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The role of the autonomic nervous system in hypertension
1Department of Internal Medicine, University of Michigan, Ann Arbor 48109-0356, USA.
Insights
The autonomic nervous system plays a key role in hypertension. Autonomic imbalance, characterized by increased sympathetic and decreased parasympathetic tone, contributes to high blood pressure and associated cardiovascular risks.
Area of Science:
- Cardiovascular Physiology
- Autonomic Neuroscience
Background:
- Historically, the autonomic nervous system's role in hypertension was underestimated.
- Early research indicated hypertension was independent of autonomic tone.
Purpose of the Study:
- To elucidate the evolving role of the autonomic nervous system in the development and persistence of hypertension.
- To investigate the transition from hyperkinetic borderline hypertension to established hypertension.
Main Methods:
- Review of recent studies on hemodynamic abnormalities in hypertension.
- Analysis of sympathetic and parasympathetic tone markers.
- Examination of structural changes in cardiovascular system.
Main Results:
- Initial hypertension shows normal vascular resistance with elevated cardiac output and heart rate, linked to autonomic imbalance (increased sympathetic, decreased parasympathetic tone).
- Established hypertension involves high peripheral resistance and normal cardiac output, due to structural vascular and cardiac adaptations.
- Autonomic dysfunction in hypertension correlates with increased risk for coronary heart disease.
Conclusions:
- Autonomic nervous system imbalance is integral to hypertension's progression.
- Genetic factors may predispose individuals to heightened defense reactions, contributing to hypertension and cardiovascular disease risk.
- Understanding autonomic contributions is crucial for managing hypertension and its sequelae.
Abstract:
The role of the autonomic nervous system in the genesis and maintenance of hypertension is becoming clearer with time. Early research suggested that increased vascular resistance in hypertension was not dependent on excess autonomic tone and thus it was presumed that the autonomic nervous system had little to do with hypertension. More recent studies have demonstrated that the initial hemodynamic abnormality in hyperkinetic borderline hypertension is "normal" vascular resistance, with an elevated cardiac optput and heart rate, associated with markers of increased sympathetic and decreased parasympathetic tone of central origin. Over time there is a transition to the high peripheral resistance and normal cardiac output hemodynamic state characteristic of established hypertension, which is due to the development of adaptive structural changes in the peripheral resistance vessels and heart. The autonomic abnormality in hypertension and subsequent vascular and cardiac changes may explain some of association between hypertension and risk factors for coronary heart disease. The autonomic imbalance found in hypertension may not be a chance occurrence and we postulate that it is due to the inheritance of the genes responsible for a more pronounced defense reaction, which in earlier times may have conferred a survival advantage but now permit the negative impact of this trait to become evident.