What is the next step in managing a patient with a patent membranous ventricular septal defect (VSD) and elevated pulmonary pressures?

Management of 6-Year-Old with Perimembranous VSD and Severe Pulmonary Hypertension

This child should NOT undergo VSD closure at this time—the hemodynamics demonstrate severe pulmonary arterial hypertension with borderline operability that requires initiation of pulmonary arterial hypertension-targeted medical therapy, followed by repeat catheterization in 4-6 months to reassess for potential surgical candidacy. 1

Critical Hemodynamic Analysis

Your patient's right heart catheterization reveals concerning findings:

• mPAP of 50 mmHg indicates severe pulmonary arterial hypertension (normal <25 mmHg) 1
• PVR of 0.48 Wood units appears falsely reassuring but must be indexed to body surface area in children 1
• PVR/SVR ratio of 0.05 is well below the critical threshold of 0.3, which is encouraging 1
• Flow ratio (Qp:Qs) of 12 suggests massive left-to-right shunting 1

The critical issue is determining whether this represents reversible pulmonary arterial hypertension from high flow versus fixed pulmonary vascular disease.

Guideline-Based Decision Algorithm

Step 1: Determine Operability Status

According to the American Heart Association/American Thoracic Society 2015 guidelines for pediatric pulmonary hypertension 1:

• Repair should be considered if PVRI <6 Wood units·m² OR PVR/SVR <0.3 at baseline (Class I, Level B) 1
• Your patient's PVR/SVR of 0.05 meets this criterion for potential operability 1

However, the absolute mPAP of 50 mmHg with SPAP of 70 mmHg at age 6 raises concern for developing pulmonary vascular disease despite the favorable ratio 1

Step 2: Assess for Reversibility

The guidelines mandate 1:

• If PVRI ≥6 WU·m² or PVR/SVR ≥0.3, repair can be beneficial if acute vasodilator testing (AVT) reveals reversibility (Class IIa, Level C) 1
• Your hemodynamics don't clearly fall into the "definitely operable" or "definitely inoperable" categories given the severe absolute pressures

Step 3: Medical Therapy Trial

The most appropriate next step is 1:

• Implement PAH-targeted therapy followed by repeat catheterization with AVT after 4-6 months (Class IIb, Level C) 1
• If repeat catheterization shows PVRI <6 WU·m² and PVR/SVR <0.3, proceed with repair 1

Recommended Medical Therapy Regimen

Initiate oral PAH-targeted therapy immediately 1:

• First-line options include either a phosphodiesterase type 5 (PDE5) inhibitor OR an endothelin receptor antagonist (ERA) (Class I, Level B) 1
• Sildenafil has demonstrated efficacy in pediatric PAH with improved exercise capacity 2
• Use a goal-targeted therapy approach, adding drugs progressively to achieve therapeutic targets (Class IIa, Level C) 1

Do NOT initiate calcium channel blockers 1:

• CCBs are contraindicated in children who have not undergone or are nonresponsive to AVT (Class III, Level C) 1
• Potential for negative inotropic effects with right-sided heart dysfunction 1

Fenestrated Device Consideration

A fenestrated device approach may be considered if you proceed to closure, based on surgical experience 3:

• A 1998 study demonstrated successful outcomes using a fenestrated flap valve double VSD patch in 18 children (mean age 5.7 years) with elevated PVR (mean 11.4 Wood units) 3
• All children survived operation and were weaned from support within 48 hours 3
• The fenestration (4-6 mm) with a flap valve mechanism allows right-to-left decompression during pulmonary hypertensive crises while preventing significant left-to-right shunting 3

However, this should only be considered AFTER demonstrating hemodynamic improvement with medical therapy 1

Critical Pitfalls to Avoid

Do not proceed directly to surgical closure 1:

• Repair is not indicated if PVRI ≥6 WU·m² or PVR/SVR ≥0.3 with minimal AVT responsiveness (Class III, Level A) 1
• The absolute pulmonary pressures (mPAP 50, SPAP 70) at age 6 suggest risk of irreversible changes despite favorable PVR/SVR ratio 1

Do not assume the low PVR/SVR ratio alone indicates safety 1:

• Children with significant structural heart disease who have not undergone early repair (by 1-2 years) require cardiac catheterization to measure PVRI and determine operability 1
• At age 6 with these pressures, there is concern for developing Eisenmenger physiology 1

Do not delay referral to specialized center 1:

• This patient requires management at an experienced pediatric pulmonary hypertension center 1
• Multidisciplinary discussion among pediatric cardiologists, cardiac surgeons, and PH specialists is essential 1

Follow-Up Protocol

After initiating PAH-targeted therapy 1:

• Repeat right heart catheterization with acute vasodilator testing in 4-6 months 1
• Monitor for clinical improvement: exercise tolerance, oxygen saturations, symptoms 1
• Serial echocardiography every 3-6 months to assess RV function and estimated PA pressures 1

If repeat catheterization shows improvement to PVRI <6 WU·m² and PVR/SVR <0.3 1:

• Proceed with surgical or catheter-based VSD closure 4
• Consider fenestrated patch technique given the history of severe PAH 3

If minimal hemodynamic improvement 1:

• Continue escalating PAH-targeted therapy 1
• Consider atrial septostomy as palliative bridge if severe right heart failure develops 1
• Evaluate for lung transplantation if WHO functional class III-IV on optimized therapy 1