[Drug therapy of chronic congestive heart failure: the why and how]

As the prevalence of congestive heart failure is steadily increasing correct treatment becomes more and more important. In pathophysiology, clinical signs once believed to express the effort of the body to "compensate" for the failure (hypervolaemia, tachycardia, sympathetic stimulation) have been recognized as sort of a physiological error: to a primary signal which still remains not fully understood, the body responds in a similar way as to dehydration. As late as the mid-sixties, "function curves" represented a framework for our conceptual thinking and digitalis the essential treatment. Since then, we had to realize that the function of the failing ventricle is not determined just by filling and contractility-the way it is in the healthy ventricle is-but also by aortic impedance. Vasodilators have become the cornerstone of therapy. At present, diuretics are the most important drugs for congestive heart failure treatment. Thiazides, given together with loop diuretics, ameliorate extracellular fluid volume in all treated patients, but their effect is accompanied by potassium losses due to increased aldosterone levels. Angiotensin converting enzyme (ACE) inhibitors are unique in not only decreasing ventricular afterload and improving haemodynamics but, also, in decreasing circulating norepinephrine levels, protecting kidneys from inappropriate efferent arteriolo-constriction and suppression of aldosterone secretion. In other words, ACE inhibitors change the essential physiological set-up: they turn a high-perfusion-pressure body into a low-perfusion-pressure one. Furthermore, they convincingly improve life expectancy. Combination of diuretics and ACE inhibitors is the best we can do for our patients today. Although useful in some patients, the definite value of digitalis, and particularly its effect on longevity, remains an unresolved question.