Abstract 184: Aortic Pulse Wave Velocity Does Not Correlate with Flow Wave Velocity or Mean Arterial Pressure in Robust, in Vitro Cardiovascular Hemodynamic Simulation
Introduction: Arterial compliance is a marker for cardiac burden in atherosclerotic disease, with the pressure Pulse Wave Velocity (PWV) correlated to compliance. Current clinical practice employs pulsed wave Doppler to measure Flow Wave Velocity (FWV) as a surrogate of PWV. We hypothesized that PWV and FWV are not directly related and are affected by left ventricular ejection time (LVET). Furthermore, we proposed that aortic PWV is independent of mean arterial pressure (MAP) in the setting of isolated systolic hypertension.
Methods: Using a physiologically accurate electromechanical cardiovascular simulator, two solid state manometer-tipped pressure transducers and two transit time flow sensors were located at the aortic root and at the aortic bifurcation. PWV and FWV were directly measured while individually varying contractility and thus LVET. The experiments were repeated at various systemic vascular resistances (SVR) and vascular compliances. Automated signal processing and data extraction techniques were used to calculate the key parameters.
Results: As LVET increased, FWV decreased but PWV increased while MAP remained constant for a fixed SVR and compliance. (Figure 1) This trend held consistent at different SVR’s and compliances. The relationship of PWV and FWV with LVET appeared to be exponential and linear respectively. For a constant MAP, the associated PWV varied by up to 50m/s and FWV by up to 10m/s for a change in LVET of 225ms.
Conclusions: In conclusion, our data shows that PWV and FWV appear to be inversely related. Our data also suggest that PWV and FWV are independent of MAP in the setting of isolated systolic hypertension. These findings suggest that FWV measured by pulsed wave Doppler may not be a simple surrogate for true PWV. Future work is needed to elucidate the hemodynamic principals governing the relationship between PWV and FWV.
- © 2012 by American Heart Association, Inc.