USMLE (United States Medical Licensing Examination) Step 1 Practice Exam

How does volume overload contribute to the development of Eccentric LVH?

1. Decreased cardiac output

2. Impaired contractility

3. Increased preload

4. Increased afterload

The correct answer is: Increased preload

Volume overload leads to eccentric left ventricular hypertrophy (LVH) primarily through the mechanism of increased preload. When the heart experiences a volume overload, such as in conditions like mitral regurgitation or aortic regurgitation, there is an increase in the amount of blood returning to the left ventricle during diastole. This results in the left ventricle being filled with a greater volume of blood than normal. The increased preload stretches the ventricular walls, prompting the cardiac muscle fibers to expand and adapt. In response to this chronic volume overload, the left ventricular muscle cells undergo hypertrophy, which is characterized by an increase in the length of the muscle fibers rather than just an increase in wall thickness, leading to eccentric hypertrophy. This type of remodeling helps the heart accommodate the excess volume and maintains forward flow. In contrast, decreased cardiac output and impaired contractility are factors typically associated with heart failure symptoms rather than direct causes of eccentric LVH. Increased afterload relates more to conditions like aortic stenosis or systemic hypertension, which typically lead to concentric hypertrophy rather than eccentric hypertrophy. Eccentric LVH is thus specifically linked to the preload increase resulting from volume overload.