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The heart as a self-regulating system: integration of homeodynamic mechanisms
1Department of Cardiothoracic Surgery and Medicine, Medical College of Pennsylvania, Philadelphia, USA.
Insights
This paper reviews the tightly coupled mechanical and electrical properties of the heart. It highlights how integrated mechanisms regulate cardiac output and myocyte function for overall heart health.
Area of Science:
- Cardiovascular Physiology
- Cardiac Mechanics
- Cardiac Electrophysiology
Background:
- Historically, mechanical and electrical aspects of cardiac function were studied in isolation.
- These properties are fundamentally interconnected and crucial for maintaining heart function.
- Adequate cardiac output depends on integrated autoregulation and cardiac myocyte modulation.
Purpose of the Study:
- To provide an overview of the regulation of mechanical and electrical properties of the heart.
- To emphasize the integrated nature of cardiac function.
- To discuss the interplay between mechanics, energetics, perfusion, and electrical activation.
Main Methods:
- Literature review and synthesis of existing knowledge.
- Discussion of key physiological components influencing cardiac function.
- Overview of regulatory mechanisms.
Main Results:
- Cardiac output is maintained by integrated autoregulatory mechanisms and cardiac myocyte function modulation.
- Ventricular mechanics and energetics depend on fiber stress-strain rate, collagen matrix, vascular perfusion, transport, and electrical activation.
- Coronary dynamics regulate intramural hydraulic loading.
- Autonomic neurons and hormones influence these cardiac components.
Conclusions:
- The mechanical and electrical properties of the heart are intrinsically linked and essential for its function.
- A comprehensive understanding requires considering the interplay of various physiological systems.
- The paper presents a framework for understanding the regulation of these integrated cardiac functions.
Abstract:
In the past the study of mechanical and electrical properties of the heart has been disjointed with minimal overlap and unification. The fact remains that these features are tightly coupled and central to the functioning heart. The maintenance of adequate cardiac output relies upon the highly integrated autoregulatory mechanisms and modulation of cardiac myocyte function. Regional ventricular mechanics and energetics are dependent upon muscle fiber stress-strain rate, the passive properties of myocardial collagen matrix, adequate vascular perfusion, transcapillary transport and electrical activation pattern. Intramural hydraulic "loading" is regulated by coronary arterial and venous dynamics. All of these components are under the constant influence of intrinsic cardiac and extracardiac autonomic neurons, as well as circulating hormones. A brief overview of the putative regulation of these various components is presented in this paper.