Clinical cerebrovascular anatomy

Total aortic arch replacement without deep hypothermic circulatory arrest in type A aortic dissection: Left axillar artery for arterial cannulation

Objective

Total aortic arch replacement (TAR) necessitates hypothermic circulatory arrest (CA). The frozen elephant trunk technique (FET) additionally requires commercial hybrid grafts. Herein we describe a novel modified FET technique without CA using standard grafts thanks to left axillary artery (LAxA) cannulation in patients with acute type A aortic dissection.

Methods

LAxA anastomosis is made first using a homemade debranching graft, and cardiopulmonary bypass is initiated, followed by anastomoses of left common carotid and innominate arteries. The rest of the operation is performed with complete cerebral perfusion. Following replacement of ascending aorta/root, cardiac reperfusion is started using a root cannula which continues throughout the procedure. Distal arch anastomosis is performed clamp-on, allowing lower body perfusion via left subclavian artery. Lower body perfusion is interrupted for 5 to 8 minutes to deploy an endograft to complete a modified FET. Following cannulation of distal arch graft, perfusion of distal aorta is restarted, and all three grafts are incorporated to construct a neo-ascending aorta and arch.

Results

Between December 2018 and May 2022, 38 patients underwent TAR without operative mortality. Hospital mortality was %15.7, and spinal cord ischemia and stroke were not encountered in surviving patients. The mean lower body CA time was 7.2 ± 2.8 minutes.

Conclusions

TAR using standard endografts without CA is possible with LAxA cannulation. To perform a FET, only a short interruption of lower body circulation is sufficient to deploy an endograft, also improving hemostasis of distal anastomosis. Further studies are required with a higher number of patients to evaluate the efficiency of this novel technique.

Circle of Willis variants and their association with outcome in patients with middle cerebral artery-M1-occlusion stroke

Background

An incomplete circle of Willis (CoW) has been associated with a higher risk of stroke and might affect collateral flow in large vessel occlusion (LVO) stroke. We aimed to investigate the distribution of CoW variants in a LVO stroke and transient ischemic attack (TIA) cohort and analyze their impact on 3‐month functional outcome.

Methods

CoW anatomy was assessed with time‐of‐flight magnetic resonance angiography (TOF‐MRA) in 193 stroke patients with acute middle cerebral artery (MCA)‐M1‐occlusion receiving endovascular treatment (EVT) and 73 TIA patients without LVO. The main CoW variants were categorized into four vascular models of presumed collateral flow via the CoW.

Results

82.4% (n = 159) of stroke and 72.6% (n = 53) of TIA patients had an incomplete CoW. Most variants affected the posterior circulation (stroke: 77.2%, n = 149; TIA: 58.9%, n = 43; p = 0.004). Initial stroke severity defined by the National Institutes of Health Stroke Scale (NIHSS) on admission was similar for patients with and without CoW variants. CoW integrity did not differ between groups with favorable (modified Rankin Scale [mRS]): 0–2) and unfavorable (mRS: 3–6) 3‐month outcome. However, we found trends towards a higher mortality in patients with any type of CoW variant (p = 0.08) and a higher frequency of incomplete CoW among patients dying within 3 months after stroke onset (p = 0.119). In a logistic regression analysis adjusted for the potential confounders age, sex and atrial fibrillation, neither the vascular models nor anterior or posterior variants were independently associated with outcome.

Conclusion

Our data provide no evidence for an association of CoW variants with clinical outcome in LVO stroke patients receiving EVT.

Variants of the circle of Willis in ischemic stroke patients

PURPOSE

We aim to provide prevalence and pattern of anatomical variants of circle of Willis in over one thousand ischemic stroke patients compared to an age- and sex-matched control group, and to determine their role in the severity and in-hospital prognosis.

METHODS

Two groups of neuroradiologists evaluated all vascular images of ischemic stroke patients and controls to identify anatomical variants using a preexisted classification. We collected data concerning patient characteristics, stroke severity on admission and discharge, in-hospital mortality, hemorrhagic transformation, acute treatment performed, and etiology.

RESULTS

We included 1131 patients with acute ischemic stroke and 562 controls. Among stroke patients, 702 (62.1%) had one or more vascular variants, compared to 308 (54.8%) of the control group (p < 0.01), 165/702 (23.5%) had an anterior circulation variant only, 384/702 (54.7%) had a posterior circulation variant only, and 153/702 (21.8%) patients had variants in both anterior and posterior circulation. Patients with variants were older (69.7 ± 13.9 years vs 72.0 ± 12.9 years; p = 0.039). The most prevalent variant was the agenesis/hypoplasia of the ACA (201/1131; 17.8%) followed by the unilateral fetal type of the PCA (137/1131; 12.11%).

