What does restrictive cardiomyopathy refer to?

Restrictive cardiomyopathy is characterized by a decreased ability of the heart muscle to expand and fill with blood properly. This condition arises when the heart's walls become rigid or stiff, which hinders the normal filling of the ventricles during diastole—the phase of the heart cycle when the heart relaxes and fills with blood. As a result, even though the heart may still pump blood effectively during systole (the contraction phase), its overall function is compromised due to the restricted filling capacity. This leads to symptoms such as fatigue and shortness of breath due to reduced cardiac output.

In contrast, other options describe different cardiac conditions. Increased heart enlargement pertains to dilated cardiomyopathy, fluid build-up around the heart reflects pericardial effusion rather than restrictive cardiomyopathy, and uncontrolled heart rhythm relates to arrhythmias. Each of these involves distinct pathophysiological processes that are not applicable to the definition of restrictive cardiomyopathy. Understanding these differences reinforces the specific nature of restrictive cardiomyopathy and its implications on heart function.