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A. Mitral Regurgitation (MR) [2]navigator

  1. Extremely common valve abnormality
    1. Increasing incidence in elderly
    2. ~500,000 discharge diagnoses of mitral valve disease per year in USA
    3. ~18,000 cases of mitral valve surgery per year in USA
    4. MR usually diagnosed by new onset murmer or on echocardiography
  2. Causes be considered as organic valve lesions or functional abnormalities
  3. Organic Valve Lesions (prevalence is shrinking)
    1. Rheumatic Heart Disease
    2. Mitral prolapse due to myxomatous degeneration
    3. Flail Leaflet - idiopathic, endocarditis, trauma
    4. Infective endocarditis with valve perforation
    5. Papillary muscle rupture or dysfunction - often ischemic
    6. Ruptured chordae tendinea
    7. Calcification of mitral annulus
    8. Incomplete leaflet closure due to dilated Left ventricle
    9. Carcinoid-like changes due to appetite suppressant (serotonergic) drugs [11,12,13]
    10. Regurgitation due to appetite suppressants does not or only minimally progresses [18,19]
    11. Progression of valve disease with carcinoid related to serotonin levels, chemotherapy [21]
  4. Functional Lesions (increasing prevalence)
    1. Due to Primary Myocardial Disease
    2. Usually occurs post-myocardial infarction
    3. Due to Left Ventricular (LV) dilatation from muscle death and remodelling
    4. This leads to widening of mitral apperture and failure of full valve closure
    5. Mitral valve prolapse (see below) and ischemia are most common reasons for surgery
  5. Diseases Frequently Associated with MR
    1. Atrial fibrillation (AFib)
    2. Idiopathic left atrial enlargement
    3. Ischemic cardiomyopathy (and post-myocardial infarction)
    4. Other dilated cardiomyopathy
    5. Acute pulmonary edema often accompanied by ischemic MR [4]
    6. Systemic Lupus Erythematosus (often asymptomatic) [5]
    7. Increasing association with anorexic drug use (along with other valves) [7]
  6. Pathophysiology
    [Figure] "Cardiac Cycle with Valve Abnormalities"
    1. Volume overloaded LV occurs since true cardiac output decreases
    2. Blood flow will regurgitate through mitral valve rather than higher pressure aorta
    3. The end-diastolic volume (LVEDV) increases from normal of 150mL to >170mL
    4. The end-systolic volume (LVESV) decreases from normal of 50mL to ~30mL
    5. Left atrial pressure increases due to high regurgitant volume (~50% of stroke volume)
    6. Forward stroke volume is reduced from normal ~100mL to ~70mL
    7. Chronic compensation occurs by cardiac dilatation, leading to increased wall stress
    8. Eventually the LV muscle fails, and stroke volume decreases, leading to severe CHF
    9. In addition, dilated LV is associated with increased risk of sudden cardiac death (SCD)
    10. SCD most likely due to ventricular arrhythmias
    11. AFib risk is greatly increased in patients with dilated cardiac chambers
  7. Murmur
    1. Apex radiating to axilla
    2. Crescendo - decrescendo holosystolic murmur
    3. An S3 gallop suggests the disease is severe, with or without actual CHF
  8. Symptoms
    1. May be asymptomatic, particularly in early or acute phase
    2. Dyspnea on Exertion (DOE) - pulmonary pressures elevated ± frank pulmonary edema
    3. Congestive Heart Failure (CHF)
    4. Pulmonary Hypertension with Right Ventricular Failure
    5. AFib will develop in >30%
    6. Onset of AFib or CHF is evidence of significant dysfunction
  9. Evaluation [8]
    1. Echocardiographic of all patients with potential MR is required
    2. Echocardiographic measurements can be used to accurately predict prognosis
    3. LV End Systolic Diameter (ESD) and LV ejection fraction (EF) are key parameters
    4. Electrocardiography (ECG) is also important for evaluation of ischemia, arrhythmias
    5. Long term cardiac rhythm recorders for intermittent AFib, other arrhythmias
    6. Presence of clinical symptoms or signs is not sufficiently sensitive for full evaluation
  10. Classification and Echocardiographic Evaluation Frequency [2]
    1. Mild: normal ESD and EF; echocardiogram every (q) 5 years
    2. Moderate MR on echocardiogram: normal ESD and EF; echo q 1-2 years
    3. Moderate MR: ESD >40mm or EF <65%; echo annually
    4. Severe MR: normal ESD and EF; echo annually
    5. Severe MR: ESD >40mm or EF <65%; echo q 6 months
  11. Disease Progression and Outcomes [2,8]
    1. Untreated disease has poor prognosis
    2. Average interval from diagnosis to symptoms ~16 years
    3. Despite medical treatment, long term prognosis with LV dysfunction is poor
    4. Surgical therapy with valve repair (preferred) or replacement is generally preferred
  12. Medical Treatment
    1. In many patients, this should be considered a temporizing measure
    2. Afterload reduction (ACE inhibition, Calcium channel blockers) may improve symptoms
    3. These agents reduce forward afterload and increase forward stroke volume
    4. They provide initial symptomatic improvement, but no clear long term benefit
    5. Diuretics (low intravascular volume) -symptomatic improvement
    6. AFib is treated as usual; digoxin may be included for EF <30%
    7. Pulmonary hypertension is very difficult to treat medically
  13. Surgical Therapy [2,8]
    1. For patients with estimated operative mortality <2%, surgery is generally preferred
    2. Surgery also preferred for patients with any symptoms, unless LV EF <30% then medical
    3. Valve repair is generally preferred over replacement with better long term results
    4. In patients with ruptured chordae, repair or replacement of chrodae is advocated
    5. Surgery undertaken prior to onset of symptoms or complications strongly recommended
    6. Surgery recommended LV EF <60% or ESD >45 mm or AFib or pulmonary hypertension
    7. Surgery also for effective regurgitant area of >40 square mm
    8. MR due to flail leaflet should generally be treated surgically
    9. In good centers in USA, surgical mortality is now ~1%
  14. Poor Prognostic Signs [8]
    1. LV Ejection Fraction of <60% (by echocardiography)
    2. Atrial Fibrillation
    3. Significant Heart Failure (Class III or IV)
    4. End Diastolic Diameter >45 mm

