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The functional ambivalence of adaptive processes--considerations based on the example of the hemodynamically
1Physiologisches Institut II, Universität Tübingen, FRG.
Insights
Adaptive processes in cardiac hypertrophy, while aiding organ function under stress, inherently involve detrimental effects. Unfavorable outcomes arise early from structural changes, blurring lines between physiological and pathological responses.
Area of Science:
- Cardiovascular Physiology
- Pathophysiology
Background:
- Hemodynamic overload triggers adaptive responses in the heart, such as cardiac hypertrophy.
- These adaptations aim to maintain organ function under increased workload but often include detrimental components.
Purpose of the Study:
- To examine the ambivalent nature of adaptive processes in cardiac hypertrophy.
- To investigate the early onset of unfavorable effects at organ and macromolecular levels.
- To clarify the role of vascular alterations in pressure-induced hypertrophy.
Main Methods:
- Analysis of adaptive processes in cardiac hypertrophy and neuro-humoral reactions.
- Evaluation of functional consequences of myocardial mass increase and configurational changes.
- Assessment of structural modifications and their impact on cardiac function.
Main Results:
- Adaptive processes, including myocardial mass increase, lead to unfavorable functional consequences.
- Structural modifications in the heart initiate detrimental effects at both organ and molecular levels.
- Distinguishing between physiological and pathological hypertrophy is challenging due to early unfavorable changes.
Conclusions:
- Cardiac hypertrophy presents an ambivalent adaptive process with inherent unfavorable components.
- Early structural changes contribute to adverse effects, complicating the physiological vs. pathological distinction.
- Therapeutic strategies should focus on reducing hemodynamic overload, while clarifying the role of vascular alterations in hypertrophy is crucial.
Abstract:
Cardiac hypertrophy and neuro-humoral reactions in hemodynamic overload are employed as examples to show that adaptive processes, while in principle enabling the whole organ to cope with increased load, as a rule also include unfavorable components. This is primarily due to competition between different demands with respect to, for instance, mechanical or energetic parameters. An impressive demonstration of the ambivalence of adaptive processes can be seen in the functional consequences of myocardial mass increase, eccentric configurational changes, and the alteration of the myocardium towards a "slower muscle". It can be demonstrated that, due to structural modifications in the heart, unfavorable effects occur at the level of the whole organ as well as in macromolecular dimensions from the very beginning, and not only as a consequence of qualitatively and quantitatively inappropriate adaptation. Thus, a clear-cut distinction between "physiological" and "pathological" processes is almost impossible. In the clinic, the unfavorable effects of the process of hypertrophy are often emphasized and the reduction of hypertrophy is declared the principal therapeutic aim. However, in the individual case the extent to which vascular alterations participate in, or are even mainly responsible for the unfavorable effects occurring in pressure hypertrophy should be clarified. In any case, reduction of hemodynamic overload should be the focus of therapeutic concern.