Simulation of exercise-induced syncope in a heart model with severe aortic valve stenosis.

Severe aortic valve stenosis (AVS) can cause an exercise-induced reflex syncope (RS). The precise mechanism of this syncope is not known. The changes in hemodynamics are variable, including arrhythmias and myocardial ischemia, and one of the few consistent changes is a sudden fall in systemic and pulmonary arterial pressures (suggesting a reduced vascular resistance) followed by a decline in heart rate.

Simulation of the Frank-Starling Law of the Heart.

We developed a lumped parameter, computer-based model of an equivalent electronic circuit for a one-atrium one-ventricle (frog) heart attached to a vascular circuit, to simulate a basic concept of cardiovascular physiology, the Frank-Starling Law of the Heart. A series of simulations was performed, to observe changes in cardiovascular variables (e.g.

Simulation of left ventricular function during dyskinetic or akinetic aneurysm.

The purpose of our study was to simulate the hemodynamics of left ventricular function after left ventricular aneurysm (LVA) of various sizes and to validate the results of this computer based simulation with patient data. We developed an equivalent electronic circuit (EEC) that reflects the hemodynamic conditions of LVA (after acute myocardial infraction) while taking into consideration the resetting of the sympathetic nervous tone in the heart and systemic circuit, the fluctuating intrathoracic pressure during respiration and passive relaxation of the ventricle during diastole. The key feature of the EEC was a subcircuit representing the LVA, with a subcircuit to measure ventricular blood volume (i.

Teaching cardiovascular physiology with equivalent electronic circuits in a practically oriented teaching module.

Here, we report on a new tool for teaching cardiovascular physiology and pathophysiology that promotes qualitative as well as quantitative thinking about time-dependent physiological phenomena. Quantification of steady and presteady-state (transient) cardiovascular phenomena is traditionally done by differential equations, but this is time consuming and unsuitable for most undergraduate medical students. As a result, quantitative thinking about time-dependent physiological phenomena is often not extensively dealt with in an undergraduate physiological course.