RIGHT ATRIAL COMPRESSION RELATED TO DEFIBRILLATOR PATCHES

Acceptable function of an internal defibrillator can be achieved with different patch orientations. For patients requiring defibrillator pat ches concomitant with a cardiac procedure requiring extracorporeal cir culation, application of one of the patches within the pericardium adj acent to the right atrium has provided excellent defibrillation thresh olds. We describe 4 such patients in whom a compressing thrombus subse quently developed between the patch and the atrium. The thrombus was s mall and asymptomatic in 1 patient, but caused localized tamponade req uiring reexploration in 2 patients and a fatal superior vena caval obs truction in 1. The precise etiology of this serious complication remai ns unclear, but its occurrence argues against the application of intra pericardial defibrillator patches in this orientation.