Pediatric subspecialty outreach clinics: reach and impact on access to care.

BACKGROUND: Recent research highlighting a shortage of pediatric subspecialists in the United States has shown wide variations in the distance from children to the nearest subspecialists but has not accounted for subspecialty outreach clinics, in which specialists may improve access in rural areas by periodically staffing clinics there. This study aimed to determine the impact of pediatric subspecialty outreach clinics on the driving times to the nearest pediatric subspecialists for children in Maine. METHODS: This cross-sectional study utilized administrative data on the schedule and location of pediatric subspecialty clinics in Maine in 2022 to estimate the driving time from each ZIP-code tabulation area to the nearest subspecialist, with and without the inclusion of outreach clinics. Using 2020 census data, we calculated the median and interquartile ranges of driving times for the state's overall child population, as well as for children living in urban and rural areas. RESULTS: Of 207,409 individuals under 20 years old in Maine, 68% were located closer to an outreach location than to a clinical hub. Across the seven subspecialties offering outreach clinics, outreach clinics decreased median driving times to the nearest pediatric subspecialist by 5 to 26 minutes among all children, and by 16 to 46 minutes among rural children. CONCLUSIONS: Pediatric subspecialty outreach clinics can substantially reduce the driving time to the nearest pediatric subspecialist , especially for children living in rural areas. The use of outreach clinics should be accounted for in research describing the geographic access or barriers to care. Expanding the number of outreach clinics should be considered by policymakers hoping to improve access.

Lethal presentation of neurofibromatosis and Noonan syndrome.

Neurofibromatosis type 1 and Noonan syndrome are both common genetic disorders with autosomal dominant inheritance. Similarities between neurofibromatosis type 1 and Noonan syndrome have been noted for over 20 years and patients who share symptoms of both conditions are often given the diagnosis of neurofibromatosis-Noonan syndrome (NFNS). The molecular basis of these combined phenotypes was poorly understood and controversially discussed over several decades until the discovery that the syndromes are related through disturbances of the Ras pathway. We present an infant male with coarse facial features, severe supravalvar pulmonic stenosis, automated atrial tachycardia, hypertrophic cardiomyopathy, airway compression, severe neurological involvement, and multiple complications that lead to death during early infancy. The severity of clinical presentation and significant dysmorphic features suggested the possibility of a double genetic disorder in the Ras pathway instead of NFNS. Molecular analysis showed a missense mutation in exon 25 of the NF1 gene (4288A>G, p.N1430D) and a pathogenic mutation on exon 8 (922A>G, p.N308D) of the PTPN11 gene. Cardiovascular disease has been well described in patients with Noonan syndrome with PTPN11 mutations but the role of haploinsufficiency for neurofibromin in the heart development and function is not yet well understood. Our case suggests that a double genetic defect resulting in the hypersignaling of the Ras pathway may lead to complex cardiovascular abnormalities, cardiomyopathy, refractory arrhythmia, severe neurological phenotype, and early death.

Left ventricular T2 distribution in Duchenne muscular dystrophy.

BACKGROUND: Although previous studies have helped define the natural history of Duchenne muscular dystrophy (DMD)-associated cardiomyopathy, the myocardial pathobiology associated with functional impairment in DMD is not yet known.The objective of this study was to assess the distribution of transverse relaxation time (T2) in the left ventricle (LV) of DMD patients, and to determine the association of myocardial T2 heterogeneity to the severity of cardiac dysfunction. DMD patients (n = 26) and normal control subjects (n = 13) were studied by cardiovascular magnetic resonance (CMR). DMD subject data was stratified based on subject age and LV ejection fraction (EF) into the following groups: A (<12 years old, n = 12); B (>or=12 years old, EF or=12 years old, EF = 55%, n = 6). Controls were also stratified by age into Groups N1 (<12 years, n = 6) and N2 (>12 years, n = 5). LV mid-slice circumferential myocardial strain (epsilon cc) was calculated using tagged CMR imaging. T2 maps of the LV were generated for all subjects using a black blood dual spin echo method at two echo times. The full width at half maximum (FWHM) was calculated from a histogram of LV T2 distribution constructed for each subject. RESULTS: In DMD subject groups, FWHM of the T2 histogram rose progressively with age and decreasing EF (Group A FWHM= 25.3 +/- 3.8 ms; Group B FWHM= 30.9 +/- 5.3 ms; Group C FWHM= 33.0 +/- 6.4 ms). Further, FWHM was significantly higher in those with reduced circumferential strain (|epsilon cc| 12% (Group A). Group A FWHM was not different from the two normal groups (N1 FWHM = 25.3 +/- 3.5 ms; N2 FWHM= 24.0 +/- 7.3 ms). CONCLUSION: Reduced EF and epsilon cc correlates well with increased T2 heterogeneity quantified by FWHM, indicating that subclinical functional impairments could be associated with pre-existing abnormalities in tissue structure in young DMD patients.

