DESCRIPTION

Congenital abnormalities of the mitral valve result in incompetence during systole (ventricular contraction), causing regurgitation of blood into the left atrium (LA) with each LV contraction.

RISK FACTORS

• Congenital mitral abnormality
• History of rheumatic fever
• Endocardial cushion defect
• Mitral valve prolapse
• Connective tissue disease

Genetics

Isolated congenital mitral insufficiency is a rare isolated congenital anomaly in pediatric patients. However, mitral regurgitation is often associated with other cardiac defects, including endocardial cushion defect.

GENERAL PREVENTION

• When indicated, bacterial endocarditis prophylaxis for dental and invasive procedures is continued for life.
• Rheumatic fever prophylaxis when indicated

PATHOPHYSIOLOGY

Mitral regurgitation results in volume loading of the LV because cardiac output must be maintained despite a regurgitant fraction returning to the LA through the incompetent mitral apparatus. Given the lower pressure in the LA, "unloading" of the LV occurs at low resistance. This may result in apparent normalization of LV function with ejection fractions that may not reflect true ventricular function.

ETIOLOGY

• Most often seen in association with other congenital heart defects, connective tissue disease, or metabolic/storage disease
• Secondary/acquired mitral regurgitation (MR) is seen following acute rheumatic fever, Kawasaki disease, cardiomyopathy, and endocarditis in children.

COMMONLY ASSOCIATED CONDITIONS

Mitral insufficiency is a component of numerous congenital and acquired cardiac abnormalities. These include:

• Endocardial cushion defects
• Mitral valve prolapse
• Cleft of the anterior leaflet
• Rheumatic fever
• Cardiomyopathy
• Myocardial or papillary muscle infarction
• Ruptured chordae tendinea
• Connective tissue disorders
• Endocarditis
• Kawasaki disease
• Endocarditis

Outline

• Description
• Risk Factors
  • Genetics
• General Prevention
• Pathophysiology
• Etiology
• Commonly Associated Conditions

Signs and symptoms:

• General:
  • Symptoms usually depend on the severity and acuity of MR, although patients may be asymptomatic even with severe MR.
  • Chronic MR is usually well-tolerated in children.
• Most common signs and symptoms:
  • Shortness of breath
  • Tachypnea
  • Increased frequency of respiratory tract infections
  • Cough
  • Fatigue
  • Poor feeding
  • Exercise intolerance
• Other signs and symptoms:
  • Growth failure, if advanced

History

• Murmur
• Rheumatic fever
• Connective tissue disease
• Mitral valve prolapse
• Congenital cardiac abnormality

Physical Exam

• Increased precordial activity
• RV heave if associated with increased pulmonary arterial pressure
• Laterally displaced LV impulse
• Increased intensity of 2nd heart sound if pulmonary arterial pressure is elevated
• S3 may be prominent.
• Murmur of MR is a high-frequency, blowing, pansystolic sound heard best at the apex, with radiation to the axilla (appreciated best when patient is supine and leaning leftward).
• If MR is moderate to severe, a low-frequency diastolic rumble may be appreciated at the apex, which represents increased diastolic flow across the mitral valve.

DIAGNOSTIC TESTS & INTERPRETATION

ECG:

• May remain normal until MR is severe
• LA enlargement (manifested by broad, notched P waves prominent in lead II)
• Prominent LV forces
• RV hypertrophy may eventually be present in severe cases with pulmonary HTN.
• If LA enlargement is severe, atrial arrhythmias are more likely to be observed.

Imaging

• CXR:
  • Cardiomegaly (enlarged LA and LV)
  • Pulmonary venous congestion
  • Pulmonary edema (if severe mitral regurgitation) with heart failure
• Echo:
  • Detailed visualization of the mitral valve and valve apparatus
  • LV systolic function is normal to increased because the ventricle is unloaded. If "normal," it must be compared with previous echo to ensure that function has not deteriorated.
  • LA may appear dilated.
  • Color Doppler can be used to qualitatively assess MR.
  • If severe, pulmonary venous flow reversal may be observed (ie, reflux into the pulmonary veins).
• MRI:
  • May use for LV volume assessment
  • Can be used to help quantify MR fraction
• Cardiac catheterization:
  • May be indicated if echo is not conclusive regarding the cause of MR, cardiac function, associated lesions, or degree of pulmonary HTN
  • Mitral valve anatomy, cardiac output, pulmonary vascular resistance, and associated lesions should be assessed.
  • Pressure tracings demonstrate an elevated pulmonary capillary wedge pressure A-wave or an elevated left atrial A-wave if LA is entered.

