Image-based patient-specific flow simulations are consistent with stroke in pediatric cerebrovascular disease
Shaolie S Hossain1,2, Zbigniew Starosolski3,4, Travis Sanders5
1Molecular Cardiology Research Laboratory, Texas Heart Institute, 6770 Bertner Avenue, Houston, TX, 77030, USA. shossain@texasheart.org.
Abstract:
Moyamoya disease (MMD) is characterized by narrowing of the distal internal carotid artery and the circle of Willis (CoW) and leads to recurring ischemic and hemorrhagic stroke. A retrospective review of data from 50 pediatric MMD patients revealed that among the 24 who had a unilateral stroke and were surgically treated, 11 (45.8%) had a subsequent, contralateral stroke. There is no reliable way to predict these events. After a pilot study in Acta-/- mice that have features of MMD, we hypothesized that local hemodynamics are predictive of contralateral strokes and sought to develop a patient-specific analysis framework to noninvasively assess this stroke risk. A pediatric MMD patient with an occlusion in the right middle cerebral artery and a right-sided stroke, who was surgically treated and then had a contralateral stroke, was selected for analysis. By using an unsteady Navier-Stokes solver within an isogeometric analysis framework, blood flow was simulated in the CoW model reconstructed from the patient's postoperative imaging data, and the results were compared with those from an age- and sex-matched control subject. A wall shear rate (WSR) > 60,000 s-1 (about 12 × higher than the coagulation threshold of 5000 s-1 and 9 × higher than control) was measured in the terminal left supraclinoid artery; its location coincided with that of the subsequent postsurgical left-sided stroke. A parametric study of disease progression revealed a strong correlation between the degree of vascular morphology altered by MMD and local hemodynamic environment. The results suggest that an occlusion in the CoW could lead to excessive contralateral WSRs, resulting in thromboembolic ischemic events, and that WSR could be a predictor of future stroke.
Insights
Moyamoya disease (MMD) patients undergoing surgery face a high risk of contralateral stroke. Local hemodynamics, specifically high wall shear rate (WSR), may predict these future events, offering a new risk assessment tool.
Area of Science:
- Neurology
- Biomedical Engineering
- Vascular Surgery
Background:
- Moyamoya disease (MMD) involves progressive narrowing of cerebral arteries, leading to recurrent strokes.
- Pediatric MMD patients treated surgically for unilateral stroke have a significant risk (45.8%) of subsequent contralateral strokes.
- Current methods lack reliable prediction of these secondary stroke events.
Purpose of the Study:
- To develop a patient-specific computational framework for assessing stroke risk in MMD.
- To investigate the role of local hemodynamics in predicting contralateral strokes after MMD surgery.
- To identify hemodynamic parameters that correlate with stroke occurrence in MMD patients.
Main Methods:
- Utilized a retrospective review of pediatric MMD patients and a case study of a patient with sequential contralateral strokes.
- Employed an unsteady Navier-Stokes solver within an isogeometric analysis framework to simulate blood flow in patient-specific Circle of Willis (CoW) models.
- Reconstructed CoW models from postoperative imaging data and compared hemodynamic parameters with a healthy control subject.
Main Results:
- Identified a high wall shear rate (WSR) > 60,000 s⁻¹ in the terminal left supraclinoid artery of the MMD patient, coinciding with the location of a subsequent stroke.
- This elevated WSR was significantly higher than normal (9x) and the coagulation threshold (12x).
- Demonstrated a strong correlation between altered vascular morphology due to MMD and the local hemodynamic environment, with parametric studies showing disease progression impacts WSR.
Conclusions:
- Cerebral artery occlusion in MMD can lead to excessive contralateral wall shear rates (WSRs).
- Elevated WSR is a potential predictor of future thromboembolic ischemic events in MMD patients.
- This hemodynamic analysis framework offers a novel, noninvasive method for assessing stroke risk in MMD.
