P145 MEASUREMENT OF BLOOD PRESSURE DEPENDENCY OF CAROTID-FEMORAL PULSE WAVE VELOCITY

Background: Carotid-femoral pulse wave velocity (cfPWV) is predictive of cardiovascular outcomes but clinical interpretation is confounded by blood pressure (BP) interaction. This study proposes a method for PWV pressure dependency measurement suitable for routine clinical or research use. Methods: Carotid tonometry and thigh-cuff volumetric displacement allowed cfPWV measurement in the seated and supine position. Brachial oscillometry gave systemic BP. Solving simultaneous equations describing the seated and supine measurement gave hydrostatic BP change across the carotid-femoral arterial path and the pressure dependency of cfPWV. Stepwise multiple linear regression quantified the association of pressure dependency of cfPWV with demographic and cardiovascular parameters. Results: Of 88 subjects (19 to 91 years, 41 female), 4 (4.5%) had an unexpected increase in cfPWV with decreased BP from seated to supine position. Cross-sectional analysis in the remaining cohort showed blood pressure dependency of cfPWV correlated with brachial pulse pressure (β = 0.40, p < 0.001), diastolic pressure (β = −0.33, p < 0.001), gender (β = 0.25 for female/male = 1/0, p = 0.010), and heart rate (β = 0.23, p = 0.033). There was no correlation with supine cfPWV nor age. Average pressure dependency of cfPWV was 0.6±0.3 m/s per 10 mmHg (range of 0.09 to 1.5 m/s per 10 mmHg). Average change in transmural BP across the carotid-femoral arterial path was 20±7 mmHg (diastolic BP change 4±7 mmHg; hydrostatic BP change 16±2 mmHg). Conclusions: Changing from seated to supine position imparts a BP change across the carotid- femoral arterial path, the majority of the effect being hydrostatic. Measuring cfPWV in these two stable BP positions allows calculation of the BP dependency of cfPWV.