Mitral regurgitation resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Raviteja Guddeti, M.B.B.S. [2]; Mugilan Poongkunran M.B.B.S [3]

Pericarditis Resident Survival Guide Microchapters
Overview
Causes
FIRE
Complete Diagnostic Approach
Treatment Acute MR Chronic MR
Do's
Don'ts

Overview

Mitral regurgitation (MR), mitral insufficiency or mitral incompetence refers to a disorder of the heart in which the mitral valve fails to close properly during systole. This leads to leakage of blood flow from left ventricle to left atrium during systole and reduction in cardiac output. The symptoms associated with mitral regurgitation are dependent on which phase of the disease process the individual is in. Individuals with acute mitral regurgitation are often gravely ill with significant hemodynamic abnormalities due to decompensated congestive heart failure and low cardiac output that require urgent treatment, whereas individuals with chronic compensated mitral regurgitation may be asymptomatic, with a normal exercise tolerance and no evidence of heart failure. The management of chronic MR depends on whether the condition is chronic primary MR (the mitral valve is usually abnormal) or chronic secondary MR (the mitral valve is usually normal) and the severity of the valve anatomy.

Causes

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.

• Acute myocardial infarction
• Chest trauma
• Infective endocarditis

Common Causes

Acute Mitral Regurgitation

• Papillary muscle rupture: Acute myocardial infarction, chest trauma, ischemia
• Ruptured mitral chordae tendinae: Acute rheumatic fever, chest trauma, mitral valve prolapse, infective endocarditis, spontaneous rupture

Chronic Primary Mitral Regurgitation

• Marfan's syndrome
• Mitral annular calcification
• Mitral valve prolapse
• Myxomatous degeneration

Chronic Secondary Mitral Regurgitation

• Dilated cardiomyopathy
• Infective endocarditis
• Ischemic heart disease

Click here for the complete list of causes.

FIRE: Focused Initial Rapid Evaluation

A Focused Initial Rapid Evaluation (FIRE) should be performed to identify patients in need of immediate intervention.

Boxes in red signify that an urgent management is needed

Complete Diagnostic Approach to Mitral Regurgitation

Shown below is an algorithm summarizing the complete diagnostic approach to mitral regurgitation according to 2014 AHA/ACC guidelines for management of valvular heart disease..
AF: Atrial fibrillation; MR: Mitral regurgitation; EKG: Electrocardiogram; S1: First heart sound; S2: Second hert sound; S3; Third heart sound; LV: Left ventricle; MVP: Mitral valve prolapse

Characterize the symptoms: Acute mitral regurgitation: ❑ Symptoms of shock and pulmonary edema: ❑ Shortness of breath ❑ Orthopnea ❑ Paroxysmal nocturnal dyspnea ❑ Cough ❑ Altered mental status ❑ Pedel edema ❑ Oliguria ❑ Cyanosis ❑ Pallor ❑ Diaphoresis ❑ Abdominal pain (may be suggestive of mesenteric ischemia) ❑ Symptoms suggestive of precipitating events: ❑ Chest pain (suggestive of myocardial ischemia) ❑ Fever (suggestive of infective endocarditis) ❑ Petechiae, Osler's nodes, Janeway lesions (suggestive of infective endocarditis) Chronic mitral regurgitation: ❑ Asymptomatic ❑ Typical in isolated mild to moderate MR ❑ Severe MR until there is left ventricular failure, pulmonary hypertension or atrial fibrillation ❑ Symptoms associated with decreased forward flow and increased backflow across mitral valve: ❑ Exertional dyspnea ❑ Orthopnea ❑ Paroxysmal nocturnal dyspnea ❑ Exercise intolerance ❑ Fatigue ❑ Light-headedness ❑ Exertional syncope ❑ Exertional angina ❑ Cough ❑ Symptoms associated with complications: ❑ Palpitations (suggestive of atrial fibrillation) ❑ Hoarseness (recurrent laryngeal nerve compression due to left atrium enlargement) ❑ Fever (suggestive of infective endocarditis) ❑ Stroke (suggestive of thromboembolism) ❑ Hemoptysis (suggestive of thromboembolism) ❑ Flank pain and hematuria (suggestive of septic emboli or glomerulonephritis) ❑ Seizures (suggestive of thromboembolism) ❑ Symptoms of right heart failure: ❑ Ascites ❑ Pedel edema ❑ Abdominal pain (hepatomegaly) ❑Other etiology associated symptoms: ❑ Joint pains (suggestive of rheumatic etiology) ❑ Skin lesions (suggestive of rheumatic etiology)

Obtain a detailed history: ❑ Past medical history: ❑ Congenital heart disease ❑ Rheumatic heart disease ❑ Ischemic heart disease ❑ Valvular heart disease ❑ Cardiomyopathy ❑ Cardiac surgery ❑ Hypertension ❑ Diabetes mellitus ❑ Radiation exposure ❑ Collagen vascular disease ❑ Chest trauma ❑ Family history: ❑ Valvular heart disease ❑ Medications: ❑ Anorectic drug combinations ❑ Ergotamine ❑ Pergolide ❑ Cabergoline