CONCLUSIONS

We provided the prevalence and the pattern of the brain vascular variants of the circle of Willis in a cohort of patients with ischemic stroke. The prevalence of variants was higher in stroke patients compared to controls. Patients with variants were older but had no differences in sex, neurological admission severity, hemorrhagic transformation, etiology, and in-hospital outcome compared to patients with a typical circle of Willis.

[Method of surgical treatment of patients with combined pathological tortuosity of the common and internal carotid arteries]

Pathological tortuosity of the internal carotid artery ranks next to atherosclerosis amongst causes leading to development of ischaemic strokes. In some patients pathological tortuosity of the internal carotid artery is combined with pathological kinking of the common carotid artery. Existing methods of surgical treatment for such concomitant pathology include stegewise elimination of kinking of the internal then common carotid artery, with two anastomoses sequentially formed, thus increasing the overall duration of arterial cross-clamping an prolonging cerebral ischaemia. Another method consists of resection of the common carotid artery with bringing down its bifurcation, restoration of straightness of the internal carotid artery, and formation of an end-to-end anastomosis. The second technique is often associated with technical requirement for ligation of the external carotid artery. In the presence of prolonged atherosclerotic lesions of the bifurcation of the internal and external carotid arteries, this method does not always allow carrying out adequate endarterectomy and fix the intima of the internal carotid artery distal to the bifurcation. The authors developed a method of surgical treatment of patients with a combination of pathological kinking of carotid arteries, providing herein a detailed description of the procedure of performing an operation according to an original technique. The proposed method of reconstruction makes it possible to eliminate pathological kinking of the common and internal carotid arteries in single cross-clamping of vessels, to preserve patency of the external carotid artery and in the presence of an atherosclerotic lesion of the bifurcation to perform adequate endarterectomy. Over the period from 2015 to 2019, a total of 10 patients were operated on according to this technique at the Municipal Vascular Centre of Samara, with no postoperative complications observed. The proposed technique of a reconstructive operation may be effectively used in patients with cerebral ischaemia in concomitant pathological kinking of the common and internal carotid arteries.

Posterior communicating and anterior communicating arteries on pre-thrombectomy computed tomography scans are associated with good outcomes irrespective of leptomeningeal collateral status

BACKGROUND

Collateral blood flow is known to be an important factor that sustains the penumbra during acute stroke. We looked at both the leptomeningeal collateral circulation and the presence of anterior and posterior communicating arteries to determine the factors associated with good outcomes and mortality.

METHODS

We included all patients with acute ischaemic stroke in the anterior circulation, who underwent thrombectomy with the same thrombectomy device from 2013 to 2016. We assessed the leptomeningeal circulation by the Tan, Miteff and Maas validated scoring systems on pre-treatment computed tomographic angiography scans and looked at collateral flow through anterior and posterior communicating arteries. The results were good functional outcomes at 3 months (modified Rankin scale 0-2) and mortality.

RESULTS

A total of 147 consecutive acute stroke patients treated with the Embotrap device were included with a median National Institutes of Health stroke scale of 15 (range 2-26). On multivariate analysis only younger age (odds ratio (OR) 0.96/year, 95% confidence interval (CI) 0.94-0.99, P = 0.026), lower National Institutes of Health stroke scale score (OR 0.87/point, 95% CI 0.80-0.93, P < 0.001), number of attempts (OR 0.80/attempt, 95% CI 0.65-0.99, P = 0.043) and the presence of a patent anterior communicating artery (OR 14.03, 95% CI 1.42-139.07, P = 0.024) were associated with good functional outcomes. The number of attempts (OR 1.66/attempt, 95% CI 1.21-2.29, P = 0.002) was significantly associated with mortality and the presence of a patent posterior communicating artery (OR 0.098, 95% CI 0.016-0.59, P = 0.011) was inversely associated with mortality.

CONCLUSIONS

Our study shows that the presence of anterior and posterior communicating arteries is significantly associated with good functional outcomes and reduced mortality, respectively, independent of the leptomeningeal circulation status.

Anterior Borderzone Angle for Hemodynamic Collateral Metric in Patients with Symptomatic Middle Cerebral Artery Stenosis

BACKGROUND AND AIMS

We aimed to introduce a parameter of anterior borderzone angle (ABZA) to quantitatively evaluate the ACA-MCA leptomeningeal collaterals for middle cerebral artery stenosis (MCAS).

METHODS

Two hundred seventy-five patients with 50-100% MCAS and 100 controls were included. The 95% reference range of ABZA was obtained from the controls. ABZAtrans was defined as "ABZA/the 95% upper limit." Relationships between ABZA and MCAS, -ABZAtrans and the TICI grade, the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) collateral grade were analyzed. An ABZA grade model for the ACA leptomeningeal collaterals was tentatively developed.

