Discussion
Clot in cardiac chamber has been divided into three types: Type A- large serpiginous clot which is freely mobile and has high risk of thromboembolism, likely source of which is deep vein thrombosis; Type B - originates in cardiac chamber and is firmly attached to wall, so has less chances of embolism; Type C- originates in cardiac chamber, highly mobile resembling myxomas.1 Clot in transit represent the embolized fragment of deep vein thrombosis which is seen in cardiac chamber during its transit, hence represent Type A clot. Impending paradoxical emboli is seen in situation with high right atrial pressure than left atrium where clot gets caught in the patent foramen ovale or rarely atrial septal defect.
Clot in transit at PFO or an impending paradoxical emboli was first reviewed by Corrin in 1964 based on autopsy, and first recognized by echocardiography in 1985 by Nellessen et al.2,3It has high risk of both systemic and pulmonary thromboembolism, and thus associated with high mortality. Case reports of clot in transit patients suggest associated pulmonary embolism in upto 91% and systemic embolism in upto 55% cases. Based on one of the largest systemic review, which studied the three treatment modalities that is thrombolysis, surgical embolectomy and anticoagulation alone, there was no survival benefit seen with thrombolysis or surgical embolectomy over anticoagulation alone. Also, the risk of embolic events was found to be higher post thrombolysis compared to embolectomy. Despite management, the mortality rate of 18 % was found in patients with clot in transit.4 Another systemic review which included cases published from 1991-2015, overall mortality reported was 14%. Results on sub-analysis showed that mortality after 2005 was higher with thrombolysis compared to surgical intervention, correlating with improved surgical techniques.5 As there are no randomized trials, no definitive guidelines are there for management of the same. The preferred strategy by most remains surgical embolectomy because of high risk of systemic emboli associated with thrombolysis. But in patients who are hemodynamic unstable with associated high surgical risk, thrombolysis can be considered.
Patient presented with deep vein thrombosis, acute massive pulmonary embolism with cardiogenic shock. Because of massive pulmonary embolism the right ventricle and right atrial pressures were high, which could have stretched open the foramen ovale. Through the defect large embolic clot entered into left side of heart and was seen as a serpiginous mobile mass protruding across mitral valve into the aortic valve.