Faculty Bibliography

BACKGROUND:Adult SOT recipients with COVID-19 have higher mortality rates when compared to general population. There is paucity of data on outcomes in pediatric SOT recipients. METHODS:This is a cross-sectional study investigating the prevalence of COVID-19 infection and outcomes in pediatric SOT (heart, liver, and kidney) recipients. We extracted demographic and clinical characteristics and COVID-19 testing (PCR or [Ab] test) results from medical records. Clinical characteristics were compared between patients who were positive for COVID-19 (PCR or Ab) and those who did not, using Mann-Whitney, Student's t test, or chi-square test. p value <.05 was statistically significant. RESULTS:A total of 108 SOT recipients with a median age of 13.1 (8.4, 17.8) years and median 4.2 (2.7, 7.9) years from transplant were checked for COVID-19 via a PCR or Ab test. A positive PCR was confirmed in 10 patients (9.3%), while 12 patients (11.1%) were positive for COVID-19 Ab. The patients who tested positive in our cohort were 9/50 (18%) heart, 6/68 (8.8%) kidney, and 7/50 (14%) liver transplant recipients. There were no differences in the clinical characteristics between patients with and without COVID-19 infection. All patients were either asymptomatic (50%) or had self-limiting symptoms. No changes were made to the immunosuppressive regimen. Only one patient was hospitalized and none had an oxygen requirement. CONCLUSIONS:In our cohort of pediatric SOT recipients, COVID-19 infection was asymptomatic or mild. This data may aid clinicians in counseling patients and families in this increased-risk population.

A patent foramen ovale (PFO) is a frequent incidental finding during echocardiography in otherwise healthy children. In most healthy children with a diagnosis of isolated incidental PFO, no further follow-up or intervention is necessary. In some children, PFO is associated with certain clinical syndromes such as cryptogenic stroke, decompression sickness, migraine, and platypnea-orthodeoxia syndrome. This review discusses PFO anatomy, diagnostic imaging, PFO-associated clinical situations, management options, and the role of PFO in certain congenital heart disease. This review also highlights the current deficiency of pediatric data guiding management of these uncommon but important PFO-associated conditions. Future multicenter randomized controlled studies are necessary to guide the management of these unique and challenging PFO-associated conditions.

We describe our experience of bivalirudin use, a newer direct thrombin inhibitor, in an infant who was supported with Berlin Heart EXCOR VAD (Berlin VAD) as bridge to transplant for 122 days without complications and without need for pump exchange. An 11-month-old girl with dilated cardiomyopathy with acute heart failure was awaiting cardiac transplant. Lack of improvement despite maximizing medical therapy and anticipating a prolonged waitlist time, she was supported with Berlin LVAD as a bridge to transplant. Anticoagulation with bivalirudin was started and titrated with a goal partial thromboplastin time of 60-90 seconds. Therapeutic anticoagulation was achieved with bivalirudin for 50% of the days (61/122 days) on a dose of 2.1 mg/kg/hour and in a narrow dose range of 1.9 to 2.3 mg/kg/hour for 80% of the days (98/122 days). Antiplatelet regimen was started initially with aspirin and clopidogrel added later. She was supported for 122 days on a single pump without any evidence of thrombus or need for pump change. Berlin VAD explant and orthotopic heart transplant with biatrial anastomosis were performed uneventfully. Explanted Berlin VAD had no evidence of clot/fibrin or thrombus formation. The child was discharged to home uneventfully 15 days after cardiac transplant.

Arterial switch operation has become the standard of care for d-transposition of great arteries and has excellent short- and long-term outcomes. We report the case of a newborn with a diagnosis of d-transposition of great arteries with intact ventricular septum and a low-risk coronary artery anatomy who developed coronary artery vasospasm while coming off bypass following arterial switch operation in the operating room. The coronary artery spasm led to severe biventricular dysfunction and need for extracorporeal membranous oxygenation support. Despite extracorporeal membranous oxygenation and inotropic support, there was no improvement in the left ventricular function, and cardiac transplantation was performed after 8 days. The explanted heart showed extensive infarction of both ventricles. Both the coronary ostei were patent with no evidence of thrombus, suggesting coronary artery vasospasm rather than embolus or thrombus formation. This is the first case of coronary artery vasospasm in a neonate with d-transposition of great arteries leading to cardiac transplantation. We speculate that early identification of patients who are at a high risk for coronary vasospasm and prophylactic or timely infusion of papaverine directly into the coronary arteries may be beneficial in this condition.

Transcription factor MEF2C regulates multiple genes linked to autism spectrum disorder (ASD), and human MEF2C haploinsufficiency results in ASD, intellectual disability, and epilepsy. However, molecular mechanisms underlying MEF2C haploinsufficiency syndrome remain poorly understood. Here we report that Mef2c ^+/-(Mef2c-het) mice exhibit behavioral deficits resembling those of human patients. Gene expression analyses on brains from these mice show changes in genes associated with neurogenesis, synapse formation, and neuronal cell death. Accordingly, Mef2c-het mice exhibit decreased neurogenesis, enhanced neuronal apoptosis, and an increased ratio of excitatory to inhibitory (E/I) neurotransmission. Importantly, neurobehavioral deficits, E/I imbalance, and histological damage are all ameliorated by treatment with NitroSynapsin, a new dual-action compound related to the FDA-approved drug memantine, representing an uncompetitive/fast off-rate antagonist of NMDA-type glutamate receptors. These results suggest that MEF2C haploinsufficiency leads to abnormal brain development, E/I imbalance, and neurobehavioral dysfunction, which may be mitigated by pharmacological intervention.