VASCULAR IMPEDANCE BY PULSE CONTOUR/WINDKESSEL ANALYSIS (PCWA).

Systemic vascular impedance is an important determinant of arterial pressure and left ventricular function. Systemic vascular resistance (SVR) is often used as a measure of this impedance, since it can be calculated directly from conventionally determined cardiac output and mean arterial pressure. SVR does not account for the pulsatile nature of arterial pressure and flow and cannot provide information about non-resistive vascular properties such as compliance. These properties have been described in terms of characteristic impedance (Z//O) derived by Fourier analysis of pressure and flow measured at the aorta and by vascular compliance from analysis of a peripheral artery pressure contour during diastole. Unlike the Fourier analysis which requires both continuous aortic pressure and flow, the pulse contour method requires only a peripheral pressure waveform and cardiac output which are easily obtained in the clinical setting.