Cerebral haemodynamic considerations in obstructive carotid artery disease

Area of Science:

• Neurology
• Vascular Medicine
• Medical Imaging

Background:

• Obstructive carotid artery disease poses a risk for stroke.
• Assessing cerebrovascular reserve is crucial for managing this condition.
• Transcranial Doppler ultrasonography offers a non-invasive method to evaluate cerebral hemodynamics.

Purpose of the Study:

• To investigate the association between baseline cerebrovascular parameters and vasomotor reactivity.
• To introduce and validate a novel index (Uhem index) for assessing cerebrovascular tone.
• To determine the predictive value of the Uhem index for impaired vasomotor reserve.

Main Methods:

• 46 subjects with obstructive carotid artery disease underwent transcranial Doppler ultrasonography.
• Baseline velocities (V) and pulsatility index (PI) were measured in the middle cerebral artery (MCA), anterior cerebral artery (ACA), posterior cerebral artery (PCA), and internal carotid artery (ICA).
• Vasomotor reactivity was assessed using hypocapnic and hypercapnic challenges, and the Uhem index (VMCA.PIMCA/VPCA.PIPCA) was calculated.

Main Results:

• A strong correlation was found between the Uhem index and total vasomotor reactivity, fitting a hyperbolic curve.
• The hyperbolic tangent of the Uhem index and total vasomotor reactivity showed a highly significant correlation (r = 0.8203, p < 0.0001).
• An Uhem index ≥ 0.94 indicated normal vasomotor reactivity, while ≤ 0.81 suggested impaired reactivity, validated in a post hoc cohort.

Conclusions:

• The Uhem index is a reliable indicator of cerebrovascular tone and predicts vasomotor reactivity in obstructive carotid artery disease.
• This novel index offers a valuable tool for non-invasive assessment of cerebrovascular reserve.
• The findings support the Uhem index's utility in clinical practice for stroke risk stratification.