What is the recommended management for a pediatric patient with a parachute mitral valve?

Management of Parachute Mitral Valve in Pediatric Patients

Surgical intervention is the primary treatment for parachute mitral valve, with surgical repair strongly preferred over valve replacement, and balloon dilation should be avoided due to poor outcomes in this specific anatomic variant. 1

Initial Management Strategy

Medical Management for Mild Disease

• Beta-blockers and diuretics are appropriate for patients with mild mitral stenosis who remain asymptomatic 1
• Prevent and treat complications including pulmonary infections, endocarditis, and atrial fibrillation 1
• Serial echocardiographic monitoring is essential, as the degree of obstruction typically remains stable over time 2

Diagnostic Evaluation

• Transthoracic echocardiography is usually sufficient to evaluate the mitral valve apparatus and papillary muscles 1
• Transesophageal echocardiography may be necessary in adolescents and young adults for detailed assessment 1
• Assess for associated left-sided heart obstructions (present in 99% of cases), including aortic coarctation (68%), atrial septal defect (54%), ventricular septal defect (46%), aortic valve stenosis (32%), and subaortic stenosis (20%) 2

Surgical Indications

Class I Indication (Definitive)

• Symptomatic patients (NYHA class III-IV) with mean mitral valve gradient >10 mm Hg should undergo mitral valve surgery 1

Class IIa Indications (Reasonable)

• Mildly symptomatic patients (NYHA class II) with mean mitral valve gradient >10 mm Hg 1
• Asymptomatic patients with pulmonary artery systolic pressure ≥50 mm Hg AND mean mitral valve gradient ≥10 mm Hg 1

Class IIb Indication (May Be Considered)

• Asymptomatic patients with new-onset atrial fibrillation or multiple systemic emboli despite adequate anticoagulation 1

Surgical Approach

Preferred Technique: Mitral Valve Repair

• Creation of fenestrations among the fused chordae can dramatically increase effective orifice area and improve symptoms 1
• Surgical repair is strongly preferred over replacement to avoid complications associated with prosthetic valves 3
• Event-free survival after surgical repair is 84.8% 3

Mitral Valve Replacement

• Reserved for cases where repair is not feasible 1
• Particularly problematic in patients with hypoplastic mitral annulus, who may require an annulus-enlarging operation 1
• Left ventricular hypoplasia is an independent risk factor for mortality (P<0.001) 2

Critical Pitfall: Balloon Dilation

Balloon dilation has worse outcomes in parachute mitral valves and should generally be avoided. 1

Why Balloon Dilation Fails in Parachute Mitral Valve

• The anatomic substrate of parachute mitral valve (unifocal papillary muscle attachment with fused chordae) makes it unsuitable for balloon dilation 1
• Balloon dilation is more favorable for variants with commissural fusion and balanced chordal attachments—the opposite of parachute anatomy 1
• Utility is severely limited by significant stenosis of the subvalvular apparatus inherent to parachute mitral valve 1

When Balloon Dilation Might Be Considered

• Only in highly selected cases at specialized centers with established expertise 1
• This is "one of the most difficult and dangerous therapeutic catheterization procedures" 1
• May temporarily delay need for surgical valve replacement in rare circumstances 1

Prognostic Factors

Factors Associated with Worse Outcomes

• Left ventricular hypoplasia (strongest predictor of mortality, P<0.001) 2
• Presence of atrial septal defect (associated with mortality, P<0.003) 2
• Presence of subaortic stenosis (increases need for mitral valvotomy, P<0.04) 2
• Absence of aortic coarctation (increases need for mitral valvotomy, P<0.02) 2

Expected Outcomes

• Overall survival is 82% at 1 year and 79% at 10 years 2
• Freedom from surgical mitral valvotomy is 95% at 6 months and 80% at 10 years 2
• Mean gradient across the parachute mitral valve typically remains stable over time 2

Management of Associated Lesions

• Address all associated left-sided obstructions during surgical planning, as they are present in nearly all patients 2
• Pulmonary artery hypertension usually resolves with relief of mitral stenosis 1
• Complex anomalies are present in 14% of cases and require comprehensive surgical planning 2