Occult blood flow patterns distal to an occluded artery in acute ischemic stroke

Residual blood flow distal to an arterial occlusion in patients with acute ischemic stroke (AIS) is associated with favorable patient outcome. Both collateral flow and thrombus permeability may contribute to such residual flow. We propose a method for discriminating between these two mechanisms, based on determining the direction of flow in multiple branches distal to the occluding thrombus using dynamic Computed Tomography Angiography (dynamic CTA). We analyzed dynamic CTA data of 30 AIS patients and present patient-specific cases that identify typical blood flow patterns and velocities. We distinguished patterns with anterograde (N = 10), retrograde (N = 9), and both flow directions (N = 11), with a large variability in velocities for each flow pattern. The observed flow patterns reflect the interplay between permeability and collaterals. The presented method characterizes distal flow and provides a tool to study patient-specific distal tissue perfusion.

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Analyzing Circle of Willis blood flow in ischemic stroke patients through 3D Stroke Arterial Flow Estimation

Interventional Neuroradiology ◽

10.1177/1591019917703073 ◽

2017 ◽

Vol 23 (4) ◽

pp. 427-432 ◽

Cited By ~ 3

Author(s):

Aichi Chien ◽

Fernando Viñuela

Keyword(s):

Blood Flow ◽

Ischemic Stroke ◽

Flow Patterns ◽

Circle Of Willis ◽

Arterial Flow ◽

Patient Specific ◽

Collateral Flow ◽

Flow Data ◽

Time Resolved ◽

Flow Estimation

Background The objective of ischemic stroke (IS) treatment is to achieve revascularization in cerebral arteries to restore blood flow. However, there is no available method to extract arterial flow data from clinical CTA images. We developed 3D Stroke Arterial Flow Estimation (SAFE), which provides blood flow data throughout the Circle of Willis based on 3D CTA and allows comparison of arterial flow distribution in the brain. Methods We implemented a newly developed 3D vascular reconstruction algorithm for clinical stroke CTA images. Based on the patient-specific vascular structure, SAFE calculates time-resolved blood flow information for the entire Circle of Willis and allows quantitative flow study of IS cases. Clinical IS cases are presented to demonstrate the feasibility. Four patients with CTA images and CT perfusion data were studied. To validate the SAFE analysis, correlation analysis comparing blood flow at the MCA, ICA, and BA was performed. Results Different blood flow patterns were found in individual IS patients. Altered flow patterns and high collateral flow rates were found near occlusions in all cases. Quantitative comparison of blood flow data showed that SAFE obtained flow data and CTP were significantly correlated and provide complementary information about cerebral blood flow for individual patients. Conclusions We present SAFE analysis for collecting detailed time-resolved cerebral arterial flow data in the entire Circle of Willis for IS. Further study with more cases may be important to test the clinical utilization of SAFE and helpful to the study of the underlying hemodynamics of stroke.

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Abstract TMP89: Collaterals and Reperfusion Mediate Blood Pressure Changes in Acute Ischemic Stroke

Stroke ◽

10.1161/str.48.suppl_1.tmp89 ◽

2017 ◽

Vol 48 (suppl_1) ◽

Author(s):

David S Liebeskind ◽

Graham W Woolf ◽

Nerses Sanossian ◽

Jason D Hinman ◽

Radoslav Raychev ◽

...

Keyword(s):

Blood Pressure ◽

Ischemic Stroke ◽

Acute Ischemic Stroke ◽

Endovascular Therapy ◽

Arterial Occlusion ◽

Patient Specific ◽

Pressure Data ◽

Blood Pressure Data ◽

Pressure Changes ◽

Continuous Blood Pressure

Background: The pathophysiology and optimal management of blood pressure changes in acute ischemic stroke remain unknown. Blood pressure guidelines do not consider patient-specific or serial data on dynamic blood pressure readings. We investigated continuous blood pressure data during endovascular therapy for acute stroke to discern changes associated with collaterals, recanalization and reperfusion. Methods: Continuous monitoring blood pressure data was collected in consecutive cases of endovascular therapy for acute ischemic stroke due to ICA or proximal MCA occlusion. Angiography details were independently analyzed to document site of arterial occlusion, baseline collateral grade, time of device deployments, time of recanalization, time of final reperfusion, final AOL recanalization and final TICI reperfusion. Statistical analyses correlated instantaneous and serial blood pressure changes with these angiographic parameters. Results: 80 patients (median age 73 years; 33 women) were studied. Arterial lesions included 37 ICA and 41 proximal M1 MCA occlusions. Collateral grade prior to intervention included 2 ASITN grade 4, 26 grade 3, 23 grade 2, 6 grade 1 and 0 grade 0. oTICI2C reperfusion scores after thrombectomy included 2 TICI 3 (100%), 22 TICI 2C (90-99%), 25 TICI o2B (67-89%), 9 TICI m2B (50-66%), 19 TICI 2A (<50%) and 3 TICI 0/1. More robust collateral grade was associated with greater reperfusion scores (r=0.32, p=0.028). The change in blood pressure (ΔBP) from earliest BP to time of recanalization was mean 59% of ΔBP during the entire procedure. Better collaterals were associated with lower BP prior to recanalization (r=-0.377, p=0.012). Lower BP prior to recanalization was linked with greater TICI reperfusion (r=-0.242, p=0.050). Higher TICI reperfusion scores were also associated with a greater drop or ΔBP at the time of recanalization (r=0.269, p=0.031). AOL recanalization was not related to ΔBP. Conclusions: Collaterals and reperfusion, but not recanalization, mediate blood pressure changes in acute ischemic stroke. Prospective, precision medicine stroke studies should leverage patient-specific, real-time data on continuous blood pressure with imaging correlates to define BP goals of future in-hospital management.

