Sympathetic activation in heart failure:: A target of therapeutic approaches

In heart failure, decreased cardiac output leads to a number of adaptive mechanisms. Among these, neuroendocrine activation including activation of the renin-angiotensin-aldosterone system, augmentation of vasopressin and endothelin release, and activation of the sympathetic nervous system occur. The increase of adrenergic drive is characterized by decreased baroreceptor sensitivity. increased plasma norepinephrine: levels and cardiac norepinephrine spillover. and desensitization of postsynaptic beta-adrenergic signal transduction. While increased sympathetic drive initially helps to maintain contractile performance of the damaged heart, the above changes chronically result in cateoholamine refractoriness and are associated with a poor prognosis. Besides diuretics, the current therapy of heart failure includes ACE inhibitors, digitalis, and beta-blockers. In addition, there is evidence that AT1 receptor antagonists might be useful, and, in the presence of arrhythmia, amiodarone is widely used. The current review briefly summarizes how these drugs interfere with the sympathetic nervous system and speculates that antiadrenergic properties might contribute to the beneficial effects of some of these agents with respect to exercise tolerance and survival of patients with heart failure.