Mitral regurgitation

Background

Schematic drawing of mitral regurgitation. During systole, contraction of the left ventricle causes abnormal backflow (arrow) into the left atrium. 1) Mitral valve; 2) Left ventricle; 3) Left atrium; 4) Aorta.

Annual incidence of degenerative Mitral Valve (MV) disease causing MR ~3% in industrialized countries^[1]
Other etiologies of MR:
- Cardiac ischemia
- Endocarditis
- Rheumatic disease
- SLE, scleroderma, amyloidosis, sarcoidosis
- Connective tissue disease (myxomatous degeneration, Marfan, Ehlers-Danlos)
- HOCM
- Dilated cardiomyopathy
- Mitral valve prolapse
- Congenital disorders
Criteria for MV repair^[2]:
- Development of NYHA class II symptoms
- Deterioration in LV function
- LV end systolic diameter < 4.5 cm with EF > 60% to protect LV function^[3]
However, recent evidence suggests best outcomes of MV repair are in asymptomatic or minimally symptomatic patients selected for surgery soon after echo dx^[4]

Clinical Features

Phonocardiograms of common cardiac murmurs.

Heart failure symptoms
Atrial dilatation and atrial fibrillation
Pulmonary hypertension
Ischemic mitral incompetency, following myocardial infarction or LV aneurysm^[5]
- Most common mechanism of MR in developed countries
- Dysfunction of ventricular wall leads to papillary muscle dysfunction or chordae rupture
- Posterior papillary muscle and supporting ventricular wall most commonly affected
  - Dyspnea, tachycardia, pulmonary edema (especially if new, and no cardiomegaly)
  - S4 heart sound
  - Apical systolic murmur

Differential Diagnosis

Valvular Emergencies

Evaluation

MV Anatomy in PSS

MV Anatomy in PSL

MV Anatomy in Apical

Clinical history and exam
- Myocardial infarction, endocarditis, trauma
- Dyspnea, tachycardia, pulmonary edema
- Suspect if new-onset pulmonary edema, alongside normal heart size
- Cardiogenic shock
- S4, apical systolic murmur
- Clinical evaluation with auscultation may underestimate MR severity^[6]
Echocardiography grading
- Traditional grading is different from ischemic MR grading
  - Eyeball grading of color jet from 1+ to 4+, set to color gain that minimizes background noise
  - Color jet area in atrium during maximal MR jet, obtain both PSL and apial 4 chamber, at Nyquist limit scale set of 60 cm/s

MR Grading by Eyeball of Color Jet

MR Grading by LA Maximal Jet Area

- Ischemic MR grading based on lesion severity of papillary muscle
- Factors that increase MR grading severity
  - Hypertension
  - Concomitant aortic stenosis
- Mitral valve anatomy and scalloping much better appreciated in TEE over TTE

Management

Supportive measures until definitive surgery^[7]
Appropriate treatment if myocardial infarction must include catheterization or thrombolysis
Pulmonary edema
- Oxygen
- Nitrates and diuresis may improve filling pressures and treat edema
- Early intubation for impending respiratory failure
Decrease afterload
- Nitroprusside can be considered in normotensive patients to increase cardiac output and decrease MR
- Intra aortic balloon pump may decrease afterload, increase forward cardiac output and reduce regurgitation
Inotropes
- Dobutamine pressor of choice as α agonism and increased afterload minimal compared to beta agonism^[8]
- Avoid beta-blockers as mild to moderate tachycardia allows less time for LV to backfill
Consult Cardiology or Cardiothoracic Surgery for definitive management

Disposition

Admit for severe presentations

External Links

emDocs - Acute Valvular Emergencies: Pearls and Pitfalls

References

↑ Kouchoukos NT. Problems in mitral valve replacement. In: Kirklin TW. eds. Advances in Cardiovascular Surgery. Grune & Stratton, New York,1973:205-16.
↑ Adams DH, Anyanwu AC. Seeking a higher standard for degenerative mitral valve repair: begin with etiology. J Thorac Cardiovasc Surg 2008;136:551-6.
↑ Mohan JC and Mohan V. Subclinical left ventricular systolic dysfunction in chronic mitral regurgitation and its potential impact on management: quo vadis? Indian Heart J. 2012 May; 64(3): 249–253.
↑ Anders S, Said S, Schulz F, et al. Mitral valve prolapse syndrome as cause of sudden death in young adults. Forensic Sci Int 2007;171:127-30
↑ Kosowsky JM: Infective Endocarditis and Valvular Heart Disease, in Marx JA, Hockberger RS, Walls RM, et al (eds): Emergency Medicine: Concepts and Clinical Practice, ed. 7. St. Louis, Mosby, Inc., 2010, (Ch) 81: p.1072-1074.
↑ Mitral Regurgitation, Ahmed MI, McGiffin DC, O'Rourke RA, Dell Italia LJ. Current Problems in Cardiology Volume 34, Issue 3, March 2009, Pages 93–136
↑ DiSandro D et al. Acute Mitral Regurgitation Treatment & Management. eMedicine. Dec 28, 2015. http://emedicine.medscape.com/article/758816-treatment.
↑ Sonoda M et al. Effects of Dobutamine Infusion on Mitral Regurgitation. Echocardiography. 1998 Jan;15(1):13-20.

Authors:

[1] Kouchoukos NT. Problems in mitral valve replacement. In: Kirklin TW. eds. Advances in Cardiovascular Surgery. Grune & Stratton, New York,1973:205-16.

[2] Adams DH, Anyanwu AC. Seeking a higher standard for degenerative mitral valve repair: begin with etiology. J Thorac Cardiovasc Surg 2008;136:551-6.

[3] Mohan JC and Mohan V. Subclinical left ventricular systolic dysfunction in chronic mitral regurgitation and its potential impact on management: quo vadis? Indian Heart J. 2012 May; 64(3): 249–253.

[4] Anders S, Said S, Schulz F, et al. Mitral valve prolapse syndrome as cause of sudden death in young adults. Forensic Sci Int 2007;171:127-30

[5] Kosowsky JM: Infective Endocarditis and Valvular Heart Disease, in Marx JA, Hockberger RS, Walls RM, et al (eds): Emergency Medicine: Concepts and Clinical Practice, ed. 7. St. Louis, Mosby, Inc., 2010, (Ch) 81: p.1072-1074.

[6] Mitral Regurgitation, Ahmed MI, McGiffin DC, O'Rourke RA, Dell Italia LJ. Current Problems in Cardiology Volume 34, Issue 3, March 2009, Pages 93–136

[7] DiSandro D et al. Acute Mitral Regurgitation Treatment & Management. eMedicine. Dec 28, 2015. http://emedicine.medscape.com/article/758816-treatment.

[8] Sonoda M et al. Effects of Dobutamine Infusion on Mitral Regurgitation. Echocardiography. 1998 Jan;15(1):13-20.

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