Chong, Brian W.

Mechanical thrombectomy (MT) is the standard of care for patients who present with an acute ischemic stroke within 6 hours of symptom onset, and up to 24 hours in appropriately selected patients. However, optimal postoperative management of these patients remains uncertain, especially with regard to blood pressure control. To review the existing literature to define potential blood pressure goals in the immediate postoperative period in patients who undergo MT for acute ischemic stroke. The topic was defined through a clinical scenario and the subsequent development of a targeted clinical question. A literature search was performed, with relevant articles selected, one of which, a prospective observational study, was critically appraised. Participants included neurology residents and consultants, a medical librarian, clinical epidemiologists, as well as content experts from vascular neurology and interventional neuroradiology. Permissive hypertension (defined as <220/120 or <180/105 mm Hg as per the American Heart Association/American Stroke Association guidelines) may be harmful in the postoperative period following MT, especially in patients who were successfully recanalized. Moderate blood pressure control (<160/90) was found to be a predictor of improved 3-month mortality on multivariable logistic regression analysis in patients who sustained successful reperfusion [odds ratio (OR), 0.08; 95% confidence interval (CI), 0.01-0.054; P=0.01]. A 10 mm Hg increase in systolic blood pressure was found to result in a lower OR of having a favorable 3-month functional independence (OR, 0.70; 95% CI, 0.56-0.85; P=0.001) as well as higher rates of 3-month mortality (OR, 1.49; 95% CI, 1.18-1.88; P=0.001). Blood pressure goals in the immediate postoperative period in patients who undergo MT should differ than those who do not undergo MT, with data suggesting that lower blood pressure than permissive hypertension may be related to improved outcomes, especially in cases of successful reperfusion. However, current data are derived from observational studies; further studies, preferably in the form of randomized-controlled trials, are needed to further clarify the relationship between postoperative blood pressures and outcomes in this patient population.

Arteriovenous malformations (AVMs) are a subset of congenital vascular malformations (CVMs). They comprise abnormal connections between arterial and venous circulation; treatment approaches are dependent on the angioarchitecture of the AVM, specifically the number and arrangement of the feeder arteries and outflow veins. Various imaging modalities can be used to diagnose and plan treatment. Here we will review the use of transarterial approaches to treat AVMs.

Embolic coiling is one of the most effective treatments for cerebral aneurysms (CAs), largely due to the hemodynamic modifications that the treatment effects in the aneurysmal environment. However, coiling can have very different hemodynamic outcomes in aneurysms with different geometries. Previous work in the field of biofluid mechanics has demonstrated on a general level that geometry is a driving factor behind aneurysmal hemodynamics. The goal of this study was to relate two specific geometric factors that describe CAs (i.e., dome size (DS) and parent-vessel contact-angle (PV-CA)) and one factor that describes treatment (i.e., coil packing density (PD)) to three clinically relevant hemodynamic responses (i.e., aneurysmal root-mean-square velocity (Vrms), aneurysmal wall shear stress (WSS), and cross-neck flow (CNF)). Idealized models of basilar tip aneurysms were created in both virtual and physical forms to satisfy two-level multifactorial experimental designs. Steady and pulsatile flow hemodynamics were then evaluated in the virtual models using computational fluid dynamics (CFD) (before and after virtual treatment with finite element (FE) embolic coil models), and hemodynamics were also evaluated in the physical models using particle image velocimetry (PIV) (before and after treatment with actual embolic coils). Results showed that among the factors considered, PD made the greatest contributions to effects on hemodynamic responses in and around the aneurysmal sac (i.e., Vrms and WSS), while DS made the greatest contributions to effects on hemodynamics at the neck (i.e., CNF). Results also showed that while a geometric factor (e.g., PV-CA) may play a relatively minor role in dictating hemodynamics in the untreated case, the same factor can play a much greater role after coiling. We consider the significance of these findings in the context of aneurysmal recurrence and rupture, and explore potential roles for the proposed methods in endovascular treatment planning.

Intravenous recombinant tissue plasminogen activator continues to be first-line therapy for patients with acute ischemic stroke presenting within the appropriate time window, but one potential limitation is the low rate of recanalization in the setting of large artery occlusions. Intra-arterial (IA) treatment is effective for emergency revascularization of proximal intracranial arterial occlusions, but proof of benefit has been lacking until recently. Our goal is to outline the history of endovascular therapy and review both IA thrombolysis and mechanical interventions. In addition, we will discuss the impact of important trials such as the Third Interventional Management of Stroke (IMS3) trial, and the more recent trials Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands (MR CLEAN), Endovascular Treatment for Small Core and Proximal Occlusion Ischemic Stroke (ESCAPE), Extending the Time for Thrombolysis in Emergency Neurological Deficits—Intra-Arterial (EXTEND-IA), and Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment (SWIFT PRIME) on acute stroke management and the implications for the practicing neurohospitalist.

Endovascular coiling is the most common treatment for cerebral aneurysms. The treatment consists of deploying coils of different shapes and sizes into the aneurysm with the intent of reducing blood flow therein. While the treatment has been shown to be more effective than conventional surgical methods, it is successful in only 50–80% of cases, depending on the type of aneurysm [1]. Treatment success has been correlated with favorable post-treatment hemodynamics [2]. Understanding of the effects of coils on post-treatment hemodynamics is limited, however, due to limited in-vivo and in-vitro flow measurement techniques. Previous computational studies have also suffered from drastic assumptions about coil geometry.