POSTMORTEM CHANGES AFTER LEAD EXTRACTION FROM THE OVINE CORONARY SINUS AND GREAT CARDIAC VEIN

We investigated in sheep, non-thoracotomy extraction of leads which ha d been chronically implanted in the right atrium (RA), coronary sinus/ great cardiac vein (CS/GCV) and right ventricle (RV) for atrial implan table defibrillation. Clinical success of extraction as well as gross and histologic findings in the heart are reported. Six of nine sheep h ad successful extractions. The major complication was laceration of th e wall of the great coronary vein with hemorrhage into the pericardial space and cardiac tamponade. Tissue damage included several reversibl e changes: intra-tissue hemorrhage, thrombosis in the veins, and some necrosis of fat, vascular wall and myocardium. Myocyte necrosis was es timated as 0.03 to 0.3 grams of tissue. Osseous and cartilaginous meta plasia was more common around the RA lend than the CS/GCV lead. In cas es where the lead must be removed, removal from the venous insertion s ite using lead extraction equipment should only be attempted with surg ical back-up for emergency thoracotomy to control hemorrhage in the ev ent of vessel laceration. Safer explantation of these leads from the v ein entry site will require the development of new extraction procedur es.