Examine the patient: Vital signs: ❑ Pulse ❑ Rapid and thready (in acute MR) ❑ Low volume with brisk upstroke (in chronic MR) ❑ Irregularly irregular pulse (with onset of AF) ❑ Blood pressure ❑ Hypotension (in acute MR) ❑ Normotensive (in chronic MR with preserved ejection fraction) ❑ Temperature ❑ Fever (suggestive of infective endocarditis) ❑ Respiratory rate ❑ Tachypnea (typical) Skin: ❑ Cool and clammy (in cardiogenic shock) ❑ Cyanosis ❑ Peripheral edema (suggestive of right heart failure) Cardiovascular system: Palpation: ❑ Apical impulse ❑ Leftward displacement (in chronic MR due enlargement of the left ventricle) ❑ Hyperdynamic but in normal location (in acute MR) ❑ Thrill (in acute MR and severe chronic MR) ❑ Elevated jugular venous pulse ❑ Sign of elevated right sided pressure ❑ Seen in acute MR and severe chronic MR Auscultation: ❑ Heart sounds ❑ S1 is diminished (suggestive of MR) ❑ Wide splitting of S2 (low forward flow causing early A2) ❑ Loud and delayed P2 (suggestive of pulmonary hypertension) ❑ New S3 (suggestive of left ventricular dilation) ❑ Murmur ❑ High pitched and blowing holosystolic murmur (typical) ❑ Best heard over the apex radiating to the axilla and back ❑ Starts after S1 and continues up to and sometime beyond and obscuring A2 ❑ Other types of murmur ❑ Silent (in cases of acute MR) ❑ Mid to late systolic murmur (in case of papillary muscle prolapse) ❑ Early diastolic murmur (due to large diastolic flow across severe MR) ❑ Mid systolic click (suggestive of mitral valve prolapse) Respiratory system: ❑ Crackles or rales (suggestive of pulmonary edema) ❑ Tachypnea Abdominal system: ❑ Hepatojugular reflex ❑ Hepatomegaly ❑ Ascites Neurological system: ❑ Stroke (in case of thromboembolism)

Order electrocardiogram (Urgent): ❑ Mostly normal in acute MR ❑ In chronic MR ❑ Findings of left ventricular hypertrophy with strain ❑ Findings of left atrial enlargement ❑ Findings of pulmonary hypertension ❑ Findings of atrial fibrillation complication Order chest X-ray (urgent): ❑ Acute MR ❑ Normal size cardiac silhouette ❑ Signs of pulmonary edema ❑ Chronic MR ❑ Cardiomegaly ❑ Signs of pulmonary edema if left ventricle fails ❑ Calcification of the mitral valve annulus Order transthoracic echocardiography (TTE) (urgent): ❑ Confirmatory ❑ To determine severity and assess hemodynamic consequences ❑ To establish etiology ❑ To determine prognosis and evaluate for timing of intervention Order lab tests: ❑ CBC ❑ Electrolytes ❑ ESR ❑ Serum creatinine Other tests ❑ Transesophageal echocardiography (TEE if TTE is equivocal) ❑ Cardiac catheterization ❑ In stable acute MR to detect coronary obstruction ❑ To assess hemodynamic status in symptomatic patients when noninvasive tests are inconclusive ❑ To assess the severity when there is discrepancy between noninvasive testing and physical examination ❑ Exercise testing ❑ Done in asymptomatic severe MR ❑ To confirm the absence of symptoms ❑ To assess the hemodynamic response to exercise ❑ Cardiac MRI ❑ To assess severity when there is a discrepancy between clinical findings and echocardiography

Cardinal findings that are suggestive of acute mitral regurgitation ❑ Sudden onset and rapid progression of pulmonary edema ❑ Signs and symptoms of cardiogenic shock ❑ Silent to holosystolic murmur on auscultation ❑ Normal ECG ❑ Normal size cardiac silhouette on chest X-ray ❑ Echocardiography findings: ❑ Acute severe mitral regurgitation ❑ Normal left ventricular size ❑ Ruptured papillary muscle

Cardinal findings that are suggestive of chronic mitral regurgitation ❑ Asymptomatic to chronic symptoms ❑ Pre-existing heart disease ❑ Classic holosystolic murmur on auscultation ❑ ECG findings of left ventricular hypertrophy with strain and left atrial enlargement ❑ Cardiomegaly on chest X-ray ❑ Echocardiography findings: ❑ Mitral regurgitation ❑ Left ventricular dilation ❑ Preserved to decreased EF

Mitral valve anatomy

Normal

Abnormal

Chronic primary mitral regurgitation

Chronic secondary mitral regurgitation

Treatment

Treatment of Acute Mitral Regurgitation

Shown below is an algorithm summarizing the approach to the management of acute severe mitral regurgitation according to 2014 AHA/ACC guidelines for management of valvular heart disease..
MR: Mitral regurgitation; IE: Infective endocarditis

❑ Establish the diagnosis of acute MR

❑ Assess if the patient is hemodynamically stable?

