In cases of congestive heart failure (CHF), what is generally not observed?

In cases of congestive heart failure (CHF), elevated cardiac isoenzymes are generally not observed. Cardiac isoenzymes, such as troponins and creatine kinase (CK-MB), typically indicate myocardial injury or infarction rather than heart failure itself. In CHF, the heart's ability to pump effectively is compromised, leading to symptoms and signs related to fluid overload and reduced cardiac output, but not directly associated with elevated isoenzymes unless there is concurrent myocardial injury or damage.

In contrast, shortness of breath, swelling in the legs, and fatigue are hallmark symptoms related to CHF. Shortness of breath occurs due to fluid accumulation in the lungs and decreased oxygenation. Swelling in the legs is related to fluid retention and poor circulation, as the heart struggles to manage blood flow properly. Fatigue arises from the heart's diminished capacity to supply sufficient oxygenated blood to meet the body's demands, leading to a general feeling of tiredness and reduced exercise tolerance. These symptoms are more indicative of the heart's compromised function found in CHF.