Peak Oxygen Consumption (V̇O 2peak ) Recovery Delay in a Pediatric Fontan Population.

PURPOSE: The purpose of this study is to identify predictors and correlates of VO2RD in youth with Fontan. METHODS: Cardiopulmonary exercise test data was used from a single center, cross-sectional study of children and adolescents (age, 8-21 yr) with Fontan physiology. The VO2RD was determined using time (s) to <90% of V̇O 2peak and categorized as "low" (≤10 s) or "high" (≥10 s). t Tests and χ 2 analysis were used to compare continuous and categorical variables, respectively. RESULTS: The analysis sample included 30 adolescents with Fontan physiology (age, 14.2 ± 2.4 yr; 67% male) with either right ventricular (RV) dominant (40%) or co/left ventricular (Co/LV) dominant (60%) systemic ventricular morphology. There were no differences in V̇O 2peak between the high and low VO2RD groups (high = 1.3 ± 0.4 L·min -1 ; low = 1.3 ± 0.3 L·min -1 ; P = 0.97). VO2RD in participants with RV dominance was significantly greater than in patients with Co/LV dominance (RV = 23.8 ± 15.8 s; Co/LV = 11.8 ± 16.1 s; P = 0.03). CONCLUSIONS: V̇O 2peak was not correlated with VO2RD when analyzed as high/low VO2RD groups. However, morphology of the systemic single ventricle (RV vs Co/LV) may be related to rate of recovery in V̇O 2 after a peak cardiopulmonary exercise test.

Moderators of peak respiratory exchange ratio during exercise testing in children and adolescents with Fontan physiology.

OBJECTIVES: Many patients with Fontan physiology are unable to achieve the minimum criteria for peak effort during cardiopulmonary exercise testing. The purpose of this study is to determine the influence of physical activity and other clinical predictors related to achieving peak exercise criteria, signified by respiratory exchange ratio ≥ 1.1 in youth with Fontan physiology. METHODS: Secondary analysis of a cross-sectional study of 8-18-year-olds with single ventricle post-Fontan palliation who underwent cardiopulmonary exercise testing (James cycle protocol) and completed a past-year physical activity survey. Bivariate associations were assessed by Wilcoxon rank-sum test and simple regression. Conditional inference forest algorithm was used to classify participants achieving respiratory exchange ratio > 1.1 and to predict peak respiratory exchange ratio. RESULTS: Of the n = 43 participants, 65% were male, mean age was 14.0 ± 2.4 years, and 67.4% (n = 29) achieved respiratory exchange ratio ≥ 1.1. Despite some cardiopulmonary exercise stress test variables achieving statistical significance in bivariate associations with participants achieving respiratory exchange ratio > 1.1, the classification accuracy had area under the precision recall curve of 0.55. All variables together explained 21.4% of the variance in respiratory exchange ratio, with peak oxygen pulse being the most informative. CONCLUSION: Demographic, physical activity, and cardiopulmonary exercise test measures could not classify meeting peak exercise criteria (respiratory exchange ratio ≥ 1.1) at a satisfactory accuracy. Correlations between respiratory exchange ratio and oxygen pulse suggest the augmentation of stroke volume with exercise may affect the Fontan patient's ability to sustain high-intensity exercise.

Practices and Procedures in Clinical Pediatric Exercise Laboratories in North America.

