Quantification of the Tissue Oxygenation Delay Induced by Breath-Holding in Patients with Carotid Atherosclerosis

Area of Science:

• Neuroscience
• Vascular Biology
• Medical Imaging

Background:

• Carotid artery stenosis (CAS) is a prevalent vascular condition linked to brain damage.
• Impaired cerebral hemodynamics in the microvasculature of CAS patients are not well understood.
• Understanding these hemodynamic changes is crucial for managing neurological consequences.

Purpose of the Study:

• To introduce and validate a novel methodological approach for quantifying temporal delays in evoked hemodynamic responses.
• To assess cerebral hemodynamic impairment in patients with carotid artery stenosis (CAS) using functional near-infrared spectroscopy (fNIRS).

Main Methods:

• Functional near-infrared spectroscopy (fNIRS) was utilized to measure hemodynamic responses.
• A vasodilatory task (breath-holding) was employed to evoke a measurable hemodynamic response.
• The methodology was validated in 50 CAS patients and 20 healthy controls.

Main Results:

• A significant delay in the hemodynamic response to breath-holding was observed in severe CAS patients (up to 6s) compared to controls (median 4s).
• The proportion of brain regions responding to the task decreased with increasing CAS severity (90% in controls to 73% in severe CAS).
• Collateral circulation improved the response but did not fully normalize time delays; artery count alone was not predictive.

Conclusions:

• A new quantitative method using fNIRS can effectively assess impaired cerebral hemodynamics in CAS patients.
• The findings highlight significant hemodynamic alterations in the brain microvasculature due to CAS.
• This method offers potential for improved diagnosis and monitoring of neurological complications in CAS.