Which feature characterizes pediatric restrictive cardiomyopathy?

• A. Ventricle walls are stiff.
• B. Heart muscle is unusually thick.
• C. Ventricle filling is normal.
• D. It only affects the left ventricle.

Answer: (A)

Diastolic dysfunction from a noncompliant ventricle is what defines restrictive cardiomyopathy. In pediatric cases the heart muscle becomes stiff, so it cannot relax and fill properly during diastole, even though its pumping strength (systolic function) is often preserved. That stiffness of the ventricular walls best captures the characteristic feature.

Thickened heart muscle describes hypertrophic cardiomyopathy, not restrictive. If filling were normal, that would contradict the hallmark impaired filling due to noncompliance. And restrictive disease can affect both ventricles, not just the left, so unilateral involvement isn’t the defining feature.