10 Apr

Overview of Beta Blockers for Systolic Heart Failure

Heart FailureIntroduction

Congestive heart failure (CHF) is one of the costliest chronic conditions in the U.S., with direct and indirect expenditures of approximately $27.9 billion in 2005. It is estimated that more than 4.5 million Americans have this condition. Each year, more than 500,000 new cases of heart failure are diagnosed in the U.S. Data from the Framingham Heart Study indicate that 20% of both men and women, at 40 years of age, will develop CHF at some point in their lifetime.

Given this significant burden, it is incumbent upon health care providers to ensure that patients with systolic dysfunction are receiving optimal therapy. Until recently, such therapy was directed toward volume control, afterload reduction, inotropic support, and avoidance of negative inotropes. More recently, the focus has changed to include therapy aimed at some of the underlying neurohormonal adaptations associated with CHF. canadian antibiotics

Few paradigm shifts have been as striking as that regarding the use of beta blockers in patients with systolic dysfunction. Just 15 years ago, trainees were still being taught, in many cases quite dogmatically, that heart failure was an absolute contraindication to beta blockade. This belief was based on the known negative inotropic effects of these agents and the predominant pathophysiological view that heart failure was primarily a hemodynamic disorder. Since the 1980s, a new understanding of the pathophysiology of CHF has emerged. This new view emphasizes the deleterious effects of enhanced sympathetic tone and the neurohormonal system.

The demonstration that plasma nor-epinephrine levels were independently related to mortality in patients with heart failure was one of the first lines of evidence in support of the deleterious role of sympathetic activation in this disorder. Activation of compensatory vasoconstriction in these patients via mediators of the sympathetic system (the renin-angiotensin-aldosterone system and arginine vasopressin) was postulated to eventually add to the burden of a failing myocardium. This led to the recognition that inhibiting these neuro-hormonal systems in heart failure might prove beneficial, a view that has endured for the ensuing 15 years. This expanded understanding of the pathophysiology of CHF has resulted in the paradigm shift. As a result, beta blockers are now seen as an integral part of the proper management of patients with symptomatic systolic dysfunction.

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