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Effects of hypertrophy on contractile function in man
Insights
Chronic pressure and volume overload depress left ventricular contractile function. Aortic valve replacement improves ventricular muscle mass and contractile function in patients with aortic stenosis.
Area of Science:
- Cardiology
- Cardiovascular Physiology
Background:
- Chronic pressure and volume overload conditions, such as aortic stenosis, lead to left ventricular hypertrophy.
- Contractile function is often depressed in these conditions despite increased muscle mass.
Purpose of the Study:
- To compare the effects of pressure and volume overload on left ventricular contractile function.
- To evaluate the impact of aortic valve replacement on ventricular mass and function.
Main Methods:
- Assessment of contractile function using isovolumic and ejection phase indexes.
- Measurement of left ventricular muscle mass.
- Evaluation of changes following aortic valve replacement.
Main Results:
- Contractile function is depressed to a similar extent in pressure and volume overload with matched left ventricular muscle mass.
- Pressure overload hypertrophy in aortic stenosis is linked to reduced inotropic state.
- Aortic valve replacement significantly reduces ventricular muscle mass and improves contractile function.
Conclusions:
- Hypertrophy can maintain ejection fraction despite diminished contractility if afterload is not excessive.
- Aortic valve replacement is effective in reversing detrimental changes in ventricular mass and function.
Abstract:
In patients with chronic pressure and volume overload matched with respect to elevated left ventricular muscle mass contractile function assessed by isovolumic as well as by ejection phase indexes is depressed to a similar extent. Pressure overload hypertrophy in aortic stenosis is associated with a reduced inotropic state of the individual contractile units. Despite this diminution of contractility hypertrophy may be effective in maintaining a normal ejection fraction as long as afterload does not become excessive. Aortic valve replacement leads to a significant reduction of the preoperatively elevated ventricular muscle mass and to a significant improvement of contractile function.