Quantifying the Healthcare Burden of Pediatric Feeding Disorder after Congenital Heart Surgery.

OBJECTIVE: To determine the healthcare costs and use burden of pediatric feeding disorder after congenital heart surgery. STUDY DESIGN: A retrospective, population-based cohort study using claims data (2009-2018) was performed. Participants include patients aged 0-18 years who had undergone congenital heart surgery and were included in the insurance database ≥1 year after surgery. The main exposure variable was the presence of a pediatric feeding disorder, defined as a need for a feeding tube at discharge or diagnosis of dysphagia or feeding-related difficulty within the study timeframe. Main outcomes include overall and feeding-related medical care use, defined as readmissions and outpatient use, and feeding-related cost of care within 1 year of surgery. RESULTS: A total of 10 849 pediatric patients were identified, with 3347 (30.9%) presenting with pediatric feeding disorder within 1 year of surgery. Patients with pediatric feeding disorder spent a median of 12 days (IQR, 6-33 days) in the hospital, compared with 5 days (IQR, 3-8 days) in patients without (P < .001). Rate ratios for overall readmissions, feeding-related readmissions, feeding-related outpatient use, and cost of care over the first year after surgery were significantly increased at 2.9 (95% CI, 2.5-3.4), 5.1 (95% CI, 4.6-5.7), 7.7 (95% CI, 6.5-9.1), and 2.2 (95% CI, 2.0-2.3) among patients with pediatric feeding disorder as compared with those without. CONCLUSIONS: Pediatric feeding disorder after congenital heart surgery is associated with a significant healthcare burden. Multidisciplinary care for and research on this health condition is needed to identify optimal management strategies to reduce this burden and improve outcomes.

Mitochondrial functional resilience after TFAM ablation in the adult heart.

The nuclear genome-encoded mitochondrial DNA (mtDNA) transcription factor A (TFAM) is indispensable for mitochondrial energy production in the developing and postnatal heart; a similar role for TFAM is inferred in adult heart. Here, we provide evidence that challenges this long-standing paradigm. Unexpectedly, conditional Tfam ablation in vivo in adult mouse cardiomyocytes resulted in a prolonged period of functional resilience characterized by preserved mtDNA content, mitochondrial function, and cardiac function, despite mitochondrial structural alterations and decreased transcript abundance. Remarkably, TFAM protein levels did not directly dictate mtDNA content in the adult heart, and mitochondrial translation was preserved with acute TFAM inactivation, suggesting maintenance of respiratory chain assembly/function. Long-term Tfam inactivation, however, downregulated the core mtDNA transcription and replication machinery, leading to mitochondrial dysfunction and cardiomyopathy. Collectively, in contrast to the developing heart, these data reveal a striking resilience of the differentiated adult heart to acute insults to mtDNA regulation.

Analyses of Mitochondrial Calcium Influx in Isolated Mitochondria and Cultured Cells.

Ca2+ handling by mitochondria is a critical function regulating both physiological and pathophysiological processes in a broad spectrum of cells. The ability to accurately measure the influx and efflux of Ca2+ from mitochondria is important for determining the role of mitochondrial Ca2+ handling in these processes. In this report, we present two methods for the measurement of mitochondrial Ca2+ handling in both isolated mitochondria and cultured cells. We first detail a plate reader-based platform for measuring mitochondrial Ca2+ uptake using the Ca2+ sensitive dye calcium green-5N. The plate reader-based format circumvents the need for specialized equipment, and the calcium green-5N dye is ideally suited for measuring Ca2+ from isolated tissue mitochondria. For our application, we describe the measurement of mitochondrial Ca2+ uptake in mitochondria isolated from mouse heart tissue; however, this procedure can be applied to measure mitochondrial Ca2+ uptake in mitochondria isolated from other tissues such as liver, skeletal muscle, and brain. Secondly, we describe a confocal microscopy-based assay for measurement of mitochondrial Ca2+ in permeabilized cells using the Ca2+ sensitive dye Rhod-2/AM and imaging using 2-dimensional laser-scanning microscopy. This permeabilization protocol eliminates cytosolic dye contamination, allowing for specific recording of changes in mitochondrial Ca2+. Moreover, laser-scanning microscopy allows for high frame rates to capture rapid changes in mitochondrial Ca2+ in response to various drugs or reagents applied in the external solution. This protocol can be applied to measure mitochondrial Ca2+ uptake in many cell types including primary cells such as cardiac myocytes and neurons, and immortalized cell lines.