Introducere: Acute pulmonary thromboembolism complicates deep vein thrombosis in about one-third of cases. Most patients have risk factors such as genetic disorders associated with hypercoagulability, pelvic or lower limb surgery, neoplasms. The presence of floating thrombi in the right heart is always associated with acute pulmonary thromboembolism. Due to pulmonary hypertension and increased pressure in the right atrium, in the presence of a patent foramen ovale, paradoxical thrombus migration can occur. Thrombus entrapped in a patent foramen ovale are difficult to visualize due to their transient nature. Around 100 cases are described in the literature. Therapeutic options in this situation include anticoagulant treatment with he-parin, thrombolysis or surgical thrombectomy. There is no optimal consensus, individualised management depends on the hemodynamic stability and associated risks. For patients with high surgical risk or those with small foramen ovale, conservative anticoagulant treatment may be chosen. Thrombolysis has the highest risk due to higher probability of systemic embolism and hemorrhage.

Case presentation: We present the case of an 81 yo female patient admitted for syncope, followed by resting dyspnea. The pacient underwent surgery for serous ovarian cyst 3 months before, with early postoperative mobilization. At admission, she was hemodynamically stable, tachycardic, slightly dyspneic, with oxygen sa-turation 90%. The ECG recorded sinus rhythm, right bundle branch block, S1Q3T3 pattern. Transthoracic echocardiogram revealed a floating thrombus in the right atrium, entrapped in a patent foramen ovale, with slightly enlarged right heart chambers. Doppler ultrasound showed bilateral deep vein thrombosis of the common femoral vein. CT pulmonary angiogram confirmed the diagnosis of bilateral acute pulmonary thromboembolism. The tumor marker tests and the abdominal CT ruled out the presence of a neoplasm. Clinical neurological examination was normal and no further neurological imagistics were ordered. The evolution was favorable under anticoagulation with un-fractionated heparin, with clinical improvement and important reduction in size of the intraatrial thrombus, without other embolic complications.

Particularity: The particularity of this case consists in the presence of a deep deep vein thrombosis compli-cated with acute pulmonary thromboembolism in a physically active patients, months after pelvic surgery that did not require prolonged immobilization of the patient, without other identified risk factors. Another particularity is the finding of an intraatrial thrombosis with thrombus entrapped in a patent formen ovale, without paradoxical embolism. This patient presented for a syncopal episode in the context of acute pulmonary thromboembolism. During hospitalization she remained hemodynamically stable with a favorable evolution with anticoagulant treatment. This case emphasizes the importance of transthoracic echocardiography for the evaluation of a syncopal episode, the diagnosis of acute pulmonary thromboembolism and in the decision to initiate rapid anticoagulant treatment.