Interinstitutional differences in clinical pediatric exercise laboratory (CPEL) practices may affect patient care and efficacy of multicenter research. PURPOSE: To describe current practices/procedures in CPELs and explore differences in CPELs employing exercise physiologists to those that do not. METHODS: A 40-item survey was distributed to CPELs in North America focusing on (1) staffing; (2) exercise stress testing (EST) volumes, reporting, and interpretation; and (3) EST procedures/protocols. RESULTS: Of the 55 responses, 89% were in the United States, 85% were children's hospitals with university affiliation, and 58% were cardiology specific. Exercise physiologists were employed in 56% of CPELs, and 78% had master's degrees or higher. Certifications were required in most CPELs (92% emergency life-support, 27% professional, and 21% clinical). Median volume was 201 to 400 ESTs per year, 80% used treadmill, and 10% used cycle ergometer as primary modalities. Ninety-three percent of CPELs offered metabolic ESTs, 87% offered pulmonary function testing, 20% used institution-specific EST protocols, and 72% offered additional services such as cardiac/pulmonary rehabilitation. CPELS staffing exercise physiologists performed higher volumes of ESTs (P = .004), were more likely to perform metabolic ESTs (P = .028), participated in more research (P < .001), and provided services in addition to ESTs (P = .001). CONCLUSIONS: Heterogeneity in CPELs staffing and operation indicates need for standardization.

Heart Rate Recovery Following Exercise Testing in Pediatric Patients with Acyanotic Repaired Congenital Heart Disease.

Attenuated heart rate recovery (HRR) following peak exercise has been shown to be a predictor of mortality in populations of adults with Fontan palliation, coronary artery disease, heart failure, and heart transplantation. However, few have studied HRR in children and adolescents with congenital heart disease (CHD). This case-control study compared HRR patterns from exercise stress testing in children and adolescents with and without repaired acyanotic CHD (raCHD). Retrospective analysis included patients aged 10-18 years who had exercise testing between 2007 and 2017. The raCHD cohort included patients with Tetralogy of Fallot, transposition of the great arteries, coarctation, truncus arteriosus, atrioventricular septal defect, pulmonary outflow obstruction, aortic stenosis and/or insufficiency, or septal defects. Those in the control cohort were matched for age, sex, BMI, peak METs achieved, and peak heart rate (HR). HR at 1-min intervals throughout the 10-min recovery period and HRR patterns were analyzed. The study included n = 584 individuals (raCHD: n = 146), median age 14 years old, 67.1% male. The cohorts had similar resting and peak HRs. Linear mixed-effects models (LMM) suggested statistically significant cohort-by-time interaction for HR in exercise recovery, with the largest mean difference at minute-6 (2.9 bpm, p = 0.008). When comparing lesion types, LMM found no cohort or cohort-by-time interaction. While minute-6 of exercise recovery was statistically significant, the difference was 2.9 bpm and may not have clinical significance. These results suggest that HRR in pediatric raCHD patients should not vary from their healthy peers, and an attenuated HRR may not be directly attributed to underlying raCHD.

Physical Activity Patterns in Children and Adolescents With Heart Disease.

PURPOSE: To quantify the differences in daily physical activity (PA) patterns, intensity-specific volumes, and PA bouts in youth with and without heart disease (HD). METHODS: Seven-day PA was measured on children/adolescents with HD (n = 34; median age 12.4 y; 61.8% male; 70.6% single ventricle, 17.7% heart failure, and 11.8% pulmonary hypertension) and controls without HD (n = 22; median age 12.3 y; 59.1% male). Mean counts per minute were classified as sedentary, light, and moderate to vigorous PA (MVPA), and bouts of MVPA were calculated. PA was calculated separately for each hour of wear time from 8:00 to 22:00. Multilevel linear mixed modeling compared the outcomes, stratifying by group, time of day, and day part (presented as median percentage of valid wear time [interquartile range]). RESULTS: Compared with the controls, the HD group had more light PA (33.9% [15%] vs 29.6% [9.5%]), less MVPA (1.7% [2.5%] vs 3.2% [3.3%]), and more sporadic bouts (97.4% [5.7%] vs 89.9% [9.2%]), but fewer short (2.0% [3.9%] vs 7.1% [5.7%]) and medium-to-long bouts (0.0% [1.9%] vs 1.6% [4.6%]) of MVPA. The HD group was less active in the late afternoon, between 15:00 and 17:00 (P < .03). There were no differences between groups in sedentary time. CONCLUSION: Children/adolescents with HD exhibit differences in intensity-specific volumes, PA bouts, and daily PA patterns compared with controls.