[Adherence of pacemaker electrodes to the endomyocardium--a postmortem study]

The weight of extraction of a pacemaker electrode from the endomyocardium was evaluated in 29 hearts (31 pacemakers). The maximum weight of extraction was 2375 g, the mean being 760 g. The weight of extraction depends on the duration of the implantation of the pacemaker, and on the thickness of the right ventricle, but there is no relationship to the shape of the pacemaker electrode, nor to the site of insertion in the right ventricular endomyocardium. In half the cases, pieces of endomyocardium adhered to the extracted electrode, the largest piece being 5 cm x 0.5 cm x 0.5 cm. The epicardium was not injured in any of these cases. It was often noticed that scarred adhesions existed between the cable of the pacemaker and the endocardium and/or the intima of the blood vessels. During traction in vivo, strangulation of the right heart and the blood vessels may occur.