Progressive Care Nursing Certification (PCCN) Practice Exam

What occurs when a medication dilates both the venous and arterial beds?

1. Increased preload, decreased afterload

2. Decreased preload, decreased afterload

3. Increased preload, increased afterload

4. Decreased preload, increased afterload

The correct answer is: Decreased preload, decreased afterload

When a medication dilates both the venous and arterial beds, the correct result is a decrease in both preload and afterload. Venous dilation leads to a reduction in venous return to the heart, which decreases preload, the amount of blood in the ventricles before contraction. When the volume of blood returning to the heart is lower, the stretch on the heart muscle is reduced, thus lowering preload. On the arterial side, dilation results in decreased systemic vascular resistance (SVR). This reduction in resistance means that the heart does not have to work as hard to eject blood, which translates into decreased afterload, the pressure the heart must overcome during systole to eject blood. Consequently, when a medication causes dilation in both vascular beds, it effectively reduces the workload on the heart by lowering both preload and afterload, facilitating better cardiac output without increasing the myocardial oxygen demand.