Mitral Stenosis

Question 1

What is the Mitral valve composed of?

Answer 1

1. Leaflets 2. Chordae tendineae 3. Papillary muscles 4. Annulus

Question 2

What is the normal size of the mitral valve?

Answer 2

The normal mitral valve area is 4-6 cm2

Question 3

Explain the leaflets of the mitral valve? Where do they attach?

Answer 3

Continuous veil of fibrous tissue around the circumference of the annulus. The triangular anterior leaflet is a relatively thin flaplike and mobile structure attached to the fibrous skeleton of the heart at a point common to the aorta & aortic valve stretching along the annulus to the anterolateral wall and interventricular septum. The quadrangular posterior leaflet attaches to the mitral annulus at the junction of the left atrium and left ventricle and is less mobile, occupying 2/3 of the mitral circumference.

Question 4

The Chordea Tendineae arise from where? insert where? What muscles supply the chordae in the lateral half of the leaflets? the medial? (aka the submitral apparatus)

Answer 4

*The chordae tendineae arise from the tips of the papillary muscles and insert on the mitral leaflets (many more attachments on the mitral side composed to papillary muscles). *The anterolateral papillary muscles supplies chordae to the lateral half of both leaflets while the posterior medial papillary muscle supplies chordae to the medial half of both leaflets.

Question 5

What is the blood supply to the anterolateral papillary muscles? the posteriormedial muscles?

Answer 5

*The anterolateral papillary muscle receives its blood supply from branches of the left anterior descending artery while the posterior medial is usually supplied by the right coronary artery. The circumflex coronary artery can supply blood to both papillary muscles.

Question 6

What is the definition of mitral stenosis? What is the most likely etiology of Mitral Stenosis?

Answer 6

the development of valvular obstruction to left ventricular inflow. The vast majority of mitral stenosis cases are caused by Rheumatic Heart Disease.

Question 7

What are the full list of etiologies for mitral stenosis?

Answer 7

Rheumatic heart disease is by far the most common cause of mitral stenosis. Grp A hemolytic strept likely has M protein antigen in common with the heart leading to autoimmune effects on the endocardium and, to a much lessor extent, myocardium and pericardium. This leads to progressive scarring and fibrosis of the valve and submitral apparatus and restriction of mobility. • Cor triatiatum • Left atrial myxoma • Malfunctioning mitral prosthesis • Mitral annular calcification (usually mild MS) • Endocarditis with very large vegetations • Anorectic drugs and carcinoid syndrome (rare) • Pulmonary venous obstruction • Very,very rare: SLE, rheumatoid arthritis, methsergide toxicity, amyloid, mucopolysaccharidosis

Question 8

Explain the pathophysiology of Mitral Stenosis? Myocardial contractility in mitral stenosis? (full pathophysiology)

Answer 8

–Hallmark is commisural fusion • Elevation of LA pressure • Reflected into pulmonary bed results in left heart failure • Atrial arrhythmias • Right sided failure * Scarring of the valve leaflets and commissures leads to restricted valve mobility. Retractions can lead to a funnel shaped valve, chordal fibrosis, obliteration of interchordal spaces and LV inflow obstruction. * A diastolic pressure gradient develops between the left atrium (increasing LA pressure) and the left ventricle ultimately leading to increased pulmonary venous and capillary pressure causing exertional dyspnea. * An increase in heart rate shortens diastole and diminishes time for mitral inflow. Tachycardia can cause dramatic increases in left atrial pressure (and dyspnea). * LV flow becomes more dependent atrial contractions to augment the presystolic transmitral gradient (atrial fibrillation causes approximately 20% reduction in cardiac output). * Myocardial contractility is normal in the majority of patients. *In a few patients the ejection fraction is reduced (usually mild) probably from chronically reduced preload and elevated afterload. Regional wall motion abnormalities can occur due to scarring or myocarditis. *Largely because of inability to increase ventricular filling, cardiac output cannot rise appropriately with exertion leading to weakness and fatigue. With severe MS (<1.5 cm2), cardiac output is depressed at rest. * Elevated left atrial pressure leads to pulmonary venous congestion, pulmonary arteriolar constriction, elevated pulmonary vascular resistance (reactive) and ultimately chronic changes in the pulmonary vascular bed. Right-sided heart failure is common. * LA dilatation, fibrosis and disorganization of muscle bundles leads to changes in atrial conduction and commonly atrial fibrillation.

