Longitudinal exercise capacity of patients with repaired tetralogy of fallot

Exercise Capacity and Reoperation Late After Transatrial Fallot Repair

BACKGROUND

The exercise capacity long after repair of tetralogy of Fallot, when performed exclusively with a transatrial repair, is unclear. It is also unknown whether echocardiography and cardiopulmonary exercise testing can predict the risk of reoperation in this patient group.

METHOD

We retrospectively reviewed the clinical records of 59 patients who underwent cardiopulmonary exercise testing after transatrial Fallot repair at a single centre. Patients underwent cardiopulmonary exercise testing at a mean age of 16.6±4.4 years, and at 15.3±4.1 years after Fallot repair.

RESULTS

At testing, the volume of oxygen consumption at maximal exercise (VO2 max) was 71%±13% and the oxygen pulse was 80%±17% of predicted values. Seventeen (17) patients (29%) had a VO2 max superior to 80% of the predicted value. Thirty-two (32) patients (56%) had severe pulmonary regurgitation, three (5%) had moderate pulmonary regurgitation, and 12 (21%) had mild pulmonary regurgitation. After a mean of 7.8±3.9 years following cardiopulmonary exercise testing (23±5.3 years after the repair), 21 (40%) patients underwent reoperation. Right ventricular dilation and systolic function on echocardiography were both significantly associated with subsequent reoperation rates. Patients who had severe right ventricular dilation were eight times more likely to undergo subsequent reoperation (hazard ratio 8.67; 1.82-41.3; p=0.007). No cardiopulmonary exercise testing variable independently predicted reoperation.

CONCLUSIONS

The exercise capacity at adolescence following transatrial repair of tetralogy of Fallot is maintained at around 70% of predicted values. Only the patients with normal right ventricular size and normal right ventricular function seemed to be protected from reoperation over the subsequent decade. We found no exercise variables which predicted reoperation.

Cardiopulmonary Exercise Testing in Children and Adolescents with Repaired Tetralogy of Fallot: Mechanisms of Exercise Intolerance and Clinical Implications

By comparison with adults, cardiopulmonary exercise testing in children with Tetralogy of Fallot is limited, and its clinical application less clarified. This study provides a comprehensive CPET profile in a child-adolescent population with repaired TOF, explores mechanisms underpinning exercise intolerance and associations with clinical outcome. Seventy-four CPETs were completed in 58 child-adolescents with rTOF (age 13.8 SD 2.4 years). CPET parameters were corrected for age, sex and body size. At follow-up (4.9 years, IQR 3.5-7.9) clinical status and re-intervention was evaluated and CPET indices predicting these outcomes determined. Cohort peak V̇O2 was within low-normal limits (% pred: 74.1% SD 15.4) with 15 patients (26%) displaying moderately severe reduction in V̇O2peak (< 65% pred). Oxygen uptake efficiency slope highly correlated with V̇O2peak (r = 0.94, p < 0.001) and was insensitive to exercise intensity. No significant change in CPET occurred in patients who underwent interval testing at 24 SD 14.5 months, although there was a variable response in V̇O2peak between individuals. Chronotropic response, lung vital capacity, heart rate-V̇O2 slope (indicator of stroke volume) predicted oxygen consumption: V̇O2peak (R2 = 50.91%, p < 0.001) and workload (R2 = 58.39%, p < 0.001). Adverse clinical status was associated with reduced workload (OR 0.97, p = 0.011). V̇E/V̇CO2 slope was steeper in those that died ((%pred:137.8 SD 60.5 vs. 108.4 SD 17.0, p < 0.019). RVOT reintervention post-CPET (24 patients, 43.8%) was associated with an increased gradient of HR-VO2 slope (OR 1.042, p = 0.004). In child-adolescents with TOF important reductions in cardiopulmonary functioning were apparent in 25% of patients. Exercise intolerance was related to reduced vital capacity, impaired chronotropic response and deficient stroke volume increment.

