[Heart failure due to ischemia--the adaptive mechanisms].
Chronic myocardial ischemia is the leading cause of disturbances in myocardial contractility (myocardial infarction) or hemodynamic overload upon the left ventricle. The heart reactions consist in a series of adaptative mechanisms in order to maintain its pump function: Frank-Starling mechanism, myocardial hypertrophy and neurohumoral activation. In heart failure, the cardiac output is maintained by an increase of the preload which enhances the contractility (Frank-Starling law). Myocardial ischemia influences the systolic and diastolic function. The decrease of cardiac output leads to neurohumoral responses which, in the initial stages of cardiac failure are compensatory; along with the progression of the disease, they exert adverse effects. Increased activity of the sympathetic nervous system induces high cardiac rates, chronotropic incompetence. Activation of the renin-angiotensin system held to myocardial and vascular hypertrophy, vasoconstriction, fluid retention. Endothelin is the most powerful vasoconstrictor; its plasmatic concentrations correlate with the severity of the disease. Vasodilator mediators released in cardiac failure are the natriuretic peptide, nitric oxide, dopamine, prostacicline, bradikinin.
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Clinica a VI-a Medicală, Facultatea de Medicină, Universitataea de Medicină şi Farmacie Gr. T. Popa, Iaşi.
Mitu
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D000222:Adaptation, Physiological; D006332:Cardiomegaly / Q000503:physiopathology; D006333:Heart Failure / Q000209:etiology* / Q000503:physiopathology; D006801:Humans; D009200:Myocardial Contraction / Q000502:physiology; D017202:Myocardial Ischemia / Q000150:complications* / Q000503:physiopathology; D018377:Neurotransmitter Agents / Q000502:physiology; D012084:Renin-Angiotensin System / Q000502:physiology
D018377:Neurotransmitter Agents