Cardiovascular Model

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The cardiovascular model combines a ventricular pump together with a four element 'Windkessel' model (Stergiopulos et al). The pump is pre- and after-load sensitive and generates a sinusoidal output. The intra-vascular pressure calculations are computed every 5 msecs.


The effect of variation in pre-load on the cardiac output of the model (in  a patient with normal contractility and sympathetic tone) is illustrated below. These data were generated from the system itself and recorded using the data recording system.



Starling Curve


In addition to exhibiting Frank-Starling behaviour, the cardiovascular model also incorporates some reflex activity. The effect of haemorrhage on blood pressure and pulse rate is shown below. Over a 60 second period, a 70 kg patient loses 1L of blood. As a result, the systolic blood pressure falls from ~115 to ~ 50 and the pulse rate increases from ~ 70 to ~ 115.



Effect of Blood Loss




Stergiopulos N, Westerhof BE, Westerhof N. Total arterial inertance as the fourth element of the windkessel model. Am J Physiol. 1999 Jan;276(1 Pt 2):H81-8.