DIFFERENTIAL DIAGNOSIS

The main considerations for differential diagnosis of types of MR include:

• Acquired heart disease, such as acute rheumatic fever or chronic rheumatic heart disease
• Congenital mitral regurgitation alone or in association with endocardial cushion defects or mitral valve prolapse
• Connective tissue disease
• Acute trauma, infarcted papillary muscle

Outline

• Information
• History
• Physical Exam
• Diagnostic Tests & Interpretation
  • Imaging
• Differential Diagnosis

• Mild to moderate chronic MR often can be managed medically with digoxin and diuretics.
• ACE inhibitors (ACE-Is) may be used for afterload reduction, although they usually are reserved for moderate to severe MR (long-term use in children has not been well studied).
• If MR is acute, patients are usually more symptomatic because the uncompensated LA has a sudden increase in volume overload. These patients usually require IV afterload reduction with nitroprusside or hydralazine, in addition to digoxin or IV inotrope and diuretics.
• If atrial arrhythmias are present, antiarrhythmic medications should be administered as needed.
• If MR is secondary to rheumatic fever, following initial treatment, long-term prophylaxis is necessary: 1.2 million units penicillin G benzathine IM q4wk or penicillin V 250 mg PO b.i.d.
• Bacterial endocarditis prophylaxis per AHA guidelines.
• For patients who undergo MVR, anticoagulation (heparin) should be started within 8–12 hr of surgery at a dose that achieves a partial thromboplastin time of 1.7–2.0 times normal. PO anticoagulation also may be started once no active surgical issues are present, such as chest tubes or pacing wires requiring removal.
• Warfarin should be dosed to achieve an INR of 2.0–3.0. Discontinue heparin once warfarin is in the therapeutic range.
• Contraindications: Penicillin or other drug allergies
• Precautions: Refer to manufacturer’s profile of each drug.

ADDITIONAL TREATMENT

General Measures

• Outpatient, except for complications or surgery
• Treatment options are medical or surgical.
• For children, the size/age of the patient is an important factor in selecting a treatment plan because the smaller the patients, the more likely they will need serial valve replacements as they outgrow an initial prosthetic valve.
• Manage medically, if possible. If medical therapy fails, consider valvuloplasty if technically feasible or mitral valve replacement (MVR) if necessary.
• Timing of surgery is controversial; intervene before LV function decreases and/or pulmonary HTN occurs. In children, unlike adults, decreased LV function may improve postoperatively.

SURGERY

• Mitral valve repair and MVR are the surgical options and indicated if medical therapy fails.
• Mitral valve repair is preferred if technically feasible to avoid complications related to size and growth, as well as anticoagulation.
• The type of mitral valve repair depends on the type of mitral valve defect. For a regurgitant valve, annuloplasty or valvuloplasty is performed. In the larger child, the annulus may be supported by a DeVega or Carpentier ring (this will not grow with the child).
• Mitral valve leaflet cleft or chordae tendinea abnormalities usually can be repaired surgically.
• MVR is reserved for patients with moderate to severe MR who failed medical management and who are not candidates for valve repair.
• Most common type of prosthetic valve is the St. Jude bileaflet tilting disk valve for children.
• Current operative mortality rate is <5%.

Outline

• Additional Treatment
  • General Measures
• Surgery

FOLLOW-UP RECOMMENDATIONS

Patient Monitoring

• Close, regular follow-up is essential to monitor for development or progression of symptoms or change in physical status.
• For all nonoperated and postsurgical patients, close attention should be directed to the ECG appearance of the mitral apparatus, severity of MR, and ventricular function at time intervals dependent on severity.
• Recommendations for unoperated patients regarding frequency of visits, serial EKGs, and ECGs depend on the severity of MR.
• Close monitoring of the INR during anticoagulation therapy following MVR
• Children are at particular risk for bleeding because of their activity level, but with proper monitoring and management, significant events are rare.
• Children have up to a 2% risk of thromboembolic events, even with appropriate anticoagulation.

