Measured via intraoperative micro-Doppler probe on isolated STA trunk.
MCA Recipient
Inflow Angle
Hemodynamic Anchor
Flow modeling is based on Poiseuille-derived principles where graft resistance and geometry significantly influence final revascularization capacity.
Microvascular Sentinel Probe
Input the donor baseline flow and recipient anatomical characteristics to estimate the theoretical graft capacity and revascularisation adequacy.
Guidelines & Evidence
Clinical Details
Section 1
When to Use
When to Use
Pre-operative planning for Moyamoya revascularisation (STA-MCA bypass).
Assessing donor vessel suitability in bypass surgery for complex aneurysms or carotid occlusive disease.
Section 2
Literature
Development
EC-IC (Extracranial-Intracranial) bypass was systematised by M. Gazi Yasargil in the 1960s-70s. The first STA-MCA bypass was performed in 1967. The concept of measuring pre-operative STA flow by Doppler to predict graft patency was established through decades of cerebrovascular surgery experience. A graft flow exceeding 20 mL/min is considered adequate to meaningfully augment cerebral perfusion.
Section 3
Pearls/Pitfalls
The Patency Paradox
A patent bypass with good flow does not guarantee clinical benefit if the native circulation compensates (as demonstrated by the EC-IC Bypass Study in 1985). Modern indications are focused on patients with proven haemodynamic cerebral insufficiency — documented by acetazolamide-challenge SPECT or quantitative MRI perfusion, showing a "misery perfusion" pattern.
Section 4
Evidence Appraisal
Primary Reference
Failure of extracranial–intracranial arterial bypass to reduce the risk of ischemic stroke
The EC/IC Bypass Study Group. • N Engl J Med. 1985;313(19):1191-200