The Role of Cardiopulmonary Testing to Risk Stratify Tetralogy of Fallot Patients

Neonatal repair has completely changed the clinical history of patients with tetralogy of Fallot (ToF); however, these patients carry a significant risk of severe arrhythmias and sudden cardiac death in the long term. The exact mechanism for late sudden cardiac death is multifactorial and still not well defined, and the risk stratification for primary prophylaxis in these patients remains challenging. Cardiopulmonary exercise testing (CPET) is a well-established and safe method to assess cardiopulmonary function in children and adults with congenital heart disease. Several parameters obtained with CPET have been identified as potential prognostic of major adverse cardiovascular events in congenital heart disease. CPET is routinely used to assess functional capacity also in patients with ToF, and there is some evidence showing its usefulness in predicting the cardiac adverse events in patients with repaired ToF. Current guidelines recognize the importance of CPET in the evaluation and management of patients with ToF, but there is no clear consensus on which the CPET parameter or level of exercise intolerance, as measured by CPET, is truly predictive of an increased risk of arrhythmia and major adverse cardiovascular events in this population. Therefore, the aim of this narrative review is to describe the current evidence on the potential use of CPET in the risk stratification of patients with repaired ToF.

Multimodality Imaging Assessment of Tetralogy of Fallot: From Diagnosis to Long-Term Follow-Up

Tetralogy of Fallot (TOF) is the most common complex congenital heart disease with long-term survivors, demanding serial monitoring of the possible complications that can be encountered from the diagnosis to long-term follow-up. Cardiovascular imaging is key in the diagnosis and serial assessment of TOF patients, guiding patients' management and providing prognostic information. Thorough knowledge of the pathophysiology and expected sequalae in TOF, as well as the advantages and limitations of different non-invasive imaging modalities that can be used for diagnosis and follow-up, is the key to ensuring optimal management of patients with TOF. The aim of this manuscript is to provide a comprehensive overview of the role of each modality and common protocols used in clinical practice in the assessment of TOF patients.

Intracardiac Flow Analysis of the Right Ventricle in Pediatric Patients With Repaired Tetralogy of Fallot Using a Novel Color Doppler Velocity Reconstruction

BACKGROUND

Repaired tetralogy of Fallot (RTOF) patients will develop right ventricular (RV) dysfunction from chronic pulmonary regurgitation (PR). Cardiac magnetic resonance sequences such as four-dimensional flow can demonstrate altered vorticity and flow energy loss (FEL); however, they are not as available as conventional echocardiography (echo). The study determined whether a novel, vendor-independent Doppler velocity reconstruction (DoVeR) could measure RV intracardiac flow in conventional echo of RTOF patients. The primary hypothesis was that DoVeR could detect increased vorticity and diastolic FEL in RTOF patients.

METHODS

Repaired tetralogy of Fallot patients with echo were retrospectively paired with age-/size-matched controls. Doppler velocity reconstruction employed the stream function-vorticity equation to approximate intracardiac flow fields from color Doppler. A velocity field of the right ventricle was reconstructed from the apical 4-chamber view. Vortex strength (VS, area integral of vorticity) and FEL were derived from DoVeR. Cardiac magnetic resonance and exercise stress parameters (performed within 1 year of echo) were collected for analysis.

RESULTS

Twenty RTOF patients and age-matched controls were included in the study. Mean regurgitant fraction was 40.5% ± 7.6%, and indexed RV end-diastolic volume was 158 ± 36 mL/m2. Repaired tetralogy of Fallot patients had higher total, mean diastolic, and peak diastolic VS (P = .0013, P = .0012, P = .0032, respectively) and higher total, mean diastolic, and peak diastolic body surface area-indexed FEL (P = .0016, P = .0022, P < .001, respectively). Peak diastolic indexed FEL and peak diastolic VS had weak-to-moderate negative correlation with RV ejection fraction (r = -0.52 [P = .019] and r = -0.49 [P = .030], respectively) and left ventricular ejection fraction (r = -0.47 [P = .034] and r = -0.64 [P = .002], respectively). Mean diastolic indexed FEL and VS had moderate-to-strong negative correlation with percent predicted maximal oxygen consumption (r = -0.69 [P = .012] and r = -0.75 [P = .006], respectively).

CONCLUSIONS

DoVeR can detect alterations to intracardiac flow in RTOF patients from conventional color Doppler imaging. Echo-based measures of diastolic VS and FEL correlated with ventricular function. DoVeR has the potential to provide serial evaluation of abnormal flow dynamics in RTOF patients.

