title: The sympathetic nervous system in heart failure physiology, pathophysiology, and clinical implications.
abstract: Heart failure is a syndrome characterized initially by left ventricular dysfunction that triggers countermeasures aimed to restore cardiac output. These responses are compensatory at first but eventually become part of the disease process itself leading to further worsening cardiac function. Among these responses is the activation of the sympathetic nervous system (SNS) that provides inotropic support to the failing heart increasing stroke volume, and peripheral vasoconstriction to maintain mean arterial perfusion pressure, but eventually accelerates disease progression affecting survival. Activation of SNS has been attributed to withdrawal of normal restraining influences and enhancement of excitatory inputs including changes in: 1) peripheral baroreceptor and chemoreceptor reflexes; 2) chemical mediators that control sympathetic outflow; and 3) central integratory sites. The interface between the sympathetic fibers and the cardiovascular system is formed by the adrenergic receptors (ARs). Dysregulation of cardiac beta(1)-AR signaling and transduction are key features of heart failure progression. In contrast, cardiac beta(2)-ARs and alpha(1)-ARs may function in a compensatory fashion to maintain cardiac inotropy. Adrenergic receptor polymorphisms may have an impact on the adaptive mechanisms, susceptibilities, and pharmacological responses of SNS. The beta-AR blockers and the inhibitors of the renin-angiotensin-aldosterone axis form the mainstay of current medical management of chronic heart failure. Conversely, central sympatholytics have proved harmful, whereas sympathomimetic inotropes are still used in selected patients with hemodynamic instability. This review summarizes the changes in SNS in heart failure and examines how modulation of SNS activity may affect morbidity and mortality from this syndrome.
authors.affiliation: Department of Cardiology, Larissa University Hospital, Larissa, Greece.
authors.forename: Filippos
authors.initials: F
authors.lastname: Triposkiadis
authors.forename: George
authors.initials: G
authors.lastname: Karayannis
authors.forename: Grigorios
authors.initials: G
authors.lastname: Giamouzis
authors.forename: John
authors.initials: J
authors.lastname: Skoularigis
authors.forename: George
authors.initials: G
authors.lastname: Louridas
authors.forename: Javed
authors.initials: J
authors.lastname: Butler
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000627:therapeutic use; D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D002316:Cardiotonic Agents / Q000627:therapeutic use*; D004077:Digoxin / Q000627:therapeutic use; D017079:Exercise Tolerance; D006333:Heart Failure / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D010275:Parasympathetic Nervous System / Q000187:drug effects / Q000503:physiopathology; D011110:Polymorphism, Genetic; D016032:Randomized Controlled Trials as Topic; D011941:Receptors, Adrenergic / Q000235:genetics; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects / Q000378:metabolism; D018343:Receptors, Adrenergic, beta-2 / Q000187:drug effects / Q000378:metabolism; D012084:Renin-Angiotensin System / Q000187:drug effects; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000503:physiopathology*; D013565:Sympatholytics / Q000627:therapeutic use*; D013566:Sympathomimetics / Q000627:therapeutic use*
chemical_list: D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D002316:Cardiotonic Agents; D011941:Receptors, Adrenergic; D018340:Receptors, Adrenergic, alpha-1; D018343:Receptors, Adrenergic, beta-2; D013565:Sympatholytics; D013566:Sympathomimetics; D004077:Digoxin