A teenager with Marfan syndrome and left ventricular noncompaction.

We report a teenager with Marfan syndrome who presented to Cincinnati Children's Hospital Medical Center as part of a preoperative evaluation for an orthopedic procedure after asymptomatic arrhythmia was recognized. Continuous cardiac monitoring showed frequent premature ventricular contractions and nonsustained runs of ventricular tachycardia. Cardiac magnetic resonance imaging showed left ventricular noncompaction (LVNC), prompting insertion of an implantable cardiac defibrillator. Although Marfan syndrome is associated with cardiac lesions, it has not previously been described with LVNC. Likewise LVNC has been seen in association with other cardiac lesions; however, this report represents the first reference of LVNC in the context of Marfan syndrome.

Exercise tolerance and thermoregulatory responses during cycling in boys and men.

PURPOSE: Physiological responses to exercise in the heat differ between prepubertal children and young adults. Whether these maturity-related variations imply lower exercise tolerance, inferior thermoregulation, and greater risk for heat injury in the child is uncertain. This study directly compared thermoregulatory and cardiovascular responses as well as endurance performance between prepubertal boys and adult males during steady-load cycling in moderately hot and cool ambient conditions with moderate humidity. METHODS: Eight prepubertal boys (age 11.7 +/- 0.4 yr) and eight adult men (age 31.8 +/- 2.0 yr) performed steady-load cycling to exhaustion at an intensity equivalent to approximately 65% peak V O2 in both hot (approximately 31 degrees C) and cool (approximately 19 degrees C) environments, with fluid intake ad libitum. RESULTS: Exercise duration in the heat was shorter for both groups (hot: men 30.46 +/- 8.84 min, boys 29.30 +/- 6.19 min; cold: men 42.88 +/- 11.79 min, boys 41.38 +/- 6.30 min), with no significant difference between men and boys (P > 0.05). Increases in rectal temperature, heart rate, and cardiac index were similar between groups and conditions. Stroke index, mean arterial pressure, and arterial venous oxygen difference were stable and similar in both conditions, without group differences. No significant dehydration was observed in men or boys. CONCLUSIONS: This study failed to reveal differences in exercise tolerance, thermoregulatory adaptation, or cardiovascular response to exercise in the heat between euhydrated prepubertal boys and adult men.

Detection of progressive cardiac dysfunction by serial evaluation of circumferential strain in patients with Duchenne muscular dystrophy.

The present study evaluated progressive cardiac dysfunction using serial circumferential strain (epsilon(cc)) measurements in patients with Duchenne muscular dystrophy (DMD). DMD is characterized by progressive cardiac dysfunction and myocardial fibrosis late in the disease process. We hypothesized that serial epsilon(cc) changes could be detected in individual patients with DMD during a time when the left ventricular ejection fraction (EF) changes are insignificant. Cardiac magnetic resonance imaging data from patients with DMD were evaluated. The left ventricular EF was calculated from steady-state free precession cine images and the composite epsilon(cc) measurement from tagged cine images. The serial epsilon(cc) and EF values for each patient were analyzed using the Wilcoxon sign rank test. Data from 51 patients with DMD (2 studies per patient, mean age at the initial study 11.8 +/- 3.5 years, range 7.4 to 25.4) were analyzed, with a mean interval between cardiac magnetic resonance studies of 15.6 +/- 6.0 months (range 6.2 to 28.1). In the interval between studies, the epsilon(cc) had decreased in all patients with DMD. The average decrease was 1.8 +/- 1.3 (p <0.001). However, the EF had decreased in 33 of the 51 patients and had increased in 18 of the 51 patients. On average, the EF decreased by 2.9 +/- 8.57% (p = NS). In conclusion, in patients with DMD, epsilon(cc) abnormalities indicate progression within a relatively short period when the EF changes were not significant. Serial epsilon(cc) measurements might provide reliable monitoring of the progression of DMD-associated cardiac dysfunction before overt heart failure develops, because it is more sensitive than the EF.