Influence of applied brachial recording forces on pulse wave velocity and transmission in the brachio-radial arterial segment.

Arterial stiffness in hypertension and heart failure may increase afterload on the left ventricle. Pulse wave velocity and transmission ratio measurements are noninvasive methods to assess arterial stiffness. Since noninvasive pressure pulse recording requires sufficient applied force to distort the vessel wall, we hypothesized that the pulse wave velocity, transmission ratios, and distal pulse amplitudes and contours may be altered by the recording technique. Brachial and radial arterial pressure pulses were recorded simultaneously using a piezoelectric pulse transducer in 14 young, normal, male subjects using 10 brachial artery recording forces (0.35-3.58N, approximately equal to 0.36N increments) applied in a random order and a constant radial force (2.35N). Pulses were Fourier analyzed. One subject was excluded from analysis because of improper transducer positioning over the brachial artery. In 8 subjects, no significant changes occurred in any variable over all brachial recording forces. In the remaining 5 subjects, the measured variables remained constant until brachial artery recording forces exceeded 2.42 +/- 0.03N. The pulse wave velocity (p < 0.04), transmission ratios (harmonics 2-5, p < 0.0001), radial pulse amplitude (p < 0.0003), and relative powers (harmonics 2-5, p < 0.02) then decreased. In these subjects, brachial artery depths were less than the other subjects (5.9 +/- 0.4 vs. 7.7 +/- 0.4 mm, p < 0.05). The brachial and radial artery recording forces normally used during clinical measurements by 2 investigators were 1.43 +/- 0.01N (95% confidence intervals (CI) = 1.23N, 1.62N) and 1.88 +/- 0.11N (95% CI = 1.65N, 2.10N), respectively. Therefore, at forces normally used by clinical investigators, the pulse wave velocity, harmonic transmission ratios, and pulse amplitudes and contours obtained at the brachial and radial artery are not significantly influenced by forces applied at the brachial artery. However, these variables may be decreased in subjects with more superficial arteries when higher recording forces are used.