In order to understand the valve disorders, we first have to have a clear understanding of the sequence of events during each beat of the heart.
To the right are tracing of the pressures that determine the opening and closing of the valves on the left side of the heart. The right side would be similar, except the pressures are 1/7 as large.
The top graph shows the pressures that determine the opening of the left atrioventricular valve:
The bottom graph shows the pressures that determine the opening of the aortic valve:
The vertical line indicates when an action potential travels over the ventricles, triggering their contraction.
On these graphs, identify when the left atrioventricular valve opens and closes and when the aortic valve opens and closes. When is the first heart sound and when is the second heart sound? When is systole and diastole?
On the right is shown a graph with all three pressures. Lines indicate the times of the opening and closing of the valves. On the graph, you will want to identify the specific phases of the ventricular systole and diastole and understand what is occurring in each phase. The phases are:
If you like, you can download a worksheet to practice learning the phases of the cardiac cycle.
Finally, try the quiz below.