Echocardiography Techniques I Exam 1 Practice

During the isovolumic phase, all valves are closed. This moment occurs after the AV valves (mitral/tricuspid) have closed and before the semilunar valves (aortic/pulmonary) open. With both sets of valves shut, the ventricle can contract or relax without any change in its volume—the pressure changes but no blood is leaving or entering the ventricle. The phase ends when the ventricular pressure becomes high enough to open the semilunar valves and allow ejection, or, in the relaxation side, when the semilunar valves close and the AV valves remain closed until atrial pressure exceeds ventricular pressure again.