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Recognized molecular mechanisms of heart failure: approaches to treatment
C Ceconi1, A Cargnoni, S Curello
1Chair of Cardiology, University of Breschia, Italy. master.cci.unibs.it
Insights
Heart failure involves impaired calcium handling and energy metabolism in heart cells. Despite compensatory mechanisms, neuroendocrine responses contribute to disease progression, suggesting a humoral basis for heart failure.
Area of Science:
- Cardiology
- Physiology
- Pathophysiology
Background:
- Heart failure is characterized by contractile dysfunction due to abnormal cytosolic calcium handling and myocyte energetics.
- These cellular abnormalities, including impaired excitation-contraction coupling and myofilament calcium sensitivity, can be viewed as compensatory energy-preserving mechanisms.
Purpose of the Study:
- To review the role of humoral factors and neuroendocrine responses in the pathogenesis of congestive heart failure.
- To explore the potential of targeting these humoral mechanisms for therapeutic benefit.
Main Methods:
- Review of existing literature on heart failure pathophysiology, focusing on cellular mechanisms and systemic neuroendocrine responses.
- Analysis of the interplay between contractile dysfunction, myocyte energetics, and humoral factors.
Main Results:
- Impaired myocyte function leads to reduced cardiac output, triggering compensatory neuroendocrine responses like sympathetic nervous system and renin-angiotensin-aldosterone system activation.
- While atrial natriuretic peptides exert beneficial vasodilatory and natriuretic effects, they are often outweighed by detrimental vasoconstriction and sodium retention.
- Dysfunctional atrial stretch receptors and adaptation to atrial peptides may contribute to the progression of heart failure.
Conclusions:
- Congestive heart failure exhibits characteristics of a humoral disease due to dysregulated neuroendocrine system activation.
- Pharmacologic interventions aimed at mitigating the adverse effects of the neuroendocrine response may offer a promising therapeutic strategy for heart failure patients.
Abstract:
Abnormalities of cytosolic calcium handling and myocyte energetics appear to play an important role in mediating contractile dysfunction in heart failure. Systolic and diastolic dysfunction in the failing heart are related to abnormalities of the excitation-contraction mechanism as well as myofilament calcium sensitivity. These abnormalities can be viewed as a compensatory mechanism as the myocytes by down regulating its function and metabolic activity preserve energy consumption and allow better maintenance of basal cellular homeostasis. The end point of myocyte dysfunction, however, is a reduced contraction, which, in turn, might cause a reduced cardiac output and a threatening of arterial pressure. This causes a second level of adaptation, which implies a neuroendocrine response of the whole organism. Consequently, the syndrome of congestive heart failure is characterized not only by impaired ventricular function, but also by an increase in some endogenous substances leading to vasoconstriction and water and salt retention. Although activation of the systems that release these substances is presumed to be compensatory, the sympathetic nervous system and renin-angiotensin-aldosterone system as well as the endothelins may contribute to the pathogenesis of the syndrome. Opposite to the effects of these systems are those evoked by the release of atrial natriuretic peptides. The peptides exert a potent direct vasodilatation and natriuresis. In addition, atrial natriuretic peptides inhibit the release of norepinephrine from nerve terminals and suppress the formation of renin. However, the natriuretic and vasodilator effects of these peptides in patients with congestive heart failure are outweighed by the sodium retention and vasoconstriction caused by sympathetic stimulation and activation of the renin-angiotensin-aldosterone system. The reasons for this are not entirely known. The atrial stretch receptors that are responsible for the release of the atrial peptides become impaired, and it has been suggested that patient with heart failure may adapt to the physiologic effects of atrial natriuretic peptides. The possibility that congestive heart failure is in part a humoral disease is reviewed here and consequently pharmacologic treatment aimed at reducing the effects of the neuroendocrine response as to be advantageous for patients with heart failure.