Abstract and Introduction
Abstract
Blood pressure (BP) elevations often complicate the management of intracerebral hemorrhage and aneurysmal subarachnoid hemorrhage, the most serious forms of acute stroke. Despite consensus on potential benefits of BP lowering in the acute phase of intracerebral hemorrhage, controversies persist over the timing, mechanisms, and approaches to treatment. BP control is even more complex for subarachnoid hemorrhage, where there are rationales for both BP lowering and elevation in reducing the risks of rebleeding and delayed cerebral ischemia, respectively. Efforts to disentangle the evidence has involved detailed exploration of individual patient data from clinical trials through meta-analysis to determine strength and direction of BP change in relation to key outcomes in intracerebral hemorrhage, and which likely also apply to subarachnoid hemorrhage. A wealth of hemodynamic data provides insights into pathophysiological interrelationships of BP and cerebral blood flow. This focused update provides an overview of current evidence, knowledge gaps, and emerging concepts on systemic hemodynamics, cerebral autoregulation and perfusion, to facilitate clinical practice recommendations and future research.
Introduction
The main forms of hemorrhagic stroke, intracerebral hemorrhage (ICH) and aneurysmal subarachnoid hemorrhage (SAH), are often complicated by elevated blood pressure (BP),[1,2] which in turn increases the likelihood for ongoing and recurrent hemorrhage,[3,4] and death and disability.[5,6] Despite considerable research effort undertaken to date, controversy persists as to the most appropriate management of BP in these 2 serious conditions, that globally contribute greater disability-adjusted-life-years than the more common, acute ischemic stroke. While consensus has formed as to there being benefits from initiating BP lowering early after the onset of ICH,[7] uncertainty persists as to the optimal approach to such treatment in terms of timing, speed, agent(s), and target level of systolic BP to be achieved. The situation is even more complex for SAH, where BP lowering on the one hand can be justified to reduce the risk of rebleeding, but on the other hand may increase the already substantial risk of delayed cerebral ischemia (DCI).
In this review, we summarize the evidence for BP control in acute spontaneous ICH and aneurysmal SAH, acknowledge management issues germane to both conditions, and emphasize knowledge gaps and emerging concepts on systemic hemodynamics, cerebral autoregulation, and perfusion. There exist similarities between cerebral small vessel disease-related ICH and aneurysmal SAH that justify this comparative consideration of approaches to acute management (Figure). We avoid reference to secondary causes of ICH, such as arteriovenous malformations or cavernomas, which are low pressure abnormalities without any relation to BP; and similarly of perimesencephalic SAH, which is characterized by a typical pattern of hemorrhage on CT and absence of an aneurysm,[8] where BP is usually normal,[9] rebleeding is extremely rare, and DCI does not occur.[8] In drawing upon our recent epidemiological studies, systematic reviews, randomized controlled trials (RCTs) and individual participant data (IPD) meta-analysis of RCTs of BP control in acute ICH,[10] we aim to provide guidance for clinical practice and future research.
Figure.
Spot the difference: similarities between cerebral small vessel disease-related intracerebral hemorrhage (ICH; left: thalamic ICH with intraventricular and adjacent subarachnoid extension) and aneurysmal subarachnoid hemorrhage (SAH; right: ruptured basilar tip aneurysm with intracerebral and intraventricular extension).
High blood pressure (BP) is a major risk factor. Critical illness requiring rapid emergency assessment and management. Subarachnoid extension of ICH can occur and vice versa, intraventricular extension is common to both. Early neurological deterioration and death from mass effect and hydrocephalus is common. High BP is common during the acute phase and is associated with poor outcomes. Uncertainties remain regarding optimal management of BP to improve outcomes, particularly in regard to balancing risks of bleeding and ischemia.
Stroke. 2022;53(4):1065-1073. © 2022 American Heart Association, Inc.