Question 9

Complications of Mitral stenosis?

Answer 9

– Right heart failure – Hepatic congestion – JVD – Tricuspid regurgitation – Right atrial enlargement – Pulmonary hypertension – Pulmonary congestion – LAE – Afib – LA thrombi – Increased LA pressure –RV pressure overload –RVH –RV failure – Decreased LV filling * LV function is generally preserved *

Question 10

Mitral valve areas and the type of symptoms that can be affected with those?

Answer 10

• Symptoms are rare if the valve area is >2 cm2 • Exertional symptoms may occur if the valve are is <2 cm2 (usually less) • Rest symptoms can occur if the valve area is <1-1.5 cm2

Question 11

Mitral Stenosis Clinical Manifestations/Symptoms?

Answer 11

• Dyspnea, PND, orthopnea (LHF) – Slow progressive course – Denial of symptoms is common • Palpitations • Cough • Fatigue • *Only 50% have hx of rheumatic fever • 2/3 women • Afib • Hoarseness • Systemic embolization (1025%) • Pulmonary infection/infarction • Hemoptysis • Right sided failure • Endocarditis • *Worsened by conditions which increase cardiac output/heart rate: exertion, fever, anemia, tachycardia, afib, pregnancy, thyrotoxicosis

Question 12

Signs of Mitral stenosis?

Answer 12

• Malar flush • JVD • Irregular rhythm (Afib) • Apical impulse normal or diminished • RV lift (in severe dx) • Carotid pulse usually preserved • Palpable S2 or OS • Loud S1 (early in course) • S2 to OS inversely proportional to severity • Diastolic rumble—length proportional to severity • Presystolic accentuation in sinus rhythm • Loud P2 • In severe MS/low flow-S1, OS & rumble may be inaudible • S2-OS interval –Mild: 110 msec –Mod: 80-110 msec –Severe: <70-80 msec • If auscultatory findings (rumble) are not present–exercise

Question 13

What sound can you NOT get with significant Mitral stenosis?

Answer 13

S3

Question 14

EKG findings in Mitral stenosis?

Answer 14

a) Left atrial enlargement in sinus rhythm b) Coarse atrial fibrillation c) Right axis deviation/right ventricular hypertrophy

Question 15

Chest x-ray findings of mitral stenosis?

Answer 15

a) Enlarged left atrium b) Enlarged pulmonary artery, right ventricle and right atrium in severe MS c) Cephalization of pulmonary vasculature d) Interstitial edema

Question 16

What is the Gold standard of diagnosing mitral stenosis? what can it do?

Answer 16

Echocardiography—the ‘Gold Standard’ a) Identifies characteristic thickened, restricted valve which can be planimetered for area. –The transmitral gradient obtained by echo/Doppler is the gold standard and more accurate than a gradient obtained by conventional cardiac catheterization

Question 17

What can doppler determine for Mitral stenosis?

Answer 17

b) Doppler can quantify the severity of MS using pressure halftime (mitral valve area=220/pressure half time) and gradient. Tricuspid regurgitation velocities can be used to estimate pulmonary artery pressure.

Question 18

What can cardiac catheterization see for Mitral stenosis?

Answer 18

c) Cardiac catheterization- Quantifies the transmitral gradient and valve area (MVA=cardiac output/sq.root of mean mitral valve gradient) and any associated pathology.

Question 19

What is the role of echo/doppler in diagnosing Mitral Stenosis?

Answer 19

• Diagnosis of mitral stenosis • Assess hemodynamic severity: mean gradient, MVA, pulmonary artery pressures • Assess RV size and function • Assess valve morphology for suitability for PBMV • Diagnosis & assessment of concommitent valvular lesions and effect on LV function • Reevaluation of pts with changing signs or symptoms • Reevaluation of asymptomatic pts with moderate or severe MS

Question 20

Explain the severity of Mitral stenosis and the associated MVA and mean gradient?

