Thrombus in transit through a patent foramen ovale: catch it if you can—a case report

Patent foramen ovale (PFO) is one of the most common congenital heart defects, but the finding of a thrombus in transit (TIT) through a PFO is extremely rare. It is a therapeutic challenge, and systemic anticoagulation, cardiac surgery, or fibrinolysis should be considered.

A 43-year-old woman was admitted with intermediate-high-risk pulmonary embolism. Transthoracic echocardiogram revealed a large right atrial mobile mass that crossed the interatrial septum through a PFO, compatible with TIT, and the patient was started on unfractionated heparin. The diagnosis was confirmed by transoesophageal echocardiogram (TOE). However, during TOE probe removal, the patient developed dyspnoea, sudoresis, and peripheral desaturation, and new image acquisition revealed sudden mass disappearance. Due to the possibility of paradoxical embolization associated with Valsalva manoeuvre, fibrinolysis with alteplase was promptly started. The patient had no signs of embolic or haemorrhagic complications and remained clinically stable. She was discharged on warfarin and then underwent percutaneous transcatheter closure of PFO.

The treatment strategy of a TIT through a PFO is controversial, but surgery might be the most appropriate treatment for haemodynamically stable patients, while thrombolysis should be used in cases of haemodynamic instability. Transoesophageal echocardiogram is generally a safe procedure but pressure changes associated with Valsalva manoeuvre may induce embolization of a TIT and attention should be given to patient sedation and tolerance. After complete embolization of a TIT, emergent thrombolysis may be the only treatment option, in order to prevent disastrous consequences related to paradoxical embolism.