RESULTS

The 95% reference range of ABZA was 0.0º-23.0º. ABZA was significantly associated with MCAS by a function of the fourth power (R2 = 0.723, p < 0.001), and could predict hemodynamic MCAS (≥70%) with an AUC of 0.928 (95% CI 0.903-0.953). ABZAtrans was negatively correlated with the TICI grade (rho = -0.752, p < 0.001) and positively with the ASITN/SIR grade (rho = 0.921, p < 0.001). The ABZA grade was created by rounding -ABZAtrans to a nearest integer, and was closely associated with the ASITN/SIR grade (rho = 0.894, p < 0.001).

CONCLUSIONS

ABZA can be used as a hemodynamic parameter to quantitatively evaluate ACA leptomeningeal collaterals.

Fetal-Type Variants of the Posterior Cerebral Artery and Concurrent Infarction in the Major Arterial Territories of the Cerebral Hemisphere

Fetal-type or fetal posterior cerebral artery (FPCA) is a variant of cerebrovascular anatomy in which the distal posterior cerebral artery (PCA) territory is perfused by a branch of the internal carotid artery (ICA). In the presence of FPCA, thromboembolism in the anterior circulation may result in paradoxical PCA territory infarction with or without concomitant infarction in the territories of the middle (MCA) or the anterior (ACA) cerebral artery. We describe 2 cases of FPCA and concurrent acute infarction in the PCA and ICA territories-right PCA and MCA in Patient 1 and left PCA, MCA, and ACA in Patient 2. Noninvasive angiography detected a left FPCA in both patients. While FPCA was clearly the mechanism of paradoxical infarction in Patient 2, it turned out to be an incidental finding in Patient 1 when evidence of a classic right PCA was uncovered from an old computed tomography scan image. Differences in anatomical details of the FPCA in each patient suggest that the 2 FPCAs are developmentally different. The FPCA of Patient 1 appeared to be an extension of the embryonic left posterior communicating artery (PcomA). Patient 2 had 2 PCAs on the left (PCA duplication), classic bilateral PCAs, and PcomAs, and absent left anterior choroidal artery (AchoA), suggesting developmental AchoA-to-FPCA transformation on the left. These 2 cases underscore the variable anatomy, clinical significance, and embryological origins of FPCA variants.

Aging is associated with changes to the biomechanical properties of the posterior cerebral artery and parenchymal arterioles

Artery remodeling, described as a change in artery structure, may be responsible for the increased risk of cardiovascular disease with aging. Although the risk for stroke is known to increase with age, relatively young animals have been used in most stroke studies. Therefore, more information is needed on how aging alters the biomechanical properties of cerebral arteries. Posterior cerebral arteries (PCAs) and parenchymal arterioles (PAs) are important in controlling brain perfusion. We hypothesized that aged (22-24 mo old) C57bl/6 mice would have stiffer PCAs and PAs than young (3-5 mo old) mice. The biomechanical properties of the PCAs and PAs were assessed by pressure myography. Data are presented as means ± SE of young vs. old. In the PCA, older mice had increased outer (155.6 ± 3.2 vs. 169.9 ± 3.2 μm) and lumen (116.4 ± 3.6 vs. 137.1 ± 4.7 μm) diameters. Wall stress (375.6 ± 35.4 vs. 504.7 ± 60.0 dyn/cm(2)) and artery stiffness (β-coefficient: 5.2 ± 0.3 vs. 7.6 ± 0.9) were also increased. However, wall strain (0.8 ± 0.1 vs. 0.6 ± 0.1) was reduced with age. In the PAs from old mice, wall thickness (3.9 ± 0.3 vs. 5.1 ± 0.2 μm) and area (591.1 ± 95.4 vs. 852.8 ± 100 μm(2)) were increased while stress (758.1 ± 100.0 vs. 587.2 ± 35.1 dyn/cm(2)) was reduced. Aging also increased mean arterial and pulse pressures. We conclude that age-associated remodeling occurs in large cerebral arteries and arterioles and may increase the risk of cerebrovascular disease.

Completeness of the circle of Willis and risk of ischemic stroke in patients without cerebrovascular disease

Introduction

We investigated circle of Willis (CoW) completeness in relation to the risk of future ischemic stroke in patients without prior cerebrovascular disease.

