Diastolic dysfunction is described as what type of heart function?

Diastolic dysfunction specifically refers to an abnormality in the heart's ability to relax and fill with blood during the diastolic phase, which is the part of the cardiac cycle when the heart muscle is not actively contracting. In healthy physiology, the left ventricle should relax properly to allow blood to flow in from the left atrium, and any impairment in this relaxation can lead to increased pressure in the heart and symptoms of heart failure.

When diastolic dysfunction occurs, the heart may exhibit stiffening or impaired relaxation, preventing adequate filling of the ventricles. This condition is often associated with various cardiac issues, including hypertension and heart failure, and can lead to a decrease in stroke volume and cardiac output.

The other options refer to normal function or dysfunction during contraction, which does not describe the specific nature of diastolic dysfunction. Thus, the correct choice accurately reflects the defining characteristic of diastolic dysfunction as being related to the impaired relaxation phase of the heart.