Paroxysmal supraventricular tachycardia utilizing concealed bypass tract induced by ventricular pacemaker

oral contraceptives, and both factors are associated with an increased risk of thrombosis. The second patient had had recurrent pulmonary emboli unrelated to the LV thrombus and perhaps indicative of a hypercoagulable state. DeMaria et al3 suggested that the 2-D echo appearance of thrombus may be useful in predicting the risk of embolism. A smooth contour indicates older, organized thrombus and an irregular edge indicates new and friable thrombus that is more likely to dislodge.3 Mobile pedunculated thrombus is less frequent than mural thrombus, but the relative risk of embolism of either type is unknown. The role of anticoagulation in the prevention of recurrent emboli from intracardiac thrombus is unclear. Asinger et a1,5 in their report of patients with LV thrombus secondary to myocardial infarction, reported no embolic events and resolution of thrombus in both anticoagulated and nonanticoagulated patients, but LV thrombus recurred in 3 of 4 patients in whom anticoagulation was withdrawn. Reeder et al2 reported that the frequency of thrombus