We describe the case of a patient who developed a thrombus on the transseptal sheath in the right atrium before transseptal puncture for circumferential pulmonary vein isolation for paroxysmal atrial fibrillation treatment. The use of intracardiac echocardiography allowed to its identification and probably prevented the patient from suffering a serious thromboembolic complication.
Keywords: ablation; intracardiac thrombus; intracardiac ultrasound; pulmonary vein; stroke; transseptal catheterization.