Background:Pulmonary vein stenosis (PVS) is a growing problem for the pediatric congenital heart population. Sirolimus has previously been shown to improve survival and slow down the progression of in-stent stenosis in patients with PVS. We evaluated patients before and after initiation of sirolimus to evaluate its effects on re-intervention and vessel patency utilizing Optical Coherence Tomography (OCT). Methods:We performed a retrospective study, reviewing the charts of patients with PVS, who had been prescribed sirolimus between October 2020 and December 2021. OCT was performed in the pulmonary vein of interest as per our published protocol. Angiographic and OCT imaging was retrospectively reviewed. Statistical analysis was performed using Chi square and Wilcoxon signed-rank test to compare pre-and post-sirolimus data. Results:Ten patients had been started and followed on sirolimus. Median age at sirolimus initiation was 25 months with median weight of 10.6kg and average follow-up of 1 year. Median total catheterizations were 7 for patients prior to starting sirolimus and 2 after starting treatment (p = 0.014). Comparing preand post-sirolimus, patients were catheterized every 3-months vs every 11-months (p = 0.011), median procedure time was 203min vs 145min (p = 0.036) and uoroscopy time, 80min vs 57.2min (p = 0.036).23 veins had severe in-stent tissue ingrowth prior to SST (luminal diameter < 30% of stent diameter). Postsirolimus, 23 pulmonary veins had moderate to severe in-stent tissue ingrowth that responded to noncompliant balloon in ation only with stent luminal improvement of > 75%. Conclusion:Our study suggests that the addition of sirolimus in patients with moderate-severe PVS helps to decrease disease progression with decrease frequency of interventions. Reaching therapeutic levels for sirolimus is critical and medication interactions and side-effects need careful consideration. OCT continues to be important for evaluation and treatment guidance in this patient population.

Background: Pulmonary vein stenosis (PVS) is a growing problem for the pediatric congenital heart population. Sirolimus has previously been shown to improve survival and slow down the progression of in-stent stenosis in patients with PVS. We evaluated patients before and after initiation of sirolimus to evaluate its effects on re-intervention and vessel patency utilizing Optical Coherence Tomography (OCT). Methods: We performed a retrospective study, reviewing the charts of patients with PVS, who had been prescribed sirolimus between October 2020 and December 2021. OCT was performed in the pulmonary vein of interest as per our published protocol. Angiographic and OCT imaging was retrospectively reviewed. Statistical analysis was performed using Chi square and Wilcoxon signed-rank test to compare pre-and post-sirolimus data. Results: Ten patients had been started and followed on sirolimus. Median age at sirolimus initiation was 25 months with median weight of 10.6kg and average follow-up of 1 year. Median total catheterizations were 7 for patients prior to starting sirolimus and 2 after starting treatment (p = 0.014). Comparing pre- and post-sirolimus, patients were catheterized every 3-months vs every 11-months (p = 0.011), median procedure time was 203min vs 145min (p = 0.036) and fluoroscopy time, 80min vs 57.2min (p = 0.036). 23 veins had severe in-stent tissue ingrowth prior to SST (luminal diameter < 30% of stent diameter). Post-sirolimus, 23 pulmonary veins had moderate to severe in-stent tissue ingrowth that responded to non-compliant balloon inflation only with stent luminal improvement of > 75%. Conclusion: Our study suggests that the addition of sirolimus in patients with moderate-severe PVS helps to decrease disease progression with decrease frequency of interventions. Reaching therapeutic levels for sirolimus is critical and medication interactions and side-effects need careful consideration. OCT continues to be important for evaluation and treatment guidance in this patient population.

Background: Pediatric heart transplant recipients are at risk for complications from prolonged exposure to immunosuppressive drugs, pharmacokinetic challenges in maintaining consistent immunosuppression, and medication non-adherence.Basiliximab (BAS), an interleukin-2 receptor antagonist, is used for induction therapy across many pediatric heart transplant centers, but use as maintenance immunosuppression has not been well described.Methods: This was a retrospective, single pediatric center cohort study of heart transplant recipients who received BAS for maintenance immunosuppression (defined as >2 monthly doses) from January 1, 2011, to December 31, 2021.Results: Ten patients met study criteria with a median age of 17.5 (5-22) years and median 9.6 (1.2-18.9) years since transplant at time of BAS initiation. The primary indications for BAS use were recurrent rejection (n = 4), fluctuating immunosuppression levels (n = 3), and renal dysfunction (n = 3). A median of 5.5 (3-32) monthly BAS doses were received. Three patients had a rejection event while on BAS. Calcineurin inhibitor exposure was reduced in 70% of patients. Three of the 10 patients were alive at last follow-up. There was one documented infection during BAS use, and no hypersensitivity reactions. Conclusions:Monthly BAS infusions were well tolerated and allowed for reduced calcineurin inhibitor exposure in most patients. Mortality commonly occurred despite BAS use, potentially reflecting the acuity of this patient cohort. BAS can be considered for maintenance immunosuppression in pediatric patients with fluctuating immunosuppressive levels and/or renal dysfunction. More studies are needed to determine long-term outcomes and explore expanded use of BAS in the pediatric heart transplant population.