Mitral Regurgitation

Question 1

Define mitral regurgitation?

Answer 1

Retrograde flow into the left atrium from the left ventricle

Question 2

What are the mechanisms of regurgitation?

Answer 2

1. Abnormalities of the valve leaflets
2. Abnormalities of the valve annulus
3. Abnormalities of the chordae tendineae
4. Abnormalities of the papillary muscles

Question 3

What are the etiologies of chronic mitral regurgitation?

Answer 3

• Mitral leaflet prolapse (congenital, myxomatous degeneration)***
• Coronary artery disease***
• Left ventricular dilatation (numerous causes)
• Rheumatic fever
• Calcified mitral annulus
• Heritable disorders of connective tissue (Marfan’s syndrome, Ehlers-Danlos syndrome, osteogensis imperfecta)
• Papillary muscle dysfunction (ischemia/infarction)**
• Lupus erythematosis
• Anorexic medications (‘phen-fen’)

Question 4

Etiologies of acute mitral regurgitation?

Answer 4

• Rupture of tendinous cords (myxomatous, endocarditis, trauma)
• Rupture of papillary muscle (infarction, trauma)
• Perforation of leaflet (endocarditis)

Question 5

What is the pathophysiology of Mitral regurgitation?

Answer 5

1. The left ventricle decompresses into the left atrium and impedance to outflow is reduced.
2. Regurgitant volume leads to LV volume overload, increased LV end diastolic pressure. Wall tension is normal or low.
3. Initially, LVEF may be normal or increased. (Moderately reduced values such as an EF of 40% may indicate severe LV dysfunction).
4. Forward cardiac output is reduced.
5. Prominent V-waves may be seen on left atrial or pulmonary capillary wedge recordings.
6. Hemodynamics are affected by left atrial compliance.

Question 6

What are the clinical manifestations of mitral regurgitation? Prognosis if untreated?

Answer 6

a) Variable depending on severity rate of progression, pulmonary artery pressure and associated cardiac disease and include dyspnea, exercise intolerance, orthopnea & PND. Right heart failure with edema and pulmonary hypertension can be associated longstanding MR.
b) Acute pulmonary edema less common in chronic MR than MS. Fatigue and weakness are more prominent.
c) Long “symptom free” interval. Severe even irreversible LV dysfunction maybe present at the onset of symptoms of low cardiac output and pulmonary congestion.
d) Overall, if untreated, severe MR has a worse prognosis than MS (?45% 5 yr. survival).

Question 7

Physical exam findings of mitral regurgitation patient?

Answer 7

a) Sharp carotid upstroke when LV function is preserved.
b) PMI brisk and displaced to the left
c) May have palpable LV filling wave or systolic expansion of LA
d) Decreased S1, often wide splitting of S2 and an S3
e) The most prominent physical sign is a pansystolic murmur starting with S1 and obscuring S2. Usually high pitched, loudest at the apex and radiating to the axilla.

Question 8

What might EKG/chest x-ray/ and echocardiography show for mitral regurgitation?

Answer 8

1. ECG – can commonly demonstrate left atrial enlargement, atrial fibrillation and LVH.
2. Chest x-ray may show LA and/or LV enlargement, congestion or valvular calcification.
3. Echocardiography may help determine the etiology and hemodynamic consequences of MR, doppler can help quantify the severity.

Question 9

Acute mitral regurgitation patients are______? more likely to have? Explain the quality of the murmur? Chest x-ray with acute mitral regurgitation?

Answer 9

Acute Mitral Regurgitation = ‘very sick patient’

1. Because of decreased left atrial compliance, more likely to have severe pulmonary edema & congestion and cardiogenic shock can occur .
2. Because of the prominent V-wave, the murmur may be decrescendo and end before S2. The murmur may be difficult to hear or radiate atypically toward the base (think: blown posterior leaflet).
3. Chest x-ray may not show any cardiac enlargement initially but likely will show congestion.

Question 10

what is the medical management of Mitral regurgitation?

Answer 10

1. Medical
   a) Diuretics, digoxin, salt restriction

b) Afterload reduction is of particular benefit in the acutely ill (1) Acutely can use nitroprusside or IABP (2) ACE inhibitors, hydralazine

Question 11

When is afterload reduction not particularly helpful as a tool to treat Mitral regurgitation? If we see functional mitral regurgitation secondary to LV dysfunction what do we do? Endocarditis prophylaxis?

Answer 11

c) Afterload reduction in chronic, asymptomatic MR is not clearly beneficial in the absence of hypertension or LV dysfunction. There is some concern that it may ‘mask’ signs and symptoms which might prompt surgical treatment. It can be helpful as interim treatment in symptomatic patients pending surgery or who are not operative candidates.
d) IF there is functional MR secondary to LV dysfunction, primary treatment of the LV dysfunction with drugs such as beta blockers and ACE inhibitors has been to reduce the severity of MR.*
e) Endocarditis prophylaxis—no longer routine.

Question 12

What features should we consider if we are thinking about referring for surgery with mitral regurgitation?

