Successful Atrial Septal Defect Closure Subsequent to Medical Pulmonary Preconditioning in an Infant With Severe Pulmonary Hypertension Associated With Bronchopulmonary Dysplasia.

While atrial septal defect (ASD) may contribute to right ventricular decompression in patients with severe pulmonary hypertension (PH), the pulmonary vasculature might be compromised by increased pulmonary blood flow, even though pulmonary vasodilators successfully reduce resistance. ASD closure is a treatment option that may ameliorate PH symptoms associated with bronchopulmonary dysplasia (BPD) in infants. However, the feasibility of ASD closure is obscure in patients with BPD-PH causing right-to-left shunting. Here, we present an eight-month-old girl with ASD complicated by BPD-PH, in which the pulmonary pressure exceeded the systemic pressure; the ASD was successfully closed after pulmonary preconditioning with dexamethasone and high-dose diuretics. Our patient was delivered as the third baby in triplets at a gestational age of 25 weeks, with a birth weight of 344 g. She was diagnosed with BPD at three months of age (37 weeks of postmenstrual age) with a body weight of 1.4 kg. Mild pulmonary hypertension was identified at the age of five months, and oral sildenafil was initiated. While her atrial septal defect was small at the time of PH diagnosis, it became hemodynamically significant when she grew up to 3.4 kg of body weight, at seven months after birth. Her estimated right ventricular pressure was apparently more than the systemic pressure, and oxygen saturation fluctuated between 82% and 97% under oxygen supplementation due to bidirectional interatrial shunt with predominant right-to-left shunting. Pulmonary preconditioning lowered the estimated right ventricular pressure to almost equal the systemic pressure and elevated arterial oxygen saturation while also suppressing right-to-left shunting. Cardiac catheterization after preconditioning revealed a ratio of pulmonary blood pressure to systemic blood pressure ratio (Pp/Ps) of 0.9, pulmonary resistance of 7.3 WU-m2 , and a pulmonary to systemic blood flow ratio (Qp/Qs) of 1.3 (approximately 1.0 in the normal circulation without significant shunt), with the cardiac index of 2.8 L/min/m2 . The acute pulmonary vasoreactivity test against the combination of 20 ppm nitric oxide and 100% oxygen was negative, although the patient had consistently high pulmonary flow with makeshift improvements after preconditioning. Despite the high pulmonary resistance even after preconditioning, aggressive ASD closure was performed so that pulmonary flow could be consistently suppressed regardless of the pulmonary condition. Her Pp/Ps under 100% oxygen with 20 ppm nitric oxide was 0.7 immediately after closure. After two years of follow-up, her estimated right ventricular pressure was less than half of the systemic pressure with the use of three pulmonary vasodilators, including sildenafil, macitentan, and beraprost. A strategy to temporarily improve PH and respiratory status aimed at ASD closure could be a treatment option for the effective use of multiple pulmonary vasodilators, by which intensive treatment of BPD can be achieved.