EXTRA-CARDIAC SHUNT: AN UNUSUAL CAUSE OF STROKE

Abstract

TOPIC: Critical Care TYPE: Medical Student/Resident Case Reports INTRODUCTION: Embolic phenomenon, while not contributing as much as a cause as atherosclerotic disease for ischemic stroke, remains an important cause for ischemic stroke. While atrial fibrillation represents the majority of the patients in this subset, there are other less conspicuous causes. Here, we present a case of an ischemic stroke, found to be due to an isolated extra-cardiac shunt without a patent foramen ovale. CASE PRESENTATION: A 56-year-old right-handed female with no significant past medical history presented with left-sided weakness concerning for acute stroke. On admission, her National Institute of Health Stroke Scale (NIHSS) was 20. MRI showed an occlusion of the right middle cerebral artery at M1 and right carotid terminus. Dual anti-platelet therapy (DAPT) and statin were started. Revascularization was achieved with thrombectomy. Deep vein thrombosis was ruled out and trans-thoracic echocardiogram was unremarkable. Telemetry revealed persistent first-degree AV block. Suspecting a cardioembolic etiology, a loop recorder was placed and DAPT was changed to apixaban. Trans-esophageal echocardiogram ruled out valvular abnormalities or clots, but identified an extra-cardiac shunt, suspected to be from pulmonary arteriovenous malformation (PAVM). Despite the findings, the patient declined further workup in the hospital and was discharged with medical management. DISCUSSION: PAVM, often associated with Osler-Weber-Rendu disease (OWRD) or migraines is a rare cause for stroke.[1] The absence of a capillary bed allows small thrombi or bacteria to reach the systemic circulation. The resulting manifestations can be severe, including cerebrovascular accidents and brain or intra-medullary abscesses.[2] In a study involving over 700 patients with stroke, only 4 with isolated PAVM were identified, suggesting this is a very rare presentation.[3] In our patient, however, there was no history of migraines or clinical features of OWRD other than PAVM (1 out of 4 per Curacao diagnostic criteria). Therefore, we believe the stroke was likely secondary to an isolated PAVM. Studies reported varied approaches on management of isolated PAVM, with majority opted for embolization. There was also varied recommendations on anti-platelet therapy or anti-coagulation. Our patient was managed with anti-coagulation therapy. CONCLUSIONS: Cryptogenic strokes in low-risk patients warrant evaluating for less common causes, such as AVM, as the implications could be devastating. Although there are treatments that lower the risk of recurrent strokes, little is known on the best practice for patients with isolated PAVM. REFERENCE #1: Peery WH. Clinical Spectrum of Hereditary Hemorrhagic Telangiectasi (Osler-Weber-Rendu Disease). Am J Med. 1987;82:9. REFERENCE #2: Kawano H, Hirano T, Ikeno K, Fuwa I, Uchino M. Brain Abscess Caused by Pulmonary Arteriovenous Fistulas without Rendu-Osler-Weber Disease. Intern Med. 2009;48(6):485-487. REFERENCE #3: Kimura K, Minematsu K, Nakajima M. Isolated pulmonary arteriovenous fistula without Rendu-Osler-Weber disease as a cause of cryptogenic stroke. J Neurol Neurosurg Psychiatry. 2004;75(2):311-313. DISCLOSURES: No relevant relationships by Vernon Chan, source=Web Response No relevant relationships by Dana Daoud, source=Web Response No relevant relationships by Jayaram Thimmapuram, source=Web Response