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Prevention of the collapse of pial collaterals by remote ischemic perconditioning during acute ischemic stroke

Journal of Cerebral Blood Flow & Metabolism ◽

10.1177/0271678x16680636 ◽

2016 ◽

Vol 37 (8) ◽

pp. 3001-3014 ◽

Cited By ~ 14

Author(s):

Junqiang Ma ◽

Yonglie Ma ◽

Bin Dong ◽

Mischa V Bandet ◽

Ashfaq Shuaib ◽

...

Keyword(s):

Blood Flow ◽

Ischemic Stroke ◽

Acute Ischemic Stroke ◽

Cerebral Artery ◽

Laser Speckle ◽

Laser Scanning Microscopy ◽

Collateral Flow ◽

Contrast Imaging ◽

Peripheral Ischemia ◽

Remote Ischemic Perconditioning

Collateral circulation is a key variable determining prognosis and response to recanalization therapy during acute ischemic stroke. Remote ischemic perconditioning (RIPerC) involves inducing peripheral ischemia (typically in the limbs) during stroke and may reduce perfusion deficits and brain damage due to cerebral ischemia. In this study, we directly investigated pial collateral flow augmentation due to RIPerC during distal middle cerebral artery occlusion (MCAo) in rats. Blood flow through pial collaterals between the anterior cerebral artery (ACA) and the MCA was assessed in male Sprague Dawley rats using in vivo laser speckle contrast imaging (LSCI) and two photon laser scanning microscopy (TPLSM) during distal MCAo. LSCI and TPLSM revealed that RIPerC augmented collateral flow into distal MCA segments. Notably, while control rats exhibited an initial dilation followed by a progressive narrowing of pial arterioles 60 to 150-min post-MCAo (constricting to 80–90% of post-MCAo peak diameter), this constriction was prevented or reversed by RIPerC (such that vessel diameters increased to 105–110% of post-MCAo, pre-RIPerC diameter). RIPerC significantly reduced early ischemic damage measured 6 h after stroke onset. Thus, prevention of collateral collapse via RIPerC is neuroprotective and may facilitate other protective or recanalization therapies by improving blood flow in penumbral tissue.

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Cerebral collateral therapeutics in acute ischemic stroke: A randomized preclinical trial of four modulation strategies

Journal of Cerebral Blood Flow & Metabolism ◽

10.1177/0271678x16688705 ◽

2017 ◽

Vol 37 (10) ◽

pp. 3344-3354 ◽

Cited By ~ 12

Author(s):

Simone Beretta ◽

Alessandro Versace ◽

Davide Carone ◽

Matteo Riva ◽

Valentina Dell’Era ◽

...

Keyword(s):

Ischemic Stroke ◽

Acute Ischemic Stroke ◽

Arterial Occlusion ◽

Mean Difference ◽

Collateral Flow ◽

Efficacy And Safety ◽

Preclinical Trial ◽

Volume Load ◽

Mca Occlusion ◽

Saving Effect

Cerebral collaterals are dynamically recruited after arterial occlusion and highly affect tissue outcome in acute ischemic stroke. We investigated the efficacy and safety of four pathophysiologically distinct strategies for acute modulation of collateral flow (collateral therapeutics) in the rat stroke model of transient middle cerebral artery (MCA) occlusion. A composed randomization design was used to assign rats (n = 118) to receive phenylephrine (induced hypertension), polygeline (intravascular volume load), acetazolamide (cerebral arteriolar vasodilation), head down tilt (HDT) 15° (cerebral blood flow diversion), or no treatment, starting 30 min after MCA occlusion. Compared to untreated animals, treatment with collateral therapeutics was associated with lower infarct volumes (62% relative mean difference; 51.57 mm3 absolute mean difference; p < 0.001) and higher chance of good functional outcome (OR 4.58, p < 0.001). Collateral therapeutics acutely increased cerebral perfusion in the medial (+40.8%; p < 0.001) and lateral (+19.2%; p = 0.016) MCA territory compared to pretreatment during MCA occlusion. Safety indicators were treatment-related mortality and cardiorespiratory effects. The highest efficacy and safety profile was observed for HDT. Our findings suggest that acute modulation of cerebral collaterals is feasible and provides a tissue-saving effect in the hyperacute phase of ischemic stroke prior to recanalization therapy.

