later degenerates into ventricular fibrillation. Further pacing spikes …