Left ventricular function in systole and diastole in aortic incompetence
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Acute aortic incompetence depresses systolic function and elevates diastolic pressures due to an unprepared ventricle. Chronic aortic incompetence allows adaptation, maintaining normal systolic function and lower diastolic pressures.
Area of Science:
- Cardiovascular Physiology
- Cardiac Mechanics
- Valvular Heart Disease
Background:
- Aortic incompetence (AI) presents acutely or chronically, significantly impacting left ventricular (LV) function.
- Understanding LV pressure-volume (P-V) relationships is crucial for characterizing cardiac adaptation and dysfunction in AI.
Purpose of the Study:
- To investigate left ventricular pressure-volume relationships in patients with varying degrees of aortic incompetence.
- To differentiate the hemodynamic responses between acute and chronic AI, and superimposed acute events.
Main Methods:
- Study included 30 patients with AI: 6 acute, 21 chronic, and 3 with superimposed acute cusp perforation.
- Analysis focused on left ventricular pressure-volume loops to assess systolic and diastolic function, and ventricular compliance.
Main Results:
- Acute AI showed depressed systolic function and elevated diastolic pressures, with reduced compliance due to operating on the steep P-V curve.
- Chronic AI demonstrated normal systolic function and adaptive mechanisms, allowing accommodation of volume load at lower end-diastolic pressures.
- Superimposed acute AI on chronic disease led to elevated diastolic pressures, despite low rate of change of stiffness, shifting from the adaptive P-V curve.
Conclusions:
- LV adaptation differs significantly between acute and chronic aortic incompetence.
- Chronic AI allows for ventricular remodeling and adaptation, maintaining function despite volume overload.
- Acute decompensation in chronic AI results in impaired diastolic function and elevated filling pressures.
Abstract:
Left ventricular pressure-volume relationships were studied in 30 patients with aortic incompetence: six with an acute lesion, 21 with chronic disease and three patients in whom a cusp perforation was superimposed on chronic disease. In acute aortic incompetence, systolic function was depressed and in diastole an unprepared ventricle with a normal modulus of elasticity and a normal rate of change of instantaneous stiffness of the pressure-volume relationship was unable to tolerate the volume load, so that the early diastolic and end-diastolic pressures were elevated. Compliance was greatly reduced at these volumes because the ventricle was operating on the steep portion of its pressure-volume curve. In chronic aortic imcompetence, systolic function was, however, normal but adaptive processes allowed the ventricle to operate with a smaller rate of change of instantaneous stiffness and a flatter pressure-volume curve, so that the volume load could be accommodated at a lower end-diastolic pressure. In patients with an acute phase superimposed on chronic disease, the sudden additional volume overload shifted the position of the diastolic pressure of the patient from the adaptive pressure-volume curve of chronic aortic incompetence, so that although the rate of change of instantaneous stiffness was low, the lowest diastolic pressure recorded and the left ventricular end-diastolic pressures were elevated.