Overshoot of the Respiratory Exchange Ratio during Recovery from Maximal Exercise Testing in Young Patients with Congenital Heart Disease

Introduction: The overshoot of the respiratory exchange ratio (RER) after exercise is reduced in patients with heart failure. Aim: The present study aimed to investigate the presence of this phenomenon in young patients with congenital heart disease (CHD), who generally present reduced cardiorespiratory fitness. Methods: In this retrospective study, patients with CHD underwent a maximal cardiopulmonary exercise testing (CPET) assessing the RER recovery parameters: the RER at peak exercise, the maximum RER value reached during recovery, the magnitude of the RER overshoot and the linear slope of the RER increase after the end of the exercise. Results: In total, 117 patients were included in this study. Of these, there were 24 healthy age-matched control subjects and 93 young patients with CHD (transposition of great arteries, Fontan procedure, aortic coarctation and tetralogy of Fallot). All patients presented a RER overshoot during recovery. Patients with CHD showed reduced aerobic capacity and cardiorespiratory efficiency during exercise, as well as a lower RER overshoot when compared to controls. RER magnitude was higher in the controls and patients with aortic coarctation when compared to those with transposition of great arteries, previous Fontan procedure, and tetralogy of Fallot. The RER magnitude was found to be correlated with the most relevant cardiorespiratory fitness and efficiency indices. Conclusions: The present study proposes new recovery indices for functional evaluation in patients with CHD. Thus, the RER recovery overshoots analysis should be part of routine CPET evaluation to further improve prognostic risk stratifications in patients with CHD.

Exercise Capacity in Patients with Pulmonary Atresia with Intact Ventricular Septum: Does the Type of Surgical Repair Matter?

Two standard surgical palliative options for neonates born with pulmonary atresia and intact ventricular septum (PA/IVS) include uni-or biventricular repair. Whenever feasible, the biventricular repair is considered to have better exercise capacity (XC) and outcomes. However, there is a paucity of data comparing objective XC between these two surgical techniques. Our aim was to compare XC, including longitudinal changes in patients with PA/IVS following uni-biventricular repair. We performed a single-center retrospective study of survivors with repaired PA/IVS who underwent comprehensive treadmill cardiopulmonary exercise testing. Initial and latest exercise parameters were compared for longitudinal analysis. Demographic and exercise parameters were collated. Peak oxygen uptake (VO₂ in ml/kg/min), an indicator of maximal aerobic capacity, peak heart rate, and other measures of spirometry performed at the same time were collected. Recorded parameters included, (a) Percentage of predicted VO₂ (% VO2) normalized for age, weight, height, and gender, (b) % oxygen (O₂) pulse, (c) anaerobic threshold (AT), (d) Chronotropic index (CI), (e) % Breathing reserve, (f) Forced vital capacity (FVC), (g) % Forced Expiratory volume in 1 s (FEV1), (h) Maximum voluntary ventilation (MVV), and (i) VE/VCO₂. Appropriate statistical tests were performed, and a p value < 0.05 was considered significant. A total of 35 patients (43% male, 57% univentricular repair) were included, with a mean (SD) age of 20.1(7.5) years. Patients with univentricular palliation demonstrated significantly impaired peak heart rate, chronotropic index (0.50 ± 0.2 vs. 0.90 ± 0.1, p = 0.02), VE/VCO₂ (35.4 ± 5.0 vs. 30.2 ± 2.8, p = 0.001), and %FVC (78.3 ± 8.3 vs. 88.6 ± 15.1, p = 0.02). There was a trend towards reduction in % VO₂ in the Fontan patients though it was statistically similar between the groups (68.4 ± 21.4 vs. 81.2 ± 18.9, p = 0.07). Longitudinal data were available for 11 patients in each group, and there was no longitudinal decline in their exercise parameters over similar intermediate follow-up duration [6.8 (UV) vs. 5.3 (BV) years]. We conclude that young survivors with PA/IVS with prior univentricular palliation demonstrated an objective impairment in their chronotropic parameters compared with the biventricular repair. However, this did not translate into a significant difference in their exercise capacity. There was no longitudinal decline in exercise capacity or other parameters over intermediate follow-up.

