Paradoxical Embolization in Right-Sided Cardiac Lesions

Mechanism and Clinical Scenarios

The American Heart Association suggests that a right-sided cardiac lesion can produce systemic emboli without pulmonary involvement through paradoxical embolization via a patent foramen ovale (PFO), where elevated right-sided pressures force thrombi through the interatrial communication directly into the systemic circulation, bypassing the pulmonary vasculature 1, 2
The European Society of Cardiology recommends considering paradoxical embolism through PFO when systemic emboli occur in right-sided infective endocarditis, particularly in intravenous drug users with tricuspid valve endocarditis, where vegetations can embolize systemically rather than only to the lungs 4
Patients with deep vein thrombosis can develop both pulmonary embolism AND paradoxical systemic embolization simultaneously, with PFO-related right-to-left atrial shunts increasing the risk of death and major adverse events, including arterial thromboembolic events 1, 2, 3

The American College of Cardiology states that the diagnosis of paradoxical embolism is almost always presumptive and relies on specific criteria, including occurrence of arterial thromboembolic event, absence of atrial fibrillation, absence of left-sided cardiac disease, absence of severe atherosclerosis of thoracic aorta, detection of right-to-left shunt, and presence of venous thrombosis or pulmonary embolism 1, 5, 6

The European Heart Journal suggests that an individualized approach to PFO closure should be considered after careful evaluation, though no strong guidelines exist for non-cerebral paradoxical embolization, and percutaneous closure may be justified to prevent recurrent events 2, 5, 6
The American Heart Association recommends surgery for microorganisms difficult to eradicate or persistent bacteremia >7 days despite adequate antimicrobial therapy in right-sided infective endocarditis, and addressing both the source (valve surgery) and the pathway (PFO closure) may be necessary when paradoxical embolization complicates right-sided IE 4