How does atherosclerosis affect stroke volume?

How does atherosclerosis affect stroke volume?

• A. It increases afterload, leading to decreased stroke volume.
• B. It increases preload, leading to increased stroke volume.
• C. It decreases afterload, leading to increased stroke volume.
• D. It has no effect on stroke volume.

Answer: (A)

Atherosclerosis raises afterload. When arteries become narrowed and stiffer, the left ventricle must generate higher pressure to push blood into the aorta. That extra pressure makes it harder to eject the full volume of blood each beat. As a result, the end-systolic volume tends to stay higher (less complete emptying), so the stroke volume, which is the difference between end-diastolic and end-systolic volumes, decreases. Preload relates to how much blood returns to the heart before contraction, and atherosclerosis doesn’t directly increase venous return. Decreasing afterload would make ejection easier and typically increase stroke volume, which isn’t the situation here. And saying there’s no effect on stroke volume ignores the clear impact of higher systemic vascular resistance on how much blood is expelled each beat.

Atherosclerosis raises afterload. When arteries become narrowed and stiffer, the left ventricle must generate higher pressure to push blood into the aorta. That extra pressure makes it harder to eject the full volume of blood each beat. As a result, the end-systolic volume tends to stay higher (less complete emptying), so the stroke volume, which is the difference between end-diastolic and end-systolic volumes, decreases.

Preload relates to how much blood returns to the heart before contraction, and atherosclerosis doesn’t directly increase venous return. Decreasing afterload would make ejection easier and typically increase stroke volume, which isn’t the situation here. And saying there’s no effect on stroke volume ignores the clear impact of higher systemic vascular resistance on how much blood is expelled each beat.