Managing Severe Pulmonary Hypertension In The ICU: The St. Louis Children’s Hospital Experience

While the last 30 years has seen remarkable progress in treating children with pulmonary hypertension (PH), children still die from their disease, most often from right ventricular (RV) failure in an intensive care unit (ICU) setting. Unfortunately, treating these critically ill children remains difficult with little data or consensus to guide caregivers. In this brief editorial, I will highlight some of our center’s considerations in caring for these children, a perspective  influenced by our center’s history of performing aorto-pulmonary (“Potts”) shunts for over 10 years and lung transplants for over 30.

Beyond standard ICU therapy, one unique medical therapy we have used to treat children with PH are glucocorticoids. The medical literature is replete with evidence for the pathogenic role inflammatory cell lines and cytokines play in PH (1). In addition, steroids can inhibit smooth muscle cell proliferation, up regulate BMPR2 and improve surfactant production. As a result, we have been aggressive in trialing steroids in children with PH, both in and out of the ICU. This is especially true if there is a parenchymal lung aspect to their disease, often noted by significant hypoxia or abnormal imaging studies. Consequently, we have found them particularly effective in children whose PH has a component of  “pulmonary under-development”, e.g., lung disease of prematurity, congenital diaphragmatic hernia, or trisomy 21. Children with rarer causes of PH such as alveolar capillary dysplasia, pulmonary veno-occlusive disease and TBX4 mutations have also benefitted. In addition, we have seen improvement in children whose PH has been exacerbated by a recent infection. Our typical dosing is a prednisone or methylprednisolone 2mg/kg/day burst for 5-7 days (typical for treating a child with an asthma flare). If we see clinical benefit we consider a multi-week taper. We feel the risk of a trial burst is very low while the benefits often surprising.

For children with PH that are failing medical therapy, the question of palliative interventional options becomes foremost. Options include creation of an atrial septal defect (ASD), creation of an aorto-pulmonary shunt or lung transplantation. Recently published clinical guidelines from the American Thoracic Society (ATS) addresses each of these interventions in children with progressive PH despite optimal medical therapy (2).  ASD creation in children can be useful in ameliorating some of the symptoms of RV failure, e.g., syncope, however there is no evidence that it impacts mortality or need for transplantation. ASD creation can be especially hazardous in the critically ill child with a failing RV and elevated filing pressures. Furthermore, ASD creation can be a complicating factor if one wants to subsequently consider an aorto-pulmonary shunt or lung transplantation.

The goal behind creating an aorto-pulmonary shunt to treat a child with “suprasystemic” PH (RV systolic pressures higher than LV systolic pressures) is to lower RV pressures to systemic levels, thereby reducing RV strain and hopefully providing for longer, symptom free survival. A study of 101 children with PH who underwent a shunt procedure suggested that it could indeed increase survival versus medical therapy alone, often with improved clinical symptoms and less PH therapy (3). A caveat to this success, however, was that children who required ICU level care at the time of their intervention had a much higher risk for early mortality. The hypothesized reason for these poor outcomes is that ICU bound children are more likely to have a RV that has failed beyond the ability of the shunt to help. As noted, an unrestrictive shunt still requires the RV to generate systemic pressures. Assessing whether the RV of a critically ill child can be relied upon to function at systemic pressures is far from straightforward, especially if the child is on multiple inotropes and mechanical support. Consequently, at our center, the more ICU support a child with PH needs, the less likely we are to consider a shunt and more likely to consider transplantation. Of note, the current ATS guidelines argue against shunt placement in a child on ECMO without a reversible cause (2). In the registry paper, most of the children in the ICU who received a shunt had it placed surgically. Such an invasive procedure in these fragile children undoubtedly contributed to their higher mortality rates. Would the option of creating a shunt via a cardiac catheterization procedure, either by stenting a patent ductus arteriosus remnant or by de novo creation, offer a better result? Regardless, to consider an aorto-pulmonary shunt in the ICU setting requires a frank discussion among caregivers and family. One final consideration is that for some lung transplant centers, placing an aorto-pulmonary shunt may exclude that child from being a transplant candidate.

Pediatric lung transplantation for PH has been an option for over 30 years. Despite this experience, long term outcomes remain less than ideal with a 5-year survival of 64% for children with idiopathic PH and only 43% for non-idiopathic PH (1). Consideration for transplanting a child with PH that needs ICU support is of course a complicated decision both for caregivers and families, especially since it often means transporting that child to another center. Medically supporting a child for the months it may take to procure organs is a crucial consideration and one that may include mechanical support such as ECMO. While not all pediatric transplant centers will consider transplanting a child on ECMO, ATS guidelines are supportive of the consideration, although with an assumption that the child can undergo active rehabilitation (3). Finally, at our center, heart-lung transplant is entertained only if there is concern for LV dysfunction and/or associated complex congenital heart disease. Overall survival for lung vs heart-lung transplantation is relatively similar although wait times can be much longer for dual organs.

1. Aggarwal M, Grady RM. Glucocorticoids for treating paediatric pulmonary hypertension: a novel use for a common medication. Cardiology in the Young 2017. 27:1410-1412.
2. Hayes D, et al. Interventional strategies for children with progressive pulmonary hypertension despite optimal therapy. Am J Respir Crit Care Med 2024.
3. Grady RM, et al. Pulmonary-to-systemic arterial shunt to treat children with severe pulmonary hypertension. J Am Coll Cardiol 2021. 78:468-477.