Silent embolism of a large thrombus in transit through the patent foramen ovale: A case report

Abstract

Background: Detection of a thrombus in transit through a patent foramen ovale (PFO) is extremely rare due to the transient nature of the process. We report an unusual case of a large, paradoxical embolus in transit seen on echocardiography through a PFO that was not found upon atriotomy. Learning points In patients with pulmonary embolism, the presence of thrombi in the right heart chambers must be excluded by echocardiography. Only rarely is a thrombus caught while in transit through a patent foramen ovale (PFO), representing a life-threatening condition. Continuous transoesophageal echocardiogram (TOE) monitoring during surgery for an intracardiac thrombus in transit through a PFO could aid in determining the precise fate of the thrombus after heparin bolus and bypass cannulation. This could even prevent extensive surgical exploration if the thrombus propagates, fragments, or dissolves during these perioperative procedures. Case summary: An 80-year-old woman presented to the emergency room with shortness of breath and right leg pain. She was haemodynamically stable on presentation, and her physical exam was unremarkable. An ultrasound of her right leg revealed a deep vein thrombus in the posterior tibial vein, and chest computed tomography angiography showed saddle pulmonary emboli. Transthoracic echocardiogram identified a large thrombus in transit through a PFO, which was confirmed with a transoesophageal echocardiogram (TOE). She underwent an emergency embolectomy. The thrombus in transit was confirmed by TOE prior to bypass initiation; however, no thrombi were found in any chambers of the heart following atriotomy. Her postoperative recovery was uneventful. She had no focal neurological deficits or any apparent signs of large vessel embolization. Discussion: Cases of silent embolism have been reported in the literature, although they are rare. To our knowledge, this is the first case of a large thrombus in transit through a PFO in an elderly female that was confirmed by an intra-operative TOE but could not be found following atriotomy, with no obvious clinical signs of embolization.