Congenital Mitral Stenosis Treatment & Management

Asymptomatic patients with mild mitral stenosis (MS) require no significant therapy. They should undergo yearly follow-up care with physical examination, chest radiography, and ECG with echocardiography as indicated by this assessment. These patients may remain stable for decades before MS progresses and the patient requires surgical intervention. Note the following:

• More significant stenosis producing mild symptoms can be managed with diuretics alone. Direct careful attention to proper diet and to early intervention for pulmonary disease.

• For the patient with congestive heart failure, loop diuretics plus potassium-sparing diuretics are essential. Digoxin may improve right ventricular function in the setting of pulmonary hypertension.

• Address cardiac rhythm abnormalities with appropriate medications.

• Patients with chronic uncontrolled atrial tachyarrhythmias should be on anticoagulant therapy.

Critically ill patients or patients unable to take oral medication may receive intravenous medications. Admission to the ICU and endotracheal intubation may be required because of ineffective breathing caused by pulmonary edema.

Closely monitor the patient's anticoagulation therapy to prevent thrombus formation and to decrease the risk of embolization in case of a mechanical mitral valve. Embolization is to the systemic circulation; these emboli originate in the left atrium and are able to reach the brain.

Consultations

Consultation with a cardiologist is indicated, and with a cardiothoracic surgeon if the cardiologist determines that MS is worse than mild.

Transfer

Transfer the patient to an intensive care unit when general status is unstable because of low cardiac output or pulmonary edema.

Diet and activity

Restrict salt and avoid excessive fluids. Proper nutrition is paramount to maintain adequate cardiopulmonary health. Caloric supplementation may be necessary in the symptomatic infant.

Patients should avoid strenuous exercise, because an increased heart rate decreases diastolic filling time. If atrial flutter and atrial fibrillation are present and atrial kick is lost, a further decrease in LV stroke volume occurs. This may result in syncope from decreased cerebral perfusion.

Surgery is considered when the peak instantaneous transmitral gradient is >10 mmHg by Doppler echocardiography. However, if MS is associated with other cardiac lesions such as atrial septal defect (which will decrease the transmitral gradient due to left to right shunting of blood), hemodynamic measurement of pulmonary artery pressures are required to aid in the decision making process. ^[6]

Worth mentioning is that unlike what occurs in acquired MS, commissural fusion of the mitral leaflets is not a predominant mechanism for stenosis in patients with congenital MS (see Background). Therefore, balloon dilation of congenital MS, although performed in some centers, is not always successful. Younger patients and those who develop significant mitral regurgitation after balloon-dilation have a worse outcome. ^[7] However, because the 5-year survival is still relatively poor in those with severe congenital MS, regardless of treatment modality, the optimal therapeutic strategy remains unclear. Surgical options depend on specific mitral valve pathology. ^[8]

Mitral valve repair

Commissurotomy consists of an incision of fused mitral valve commissures and shaving of thickened mitral valve leaflets. Open surgical commissurotomy is preferable.

Divide fused chordae tendineae and papillary muscles to relieve subvalvular stenosis.

Resect any supravalvular tissue contributing to the MS.

Mitral valve replacement with mechanical valve or bioprosthesis

Note the following:

• This is reserved for patients with severe MS in whom mitral valve repair is not possible. In older children for whom warfarin (Coumadin) therapy may be contraindicated, mitral valve replacement can be performed using a bioprosthesis, although the durability of tissue valves is less than mechanical protheses.

• The risk of warfarin therapy should be weighed against the disadvantage of progressive bioprosthetic valve deterioration resulting in the certain need for reoperation.

• Mitral valve replacement is best avoided in infants and small children because of frequent size mismatch between the smallest mechanical valves and the hypoplastic mitral valve annulus. In addition, somatic growth in children leads to the need for subsequent mitral prosthesis replacements.

• Warfarin therapy is also more difficult to administer and to monitor in children. A less-than-perfect mitral valve repair is frequently preferable to mitral valve replacement in this group of patients.

• Complications after mitral valve replacement include the risks of anticoagulation, valve thrombosis, valve dehiscence, infective endocarditis, valve malfunction, and embolic events.

• However, in complex anatomy, replacement is the only solution to achieve an acceptable result. The Ross II operation, which uses a pulmonary autograft, is a difficult technique that may be useful in the youngest patient group when prosthetic devices cannot be used. This technique is still under clinical evaluation.

Correction of associated lesions

Pediatric patients must sometimes undergo correction of associated LV obstructive lesions such as subaortic stenosis, aortic valve stenosis, coarctation of the aorta, and hypoplastic aortic arch. ^[9]

Antibiotics for endocarditis prophylaxis are required for patients with certain cardiac conditions, such as mitral stenosis, before performing procedures that may cause bacteremia. For more information, see Antibiotic Prophylactic Regimens for Endocarditis.

Note the following:

• Avoid excessive salt intake, which increases fluid retention and may worsen symptoms.

• Avoid excessive heat, excessive use of diuretics, and dehydration, which may decrease LV output by reducing preload.

• Patients taking anticoagulants should avoid contact sports because of risks of cerebral, splenic, renal, or other internal organ bleeding. Pregnant women should avoid warfarin because of its teratogenic effects and risk of miscarriage.

Long-term monitoring of patients with mitral stenosis may include the following:

• Regular visits to the pediatrician and/or generalist to monitor general health status, depending on the severity of the mitral stenosis (MS)

• Regular visits to the pediatric cardiologist to monitor hemodynamic status, antiarrhythmic drug levels, and anticoagulation

• Serial echocardiography to monitor anatomic and hemodynamic progression of the MS; the frequency varies according to the patient's general health status and according to the cardiologist's criteria.

• Stress Doppler hemodynamics using a supine bicycle or treadmill: Hemodynamics may be measured using transthoracic echocardiographic Doppler. This noninvasive test has replaced the traditional exercise stress test in the catheterization laboratory.