Question

Consider the following Pressure/Volume loop diagram for the left ventricle. If the three loops through E, E<, and E<< represent a series from relatively low to relatively high afterload (e.g., aortic blood pressure), which of the following does the diagram suggest would result from the increase in afterload?

1) An increase in the velocity at which blood is ejected from the left ventricle
2) An increase in cardiac output
3) An increase in the residual volume of blood in the left ventricle at end-systole
4) A decrease in the time it takes for the left ventricular wall to develop peak tension
5) A decrease in the maximal wall tension developed in the left ventricular muscle

Answer 1

Increasing afterload is suggested to increase the residual volume of blood in the left ventricle at end-systole, as indicated by the Pressure/Volume loop diagram.

Step-by-step explanation:

The diagram suggests that an increase in afterload, such as aortic blood pressure, would result in an increase in the residual volume of blood in the left ventricle at end-systole. This is indicated by the larger area captured within the loops marked with E< and E<<, corresponding to higher afterloads compared to the loop marked with E.

It is important to note that afterload is the tension the ventricles must develop to pump blood against the vascular resistance. As the afterload increases, the left ventricle must work harder to pump blood into the aorta, which may lead to a higher end systolic volume (ESV) if the ventricle cannot adjust its force of contraction adequately.