Postmortem Findings and Possible Causes of Unexpected Death in Patients Treated with Intraventricular Pacing

The study comprises 10 consecutive medicolegal autopsies of patients treated with intraventricular cardiac pacing who died unexpectedly outside of a hospital. The treatment was indicated by AV-block grade I-III in eight cases, by bradyarrhythmia in one case, and sick sinus syndrome in the last case. Four patients died during a sudden epileptiform seizure, three were found dead, and three died in their sleep. Recent hemorrhages close to the AV-node and His bundle were seen in five cases. The local findings in the vicinity of the pacemaker leads were numerous and multiple consisting of thrombosis of the superior vena cava, tortuous and corroded leads, leads attached to the atrial endocardium, constricted orifice of the coronary sinus, and acute ulcerations, endocarditis, shrinking, and ruptures of the cusps of the tricuspid valve. The right atrium of the pacemaker patients was significantly dilated. The mean value of the ratios between right atrial and ventricular length (AV ratio) of the 10 pacemaker patients was 1.2 in contrast to the mean value of the same ratio of 30 controls, which was 0.6. The AV ratio was particularly increased in patients with lesions of the tricuspid valve and with a long history of cardiac pacing. In 3 of the 10 patients the immediate cause of death was related to anatomical and technical complications of long-term intraventricular pacing. Such complications were clinically unrecognized thrombosis of the superior vena cava, rupture of the chordae tendinae, and cable breakage.