Aerobic fitness change with time in children with congenital heart disease: A retrospective controlled cohort study

BACKGROUND

To evaluate the change in aerobic fitness (VO_2max), measured by cardio-pulmonary exercise test (CPET), in children with congenital heart disease (CHD), compared to matched healthy controls, and identify predictors of VO_2max change with time in this specific population.

METHOD

This longitudinal retrospective multicentre cohort study was carried out from 2010 to 2020. We included CHD paediatric patients from the cohort of a previous cross-sectional study, who had a second CPET at least 1 year after the first one, during their follow-up.

RESULTS

We included 936 children, 296 in the CHD group and 640 controls. Mean time between baseline and final CPET was 4.4 ± 1.7 years. After matching on age and gender and adjustment for age and BMI, the mean VO2_max group difference was 10.5% ± 1.0% of percent-predict VO_2max at baseline and increased to 19.1% ± 1.3% at final assessment. In the CHD group, the proportion of children with impaired aerobic fitness was significantly higher at final than at baseline CPET assessment (51.4% vs 20.3%; P < 0.01). The mean annual VO_2max decrease was significantly worse in the CHD group than in controls (-1.88% ± 0.19% of percent-predict VO_2max/year vs. -0.44% ± 0.27% of percent-predict VO_2max/year, P < 0.01, respectively). In multivariate analyse, male gender, a high initial VO_2max, a high BMI, and the number of cardiac surgical procedures ≥2, were predictors of the VO_2max decrease with time.

CONCLUSION

The VO_2max decrease with time is more pronounced in children with CHD compared to healthy matched controls. This study highlighted the importance of serial CPET assessment in children with CHD. Trial registration NCT04815577.

Abnormal Diastolic Hemodynamic Forces: A Link Between Right Ventricular Wall Motion, Intracardiac Flow, and Pulmonary Regurgitation in Repaired Tetralogy of Fallot

Background and Objective

The effect of chronic pulmonary regurgitation (PR) on right ventricular (RV) dysfunction in repaired Tetralogy of Fallot (RTOF) patients is well recognized by cardiac magnetic resonance (CMR). However, the link between RV wall motion, intracardiac flow and PR has not been established. Hemodynamic force (HDF) represents the global force exchanged between intracardiac blood volume and endocardium, measurable by 4D flow or by a novel mathematical model of wall motion. In our study, we used this novel methodology to derive HDF in a cohort of RTOF patients, exclusively using routine CMR imaging.

Methods

RTOF patients and controls with CMR imaging were retrospectively included. Three-dimensional (3D) models of RV were segmented, including RV outflow tract (RVOT). Feature-tracking software (QStrain 2.0, Medis Medical Imaging Systems, Leiden, Netherlands) captured endocardial contours from long/short-axis cine and used to reconstruct RV wall motion. A global HDF vector was computed from the moving surface, then decomposed into amplitude/impulse of three directional components based on reference (Apical-to-Basal, Septal-to-Free Wall and Diaphragm-to-RVOT direction). HDF were compared and correlated against CMR and exercise stress test parameters. A subset of RTOF patients had 4D flow that was used to derive vorticity (for correlation) and HDF (for comparison against cine method).

Results

68 RTOF patients and 20 controls were included. RTOF patients had increased diastolic HDF amplitude in all three directions (p<0.05). PR% correlated with Diaphragm-RVOT HDF amplitude/impulse (r = 0.578, p<0.0001, r = 0.508, p < 0.0001, respectively). RV ejection fraction modestly correlated with global HDF amplitude (r = 0.2916, p = 0.031). VO2-max correlated with Septal-to-Free Wall HDF impulse (r = 0.536, p = 0.007). Diaphragm-to-RVOT HDF correlated with RVOT vorticity (r = 0.4997, p = 0.001). There was no significant measurement bias between Cine-derived HDF and 4D flow-derived HDF by Bland-Altman analysis.

Conclusion

RTOF patients have abnormal diastolic HDF that is correlated to PR, RV function, exercise capacity and vorticity. HDF can be derived from conventional cine, and is a potential link between RV wall motion and intracardiac flow from PR in RTOF patients.

