What is the main physiological change in heart failure?

The main physiological change in heart failure is the inability of the heart to pump effectively. In heart failure, the heart's pumping capability is compromised, which can result from various factors such as weakened heart muscle, stiffened heart muscle, or impaired filling of the heart. This reduced pumping ability leads to insufficient blood flow to meet the body's needs, which can manifest in symptoms like fatigue, shortness of breath, and fluid retention.

In contrast to heart failure, enhanced ejection fraction would indicate that the heart is pumping more efficiently than normal, which is not characteristic of this condition. Optimal cardiac output implies that the heart is functioning effectively to deliver adequate blood to the body, which again does not occur in heart failure. Increased stroke volume suggests that the heart is able to push out a larger volume of blood with each beat, which is typically not the case in heart failure, where stroke volume is often reduced due to the heart's impaired contraction.

Thus, the primary concern in heart failure is this significant reduction in the heart's ability to pump effectively, leading to various compensatory mechanisms and a range of clinical symptoms.