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Left ventricular mechanical load and contractile function in patients with chronic mitral regurgitation
Warren K Laskey1, Theodore A Plappert, Martin G St John Sutton
1Division of Cardiology, Department of Internal Medicine, University of New Mexico School of Medicine, MSC10-5550, 1 University of New Mexico, Albuquerque, NM 87131, USA. wlaskey@salud.unm.edu
The Journal of Heart Valve Disease
|June 21, 2007
Summary
Patients with mitral regurgitation (MR) experience increased heart stress but maintain ejection performance. However, symptom severity correlates with afterload, and contractile dysfunction is common despite preserved ejection fraction.
Area of Science:
- Cardiology
- Cardiovascular Physiology
- Biomedical Engineering
Background:
- Chronic volume overload from mitral regurgitation (MR) alters left ventricular geometry and hemodynamics.
- These changes impact mechanical load and contractile function.
- Understanding these adaptations is crucial for managing heart conditions.
Purpose of the Study:
- To investigate left ventricular adaptation to chronic volume overload in patients with MR.
- To assess mechanical load (wall stress) and contractile function in MR patients compared to controls.
- To correlate symptom severity with hemodynamic parameters.
Main Methods:
- Invasive evaluation of 17 MR patients and 10 controls using catheter-tip manometry and M-mode echocardiography.
- Derivation of meridional and circumferential wall stress at various cardiac cycle points.
- Assessment of contractile function via end-systolic stress-dimension relationships and minor axis shortening analysis.
Main Results:
- MR patients showed increased end-diastolic and end-systolic volumes, lower cardiac indices, and elevated preload and afterload compared to controls.
- End-systolic stress was not consistently elevated despite increased chamber size.
- Contractile dysfunction was prevalent, even in patients with preserved ejection fraction, and symptom severity correlated with increased afterload.
Conclusions:
- Symptomatic MR patients exhibit preserved ejection performance despite increased preload and afterload.
- Increased afterload is associated with symptom severity in MR.
- A significant prevalence of contractile dysfunction exists in MR patients, even with preserved ejection fraction.
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