Yvette M. Gerdes

Decreased Maximal Aerobic Capacity in Pediatric Chronic Kidney Disease

Adult and pediatric patients with ESRD have impaired maximum oxygen consumption (VO(2) max), a reflection of the cardiopulmonary systems ability to meet increased metabolic demands. We sought to determine factors associated with decreased VO(2) max in pediatric patients with different stages of CKD. VO(2) max was measured using a standardized exercise testing protocol in patients with stage 2 to 4 chronic kidney disease (CKD) (n = 46), in renal transplant recipients (n = 22), in patients treated with maintenance hemodialysis (n = 12), and in age-matched healthy controls (n = 33). VO(2) max was similar between children with stage 2 CKD and controls, whereas lower VO(2) max was observed among children with stage 3 to 4 CKD, those treated with hemodialysis, and transplant recipients. In univariate analysis, VO(2) max was significantly associated with body mass index, resting heart rate, C-reactive protein, serum triglycerides, serum creatinine, and measures of diastolic function; no significant associations with left ventricular structure or systolic function were identified. In multivariate regression analysis, patient category versus control and the presence of diastolic dysfunction were independent predictors of lower VO(2) max. These results suggest that aerobic capacity is decreased in the early stages of CKD in children and that lower VO(2) max can be predicted by the presence of diastolic dysfunction, even if systolic function is normal.

Exercise Capacity Improves after Transcatheter Closure of the Fontan Fenestration in Children

OBJECTIVESnThis study evaluated the aerobic capacity, exercise capacity, and arterial oxygen saturation (O(2)Sat) in children before and after transcatheter Fontan fenestration closure.nnnDESIGNnObservational study comparing exercise parameters and hemodynamics before and after transcatheter fenestration closure in Fontan patients.nnnOUTCOME MEASURESnWorking capacity, exercise duration, oxygen consumption (VO(2)), and arterial O(2)Sat were evaluated during aerobic exercise.nnnRESULTSnTwenty patients (mean age 11.4 years) underwent standardized exercise testing before and after fenestration closure. Twelve patients underwent cycle ergometry testing (mean age 14.8 years) (group 1), and eight younger patients (mean age 6.4 years) underwent Bruce treadmill testing (group 2). The same exercise protocol was used in each patient before and after fenestration closure (interval between tests: 118 +/- 142 days). Immediately following fenestration closure at cardiac catheterization, cardiac index decreased (3.0 to 2.1 L/minute/m(2)) and Fontan pressure increased (11 +/- 2 to 12 +/- 2 mm Hg) with an increased arterial saturation (92 to 96%) (P < .001). The total group demonstrated no significant change in pre- and postclosure maximal heart rates (164 +/- 21 and 169 +/- 19 bpm). Rest and exercise O(2)Sat increased (89 and 82 to 95 and 92%) (P < .0001). Exercise duration increased (7.7 +/- 1.9 to 9.2 +/- 2.4 minutes) (P < .0005). Maximal VO(2), indexed maximal VO(2), and total working capacity in kilopond-meters (kpm) increased (1.2 +/- 0.5, 27 +/- 7 and 2466 +/- 1012 to 1.3 +/- 0.4 L/minute, 31 +/- 9 mL/kg/minute and 2869 +/- 1051 kpm, respectively) (P < .005).nnnCONCLUSIONnIn children with a univentricular heart after Fontan palliation, transcatheter fenestration closure improves exercise arterial O(2)Sat and aerobic capacity despite a restricted resting cardiac output documented by catheterization immediately after the closure procedure.

Cardiac Rehabilitation Improves Cardiometabolic Health in Young Patients with Nonischemic Dilated Cardiomyopathy

Nonischemic dilated cardiomyopathy is deadly and costly, and treatment options are limited. Cardiac rehabilitation has proved safe and beneficial for adults with various types of heart failure. Therefore, we retrospectively evaluated the hypothesis that rehabilitation is safe and improves cardiometabolic health in young patients with nonischemic dilated cardiomypathy. From 2011 through 2015, 8 patients (4 males) (mean age, 20.6 ± 6.6 yr; range, 10-31 yr) underwent rehabilitation at our institution. They were in American Heart Association class C or D heart failure and were on maximal medical therapy. Their mean left ventricular ejection fraction at baseline was 0.26 ± 0.15. Two patients had a left ventricular assist device, and 2 were inpatients. To evaluate safety, we documented adverse events during rehabilitation sessions. Clinical endpoints were measured at baseline, immediately after completing rehabilitation, and after one year. Patients attended 120 of 141 possible sessions (85%), with no adverse events. There were no marked changes in mean left ventricular ejection fraction or body mass index. The patients mean waist circumference decreased by 1.37 ± 0.6 in (n=5; 95% CI, -2.1 to -0.63). Their 6-minute walk distance increased by a mean of 111 ± 75 m (n=5; 95% CI, 18-205). In our small sample of young patients with nonischemic dilated cardiomyopathy, cardiac rehabilitation was feasible and was associated with minimal risk. Our findings suggest that prospective studies in this population are warranted.

A Novel Mechanism for Improved Exercise Performance in Pediatric Fontan Patients After Cardiac Rehabilitation

Patients with a Fontan circulation have impaired exercise capacity. Cardiac rehabilitation (CR) has shown promise in enhancing peak exercise parameters in this population, but an improvement in submaximal exercise has not been consistently demonstrated. We assessed the hypothesis that participation in CR will be associated with more efficient oxygen extraction and ventilation during submaximal exercise. In this prospective study, pediatric Fontans completed two 60xa0min CR sessions per week for 12xa0weeks. Cardiopulmonary exercise testing and stress echocardiography were performed at baseline and last CR session, and then compared with a paired sample t test. Ten pediatric Fontans completed the study. Five had tricuspid atresia and five had hypoplastic left heart syndrome. No serious adverse events occurred during CR sessions. Peak indexed oxygen consumption increased by a mean of 3.7xa0mL/kg/min (95% CI 1.5–5.9; pu2009=u20090.004), and peak oxygen pulse increased by a mean of 0.9xa0mL/beat (95% CI 0.4–1.4; pu2009=u20090.004). The peak respiratory exchange ratio did not change significantly. The significant difference in oxygen pulse became evident during submaximal exercise without a corresponding difference in echocardiographic stroke volume. Indexed oxygen consumption at ventilatory anaerobic threshold increased by a mean of 3.0xa0mL/kg/min (95% CI −u20090.07 to 6.0; pu2009=u20090.055). The slope for the volume of expired ventilation to volume of carbon dioxide production improved by a mean of 4.5 (95% CI −u20098.4 to −u20090.6; pu2009=u20090.03). We observed significant improvements in both submaximal and peak exercise performance in pediatric Fontans undergoing CR with no serious adverse events. These changes appeared to be mediated, at least in part, by more efficient oxygen extraction and ventilation.