Frequency and pathogenesis of hemodynamic stroke.

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Abstract
Hemodynamic stroke is a recognized but poorly described entity. The aim of this study was to define the frequency and pathogenic mechanisms of hemodynamic stroke. We prospectively studied 300 consecutive patients with acute ischemic stroke for evidence of a hemodynamic mechanism. All patients with a probable or possible thromboembolic source were excluded. Twenty-nine patients (9.6%) had documented or presumed hypotension at stroke onset, with 27 of 29 (93%) having watershed infarction on computed tomography (CT). Most (21/29) patients had a slow (hours to days) progressive onset to stroke. Myocardial infarction, cardiac arrhythmias, and orthostatic changes in blood pressure related to diabetic dysautonomia and antihypertensive therapy were the predominant causes of hypotension. Ten patients had moderate or severe carotid stenosis (frequently bilateral); 9 had carotid occlusion (19/29 [66%]). Patients with normal carotid arteries (10/29 [34%]) had hypotension with a stuttering onset to stroke and watershed infarction on CT. Many patients continued to have progressive neurological deterioration, often with ongoing hemodynamic instability. Three of 7 patients who underwent carotid endarterectomy had further perioperative ischemic events. Five patients had myocardial infarction, and overall 4 died during 18.4 months of follow-up (mortality, 9%/y). Recognition of the clinical and CT features of hemodynamic stroke allows early identification and management of cardiac and carotid disease and correction of iatrogenic causes of hypotension, which may reduce the risk of further events.