Determinants of Exercise Performance in Children and Adolescents with Repaired Tetralogy of Fallot Using Stress Echocardiography.

Exercise performance is variable and often impaired in patients with repaired tetralogy of Fallot (rTOF). We sought to identify factors associated with exercise performance by comparing high to low performers on cardiopulmonary exercise testing (CPET) in patients with rTOF. We conducted a cross-sectional study of subjects presenting for CPET who underwent echocardiograms at rest and peak exercise. Patients with pacemakers and arrhythmias were excluded. Right ventricular (RV) global longitudinal strain was used as a measure of systolic function. Pulmonary insufficiency (PI) was assessed with the diastolic systolic ratio and the diastolic systolic time-velocity integral ratio by Doppler interrogation of the pulmonary artery. CPET measures included percent-predicted maximum [Formula: see text][Formula: see text], percent-predicted maximum work and oxygen pulse. High versus low performers were identified as those achieving [Formula: see text] of at least 80% or falling below, respectively. Differences in echocardiographic parameters from rest to peak exercise were examined using mixed-effects regression models. Compared to the low performers (n = 17), high performers (n = 12) were younger (12.8 ± 3.3 years vs. 18.3 ± 4.8 years), had normal chronotropic response (peak heart rate > 185 bpm) with greater heart rate reserve and superior physical working capacity. High performers also had a greater reduction in PI at peak exercise, despite greater PI severity at rest. Oxygen pulse was comparable between groups. For both groups, there was no association of PI severity and RV systolic function at rest with exercise parameters. There was no group difference in the magnitude of change in RV strain and diastolic parameters from rest to peak exercise. Chronotropic response to exercise appears to be an important parameter with which to assess exercise performance in rTOF. Chronotropic health should be taken into consideration in this population, particularly given that RV function and PI severity at rest were not associated with exercise performance.

Quality of Life is Diminished in Patients with Tetralogy of Fallot with Mild Residual Disease: A Comparison of Tetralogy of Fallot and Isolated Valvar Pulmonary Stenosis.

The objective of this study is to compare quality of life (QOL) in patients with mild pulmonary insufficiency (PI) after Tetralogy of Fallot (TOF) repair or after balloon dilation for isolated valvar pulmonary stenosis (VPS). A cross-sectional study of patients with TOF (n = 12) and VPS (n = 19), ages 8-18 years, who underwent cardiac magnetic resonance (CMR) and cardiopulmonary exercise test (CPET) was conducted. Patients with genetic syndromes were excluded. The groups were matched by severity and duration of PI using propensity scores. PI was greater than mild if the regurgitant fraction by CMR was >20%. Health status and QOL assessment included Child Health Questionnaire Child Self-Report (CHQ-CF87), Child Health Questionnaire Parent Report (CHQ-PF50), and Pediatric Cardiac QOL Instrument (parent and patient). QOL scores were compared between groups. Due to propensity matching, the groups had, at worst, mild PI and normal right ventricular ejection fraction on CMR. Parental perception of QOL was significantly worse in TOF as compared to VPS in the domains of general perception of health (P = 0.03), physical functioning (PF; P = 0.004), and family cohesion (P = 0.048). There were no differences in self-reported QOL between groups. There was no association between QOL and right ventricular function on CMR or percent-predicted maximal oxygen consumption on CPET in both groups. Parent-perceived QOL, in the domains of general health perception, PF, and family cohesion, is significantly reduced in patients with TOF with mild residual disease suggesting that the psychosocial impact of congenital heart disease may be significant even with successful repair and satisfactory medical status.

How best to assess right ventricular function by echocardiography.

Right ventricular function is a crucial determinant of long-term outcomes of children with heart disease. Quantification of right ventricular systolic and diastolic performance by echocardiography is of paramount importance, given the prevalence of children with heart disease, particularly those with involvement of the right heart, such as single or systemic right ventricles, tetralogy of Fallot, and pulmonary arterial hypertension. Identification of poor right ventricular performance can provide an opportunity to intervene. In this review, we will go through the different systolic and diastolic indices, as well as their application in practice. Quantification of right ventricular function is possible and should be routinely performed using a combination of different measures, taking into account each disease state. Quantification is extremely useful for individual patient follow-up. Laboratories should continue to strive to optimise reproducibility through quality improvement and quality assurance efforts in addition to investing in technology and training for new, promising techniques, such as three-dimensional echocardiography.