B. Mitral Stenosis [1]navigator

  1. Etiology
    1. Nearly always due to rheumatic heart disease (RHD); reduced incidence
    2. Rarely occurs with heavy calcification of mitral annulus
    3. Increased risk with certain diet drugs, ergot derivatives
    4. Diet drugs: fenfluramine, dexfenfluramine
    5. Ergot derivatives: pergolide, ergotamine, methysergide [20]
    6. Congenital mitral stenosis rarely found post-puberty
  2. Associations
    1. Pulmonary hypertension (HTN) with dyspnea on exertion common at presentation
    2. Pulmonary HTN occurs due to pulmonary arteriolar vasoconstriction
    3. Atrial Fibrillation (AFib) is very common [6]
    4. ~20% lifetime risk of thromboemoblic events
      1. This is reduced substantially by anticoagulation with warfarin
  3. Murmer and Evaluation [14]
    1. S1 loud, snapping, "tapping"
    2. Opening Snap follows A2 sound (aortic valve closure, second heart sound)
    3. Low pitched, midcycle, rumbling diastolic murmur
    4. Length of rumble usually proportional to severity at apex
    5. Echocardiography is best method for noninvasive evaluation of mitral stenosis
    6. Pulmonary hypertension should be evaluated and is indication for therapy
  4. Disease Progression
    1. Normal mitral valve area is 4-6 sq cm
    2. Symptoms rarely develop when area is >2 sq cm
    3. Severe symptoms, often at rest, develop at <1 sq cm, called "critical" mitral stenosis
    4. At <1 sq cm area, a 20mm Hg pressure gradient is required to maintain cardiac output
    5. Dyspnea on exertion - pulmonary hypertension
    6. Hypotension with light-headedness due to poor LV filling
    7. Hemoptysis due to pulmonary venous congestion ("cardiac apoplexy")
    8. AFib - mechanism often unclear
    9. Systemic embolism - age, AFib, LA thrombus, severe aortic regurgitation, increased risk
  5. Treatment
    1. Maintain normal to low-normal heart rate to allow LV filling
    2. Using ß-blockers or rate-slowing calcium blockers may also reduce atrial fibrillation
    3. Monitor RV pressures for pulmonary hypertension and Cor Pulmonale
    4. Aggressive anti-coagulation (see below)
    5. Invasive valve procedures: valvuloplasty and replacement
  6. Anticoagulation
    1. Reduces risk of systemic embolism, particularly stroke
    2. All patients with Afib and Mitral Stenosis
    3. All patients with rheumatic heart disease (high risk of embolization)
    4. Patients with left atrial (LA) thrombus on echocardiography [9]
    5. Strongly consider for moderate and severe aortic insufficiency [9]
  7. Mitral Valvuloplasty [3]
    1. Treatment for valve areas ~1.0 sq cm dilated to ~2.1cm2
    2. Reduction in transmitral pressure gradient 14mm reduced to 6mm
    3. Five year event free survival ~50%
    4. Very effective for moderate and moderately severe mitral valve disease
    5. Safer than surgery with equivalent efficacy
    6. Also appears to reduce risk of systemic emoblism, even in sinus rhythm [9]
  8. Mitral Valve Replacement
    1. Failed Valvuloplasty
    2. Concurrent with CABG or other valve replacement

