Long-Term NO Dependency, Riociguat, and Reverse Pott Shunt in an Infant with Severe PAH due to Alveolar Capillary Dysplasia

Objectives: Pulmonary arterial hypertension (PAH) due to alveolar capillary dysplasia (ACD) is usually a fatal condition. Most newborns die of cardiopulmonary failure. Bilateral lung transplantation remains the only palliative option. We report the unusual case of an infant, who suffers from suprasystemic PAH due to an atypical presentation of ACD, but survived until today. Medical treatments and cardiac interventions contributing to this outcome are discussed, as well as diagnostic pathways and specific disease conditions.

Methods: After birth, the child presented with PPHN and almost refractory arterial hypotension. Controlled ventilation, high-dose noradrenaline, terlipressin, and supplementary steroids lead to stabilization. NO (40 ppm), intravenous sildenafil (0.15 mg/kg/h), and Ilomedin (2 ng/kg/min) were used to control PAH. PDA was retained by PGE₁-infusion. At 4 weeks of age, the PDA was stented (4 × 20 mm SS-DS). Because of atrial right–left shunt, an ASD was closed by a device (ADO II). Ventilation was weaned, but NO dependency persisted. Various pulmonary antihypertensive drugs were tested, of which bosentan (3 mg/kg/d), riociguat (0.4 mg/kg/d), and amlodipine (0.5 mg/kg/d) seemed most efficient. There was extensive diagnostic work-up, including CT scan, lung biopsy, and genetic analysis.

Results: During a 2-year follow-up, suprasystemic PAH with hypoxemia remained the leading symptom. However, after ASD closure, preductal SpO₂ were normal under low-dose NO inhalation (range 1–10 ppm) and supplementary O₂ (FiO₂ 0.4–0.5). Right heart failure was prevented by right–left shunting via the stented PDA (postductal SpO₂ 70–90%). Riociguat, initiated at an age of 3 months, contributed to avoid immediate hypoxemia, when NO inhalation by nasal cannula was shortly interrupted. Diagnosis of ACD was made by CT scan (patchy pattern of lobular edema), lung biopsy (alveolar–capillary–venous malalignment) and genetics (deletion in the regulatory promotor region of the FOXF-1-gen).

In concert, these measures achieved stable cardiopulmonary conditions so that the child’s psychomotoric development is almost normal. Not to forget, the admirable commitment of his parents.

Conclusion: This case shows several important aspects:

1. We have to be aware of nonfatal presentations of ACD

2. If PAH is suprasystemic, decompression of the right heart by stenting a PDA can be lifesaving

3. Continuous NO via a nasal cannula is a rare but feasible option in severe cases of PAH

4. Riociguat seems to be useful and safe even in infancy.