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

What is the primary cause of Eccentric LVH in individuals with dilated cardiomyopathy?

1. Inherited genetic mutations

2. Myocardial ischemia

3. Pulmonary hypertension

4. Volume overload

The correct answer is: Volume overload

In the context of dilated cardiomyopathy, the primary cause of eccentric left ventricular hypertrophy (LVH) is volume overload. This condition typically arises when the heart chambers are subjected to increased volumes of blood on a chronic basis. In dilated cardiomyopathy, the heart's ability to pump effectively is impaired, leading to an increase in end-diastolic volume. As the left ventricle accommodates this increased volume, it undergoes remodeling, which results in eccentric hypertrophy. This means that the ventricular walls may become thinner and more dilated, as opposed to the concentric hypertrophy seen in conditions characterized primarily by pressure overload. The other options, while they can impact cardiac structure and function, do not directly explain the mechanism of eccentric LVH in dilated cardiomyopathy. Inherited genetic mutations might predispose individuals to develop this condition but do not directly cause the hypertrophic changes. Myocardial ischemia primarily leads to ischemic heart disease and often results in scarring rather than true hypertrophy related to volume overload. Pulmonary hypertension can lead to right ventricular changes, but its primary effect is not on the left ventricle in the context of dilated cardiomyopathy. Thus, volume overload is the most direct