Cardiac Concerns in the Pediatric Athlete

Cardiovascular disease remains the number one cause of death in Americans. It is no secret that exercise mitigates this risk. Exercise and regular physical activity are beneficial for physical health including aerobic conditioning, endurance, strength, mental health, and overall improved quality of life. Unfortunately, today many children and adolescents are sedentary, lacking the recommended daily amount of physical activity, leading to higher rates of obesity, cardiovascular disease, stroke, diabetes, anxiety, and depression. Given this rising concern, the World Health Organization launched a 12-year plan to improve physical activity in children and adolescents by reducing the inactivity rate by 15% in the world. How does this apply to children and adolescents with acquired or congenital heart disease?.

Comparative Costs of Management Strategies for Neonates With Symptomatic Tetralogy of Fallot

BACKGROUND

Recent data have demonstrated that overall mortality and adverse events are not significantly different for primary repair (PR) and staged repair (SR) approaches to management of neonates with symptomatic tetralogy of Fallot (sTOF). Cost data can be used to compare the relative value (cost for similar outcomes) of these approaches and are a potentially more sensitive measure of morbidity.

OBJECTIVES

This study sought to compare the economic costs associated with PR and SR in neonates with sTOF.

METHODS

Data from a multicenter retrospective cohort study of neonates with sTOF were merged with administrative data to compare total costs and cost per day alive over the first 18 months of life in a propensity score-adjusted analysis. A secondary analysis evaluated differences in department-level costs.

RESULTS

In total, 324 subjects from 6 centers from January 2011 to November 2017 were studied (40% PR). The 18-month cumulative mortality (P = 0.18), procedural complications (P = 0.10), hospital complications (P = 0.94), and reinterventions (P = 0.22) did not differ between PR and SR. Total 18-month costs for PR (median $179,494 [IQR: $121,760-$310,721]) were less than for SR (median: $222,799 [IQR: $167,581-$327,113]) (P < 0.001). Cost per day alive (P = 0.005) and department-level costs were also all lower for PR. In propensity score-adjusted analyses, PR was associated with lower total cost (cost ratio: 0.73; P < 0.001) and lower department-level costs.

CONCLUSIONS

In this multicenter study of neonates with sTOF, PR was associated with lower costs. Given similar overall mortality between treatment strategies, this finding suggests that PR provides superior value.

Cardiopulmonary Exercise Testing in Repaired Tetralogy of Fallot: Multiparametric Overview and Correlation with Cardiac Magnetic Resonance and Physical Activity Level

Patients with repaired Tetralogy of Fallot (rToF) typically report having preserved subjective exercise tolerance. Chronic pulmonary regurgitation (PR) with varying degrees of right ventricular (RV) dilation as assessed by cardiac magnetic resonance imaging (MRI) is prevalent in rToF and may contribute to clinical compromise. Cardiopulmonary exercise testing (CPET) provides an objective assessment of functional capacity, and the International Physical Activity Questionnaire (IPAQ) can provide additional data on physical activity (PA) achieved. Our aim was to assess the association between CPET values, IPAQ measures, and MRI parameters. All rToF patients who had both an MRI and CPET performed within one year between March 2019 and June 2021 were selected. Clinical data were extracted from electronic records (including demographic, surgical history, New York Heart Association (NYHA) functional class, QRS duration, arrhythmia, MRI parameters, and CPET data). PA level, based on the IPAQ, was assessed at the time of CPET. Eighty-four patients (22.8 ± 8.4 years) showed a reduction in exercise capacity (median peak VO₂ 30 mL/kg/min (range 25–33); median percent predicted peak VO₂ 68% (range 61–78)). Peak VO₂, correlated with biventricular stroke volumes (RVSV: β = 6.11 (95%CI, 2.38 to 9.85), p = 0.002; LVSV: β = 15.69 (95% CI 10.16 to 21.21), p < 0.0001) and LVEDVi (β = 8.74 (95%CI, 0.66 to 16.83), p = 0.04) on multivariate analysis adjusted for age, gender, and PA level. Other parameters which correlated with stroke volumes included oxygen uptake efficiency slope (OUES) (RVSV: β = 6.88 (95%CI, 1.93 to 11.84), p = 0.008; LVSV: β = 17.86 (95% CI 10.31 to 25.42), p < 0.0001) and peak O₂ pulse (RVSV: β = 0.03 (95%CI, 0.01 to 0.05), p = 0.007; LVSV: β = 0.08 (95% CI 0.05 to 0.11), p < 0.0001). On multivariate analysis adjusted for age and gender, PA level correlated significantly with peak VO₂/kg (β = 0.02, 95% CI 0.003 to 0.04; p = 0.019). We observed a reduction in objective exercise tolerance in rToF patients. Biventricular stroke volumes and LVEDVi were associated with peak VO₂ irrespective of RV size. OUES and peak O₂ pulse were also associated with biventricular stroke volumes. While PA level was associated with peak VO₂, the incremental value of this parameter should be the focus of future studies.

