Down Syndrome, Large VSD, and Reactive Pulmonary Hypertension
A 2-year-old boy with trisomy 21 and a large perimembranous ventricular septal defect is referred for surgery because of failure to thrive. He weighs 8.2 kg (below the 3rd centile). Resting SpO2 is 94%, falling to 90% with crying; he has a loud P2 and a soft systolic murmur. Chest radiography shows cardiomegaly and prominent pulmonary arteries. Echocardiography shows a non-restrictive VSD, systemic right ventricular pressure, bidirectional shunting, and a right-to-left ventricular ratio of 1.1. At catheterization, mean pulmonary artery pressure is 55 mmHg with systemic mean 62 mmHg; pulmonary vascular resistance index is 7.2 WU·m² on room air with Qp:Qs 1.3, and falls to 4.1 WU·m² with 100% oxygen and 20 ppm inhaled nitric oxide, with Qp:Qs rising to 2.1. The parents want the hole closed "so he can be normal."
1. How do you interpret these hemodynamics, and is this child operable?
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Interpretation This is markedly elevated pulmonary vascular resistance at systemic-level pressures, with near-balanced shunting at rest (Qp:Qs 1.3, desaturation to 94%). The key finding is reactivity: with oxygen and nitric oxide, PVR index falls by roughly 43% to 4.1 WU·m² and Qp:Qs rises to 2.1. Favorable multiparameter criteria include PVR index below about 6 WU·m², a fall of more than 20% with vasodilator testing, a PVR-to-SVR ratio well under 0.3, and a vasodilator Qp:Qs above 1.5.
Conclusion He is a candidate for a "treat-and-repair" strategy rather than an immediate simple closure. Optimize pulmonary hypertension therapy and non-cardiac contributors first - obstructive sleep apnea, recurrent aspiration, chronic hypoxemia from airway disease - then reassess. Reasonable plan: start pulmonary vasodilator therapy (e.g., sildenafil or another approved agent), treat sleep-disordered breathing, reassess hemodynamics after a few months, and close the defect if reactivity is preserved or improved. Warn the family that a single catheterization can overestimate reactivity and that closure carries risk of a postoperative pulmonary hypertensive crisis.
2. What is your intensive care plan for the first 72 hours after repair?
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Anticipate a pulmonary hypertensive crisis, especially at 24-72 hours
- Sedation and analgesia to blunt agitation and catecholamine surges; avoid routine hyperventilation, but prevent hypercarbia, acidosis, and hypoxia, all of which raise PVR.
- Ventilation: adequate lung recruitment with PEEP, modest tidal volumes, and a strategy that avoids atelectasis and high airway pressure; target normal oxygenation and normal pH rather than hyperventilation.
- Hemodynamics: maintain systemic pressure - hypotension reduces coronary and pulmonary perfusion; use milrinone cautiously for afterload and diastolic effects; consider low-dose inotropy.
- Pulmonary vasodilators: inhaled nitric oxide for crisis or as prophylaxis, with transition to sildenafil; have a plan for rebound on weaning.
- Monitoring: arterial and central lines, frequent echocardiography, and a crisis protocol posted at the bedside with drug doses for acute deterioration.
- Escalation: ECMO should be discussed in advance with the family and the team, given the risk of refractory crisis.
3. The parents ask whether surgery will make him "normal." How do you counsel them?
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Be honest about the two variables at play
- The VSD is only part of the problem. His pulmonary vascular bed is already remodeled, and even with a good repair he may need long-term pulmonary vasodilator therapy, activity limits, and periodic catheterization- or echocardiography-based reassessment. Some children never normalize their pulmonary pressures.
- Trisomy 21 adds obstructive sleep apnea, hypothyroidism, airway hypotonia, and feeding difficulties that interact with the pulmonary hypertension and must be actively managed.
What to say
- Name the goal: a child who grows, gains weight, and avoids pulmonary hypertensive crises - not a guarantee of normal physiology.
- Explain the treat-and-repair plan, its expected timeline, and the specific risks of repair after pulmonary hypertension has developed (crisis, prolonged ventilation, mortality).
- Confirm that the family understands that closure is conditional on his response to therapy and that the decision will be revisited at reassessment.
- Offer written information, support from the pulmonary hypertension team, and a follow-up plan that includes growth, sleep study, and genetic/developmental services.