A time-domain arterial model in 15 anesthetized dogs showed that thoracic aorta volume comprises 45.1% of total windkessel volume, implying that reflected waves are minimal.
A time-domain model of arterial hemodynamics suggests that central aortic pressure is the sum of reservoir pressure and forward-traveling waves, challenging the traditional view of substantial diastolic reflected waves.
The differences in shape between central aortic pressure (P(Ao)) and flow waveforms have never been explained satisfactorily in that the assumed explanation (substantial reflected waves during diastole) remains controversial. As an alternative to the widely accepted frequency-domain model of arterial hemodynamics, we propose a functional, time-domain, arterial model that combines a blood conducting system and a reservoir (i.e., Frank's hydraulic integrator, the windkessel). In 15 anesthetized dogs, we measured P(Ao), flows, and dimensions and calculated windkessel pressure (P(Wk)) and volume (V(Wk)). We found that P(Wk) is proportional to thoracic aortic volume and that the volume of the thoracic aorta comprises 45.1 +/- 2.0% (mean +/- SE) of the total V(Wk). When we subtracted P(Wk) from P(Ao), we found that the difference (excess pressure) was proportional to aortic flow, thus resolving the differences between P(Ao) and flow waveforms and implying that reflected waves were minimal. We suggest that P(Ao) is the instantaneous summation of a time-varying reservoir pressure (i.e., P(Wk)) and the effects of (primarily) forward-traveling waves in this animal model.
Wang et al. (2003) studied Anesthetized dogs (n=15). Time-domain arterial model was evaluated on Relationship between central aortic pressure, windkessel pressure, and aortic flow. A time-domain arterial model in 15 anesthetized dogs showed that thoracic aorta volume comprises 45.1% of total windkessel volume, implying that reflected waves are minimal.