The patient takes a blood pressure medication that reduce afterload on the heart.
This drug will:
A. Lower vascular resistance by causing the arterioles to dilate
B. Increase stroke volume by increasing heart rate
C. Limit blood returning to heart by dilating veins
D. Make capillaries leaky
The correct answer and explanation is:
The correct answer is A. Lower vascular resistance by causing the arterioles to dilate.
When a patient is prescribed a medication that reduces afterload, the primary goal is to decrease the resistance the heart must overcome to pump blood into the arteries. This can be achieved by dilating the blood vessels, specifically the arterioles, which lowers the systemic vascular resistance (SVR). Afterload is defined as the pressure the heart must work against to eject blood during systole. If the arterioles dilate, it becomes easier for the heart to pump blood, reducing the workload on the heart and improving cardiac output.
The drugs that achieve this effect typically include vasodilators, which relax the smooth muscle in the walls of blood vessels. By causing arterioles to dilate, these medications lower the pressure in the blood vessels, decreasing the resistance that the heart faces during contraction. This can be especially useful for patients with conditions like hypertension or heart failure, where high afterload makes it more difficult for the heart to pump effectively.
Option B, increasing stroke volume by increasing heart rate, is not the correct answer. While increasing heart rate can temporarily boost stroke volume, it does not directly affect afterload, which is more related to vascular resistance. Option C, limiting blood returning to the heart by dilating veins, refers to preload, not afterload. Dilation of veins reduces venous return, which can lower preload but doesn’t directly reduce afterload. Lastly, option D, making capillaries leaky, is unrelated to afterload reduction and is more associated with issues like inflammation or injury.