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[Synopsis of endocrine and hemodynamic changes in heart failure]
1Klinik für Innere Medizin, E.-M. Arndt-Universität Greifswald.
Insights
Cardiac failure involves complex systemic counter-regulations, not just hemodynamic or cardiac issues. Understanding these interactions is key to managing heart failure effectively.
Area of Science:
- Cardiology
- Physiology
- Molecular Biology
Context:
- Cardiac failure is a complex syndrome, not solely a hemodynamic or cardiac issue.
- Humoral counter-regulations are triggered by decreased cardiac output, increased filling pressures, and myocardial oxygen consumption.
- The interplay between causes and consequences of these alterations remains unclear.
Purpose:
- To elucidate the multifaceted nature of cardiac failure.
- To explore the systemic counter-regulatory mechanisms involved.
- To differentiate between causal factors and consequences of cardiac dysfunction.
Summary:
- Cardiac failure involves complex systemic counter-regulations, including neurohormonal activation (sympathetic nervous system, RAAS, ADH) and cellular changes (receptor/protein alterations).
- Desensitized cardiopulmonary mechanoreceptors and altered signaling contribute to the progression of heart failure.
- Favorable mechanisms like ANP and prostaglandin secretion counteract detrimental effects, promoting natriuresis, diuresis, and vasodilation.
Impact:
- Provides a comprehensive understanding of cardiac failure pathophysiology.
- Highlights the importance of considering systemic effects in heart failure management.
- Offers insights into potential therapeutic targets for heart failure.
Abstract:
In contradiction earlier viewpoints, cardiac failure cannot be defined as a purely hemodynamic problem nor as only a cardiac problem. On the other hand decreased cardiac output (Co), increased filling pressure, increased wallstress and myocardial O2-consumption (MVO2) are the cause of many humoral counterregulations. Therefore, it is not always certain if the observed alterations are the causes or consequences of cardiac failure. The systemic counter-regulations will be modulated by desensitized cardiopulmonary mechanoreceptors, followed by decreased inhibition of central vasomotoric stimuli and endothelial and endocardial function, by altered signal transmission, as well as by altered gene expression within the myocytes. Depending on the degree of insufficiency, it may be attempted, by increase of the preload and of the contractility, to restore the hemodynamic basic situation. Such an attempt is based upon increased activity of the sympathetic nervous system, stimulation of the renin-angiotensin-aldosterone-system (RAAS) or the increased level of ADH. The reduced contractility and response of the myocytes, caused by the downregulation of beta 1-receptors and Gs-proteins, as well as by the upregulation of Gi-proteins, and the increased afterload with increased MVO2 and decreased CO all lead to a vicious circle. There are only some mechanisms that are directed against these regulations. The decreased response of the myocardium to endogenous catecholamines, the stimulation of ANP-secretion, as well of the prostaglandin-secretion are among the favorable regulations. They cause increase of natri- and diuresis, improved renal perfusion, vasodilatation, and inhibition of the RAAS and ADH-secretion with reduction of true thirst and craving for salt.(ABSTRACT TRUNCATED AT 250 WORDS)