Simulation of Exercise-Induced Syncope in a Heart Model with Severe Aortic Valve Stenosis

Figure 3

Data are arranged in four columns according to the simulation sequence described in Figure 2. In the upper parts of each column, there are time courses of various variables during systole and part of diastole (AoP, MAoP, LVP, LAtP, CO, ventricular volume). Note that a decreased LV contractility results in a decreased rate of contraction of LV (b). After aortic stenosis, a ventriculoaortic pressure gradient appears (c). EDVLV is increased, but due to a negative feedback SVLV is almost normal. In exercise (d), the pressure gradient is further increased, but due to the negative feedback (Sy increased) the heart rate and CO are increased and the EDVLV decreased. These changes are in excellent agreement with corresponding P-V loop diagrams. Note that in decreased LV contractility, the P-V loop diagram is shifted to the right. In aortic stenosis (note the pressure gradient), due to the inotropic effect (increased Sy), the P-V loop diagram shows a large ventricular pressure. The full inotropic effect is shown in exercise, where the P-V loop diagram is shifted to the left.