Circulatory abnormalities and compensatory mechanisms in heart failure.

Knowledge of the basic alterations of central hemodynamics in congestive heart failure has failed to explain many aspects of this important syndrome. Increasing attention has recently been paid to compensatory and adaptive mechanisms occurring after the initial insult. Thus, new insights have been gained into the pathophysiology of contraction of hypertrophied myocardium and changes of adrenergic receptors in the myocardium due to chronically increased cardiac sympathetic tone. The role of the renin-angiotensin-aldosterone system in early and advanced congestive heart failure has been further elucidated, and the role of the vasodilating atrial natriuretic peptide is undergoing further definition. New results further clarify the mechanisms leading to breathlessness and muscular fatigue in congestive heart failure, with emphasis shifting from the traditional concept of the importance of increased filling pressures to changes to the peripheral circulation and exercising muscles. Although progress has been made in understanding of the pathophysiology of congestive heart failure, many aspects are still poorly understood and await clarification.