Pediatric Mitral Regurgitation (Mitral Valve Insufficiency) Treatment & Management

In mitral regurgitation (MR) (mitral valve insufficiency), administer medications to decrease the work placed on the heart; afterload-reducing medications are most useful in the management of these cases. Intravenous diuretics can be given. Intravenous inotropes (eg, milrinone) can also be used to treat heart failure.

In children, mitral regurgitation (MR) (mitral valve insufficiency) tends to progress with age. Mitral regurgitation fosters yet more mitral regurgitation because of the repeating cycle described earlier in Pathophysiology. As a result of this tendency, these patients must be regularly examined even though the mitral regurgitation may be mild. Early treatment of infants and children with mitral regurgitation is primarily medical. Guidelines for treating children are not well defined and are based largely on information derived from adult studies.

Depending on the cause of mitral regurgitation, a patient may require medications such as anti-inflammatory agents for rheumatic fever or Kawasaki disease and antibiotics for infective processes. Baseline information, such as chest radiography, electrocardiography (ECG), and echocardiography, should be obtained. Patients with mild mitral regurgitation should have follow-up monitoring at regular intervals. Little change may occur in asymptomatic patients as they age. Primary medical intervention is bacterial endocarditis prophylaxis. For more information, see Antibiotic Prophylactic Regimens for Endocarditis.

Optimal medical therapy is aimed at increasing systemic cardiac output and decreasing regurgitant flow. No clear guidelines are available regarding when to initiate medical management; however, treatment probably is indicated when the left ventricle (LV) begins to dilate.

Afterload reduction may be the most beneficial therapy, because it reduces work on the heart by decreasing systemic arteriolar resistance, thereby decreasing the regurgitant volume. However, few studies have demonstrated that afterload reduction actually delays (or eliminates) the need for surgery.

If the patient develops symptoms, such as dyspnea and exercise intolerance, anticongestive medications (digoxin, diuretics) should be added. By decreasing LV end-diastolic volume, the diameter of the mitral annulus also is decreased, thereby decreasing the regurgitant orifice.

Diuretics are also helpful in decreasing the total volume and may alleviate the pulmonary edema and congestion that may be present.

Digoxin is useful in patients with left heart failure because it allows the heart to pump more efficiently.

Acute mitral regurgitation causes a sudden decrease in cardiac output and an increase in left atrial pressure, resulting in pulmonary congestion. Severity of the mitral regurgitation depends on the size of the orifice and the time period over which the mitral regurgitation develops. If the orifice is large, a sudden decrease in systemic blood flow and pressure occurs, and pulmonary edema develops. Decreasing afterload may temporarily relieve these symptoms. Surgical repair of mitral regurgitation may also alleviate abnormal airway and respiratory tissue mechanics, but residual postoperative tissue stiffening may persist for weeks and contribute to sustained pulmonary impairment. ^[11]

Vasodilators, such as nitroprusside, are very effective; however, preexisting hypotension may be exacerbated.

Inotropic agents may improve systolic blood pressure. Intra-aortic balloon counterpulsation or immediate surgical intervention (valvuloplasty) may be necessary in severe cases.

In patients who stabilize but remain symptomatic, early semi-elective surgery should be considered to reduce the risk of irreversible ventricular dysfunction.

Patients who become asymptomatic with medical therapy can be treated in the same manner as those with chronic mitral regurgitation.

Patients with chronic mitral regurgitation should receive maintenance doses of afterload agents such as angiotensin-converting enzyme inhibitors (ACEIs), hydralazine, or calcium channel blockers. Diuretics and digoxin also are useful.

Anticoagulation may be needed if there is diminished LV function, atrial fibrillation, or evidence of thromboembolism.

Consultations

Consultation with a geneticist is indicated if associated dysmorphism is noted, because many of the syndromes are associated with mitral valve prolapse and mitral regurgitation. Trisomy 21 may be associated with mitral valve cleft.

Activity

Contact sports are contraindicated in children taking warfarin.

Outpatient care

Asymptomatic patients and those with normal findings on chest radiography, ECG, and echocardiography should have follow-up evaluations at regular intervals.

Patients without severe symptoms can be treated with oral ACEIs (captopril, enalapril) and furosemide. Digoxin can also be used if symptoms of heart failure are present.

When a patient becomes severely symptomatic (New York Heart Association class III or IV) because of left ventricular (LV) failure, they should be encouraged to undergo cardiac surgery. Surgical replacement versus repair may be an issue at this time. For children, reconstruction is preferable to avoid the need for anticoagulation therapy. Because the valve is more compliant and pliable in children than in adults, repair is often feasible. By repairing the valve instead of replacing it, the subvalvular apparatus remains intact, helping to preserve LV function. In general, patients should undergo surgery before severe symptoms develop. Operating earlier and repairing the valve improves the chance of normal postoperative function without the associated risks of prosthesis placement.

