Various methods exist to estimate central blood pressure (BP) waveforms from noninvasive peripheral BP measurements. Most methods consider only vascular effects and are based on population reference data and over-simplified boundary conditions. Because contractile properties of the heart may play a role as well, we investigated by means of a computational model the isolated and combined influences of cardiac properties as well as vascular stiffening on the central BP waveform.

A model of the circulation (Arts et al. 2005, AJP-Heart) was used to simulate central and peripheral BP waveforms from the left ventricle (LV) to femoral and radial arteries. We investigated the effect on BP waveforms of 1) a 50% reduction in the shortening velocity (v-s) of LV sarcomeres and 2) a vascular stiffness increase, corresponding to an increase in carotid-femoral pulse wave velocity from 8.6m/s to 10.2m/s. Central BP waveforms were characterized using augmentation index (AIx, based on the 2nd derivative) and pulse pressure (PP).

We obtained realistic BP waveforms for LV, central and peripheral vessels. Reducing v-s (all else equal) caused AIx to increase from respectively 16% (PP=60mmHg) to 30% (PP=60mmHg). Vascular stiffening (all else equal) resulted in an AIx increase from 16% to 36% and an increase in PP from 60 to 100mmHg. Combined reduced v and vascular stiffening resulted in an AIx of 42% with a PP of 80mmHg.

Not only vascular, but also cardiac properties influence the central BP waveform. We conclude that heart-vessel interaction should be considered in pulse wave analysis.