Mitral Regurgitation 

  • Author: Ivan Hanson, MD; Chief Editor: Richard A Lange, MD   more...
 
Updated: Oct 7, 2011
 

Background

Mitral regurgitation (MR) is defined as an abnormal reversal of blood flow from the left ventricle to the left atrium. It is caused by disruption in any part of the mitral valve apparatus, which comprises the mitral annulus, the leaflets (a large anterior [aortic] leaflet and a small posterior [mural] leaflet), the chordae tendineae, and the papillary muscles (anteromedial and posterolateral). The most common etiologies of MR include mitral valve prolapse (MVP), rheumatic heart disease, infective endocarditis, annular calcification, cardiomyopathy and ischemic heart disease. The pathophysiology, clinical manifestations and management of MR differ with the chronicity of the disease and the etiology.

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Pathophysiology

MR can be caused by organic disease (eg, rheumatic fever, ruptured chordae tendineae, myxomatous degeneration, leaflet perforation) or a functional abnormality (ie, a normal valve may regurgitate [leak] because of mitral annular dilatation, focal myocardial dysfunction, or both). Congenital MR is rare but is commonly associated with myxomatous mitral valve disease. Alternatively, it can be associated with cleft of the mitral valve, as occurs in persons with Down syndrome, or a ostium primum atrial septal defect.

Acute mitral regurgitation

Acute MR is characterized by an increase in preload and a decrease in afterload causing an increase in end-diastolic volume (EDV) and a decrease in end-systolic volume (ESV). This leads to an increase in total stroke volume (TSV) to supranormal levels. However, forward stroke volume (FSV) is diminished because much of the TSV regurgitates as the regurgitant stroke volume (RSV). This, in turn, results in an increase in left atrial pressure (LAP). According to the Laplace principle, which states that ventricular wall stress is proportional to both ventricular pressure and radius, LV wall stress in the acute phase is markedly decreased since both of these parameters are reduced.

Chronic compensated mitral regurgitation

In chronic compensated MR, the left atrium (LA) and ventricle have sufficient time to dilate and accommodate the regurgitant volume. Thus LA pressure is often normal or only minimally elevated. Because of the left ventricular dilatation via the process of eccentric hypertrophy, TSV and FSV are maintained. Wall stress may be normal to slightly increased as the radius of the LV cavity increases but the end-diastolic LV pressure remains normal. As the LV progressively enlarges, the mitral annulus may stretch and prevent the mitral valve leaflets from coapting properly during systole, thus worsening the MR and LV dilatation.

Chronic decompensated mitral regurgitation

In the chronic decompensated phase, muscle dysfunction has developed, impairing both TSV and FSV (although ejection fraction still may be normal). This results in a higher ESV and EDV, which in turn causes a elevation of LV and LA pressure, ultimately leading to pulmonary edema and, if left untreated, cardiogenic shock.

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Epidemiology

Frequency

United States

Acute and chronic MR affect approximately 5 in 10,000 people. Mitral valve disease is the second most common valvular lesion, preceded only by aortic stenosis. Myxomatous degeneration has replaced rheumatic heart disease as the leading cause of mitral valvular abnormalities. Mitral valve prolapse has been estimated to be present in 4% of the normal population. With the aid of color Doppler echocardiography, mild MR can be detected in as many as 20% of middle-aged and older adults. MR is independently associated with female sex, lower body mass index, advanced age, renal dysfunction, prior myocardial infarction, prior mitral stenosis, and prior mitral valve prolapse. It is not related to dyslipidemia or diabetes.

International

In areas other than the Western world, rheumatic heart disease is the leading cause of MR.

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Contributor Information and Disclosures
Author

Ivan Hanson, MD  Fellow, Department of Cardiovascular Disease, William Beaumont Hospital

Ivan Hanson, MD, is a member of the following medical societies: American College of Cardiology and American College of Physicians

Disclosure: Nothing to disclose.

Coauthor(s)

Luis C Afonso, MD  Assistant Professor, Department of Internal Medicine-Cardiology, Program Director of Cardiology Fellowship Program, Wayne State University; Director of Echocardiography Laboratory, Harper University Hospital

Luis C Afonso, MD is a member of the following medical societies: American College of Cardiology, American College of Physicians, American Medical Association, and American Society of Echocardiography

Disclosure: Nothing to disclose.

Specialty Editor Board

Martin Keane, MD, FACC, FAHA  Associate Professor, Cardiovascular Medicine Division, Department of Medicine, University of Pennsylvania School of Medicine

Martin Keane, MD, FACC, FAHA is a member of the following medical societies: Alpha Omega Alpha, American College of Cardiology, American College of Physicians, American College of Physicians-American Society of Internal Medicine, American Heart Association, American Society of Echocardiography, Pennsylvania Medical Society, and Phi Beta Kappa

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD  Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

Ronald J Oudiz, MD, FACP, FACC, FCCP  Professor of Medicine, University of California, Los Angeles, David Geffen School of Medicine; Director, Liu Center for Pulmonary Hypertension, Division of Cardiology, LA Biomedical Research Institute at Harbor-UCLA Medical Center

Ronald J Oudiz, MD, FACP, FACC, FCCP is a member of the following medical societies: American College of Cardiology, American College of Chest Physicians, American College of Physicians, American Heart Association, and American Thoracic Society

Disclosure: Actelion Grant/research funds Clinical Trials + honoraria; Encysive Grant/research funds Clinical Trials + honoraria; Gilead Grant/research funds Clinical Trials + honoraria; Pfizer Grant/research funds Clinical Trials + honoraria; United Therapeutics Grant/research funds Clinical Trials + honoraria; Lilly Grant/research funds Clinical Trials + honoraria; LungRx Clinical Trials + honoraria; Bayer Grant/research funds Consulting

Amer Suleman, MD  Private Practice

Amer Suleman, MD is a member of the following medical societies: American College of Physicians, American Heart Association, American Institute of Stress, American Society of Hypertension, Federation of American Societies for Experimental Biology, Royal Society of Medicine, and Society of Cardiac Angiography and Interventions

Disclosure: Nothing to disclose.

Chief Editor

Richard A Lange, MD  Professor and Executive Vice Chairman, Department of Medicine, Director, Office of Educational Programs, University of Texas Health Science Center at San Antonio

Richard A Lange, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Cardiology, American Heart Association, and Association of Subspecialty Professors

Disclosure: Nothing to disclose.

Additional Contributors

The authors and editors of eMedicine gratefully acknowledge the contributions of previous authors Shivkumar H Jha, MD; Jatin Dave, MD, MPH; Kishorkumar Desai, MD; and Abraham G Kocheril, MD, FACC, FACP to the development and writing of this article.

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Transthoracic echocardiogram demonstrating severe mitral regurgitation with heavily calcified mitral valve and prolapse of the posterior leaflet into the left atrium.
Transesophageal echocardiogram demonstrating prolapse of both mitral valve leaflets during systole.
Transthoracic echocardiogram demonstrating bioprosthetic mitral valve dehiscence with paravalvular regurgitation.
 
 
 
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