C. Mitral Valve Prolapse (MVP) [10]navigator

  1. Prolapse of valve into atrium on closing
    1. Echocardiographic definition now used
    2. Single or bileaflet prolapse of at least 2mm beyond long-axis anular phase
    3. WIth >5mm ("classic") thickening or without (<5mm) leaflet thickening
    4. No specific cardiac compromise
  2. Epidemiology of Classic and Non-classic Prolapse
    1. Current data indicate a combined prevalence of ~2.5%
    2. Equal distribution between sexes
    3. About 1.3% of the general population has classic (primary) MVP [16]
    4. Another 1.1% have non-classic MVP, which appears to be a normal variant
    5. Therefore, non-classic MVP should not be considered a disease
  3. Etiology and Associations
    1. Multiple associations or causes
    2. Histologic abnormalities of vascular tissue
    3. Geometric disparities between LV and mitral valve
    4. Associated with various connective tissue diseases
  4. Clinical Exam Findings
    1. Often no findings are present
    2. A mid- to late-systolic click may be heard, although it can be intermittant
    3. High-pitched, late systolic murmer
  5. Electrocardiogram (ECG) may show T wave abnormalities
  6. Echocardiographic Findings
    1. Modern 2-dimensional echocardiographic criteria have been developed
    2. Primary MVP have redundant and thickened mitral valve leaflets
    3. Non-classic MVP should be considered normal variant, as they have normal leaflets
    4. Associated mitral regurgitation, LV dysfunction or dilatation, or arrhythmias
  7. Primary MVP
    1. May have increased risk for endocarditis with various invasive procedures
    2. Dental work is of particular concern
    3. Endocarditis prophylaxis is usually recommended [15]
    4. Sometimes associated with panic attacks or atypical chest pain
    5. Panic attacks can be treated with ß-blockers; imipramine may be effective
    6. Risk of cerebral embolic events does not appear to be increased in MVP patients [17]
  8. Indications for Valve Surgery
    1. Acute MR in which repair is likely
    2. Symptomatic MR with normal LV function and dimensions
    3. Mild-moderate LV dysfunction or dilation (regardless of symptoms)
    4. Possible: associated with atrial fibrillation and normal LV function
    5. Possible: pulmonary hypertension (>50mm Hg at rest; >60mm Hg with exercise)

References navigator

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  2. Otto CM. 2001. NEJM. 345(10):741
  3. Reyes VP, Raju BS, Wynne J, et al. 1994. NEJM. 331(15):961 abstract
  4. Pierard LA and Lancellotti P. 2004. NEJM. 351(16):1627 abstract
  5. Roldan CA, Shively BK, Crawford MH. 1996. NEJM. 335(19):1424 abstract
  6. Brickner ME. 1996. Am J Med. 100(4):465 abstract
  7. Connolly HM, Crary JL, McGoon MD, et al. 1997. NEJM. 337(9):581 abstract
  8. Enriquez-Sarano M, Orszulak TA, Schaff HV, et al. 1997. Mayo Clin Proc. 72:1034 abstract
  9. Chiang CW, Lo SK, Ko YS, et al. 1998. Ann Intern Med. 128(11):885 abstract
  10. Hayek E, Gring CN, Griffin BP. 2005. Lancet. 365(9458):507 abstract
  11. Khan MA, Herzog CA, St Peter JV, et al. 1998. NEJM. 339(11):731
  12. Jick H, Vasilakis C, Weinrauch LA, et al. 1998. NEJM. 339(11):719 abstract
  13. Weissman NJ, Tighe JF Jr, Gottdiener JS, Gwynne JT. 1998. NEJM. 339(11):725 abstract
  14. Choudhry NK and Etchells EE. 1999. JAMA. 281(23):2231 abstract
  15. Nishimura RA and McGoon MD. 1999. NEJM. 341(1):48 abstract
  16. Freed LA, Levy D, Levine RA, et al. 1999. NEJM. 341(1):1 abstract
  17. Gilon D, Buonanno FS, Joffe MM, et al. 1999. NEJM. 341(1)8 abstract
  18. Mast ST, Jollis JG, Ryan T, et al. 2001. Ann Intern Med. 134(4):261 abstract
  19. Weissman NJ, Panza JA, Tighe JF Jr, Gwynne JT. 2001. Ann Intern Med. 134(4):267 abstract
  20. Van Camp G, Flamez A, Cosyns B, et al. 2004. Lancet. 363(9416):1179 abstract
  21. Moller JE, Connolly HM, Rubin J, et al. 2003. NEJM. 348(11):1005 abstract