P.B. Deverall

Bio: P.B. Deverall is an academic researcher from London Bridge Hospital. The author has contributed to research in topics: Transcranial Doppler & Cardiopulmonary bypass. The author has an hindex of 2, co-authored 2 publications receiving 393 citations.

Impaired Clearance of Emboli (Washout) Is an Important Link Between Hypoperfusion, Embolism, and Ischemic Stroke

Abstract: Objective To explore the relationship between hypoperfusion, embolism, and brain infarction. Design We studied 4 situations in which brain infarction is related to hypoperfusion: extracranial and intracranial occlusive vascular disease, reduced functional vascular reserve in patients with carotid artery occlusive disease, reduced collateral blood flow in patients given thrombolytic treatment, and cardiac surgery. We reviewed results of emboli monitoring using transcranial Doppler ultrasonography. Results Hypoperfusion is strongly linked to brain ischemia and infarction. The evidence includes close correlation of (1) the severity of arterial stenosis with brain infarction; (2) impaired functional blood flow reserve in patients with carotid artery disease and subsequent brain infarction; (3) reduced collateral blood flow with poor prognosis after thrombolysis; and (4) stroke-related neurologic deficits after cardiac surgery to hypoperfusion during surgery. Microembolization is common in patients with severe symptomatic carotid artery stenosis and during and after cardiac surgery. Conclusions Hypoperfusion and embolism often coexist and their pathophysiological features are interactive. Arterial lumenal narrowing and endothelial abnormalities stimulate clot formation and subsequent embolization. Reduced perfusion limits the ability of the bloodstream to clear or wash out emboli and microemboli and reduces available blood flow to regions rendered ischemic by emboli that block supply arteries. The brain border zones are a favored destination for microemboli that are not cleared. We posit that impaired washout is an important but neglected concept that intertwines hypoperfusion, embolization, and brain infarction.

The impact of microemboli during cardiopulmonary bypass on neuropsychological functioning

Abstract: Microemboli have been implicated in the etiology of neuropsychological deficits after cardiopulmonary bypass. This study examined the incidence of high-intensity transcranial signals (microemboli) and their relation to changes in neuropsychological performance after surgery.Transcranial Doppler ultrasonography was used to measure middle cerebral artery blood flow velocity and detect microemboli. The number of high-intensity transcranial signals was determined and related to a neurological examination and absolute changes in neuropsychological performance as well as the number of patients considered to exhibit a neuropsychological deficit. Data were available on 100 consenting patients undergoing routine cardiopulmonary bypass. Fifty of the patients were randomly assigned to a procedure that included a 40-microns arterial line filter, and 50 had the procedure without any arterial line filter.Significantly more patients were found to have neuropsychological deficits in the group without the arterial line fi...