Screening for Pulmonary Hypertension After Pediatric Hematopoietic Stem Cell Transplantation

Introduction: The incidence of pulmonary hypertension (PH) in pediatric patients after hematopoietic stem cell transplant (SCT) is not known. PH is likely underdiagnosed in these patients due to its non-specific presentation. We have observed PH in critically ill SCT patients especially those with transplant associated thrombotic microangiopathy (TA-TMA). Hence our goal was to determine the baseline incidence and to establish the value of routine screening for PH after SCT

Hypothesis: PH occurs in pediatric patients after SCT and echocardiographic screening may be of value in allowing prompt diagnosis and intervention.

Methods: A multi-disciplinary practice guideline was implemented in January 2012 requiring screening for PH in SCT patients after transplant. All children had pre-transplant echocardiography as well as echocardiography screening on days +7, +30, and +100 after SCT, or at the time of ICU admission if admitted to intensive care unit for known PH, TA-TMA, respiratory or cardiovascular failure. Echocardiography was repeated in 7 to 14 days if results were abnormal. Patients were stratified as being “at risk” for, or having PH if their right ventricular (RV) pressure was estimated at 35-49% or >50% of systolic blood pressure, respectively.

Results: During an 8 month period, a total of 59 patients were screened for PH (56 receiving allogeneic and 3 receiving autologous transplants), including 48 consecutive SCT patients completing 100 days of scheduled screening and 26 patients screened upon admission to the PICU. Fifteen patients overlapped the two groups (screened both per schedule on the floor and on admission to ICU). Fifteen patients (25%) were determined to be “at risk” for PH, while 4 (7%) developed PH. Of the 48 patients screened during the first 100 days, 12 (25%) were determined to be “at risk” while 2 (4%) developed PH. Of the 26 patients admitted to the PICU, 7 (27%) were determined to be “at risk” while 4 (15%) developed PH. Four patients admitted to the ICU received specific therapy for PH with one requiring an atrial septostomy for systemic RV pressure and associated low cardiac output. The median time from transplant to abnormal echocardiography was 13 days. Elevated RV pressure was significantly associated with a diagnosis of TA-TMA (p= 0.03) and presence of an oxygen requirement (p= 0.001).

Conclusions: PH may occur following pediatric SCT. Targeted echo screening of children, especially those with TA-TMA and unexplained hypoxemia, may be beneficial in detecting PH.

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