Right atrial function early after tetralogy of Fallot repair.

Diastolic dysfunction after repair for Tetralogy of Fallot (TOF) is associated with adverse long-term outcomes. Right atrial (RA) mechanics as a proxy of right ventricular (RV) diastolic function in the early post-operative period after surgical repair for TOF has not been reported. We sought to evaluate RA and RV strain prior to hospital discharge after TOF repair and to identify important patient factors associated with strain using a machine learning method. Single center retrospective cohort study of TOF patients undergoing surgical repair, with analysis of RA and RV strain from pre-and post-operative echocardiograms. RA function was assessed by the peak RA strain, systolic RA strain rate, early diastolic RA strain rate and RA emptying fraction. RV systolic function was measured by global longitudinal strain. Pre- and post-operative values were compared using Wilcoxon rank sum test. Gradient boosted machine (GBM) models were used to identify the most important predictors of post-operative strain. In total, 153 patients were enrolled, median age at TOF repair 3.5 months (25th-75th percentile: 2.2- 5.2), mostly male (67%), and White (64.1%). From pre-to post-operative period, there was significant worsening in all RA parameters and in RV strain. GBM models identified patient, anatomic, and surgical factors that were strong predictors of post-operative RA and RV strain. These factors included pulmonary valve and branch pulmonary artery Z scores, birth weight, gestational age and age at surgery, pre-operative RV fractional area change and oxygen saturation, type of outflow tract repair, duration of cardiopulmonary bypass, and early post-operative partial arterial pressure of oxygen. There is significant worsening in RA and RV strain early after TOF repair, indicating early alteration in diastolic and systolic function after surgery. Several patient and operative factors influence post-operative RV function. Most of the factors described are not readily modifiable, however they may inform pre-operative risk-stratification. The clinical application of RA strain and the prognostic implication of these early changes merit further study.

Right Ventricular Contractile Reserve Is Impaired in Children and Adolescents With Repaired Tetralogy of Fallot: An Exercise Strain Imaging Study.

BACKGROUND: Pulmonary insufficiency (PI) and right ventricular (RV) dysfunction are long-term complications in patients with repaired tetralogy of Fallot (rTOF). The aim of this study was to investigate RV contractile reserve and changes in PI that occur during exercise in patients with rTOF and the associations of these changes with exercise performance using stress echocardiography. METHODS: Subjects with rTOF (n = 32) and healthy control subjects (n = 10) were prospectively enrolled and underwent rest and peak exercise echocardiography during standard cardiopulmonary exercise test protocol on a cycle ergometer or treadmill. RV contractile reserve was defined as the change in RV global longitudinal strain from rest to peak exercise. PI was assessed with the diastolic-to-systolic time-velocity integral ratio and diastolic/systolic velocity ratio from pulmonary artery Doppler interrogation. Exercise measures included heart rate reserve, percentage predicted maximum oxygen consumption, percentage predicted maximum work, and oxygen pulse. RESULTS: RV contractile reserve was impaired in patients with rTOF compared with control subjects, with a significant drop in the absolute value of RV global longitudinal strain from 17% (range, 8%-27%) at rest to 13% (range, 5%-28%) at peak exercise. Similarly, PI decreased at peak exercise, with decreases in diastolic-to-systolic time-velocity integral and diastolic/systolic velocity ratios. Reduction in PI was directly associated with percentage predicted maximum oxygen consumption, percentage predicted maximum work, and greater oxygen pulse. Heart rate reserve was directly associated with percentage predicted maximum oxygen consumption and percentage predicted maximum work. RV contractile reserve was not associated with any exercise parameters. CONCLUSIONS: Patients with rTOF have an abnormal myocardial response to exercise with impaired RV contractile reserve compared with control subjects. Heart rate reserve and reduction in PI at peak exercise are associated with better exercise performance and appear to be significant contributors to exercise performance in rTOF. Measures to improve chronotropic health in rTOF should be explored.