Abstract 16831: Provoked PFO Shunt And Posterior Circulation Stroke: An Underrecognized Association

Abstract

Case Presentation: A 50 year old man presented with nausea and weakness. MRI brain showed a small acute infarct in the right pons. CT angiography of the head and neck was unremarkable. No thrombus, vegetation, or inter-atrial communication was seen on transthoracic echocardiogram: LVEF was 55-60% with normal left atrial size. No history of atrial fibrillation, hypertension, diabetes or drug abuse was reported; lower extremity duplex was negative for deep venous thrombosis. TSH was normal. Transesophageal echocardiography showed an aneurysmal atrial septum: agitated saline injection did not demonstrate an inter-atrial communication (figure 1). Repeat saline injection during the same procedure with Valsalva maneuver demonstrated a moderate-sized, provoked right-to-left, patent foramen ovale (PFO) shunt (figure 2). Discussion: Physiologically decreased sympathetic innervation spares posterior cerebral circulation from Valsalva-induced vasoconstriction. The disproportionate increase in posterior cerebral blood flow when venous return/cardiac output increases in the immediate post-strain period explains the association of provoked PFO shunt and paradoxical embolism to posterior circulation. Although the association has been described in literature, it remains underappreciated. Recognition of the association expedited secondary prevention of stroke in this non-elderly patient by circumventing the need to exclude atrial fibrillation on ambulatory rhythm monitoring (3-6 months) before referral for PFO closure.