Moving beyond size: vorticity and energy loss are correlated with right ventricular dysfunction and exercise intolerance in repaired Tetralogy of Fallot

BACKGROUND

The global effect of chronic pulmonary regurgitation (PR) on right ventricular (RV) dilation and dysfunction in repaired Tetralogy of Fallot (rTOF) patients is well studied by cardiovascular magnetic resonance (CMR). However, the links between PR in the RV outflow tract (RVOT), RV dysfunction and exercise intolerance are not clarified by conventional measurements. Not all patients with RV dilation share the same intracardiac flow characteristics, now measurable by time resolved three-dimensional phase contrast imaging (4D flow). In our study, we quantified regional vorticity and energy loss in rTOF patients and correlated these parameters with RV dysfunction and exercise capacity.

METHODS

rTOF patients with 4D flow datasets were retrospectively analyzed, including those with transannular/infundibular repair and conduit repair. Normal controls and RV dilation patients with atrial-level shunts (Qp:Qs > 1.2:1) were included for comparison. 4D flow was post-processed using IT Flow (Cardioflow, Japan). Systolic/diastolic vorticity (ω, 1/s) and viscous energy loss (VEL, mW) in the RVOT and RV inflow were measured. To characterize the relative influence of diastolic vorticity in the two regions, an RV Diastolic Vorticity Quotient (ωRVOT-Diastole/ωRV Inflow-Diastole, RV-DVQ) was calculated. Additionally, RVOT Vorticity Quotient (ωRVOT-Diastole/ωRVOT-Systole, RVOT-VQ) and RVOT Energy Quotient (VELRVOT-Diastole/VELRVOT-Systole, RVOT-EQ) was calculated. In rTOF, measurements were correlated against conventional CMR and exercise stress test results.

RESULTS

58 rTOF patients, 28 RV dilation patients and 12 controls were included. RV-DVQ, RVOT-VQ, and RVOT-EQ were highest in rTOF patients with severe PR compared to rTOF patients with non-severe PR, RV dilation and controls (p < 0.001). RV-DVQ positively correlated with RV end-diastolic volume (0.683, p < 0.001), PR fraction (0.774, p < 0.001) and negatively with RV ejection fraction (- 0.521, p = 0.003). Both RVOT-VQ, RVOT-EQ negatively correlated with VO2-max (- 0.587, p = 0.008 and - 0.617, p = 0.005) and % predicted VO2-max (- 0.678, p = 0.016 and - 0.690, p = 0.001).

CONCLUSIONS

In rTOF patients, vorticity and energy loss dominate the RVOT compared to tricuspid inflow, correlating with RV dysfunction and exercise intolerance. These 4D flow-based measurements may be sensitive biomarkers to guide surgical management of rTOF patients.

Influence of right ventricular pressure and volume overload on right and left ventricular diastolic function

BACKGROUND

Ventricular interdependence may account for altered ventricular mechanics in congenital heart disease. The present study aimed to identify differences in load-dependent right ventricular (RV)-left ventricular (LV) interactions in porcine models of pulmonary stenosis (PS) and pulmonary insufficiency (PI) by invasive admittance-derived hemodynamics in conjunction with noninvasive cardiovascular magnetic resonance (CMR).

METHODS

Seventeen pigs were used in the study (7 with PS, 7 with PI, and 3 controls). Progressive PS was created by tightening a Teflon tape around the pulmonary artery, and PI was created by excising 2 leaflets of the pulmonary valve. Admittance catheterization data were obtained for the RV and LV at 10 to 12 weeks after model creation, with the animal ventilated under temporary diaphragm paralysis. CMR was performed in all animals immediately prior to pressure-volume catheterization.

