Management of 2-Year-Old with Hypertrophic Cardiomyopathy and Severe Aortic Stenosis
This child requires urgent mechanical aortic valve replacement combined with septal myectomy (Option B). The combination of symptomatic severe aortic stenosis (68% obstruction) with hypertrophic cardiomyopathy causing exertional dyspnea represents a life-threatening dual left ventricular outflow tract obstruction that demands definitive surgical correction. 1
Why Combined Surgical Intervention is Mandatory
The presence of increasing dyspnea during physical activity indicates hemodynamic compromise from dual LVOT obstruction, and the natural history of untreated severe aortic stenosis in children includes sudden death risk and progressive heart failure. 1 This child has both fixed valvular stenosis (68% aortic stenosis) and dynamic muscular obstruction (hypertrophic cardiomyopathy), creating a compounded obstruction that cannot be addressed by treating only one component. 1
Evidence Supporting Combined Approach
Surgical myectomy combined with valve replacement provides the opportunity to correct all structural and anatomic issues with a single procedure in patients with symptomatic obstructive hypertrophic cardiomyopathy who have associated valvular aortic stenosis requiring surgical treatment. 1
The modified Konno procedure has been reported to provide satisfactory long-term results for basal obstruction in young children, allowing for aortic valve replacement while simultaneously addressing septal hypertrophy. 1
Transaortic septal myectomy adds minimal risk to other cardiac procedures, and relief of LVOT obstruction minimizes the risk of hemodynamic instability postoperatively. 1
Why Other Options Are Inappropriate
Option A (Reassure) - Dangerous and Contraindicated
Symptomatic severe aortic stenosis is a clear indication for intervention across all major guidelines. 2
Untreated symptomatic aortic stenosis has worse survival than many cancers, with 2-year mortality rates approaching 68% without intervention. 3
VT and VF may occur during exertion with severe obstruction in aortic stenosis patients. 2
Option C (TAVR) - Inappropriate for Pediatric Patient
TAVR durability remains uncertain, particularly problematic in a child with decades of life expectancy. 1
TAVR is indicated for severe symptomatic aortic stenosis in patients who have very high or prohibitive surgical risk, not for young children who are excellent surgical candidates. 4
When combined with another LVOT obstruction (hypertrophic cardiomyopathy), TAVR can lead to challenging hemodynamics in the peri-deployment phase, as unmasked LVOT pathology can cause acute hemodynamic instability. 4
Option D (Restricting Physical Activity) - Inadequate
Activity restriction is appropriate for managing HCM symptoms in stable patients, but it does not treat the underlying severe aortic stenosis. 1
This child already has symptoms at baseline activity levels, indicating advanced disease that requires definitive intervention. 1
No competitive sports should be restricted if obstruction is moderate or severe, but this is an adjunct to treatment, not a substitute for necessary surgery. 2
Surgical Approach and Technical Considerations
Mechanical Valve Selection
Mechanical valve replacement is typically preferred in young patients to avoid multiple reoperations that would be necessary with biological valves due to degeneration. 1
Mechanical AVR in children is associated with acceptable operative mortality (5.3%), low incidence of late events, and provides good long-term survival (91% at 10 years, 84.9% at 20 years). 5
Aortic root enlargement should be performed if necessary (performed in 50% of pediatric cases) to accommodate an appropriately sized valve. 5
Myectomy Technique
Septal myectomy involves resection of 5-10g of muscle from the proximal septum, extending 3-4 cm from near the base of the aortic valve to beyond the distal margins of mitral leaflets, thereby enlarging the LVOT and abolishing mechanical impedance to ejection. 2
The abrupt relief of gradient with surgery (in contrast to slower reduction with alcohol septal ablation) is particularly advantageous in patients with severe functional limitations. 2
Post-Operative Management
Immediate Post-Operative Care
Intraoperative transesophageal echocardiography should be performed to assess the adequacy of septal myectomy and valve function. 1
Follow-up transthoracic echocardiography within 3-6 months is recommended to evaluate procedural results. 1
Long-Term Management
Serial echocardiography every 1-2 years is recommended to monitor for residual obstruction, valve function, and progression of hypertrophy. 1
Beta-blocker therapy should be continued to manage residual hypertrophic cardiomyopathy symptoms and reduce arrhythmia risk. 1
All patients require long-term anticoagulation treatment with warfarin, aiming to maintain INR between 2.5-3.0. 5
Continued restriction from competitive sports is necessary given the underlying hypertrophic cardiomyopathy diagnosis. 1
Expected Outcomes
Mechanical AVR in children and young adults offers normalization of left ventricular size and function in most patients, with 29 of 30 patients achieving NYHA class I without thromboembolic complications on follow-up. 6
After septal myectomy, long-term actuarial survival is 99%, 98%, and 95% at 1,5, and 10 years respectively, similar to the general population. 2
Critical Pitfalls to Avoid
Do not delay valve replacement based on "optimizing" medical therapy - medical therapy is NOT indicated for symptomatic severe aortic stenosis and does not address fixed valvular stenosis. 1, 3
Do not attempt balloon aortic valvuloplasty as definitive therapy - it provides only temporary symptom relief with high mortality rates and should only be used as a bridge to definitive valve replacement. 3
Do not perform isolated valve replacement without addressing the septal hypertrophy - this leaves residual LVOT obstruction that can cause hemodynamic instability. 1
Endocarditis prophylaxis is required in all cases post-operatively. 2