Complementary methods for evaluating carotid stenosis: a biophysical basis for ocular pulse wave delays

Area of Science:

• Vascular Medicine
• Biomedical Engineering
• Diagnostic Imaging

Background:

• Noninvasive estimation of carotid arterial stenosis significance is crucial.
• Ocular pulse wave timing (OPG) and carotid phonoangiography (CPA) are emerging technologies.
• Previous studies have raised concerns regarding OPG's theoretical basis and validation.

Purpose of the Study:

• To evaluate the efficacy of OPG pulse delay and CPA in a controlled canine carotid artery stenosis model.
• To correlate OPG and CPA findings with physiological parameters under graded stenoses.
• To provide physiological validation for the OPG pulse delay concept in diagnosing arterial disease.

Main Methods:

• Graded unilateral stenoses were created in canine carotid arteries.
• Physiological parameters, including arterial diameter and pressure, were recorded distal to stenoses.
• Ocular pulse wave timing (OPG) and carotid phonoangiography (CPA) recordings were obtained.
• Arterial compliance was calculated from pressure and diameter data.

Main Results:

• OPG time delay showed a significant positive correlation with reduced flow and pressure, and increased arterial compliance (P < 0.01).
• The OPG delay is attributed to decreased pulse wave velocity due to increased compliance distal to stenoses.
• OPG demonstrated higher discrimination for more severe stenoses.
• CPA provided diagnostic information even with moderate stenoses, detecting flow disturbances.

Conclusions:

• OPG pulse delay is a valid indicator of carotid arterial stenosis, particularly for higher grades.
• CPA offers complementary diagnostic value by detecting flow disturbances earlier than OPG.
• The study supports the use of OPG pulse delay for diagnosing arterial disease and highlights the benefit of complementary diagnostic methods.