8.3 QUANTIFYING HEART AND ARTERIAL CONTRIBUTIONS TO CENTRAL BLOOD PRESSURE IN SYSTOLE

Abstract

Background: A recent study has shown that the central pressure waveform could be determined by a very small set of parameters accounting for the physical properties of the heart and the arteries [1]. Particularly, main pressure features like first systolic shoulder (P1) and systolic (P2) pressures were estimated accurately. Methods: By combining a numerical virtual population (n=3,325) similar to [2] and experimental data acquired from a pressure/Doppler flow velocity transducer place in the ascending aorta in 18 patients (meanSD: age 63±11 yr, aortic BP 136±23/73±13 mmHg) at the time of cardiac catheterization, we assessed the accuracy of those predictions for magP1 (P1-DBP) and P2 using respectively a water hammer [3] and a 3-element Windkessel models [4]. Contributions of the heart and arterial properties to these estimates though respectively blood velocity, volume and pulse wave velocity, compliance, resistance were then derived from the theoretical models used. Results: P1 and P2 estimates agreed well with theoretical pressure both in the numerical dataset (mean+//0-SD difference, 1.1±3.2 mmHg and -1.6±3.1 mmHg respectively) and the clinical cohort (mean+//0-SD difference, -2.4±5.5 mmHg and 1.9±6.5 mmHg respectively). The ratio arterial-to-heart contribution has been shown to be fairly constant as magP1 was increasing. Conclusions: Arteries and heart contribute as much to rise in P1. More clinical data are being collected to quantify the contributions of the heart and arteries to P2.