Methods

We included 976 patients with atherosclerotic disease, but no previous TIA/stroke, from the Second Manifestations of ARTerial disease (SMART) study. All patients underwent MR angiography of the CoW. Cox regression was used to determine whether anterior CoW completeness (anterior communicating artery or A1 segments) and posterior CoW completeness (posterior communicating arteries or P1 segments) were related to future stroke, and whether CoW completeness influenced the relation between internal carotid artery (ICA) stenosis/occlusion and future stroke.

Results

Thirty patients (3.1 %) had ischemic stroke after 9.2 ± 3.0 years of follow-up. Twenty-four patients (80 %) had anterior circulation stroke. An incomplete anterior CoW was related to future anterior circulation stroke (HR 2.8 (95 % CI 1.3–6.3); p = 0.01), whereas a one-sided and two-sided incomplete posterior CoW were not (HR 2.2 (95 % CI 0.7–7.1; p = 0.19) and 1.9 (95 % CI 0.6–5.9; p = 0.29), respectively). In stratified analyses, patients with an incomplete anterior CoW had the highest risk of future anterior circulation stroke when they also had a one-sided (HR 7.0 (95 % CI 1.3–38.2; p = 0.02)) or two-sided incomplete posterior CoW (HR 5.4 (95 % CI 1.0–27.8; p = 0.04). CoW completeness did not change the relation between asymptomatic ICA stenosis/occlusion and future ischemic stroke (p = 0.68).

Conclusions

An incomplete anterior CoW combined with an incomplete posterior CoW is related to future anterior circulation stroke. CoW completeness has no large effect on the relation between asymptomatic ICA stenosis/occlusion and future stroke.

Angle between the common and internal carotid arteries detected by ultrasound is related to intima-media thickness among those with atherosclerotic disease

OBJECTIVES

Although carotid artery structural variations have been detected by ultrasound, their clinical significance is not fully understood. The objective of this study was to determine whether the angle between the common carotid artery (CCA) and the internal carotid artery (ICA), designated angle α, an ultrasound-detectable carotid artery structural variation, is related to carotid artery intima-media thickness (IMT), a surrogate marker for carotid atherosclerosis.

METHODS

As a cross-sectional study, we measured angle α in routine carotid artery ultrasounds from 176 subjects (130 men) with atherosclerotic disease/risk factors that attended Kouseiren Hospital in Kagoshima City, Japan between August 2007 and April 2009. We evaluated the correlation between the angle α and CCA- or ICA-IMT.

RESULTS

Angle α was weakly correlated with age but significantly correlated with ICA-IMT. The correlation was stronger in subjects with an ICA-IMT ≥ 0.5 mm than in those with an ICA-IMT < 0.5 mm (Right side r = 0.475 vs. 0.246, Left side r = 0.498 vs. 0.301, respectively). Upon multivariate logistic regression analysis, angle α and serum low-density lipoprotein cholesterol were independent explanatory variables for ICA-IMT.

CONCLUSION

Angle α is related to ICA-IMT in subjects with atherosclerotic disease or risk factors in this study.

Basic vascular neuroanatomy of the brain and spine: what the general interventional radiologist needs to know

This article is intended to provide a review of clinically relevant neurovascular anatomy. A solid understanding of the vascular anatomy of the brain and spine are essential for the safe and effective performance of neurointerventional radiology. Key concepts to master include collateral pathways and anastomoses between the external and internal carotid circulation, the Circle of Willis as a route to otherwise inaccessible intracranial vascular distributions, and the origin of spinal arterial blood supply. These concepts will be highlighted using clinical angiographic examples with discussion of relevant embryology and pathology as needed.

Vascular remodeling after ischemic stroke: mechanisms and therapeutic potentials

The brain vasculature has been increasingly recognized as a key player that directs brain development, regulates homeostasis, and contributes to pathological processes. Following ischemic stroke, the reduction of blood flow elicits a cascade of changes and leads to vascular remodeling. However, the temporal profile of vascular changes after stroke is not well understood. Growing evidence suggests that the early phase of cerebral blood volume (CBV) increase is likely due to the improvement in collateral flow, also known as arteriogenesis, whereas the late phase of CBV increase is attributed to the surge of angiogenesis. Arteriogenesis is triggered by shear fluid stress followed by activation of endothelium and inflammatory processes, while angiogenesis induces a number of pro-angiogenic factors and circulating endothelial progenitor cells (EPCs). The status of collaterals in acute stroke has been shown to have several prognostic implications, while the causal relationship between angiogenesis and improved functional recovery has yet to be established in patients. A number of interventions aimed at enhancing cerebral blood flow including increasing collateral recruitment are under clinical investigation. Transplantation of EPCs to improve angiogenesis is also underway. Knowledge in the underlying physiological mechanisms for improved arteriogenesis and angiogenesis shall lead to more effective therapies for ischemic stroke.