Pregnancy Considerations

Pregnancy can be well-tolerated in women with mild to moderate mitral insufficiency.

DIET

No restrictions

PATIENT EDUCATION

• Patients should be educated about signs of worsening symptoms or the presence of palpitations, which may indicate new onset of an atrial arrhythmia.
• Bacterial endocarditis prophylaxis as per AHA guidelines.
• Patients receiving anticoagulation with prolonged bleeding or easy bruisability should contact their physician. Children receiving anticoagulation must be restricted from rough physical activities.
• Activity:
  • Adequate rest and reasonable physical activity
  • Patients on PO anticoagulation are restricted from contact sports.

PROGNOSIS

• Preoperatively, most patients with mild to moderate mitral insufficiency can be medically managed; however, patients who demonstrate LV dysfunction or atrial arrhythmia may be at increased risk for surgery and for long-term postoperative arrhythmias.
• Although LV function may worsen in the immediate postoperative period, children generally appear to have recovery or improvement of LV function with time.
• After MVR is carried out in childhood, eventual re-replacement is to be expected.

COMPLICATIONS

• Complications of anticoagulation may arise in patients with prosthetic mitral valves (ie, bleeding or thrombosis).
• Recurrent rheumatic fever
• Bacterial endocarditis
• Heart failure with pulmonary congestion/edema
• Atrial arrhythmias

Outline

• Follow-Up Recommendations
  • Patient Monitoring
  • Pregnancy Considerations
• Diet
• Patient Education
• Prognosis
• Complications

CODES

ICD9

424.0 Mitral valve disorders

SNOMED

48724000 mitral valve regurgitation (disorder)

ADDITIONAL READING

• Ackermann K, Balling G, Eicken A, et al. Replacement of the systemic atrioventricular valve with a mechanical prosthesis in children aged less than 6 years: l: Late clinical results of survival and subsequent replacement. J Thorac Cardiovasc Surg.2007;134:750–756.
• Agarwal S, Mukherjee K, Geelani M, et al. Mitral valve replacement in the pediatric age group: A single institution experience Indian J Thorac Cardiovasc Surg 2009;25:7–11.
• Bradley LM, et al. Anticoagulation therapy in children with mechanical prosthetic cardiac valves. Am J Cardiol.1985;56:533–535.
• Carpentier A, Branchini B, Cour C, et al. Congenital malformation of the mitral valve.Pathology and surgical treatment. J Thorac Cardiovasc Surg. 1976;7:854–857.
• Higashita R, Ichikawa S, Niinami H, et al. Long term results after Starr-Edwards mitral valve replacement in children aged 5 years or younger.Ann Thorac Surg.2003;75:826–829.
• Honjo O, Ishino K, Kawada M, et al. Midterm outcome of mitral valve repair of congenital mitral regurgitation in infants and children.Interact Cardio Vasc Thorac Surg.2006;5:589–593.
• Krishnan US, Gersony WM, Berman Rosenzweig E, et al. Late left ventricular function after surgery for children with chronic symptomatic mitral regurgitation.Circulation.1997;96:4280–4285.
• Raghuveer G, Caldarone AC, Hills CB, et al. Predictors of prosthetic survival, growth, and functional status following mechanical mitral valve replacement in children aged less than 5 years: A multi-institutional study.Circulation.2003;108:174–179.
• Skoularigis J, Sinovich V, Houbert G, et al. Evaluation of long-term results of mitral valve repair in 254 young patients with rheumatic mitral regurgitation.Circulation.1994;90:167–174.
• Zegdi R, Amahzoune B, Ladjali M, et al. Congenital mitral valve regurgitation in adult patients. A rare, often misdiagnosed but repairable, valve disease. Eur J Cardiothorac Surg.2008;34:751–754.

Erika Berman Rosenzweig

Welton M. Gersony