Cardiac pathology of permanent pacemaker implementation.

The cardiac findings in five cases of permanent pacemaker implantation seen at autopsy in a three-year period is reported. Implantation was done for complete heart block in four patients and sick sinus syndrome in one. The periods of implantation ranged from seven days to four years. The common findings were right sided valvar and mural bland thrombus formation. Additional findings included superior vena caval thrombosis, endocardial 'tunnel' formation for the pacing wires, perforation of the tricuspid leaflet and a gross morphology similar to that seen in right sided endomyocardial fibrosis.