Differentiate systolic heart failure from diastolic heart failure.

• A. Systolic heart failure is defined by reduced EF; Diastolic heart failure has increased EF.
• B. Systolic heart failure is due to increased filling pressures only.
• C. Systolic heart failure is due to a stiff ventricle causing preserved EF.
• D. Systolic heart failure features reduced EF due to impaired contractility, while diastolic heart failure features preserved EF but impaired filling due to stiff ventricle.

Answer: (D)

The key idea is how the ventricle functions during pumping versus filling. In systolic heart failure the heart's ability to contract is impaired, so the amount of blood ejected with each beat drops and the ejection fraction falls. In diastolic heart failure the contraction is relatively normal, so the ejection fraction stays about normal, but the ventricle is stiff and doesn’t relax well, so filling is impaired and filling pressures rise.

This statement matches that pattern: systolic heart failure has reduced ejection fraction due to impaired contractility, while diastolic heart failure has preserved ejection fraction but impaired filling because the ventricle is stiff.

The other ideas mix up the mechanisms or the EF findings. Systolic failure isn’t defined by only higher filling pressures, and diastolic failure isn’t marked by an increased EF. A stiff ventricle with preserved EF describes diastolic failure, not systolic.