What is heart failure?

Heart failure is characterized by the inability of the heart to pump enough blood to meet the body's needs for oxygen and nutrients. This condition can arise from various underlying issues such as weakened heart muscle, stiffening of the heart, or both, which ultimately leads to reduced cardiac output. As a result, the body may not receive adequate blood flow, causing symptoms like fatigue, shortness of breath, and fluid retention.

The distinction of heart failure lies in the heart's compromised ability to effectively function rather than any of the other provided scenarios. For example, pumping extra blood wouldn't align with the pathophysiology of heart failure, as this condition is all about limitations in capacity rather than increased output. Similarly, a temporary reduction in heart rate could affect cardiac output but is not indicative of heart failure itself, as heart failure pertains to ongoing and chronic inadequacies in pump function. Lastly, an increase in muscle mass without symptoms does not reflect the deteriorated functional status associated with heart failure, since the condition is defined more by its effects on circulation and overall health rather than just changes in heart size or shape.