The hemodynamic complexities underlying transient ischemic attacks in early-stage Moyamoya disease: an exploratory...

Area of Science:

• Cerebrovascular diseases
• Hemodynamics
• Computational fluid dynamics

Background:

• Moyamoya disease (MMD) is a rare cerebro-occlusive condition causing stroke.
• It involves internal carotid artery stenosis and collateral vessel formation.
• Early MMD can cause hemodynamic insufficiency despite mild stenosis.

Observation:

• High-resolution Large Eddy Simulations analyzed blood flow in five early-stage MMD patients.
• Investigated effects of transitional flow, flow structures, and shear-thinning in stenosed arteries.
• Explored link between hemodynamic phenomena and patient symptomatology.

Findings:

• Complex vortex structures, like Rankine-type vortices, were observed redirecting blood flow.
• Partial blood hammer (PBH) phenomenon was detected, causing significant hemodynamic insufficiency.
• PBH linked to shear-thinning, transitional flow, and pressure-velocity phase lag loss.

Implications:

• Hemodynamic complexities in early MMD can induce cerebral ischemia.
• Findings explain MMD's non-responsiveness to antiplatelet therapy.
• Highlights the role of advanced simulations in understanding MMD pathophysiology.