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.