Certified Emergency Nurse (CEN) Practice Test

Afterload refers to the resistance the heart must overcome to pump blood into the systemic circulation. Arterial vasoconstrictors are known to increase afterload by narrowing the arterial blood vessels, which increases the resistance against which the heart must pump. When arterial walls constrict, the pressure required to eject blood from the ventricle rises, leading to an increase in afterload. This can significantly affect cardiac output, particularly in conditions where the heart is already compromised. The other choices involve mechanisms that generally reduce afterload or have different effects. Diuretics primarily reduce pre-load by decreasing fluid volume in the body, which can lower the blood pressure and consequently decrease afterload. Venous dilators work by dilating the veins, which leads to decreased venous return to the heart and reduced preload. ACE inhibitors help in lowering afterload by preventing the conversion of angiotensin I to angiotensin II, resulting in vasodilation and decreased vascular resistance.