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P1449 CMR-driven computational modeling of right ventricular flow dynamics

European Heart Journal - Cardiovascular Imaging ◽

10.1093/ehjci/jez319.877 ◽

2020 ◽

Vol 21 (Supplement_1) ◽

Author(s):

F Capuano ◽

L Romano ◽

Y H Loke ◽

S Dellegrottaglie ◽

M Notorio ◽

...

Keyword(s):

Blood Flow ◽

Computational Modeling ◽

Computational Models ◽

Pulmonary Arteries ◽

Flow Patterns ◽

Imaging Biomarkers ◽

Patient Specific ◽

Right Heart ◽

The Right ◽

Blood Flow Patterns

Abstract Introduction The analysis of intracardiac blood flow patterns can significantly contribute to improve the understanding and treatment of cardiovascular disease. In contrast to the substantial literature on the left side of the heart, there is currently a significant lack of knowledge about the fluid mechanics of the right heart – pulmonary circulation unit (RH-PCU), both in healthy and diseased conditions. Purpose It is conjectured that computational modeling can be a key element to enhance current imaging techniques and provide quantitative insights into the unique RH-PCU biomechanics. Here we present a novel methodology that allows personalized numerical simulations of right heart flows, through a proper combination of cardiac magnetic resonance (CMR) with computational fluid dynamics (CFD). Methods and results We developed a patient-specific pipeline from medical images to computational models, as depicted in the figure. First, the RV geometry is reconstructed from time-resolved CMR cine images, comprising short-axis and longitudinal slices of the heart, where feature-tracking techniques are used to extract the motion of the RV endocardium contours. A time-continuous description of the moving geometry is obtained through an image-registration algorithm based on diffeomorphic mappings. The moving model of the RV, including the outflow tract and proximal pulmonary arteries, is finally fed to a dedicated CFD solver. The tool is able to provide a detailed description of the velocity and pressure fields inside the right ventricle and proximal pulmonary arteries during all phases of the cardiac cycle. From these fields, global hemodynamic quantities such as vortex properties, kinetic energy, pressure gradients and hemodynamic forces can be computed. Conclusions CMR-driven computational modeling of intra-ventricular flow enables a promising approach for understanding and evaluating the biomechanical environment of the right heart. This high-fidelity framework can be applied to investigate the RV response and adaptation to abnormal pressure and/or volume load conditions. It can also be used to reproduce the virtual flow that would realize in hypothetical conditions, and therefore adds predictive capabilities to modern flow imaging. The analysis may allow to determine an association between blood flow patterns and disease progression, and ultimately lead to derive and validate imaging biomarkers of clinical significance. Abstract P1449 Figure. Pipeline for patient-specific modeling

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Failure of Collateral Blood Flow is Associated with Infarct Growth in Ischemic Stroke

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.2013.77 ◽

2013 ◽

Vol 33 (8) ◽

pp. 1168-1172 ◽

Cited By ~ 140

Author(s):

Bruce CV Campbell ◽

Søren Christensen ◽

Brian M Tress ◽

Leonid Churilov ◽

Patricia M Desmond ◽

...

Keyword(s):

Blood Flow ◽

Ischemic Stroke ◽

Arterial Occlusion ◽

Perfusion Magnetic Resonance Imaging ◽

Lesion Volume ◽

Collateral Flow ◽

Collateral Blood Flow ◽

Collateral Vessel ◽

Magnetic Resonance Imaging Mri ◽

Simultaneous Assessment

Changes in collateral blood flow, which sustains brain viability distal to arterial occlusion, may impact infarct evolution but have not previously been demonstrated in humans. We correlated leptomeningeal collateral flow, assessed using novel perfusion magnetic resonance imaging (MRI) processing at baseline and 3 to 5 days, with simultaneous assessment of perfusion parameters. Perfusion raw data were averaged across three consecutive slices to increase leptomeningeal collateral vessel continuity after subtraction of baseline signal analogous to digital subtraction angiography. Changes in collateral quality, Tmax hypoperfusion severity, and infarct growth were assessed between baseline and days 3 to 5 perfusion-diffusion MRI. Acute MRI was analysed for 88 patients imaged 3 to 6 hours after ischemic stroke onset. Better collateral flow at baseline was associated with larger perfusion-diffusion mismatch (Spearman's Rho 0.51, P < 0.001) and smaller baseline diffusion lesion volume (Rho − 0.70, P < 0.001). In 30 patients without reperfusion at day 3 to 5, deterioration in collateral quality between baseline and subacute imaging was strongly associated with absolute ( P = 0.02) and relative ( P < 0.001) infarct growth. The deterioration in collateral grade correlated with increased mean Tmax hypoperfusion severity (Rho − 0.68, P < 0.001). Deterioration in Tmax hypoperfusion severity was also significantly associated with absolute ( P = 0.003) and relative ( P = 0.002) infarct growth. Collateral flow is dynamic and failure is associated with infarct growth.

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