Answer 20

• Hemodynamic severity is best characterized by the planimetered mitral valve area and the calculated valve area from the diastolic pressure half time
• MVA < 1.5 cm2 is now considered severe***
• This generally corresponds to transmitral gradient > 5-10mm and pressure half time > 150ms • MVA < 1.0 is now considered very severe

Question 21

What is the natural history of rheumatic fever?

Answer 21

1. Rheumatic fever usually occurs at 8-12 years of age.
2. Mitral stenosis usually detected 2025 years later
3. Symptoms usually occur by age 40-50
4. AF occurs in up to 50%
5. Embolization occurs in 10-20% 6. Usually takes 5 years to progress from mild to severe disability

Question 22

Explain the medical therapy for Mitral stenosis?

Answer 22

• Diuretics for LHF/RHF
• Heart rate control!- B-blockers, CCB, (+-digoxin if afib)
• Anticoagulation in AFib, embolic events or LA thrombus (I). LA>5.5 cm and spontaneous contrast (IIb).
• Exercise is generally symptom limited since sudden death is rare
• Instruct pt in symptoms and advise prompt medical attention if any sudden worsening of dyspnea
• Strept prophylaxis—penicillin generally until age 40 (?SBE?)

Question 23

What is a strong indication for percutaneous mitral balloon valvotomy?

Answer 23

–PMBV is recommended for symptomatic pts (NYHA II,III, IV) with severe MS (<1.5cm2) and favorable valve morphology (pliable valve) in the absence of LA thrombus or moderate to severe MR

Question 24

What is a reasonable indication for percutaneous mitral balloon valvotomy?

Answer 24

– PBMV reasonable for patients with asymptomatic patients with very severe MS (< 1 cm2)

– PBMV may be considered in asymptomatic pts with severe MS and new onset Afib

– PBMV may be considered for asymptomatic pts and MVA <1.5cm2 if there is evidence that MS is hemodynamically significant during exercise (PA>60mm, PCWP>24 or mean gradient >15mm)

– PBMV as an alternative to surgery in patients with severe MS, nonpliable, calcified valve and severe symptoms and not surgical candidates or are high risk

Question 25

What is a strong indication for surgery for mitral stenosis?

Answer 25

– MV surgery (repair if possible) is indicated in pts with symptomatic severe MS (<1.5cm2) who are not candidates for PBMV (contraindicated because of LA thrombus, significant MR, unfavorable valve morphology for PBMV, failed prior PBMV, etc) with acceptable risk

– MV surgery indicated when severe MS and undergoing other cardiac surgery

– Symptomatic pts with severe MS with mod/severe MR should have MVR unless valve is repairable

Question 26

What are the reasonable indications for surgery for mitral stenosis?

Answer 26

–Concomittent mitral surgery for moderate mitral stenosis patients undergoing other cardiac surgery

–MV surgery with excision of left atrial appendage may be considered for asymptomatic pts with severe MS with recurrent embolic events while on adequate anticoagulation.

Question 27

When do we not do surgery for mitral stenosis?

Answer 27

–Mitral valve surgery for mild MS-unwarranted

–Closed commissurotomy should not be performed for MV repair. Open commissurotomy is the preferred approach (in the developed world).

Question 28

Key summary points about Mitral stenosis?

Answer 28

• Valvular obstruction to left ventricular inflow – resulting diastolic transmitral gradient – elevated LA pressure. – usually LV function is preserved
• Major cause is rheumatic heart disease
• Symptoms often develop slowly – exertional intolerance, dyspnea, etc., – atrial fibrillation and embolization can occur – conditions which increase heart rate can dramatically increase symptoms.
• Mitral opening snap (early on) and diastolic low pitched rumble at the apex are characteristic
• Symptomatic patients with valve areas < 1.5 cm2 can be improved with balloon valvuloplasty – Surgical MVR if the valve is too calcified or there is too much regurgitation