Conservative valve surgery, when feasible, appears to be the best surgical option in pediatric patients with rheumatic heart disease. ^[12] Even in cases of rheumatic lesions in which the primary lesion was mitral stenosis, and despite a higher reoperative rate, rheumatic mitral valve repair appears to have similar outcomes to those from mitral valve replacement, with the added benefit of avoiding anticoagulation. ^[13] When conservative management is not possible or fails, mechanical valve replacement should be considered. ^[12] The specific surgical techniques for treatment of mitral regurgitation must be individualized to the patient, with the aim of achieving proper valve function. ^[14]

Note, however, that pediatric patients often have associated congenital abnormalities that may dictate the need for valve replacement. Infants and children with congenital mitral regurgitation due to restricted leaflet motion can undergo successful mitral valve reconstruction with several modified repair techniques based on the valve morphology. ^[15] In future transcatheter management, mitral valve clips may be a therapeutic option.

Surgical repair of the regurgitant mitral valve can be classified into three major groups depending on the leaflet motion: normal, prolapsing, and restricted. Repair of these conditions can proceed in several ways, depending on the specific abnormality involved.

If the mitral annulus is dilated, an annuloplasty may be successful in alleviating the degree of regurgitation. The annuloplasty may involve the use of a ring prosthesis. In younger patients (in whom restriction of valve growth is undesirable), resection of a portion of the leaflet and annular plication may be performed.

Shortening of the chordae and/or papillary muscles may address prolapsed leaflets. Lengthening may be required in cases where there are short chordae

Mitral regurgitation with restricted leaflet motion is observed in parachute and hammock valves and, along with a valvuloplasty, can be improved by incising the valve leaflets at an appropriate location.

Quadrilateral resection of a prolapsing leaflet with sliding annuloplasty may be helpful in cases with mitral valve prolapse

Edge-to-edge (E-to-E) mitral valve repair is helpful in some cases in which an apposition suture is placed in the center of the anterior and posterior leaflets, producing a double orifice

Papillary muscle surgery may also be beneficial in certain cases

Mitral valve replacement is the final option in the treatment of mitral regurgitation. ^[16] The choice of which valve to use (mechanical vs bioprosthesis) can be difficult. Some studies indicate a preference toward the use of bioprosthetic valves in children aged 15 years and older. ^[17]

A mechanical prosthesis has good longevity and performance, but the size of the valve is problematic in neonates and infants. ^[18] Low-profile valves occupy less space and cause less distortion to the LV outflow tract. The major drawback to mechanical prostheses is the need for anticoagulation therapy. Because flow through the mitral valve position is at a low velocity, anticoagulation with warfarin is the only long-term option. Warfarin must be administered daily, and the prothrombin time and international normalized ratio (INR) must be monitored closely, at least until a steady state is reached. Even then, regular monitoring of prothrombin time and INR is desirable. Too much warfarin may result in excessive bleeding, whereas insufficient anticoagulation may lead to thromboembolism. For older children, contact sports usually are contraindicated because of anticoagulation therapy.

Bioprosthetic valves resolve the anticoagulation issue but raise problems of their own. Bioprostheses may degenerate rapidly, and they may become calcified and dysfunctional as early as 6 months after insertion. Because the anticipated lifespan of a bioprosthetic valve in infants and children is shortened, and thus there is a need for early repeat surgery, bioprosthetic valves are less desirable than their mechanical counterparts. However, a bioprosthetic valve may be more desirable for women of childbearing age in view of the teratogenic potential of warfarin in the first trimester of pregnancy and the potential dangers of anticoagulation therapy during delivery.

Rao et al examined the issue with valve calcification and dysfunction with bioprosthetic valves and concluded that porcine heterografts should not be inserted in children aged 15 years and younger. ^[17] Of the 168 mitral valves replaced during a 7-year period, 54 were porcine heterografts and 114 were mechanical valves. These were divided into four groups: mechanical valves in children aged 15 years and younger, mechanical valves in patients older than 15 years, porcine heterografts in children aged 15 years and younger, and porcine heterografts in patients older than 15 years. Five and 9-year valve survival rates were lowest with porcine heterografts in children 15 years and younger. ^[17]

Definitive long-term surgical treatment of children with mitral valve regurgitation continues to be an area that needs further study. Impairment of annular growth and the need for repeated surgical intervention as the children age continue to be of concern despite current advancements in technology.

Percutaneous management techniques are being developed; these are mostly useful in adults and, perhaps, in adolescents. Mitral annular constricting devices may be implanted in the coronary sinus; because of the close proximity to the mitral annulus, the geometry of the mitral valve is altered, resulting in reduction of mitral valve regurgitation. ^{[19, 20]} Another approach is percutaneous implantation of the Evalve MitraClip device under transesophageal echocardiographic guidance. Results from clinical trials (EVEREST I) appear to be encouraging. ^{[21, 22]}

Percutaneous implantation of mitral valves has been studied in experimental animal models with reasonable success. More recently, human application has been introduced; however, larger studies and follow-up results are necessary before adoption for routine clinical use.