Unstable

Stable

❑ Stabilize the patient ❑ Intra-aortic balloon pump ❑ Vasodilator therapy ❑Nitroprusside OR ❑Nicardipine ❑ Inotropic agents if needed ❑ Dobutamine ❑ Start antibiotic therapy in cases of IE

❑ Vasodilator therapy ❑Nitroprusside

Refer for surgical repair: ❑ Mitral valve repair is preferred in cases of ruptured chordae tendineae

❑ Refer for surgical repair in: ❑ Symptomatic acute severe MR (stage D) ❑ Partial rupture of papillary muscle irrespective of the severity of MR

Treatment of Chronic Mitral Regurgitation

Diagnosis

Symptoms

• Acute mitral regurgitation causes the following symptoms:
  • Dyspnea
  • Orthopnea
  • Hypotension

• Chronic mitral regurgitation may have a prolonged asymptomatic interval phase until the heart decompensates and the symptoms of low cardiac output and pulmonary congestion start. By the time the symptoms develop, left ventricular dysfunction may have already occurred.

Physical Examination

• S₃ and S₄ may be heard on auscultation.
• A holosystolic murmur is heard in the apical region of the heart. MR murmur radiates to the axillary region. It may be soft, short and even absent. 70% of the cases of papillary muscle rupture have no murmur.

Holosystolic murmur of acute mitral regurgitation.	Holosystolic murmur of chronic mitral regurgitation.

Imaging

Transthoracic echocardiography

Echocardiographic findings indicating the presence of severe mitral regurgitation include:

• Regurgitant volume >60 ml
• Regurgitant fraction >55%
• Effective regurgitant orifice (ERO) (ratio of regurgitant flow volume to the velocity of the mitral insufficiency jet: ERO = Flow / Velocity) >0.4 cm²
• If the left ventricular and left atrial sizes are normal on echocardiography, mitral regurgitation is not severe.
• Central jets indicate the presence of a fairly normal mitral valve and therefore the mitral regurgitation is not severe.
• Wide eccentric jets indicate that the regurgitation is severe.
• Echocardiographic findings must match the symptoms, if they do not, perform transesophageal echocardiography (TEE) or cardiac catheterization. TTE can underestimate the magnitude of mitral regurgitation in patients with clinical signs of severe MR.

Treatment

Acute Severe Mitral Regurgitation

• Treatment of acute severe mitral regurgitation depends on the stability of the patient.If the patient is clinically stable, the treatment options are:
  • IV vasodilators, diuretics, antibiotics, anti-ischemic agents
  • Surgery is preferred in the following cases:
    • Endocarditis with progressive congestive heart failure
    • No response to antibiotics
    • Abscess formation
    • Recurrent embolization

• If the patient is clinically unstable , the treatment options are:
  • IV nitroprusside is used to maintain blood pressure. Inotropes are added when needed.
  • If medical therapy is not effective, an intra aortic balloon pump can be inserted to maintain hemodynamic stability.
  • Surgical treatment is usually indicated.
  • Knowledge of the etiology of the mitral regurgitation is important to know if the valve can be repaired or replaced.

Chronic Mitral Regurgitation

Why the Mitral valve is replaced Before Symptoms in Patients with Chronic Mitral Regurgitation

• Mitral regurgitation is a syndrome of pure volume overload whereas aortic regurgitation is a combination of both volume and pressure overload.
• Both syndromes are associated with an increase in preload.
• in mitral regurgitation, the afterload is reduced whereas in aortic regurgitation the afterload is increased. This is very important because when the mitral valve is repaired, there is no longer a reduction afterload and the left ventricle may fail due to an abrupt rise in the afterload. In aortic regurgitation, because the afterload is already increased chronically, replacement of the valve is not as likely to precipitate acute left ventricular failure due to an abrupt rise in afterload.

• By the time symptoms develop, there is already left ventricular dysfunction.
• Because of the low pressure system into which the blood is ejected into through the mitral valve, the ejection fraction is always high in mitral regurgitation. If the ejection fraction appears to be "normal", there is already decline in left ventricular function.
• There is no indication for vasodilator therapy in the absence of systemic hypertension in asymptomatic patients with preserved left ventricular function.

Indications for Surgery in Chronic Mitral Regurgitation

The indications for surgery in chronic mitral regurgitation are:

• Any symptoms - this is unlike mitral stenosis where surgeons operate on the heart when patients have class III or IV symptoms.
• Severe organic MR.
• Left ventricular dysfunction - ejection fraction <60% and end systolic diameter >40 mm².
• Surgery can be considered in asymptomatic patients in the following cases:
  • Truly severe MR
  • Low operative mortality
  • High chance of successful repair (e.g: posterior leaflet - MVP)

• Pre-operative ejection fraction has a prognostic impact in patients who undergo mitral valve repair or replacement. The lower the ejection fraction is, the higher the mortality is.

Do's

Don'ts

• Don't perform coronary angiography before valve surgery in patients who are hemodynamically unstable.
• Avoid coronary angiography in patients of acute coronary syndrome complicated by severe acute mitral regurgitation.

References

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