Non-invasive measurements of arterial structure and function: repeatability, interrelationships and trial sample size

Area of Science:

• Cardiovascular Physiology
• Vascular Biology
• Biomedical Engineering

Background:

• Repeatability of arterial compliance and brachial artery flow-mediated dilation measurements is infrequently reported.
• Interrelationships between various arterial indices are not well understood.
• Reliable measurements are crucial for interventional and risk-factor modification studies.

Purpose of the Study:

• To determine the repeatability of various arterial indices.
• To investigate the interrelationships among these arterial indices.
• To provide data for sample size calculations in clinical trials.

Main Methods:

• Fifty healthy volunteers (20 men, 30 women; aged 20-70) were studied twice, 2.5 weeks apart.
• Measurements included carotid intima-media thickness (IMT), systemic artery compliance (SAC), pulse wave velocity (PWV), carotid distensibility coefficient (DC), augmentation index (AI), and brachial flow-mediated dilation.
• Techniques used were tonometry, ultrasound, and Doppler.

Main Results:

• No systematic differences were found between measurements.
• Coefficients of variation ranged from 1.3% (AI) to 10.0% (DC).
• All arterial compliance indices correlated with age; central indices correlated with IMT.

Conclusions:

• Measurements of arterial mechanical properties (compliance, IMT, FMD) show good repeatability under controlled conditions.
• These indices are reliable for use in clinical trials.
• The study provides sample size tables for future research.