Answer 12

• The acuity with which it developed
• The symptoms and the severity of symptoms • The etiology of the MR: Ie: is there a primary structural abnormality of the valve or is the valve structurally normal and the MR is the result of CAD or ischemia or, alternatively, a secondary result of myocardial disease with resultant LV dilitation, papillary muscle displacement and annular dilitation?
• The effect of the MR on the heart—primarily the left ventricle
• Patient factors and comorbidities

Question 13

What do we surgically do for mitral regurgitation?

Answer 13

• Mitral repair rather than replacement (MVR) is preferred for several reasons:
– Mitral repair has lower operative mortality (1/2)
– LV function is better preserved with preserved integrity of the mitral apparatus
– Repair avoids the risks inherent inherent to prosthetic valves: thromboembolism and anticoagulant induced hemmorhage with mechanical valves and structural deterioration with biologic valves as well as the risk of endocarditis with both.

Question 14

What always warrants surgery?

Answer 14

Acute severe MR with symptoms warrants surgery

Question 15

What are the indications for mitral repair surgery in those with chronic mitral regurgitation?

Answer 15

– Chronic severe primary MR in symptomatic patients with and LVEF>30%
– Chronic severe primary MR and LV dysfunction LVEF 30-60% and or LV systolic dimension >40mm

– Concommitent mitral surgery in patients with chronic severe MR undergoing cardiac surgery for other reasons

Here we repair if possible!

Question 16

What are the indications for mitral repair surgery in those with severe chronic mitral regurgitation?

Answer 16

– Mitral valve repair in asymptomatic patients with severe primary MR (nonrheumatic) and preserved LV function with a high liklihood of durable repair (>95%) and low mortality (<1%)

– Mitral valve repair in asymptomatic patients with severe chronic MR, preserved LV function with new onset afib or pulmonary hypertension (PA systolic>50mm)

– Mitral repair with moderate primary MR undergoing cardiac surgery for other reasons

MAY consider it with:
– Chronic severe primary MR and LVEF<30% (high risk) – Chronic severe MR in patients with rheumatic disease and a likely repairable valve when anticoagulation is not advisable or likely
– Transcatheter repair in severe primary MR with favorable anatomy and prohibitive surgical risk

Question 17

Additional advice on surgery:

Answer 17

–You will note that the more difficult the clinical situation makes repair rather than replacement more desirable.

–Valve replacement should be undertaken with a conservative approach to the mitral and submitral apparatus.

–In patients > 75 symptoms should guide whether or not to operate since mortality/morbidity benefit of surgery is not as clear.

Question 18

What is the mitral valve prolapse syndrome?

Answer 18

A common but variable clinical syndrome which results from superior systolic displacement of the mitral leaflets into the left atrium in systole. Affects 3-5% of the population-females 2:1.

Question 19

What is the etiology of the mitral valve prolapse syndrome?

Answer 19

The most common course is myxomatous degeneration of the valve but MVP can be associated with Marfans, endocarditis, coronary disease, cardiomyopathy, connective tissue disease, rheumatic heart disease, and multiple other disorders. Can also be associated with a straight thoracic spine & pectorus excavatum.

Question 20

Clinical manifestations of mitral valve prolapse?

Answer 20

The majority are asymptomatic but symptoms associated may include fatigability, palpitations, chest discomfort & postural light headedness. There is an association with autonomic dysfunction and MVP is a weak risk factor for transient ischemic attack . If there is severe MR, symptoms of low cardiac reserve predominate.

Question 21

Physical examination of mitral valve prolapse?

Answer 21

The most important finding is a mid to late systolic click after associated with a mid to late crescendo systolic murmur that continues to A2. The murmur can occasionally be musical or honking. If the MR becomes more severe, the murmur can become holosystolic. Maneuvers which decrease left ventricular volume can cause the click and murmur to move closer to S1.

Question 22

CXR and EKG of mitral prolapse? Echo?

Answer 22

1. The CXR & ECG are usually normal. Ventricular ectopy is common usually involving isolated PVC’s. Supraventricular tachycardias are the most common sustained arrhythmia.
2. Echocardiography is the key diagnostic tool and can demonstrate the superior displacement of the mitral leaflets, define any other structural abnormalities and quantify the degree of regurgitation if present.

Question 23

Management of mitral valve prolapse?

Answer 23

1. Reassurance
2. Asymptomatic patients with mild or less regurgitation can be followed clinically (yearly) and should have an echo if there is a change in clinical signs or symptoms.
3. SBE prophylaxis is no longer felt to be routinely necessary.
4. If there are palpitations a 24 hour holter should be performed.
5. Avoid stimulants
6. A Beta blocker is often useful for symptomatic PVC’s, chest pain, anxiety, etc.
7. 1-7% of patients develop progressive MR (1-4% severe). These are usually those with redundant and thickened leaflets. If there is clinically significant MR (moderate or more), they should be followed with serial echoes & examinations (at least yearly) and treated like other MR patients.
8. ASA or coumadin if neurologic events.