Frequent occurrence of occult pulmonary embolism from venous sheaths during endomyocardial biopsy.

To determine the frequency of occult right heart thromboembolism during endomyocardial biopsy, 51 cardiac transplant recipients undergoing routine endomyocardial biopsy were studied echocardiographically. Patients were randomized to two groups. In Group 1, the venous sheath was flushed between each biopsy attempt; in Group 2, it was flushed only at the time of initial placement. Right heart thromboemboli were identified in 18 (35%) of 51 patients. Seventeen (94%) of these 18 patients were in Group 2. Patients requiring more than six biopsy attempts had a significantly higher incidence of embolism. Other variables such as antiplatelet therapy, operator experience and total time of the procedure did not correlate with occurrence of thrombus. All right heart emboli were asymptomatic. These data demonstrate a high incidence of occult pulmonary embolism during uncomplicated routine endomyocardial biopsy. Meticulous flushing of the introducer sheath significantly reduces the incidence of thrombus formation in intravenous sheaths.