From the Research
Yes, transpulmonic shunting can cause a cerebrovascular accident (CVA) or stroke, as evidenced by the most recent and highest quality study available 1. Transpulmonic shunting occurs when blood bypasses the lungs and flows directly from the right side of the heart to the left side, allowing deoxygenated blood containing potential emboli to enter the systemic circulation without being filtered by the lungs. This most commonly happens with a patent foramen ovale (PFO), atrial septal defect (ASD), or ventricular septal defect (VSD). When emboli such as blood clots, air bubbles, or fat particles pass through these shunts, they can travel to the brain and block cerebral blood vessels, resulting in an ischemic stroke. This mechanism is called paradoxical embolism and is particularly concerning in patients with deep vein thrombosis or other conditions predisposing to clot formation.
Key Factors Influencing Stroke Risk
The risk of stroke from transpulmonic shunting is influenced by several factors, including:
- The presence of an atrial septal aneurysm (ASA), which has been shown to be a significant predictor of recurrent stroke in patients with PFO-associated stroke 1.
- The size of the shunt, although the latest evidence suggests that shunt size may not be as significant a predictor of stroke recurrence as previously thought 1.
- The presence of other cardiovascular risk factors, which can increase the overall risk of stroke.
Management and Treatment
Management of transpulmonic shunting and stroke prevention may include:
- Anticoagulation therapy with medications like warfarin, direct oral anticoagulants, or antiplatelet agents such as aspirin or clopidogrel.
- Closure of the defect through percutaneous or surgical approaches, particularly in cases of recurrent strokes despite medical therapy or in patients with high-risk PFO characteristics 2.
Recent Evidence and Guidelines
Recent studies have demonstrated that transcatheter closure of PFO can reduce the risk of recurrent stroke in select patients, especially those younger than 60 years with PFO and embolic-appearing infarct and where no other mechanism of stroke was identified 2. The decision to close a PFO should be based on a thorough evaluation of the patient's risk factors and the presence of high-risk PFO characteristics, such as ASA or large shunt 1.