RESULTS

In the PS group, RV contractility was increased, manifested by increased end-systolic elastance (mean difference, 1.29 mm Hg/mL; 95% confidence interval [CI], 0.57-2.00 mm Hg/mL). However, in the PI group, no significant changes were observed in RV systolic function despite significant changes in RV diastolic function. In the PS group, LV end-systolic volume was significantly lower compared with controls (mean difference, 25.1 mL; 95% CI, -40.5 to -90.7 mL), whereas in the PI group, the LV showed diastolic dysfunction, demonstrated by an elevated isovolumic relaxation constant and ventricular stiffness (mean difference, 0.03 mL^-1; 95% CI, -0.02 to 0.09 mL^-1).

CONCLUSIONS

The LV exhibits systolic dysfunction and noncompliance with PI. PS is associated with preserved LV systolic function and evidence of some LV diastolic dysfunction. Interventricular interactions influence LV filling and likely account for differential effects of RV pressure and volume overload on LV function.

Impaired right and left ventricular function and relaxation induced by pulmonary regurgitation are not reversed by tardive antifibrosis treatment

Pulmonary regurgitation (PR) after repair of tetralogy of Fallot (rTOF) is associated with progressive right (RV) and left (LV) ventricular dysfunction and fibrosis. However, angiotensin II receptor blockade therapy has shown mixed and often disappointing results. The aim of this study was to serially assess changes in biventricular remodeling, dysfunction, and interactions in a rat model of isolated severe PR and to study the effects of angiotensin II receptor blockade. PR was induced in Sprague-Dawley rats by leaflet laceration. Shams (n = 6) were compared with PR (n = 5) and PR + losartan treatment (n = 6). In the treatment group, oral losartan (50 mg·kg^-1·day^-1) was started 6 wk after PR induction and continued for 6 wk until the terminal experiment. In all groups, serial echocardiography was performed every 2 wk until the terminal experiment where biventricular myocardium was harvested and analyzed for fibrosis. PR and PR + losartan rats experienced early progressive RV dilatation by 2 wk which then stabilized. RV systolic dysfunction occurred from 4 wk after insult and gradually progressed. In PR rats, RV dilatation caused diastolic LV compression and impaired relaxation. PR rats developed increased RV fibrosis compared with shams. Although losartan decreased RV fibrosis, RV dilatation and dysfunction were not improved. This suggests that RV dilatation is an early consequence of PR and affects LV relaxation. RV dysfunction may progress independent of further remodeling. Reduced RV fibrosis was not associated with improved RV function and may not be a viable therapeutic target in rTOF with predominant RV volume loading.NEW & NOTEWORTHY The time-course of RV dilatation and the mechanisms of biventricular dysfunction caused by PR have not been well characterized and the effect of losartan in volume-overloaded RV remains controversial. Our findings suggest that severe PR induces early onset of RV dilatation and dysfunction with little progression after the first 4 wk. The RV dilatation distorts LV geometry with associated impaired LV relaxation. Losartan reduced RV fibrosis but did not reverse RV dilatation and dysfunction.

Exercise capacity in patients with repaired Tetralogy of Fallot aged 6 to 63 years

OBJECTIVES

This study aimed to provide a perspective for the interpretation of exercise capacity (peakVO₂) in patients with repaired Tetralogy of Fallot (patients with rTOF) by describing the course of peakVO₂ from patients aged 6-63 years.

METHODS

A retrospective study was performed between September 2001 and December 2016 in the German Heart Centre Munich, Germany, and in the University Medical Centre Groningen, the Netherlands. A total of 1175 cardiopulmonary exercise tests (CPETs) were collected from 586 patients with rTOF, 46% female. Maximal exertion was verified using a respiratory exchange ratio ≥1.00. PeakVO₂ was modelled using time-dependent multilevel models for repeated measurements (n=889 in 300 patients), and compared with subject-specific reference values calculated by the models of Bongers et al and Mylius et al. RESULTS: The peakVO₂ of patients with rTOF was reduced at all ages. At the age of 6, the peakVO₂ was 614 mL/min (70% of predicted (95% CI 67 to 73)). The reduced increase in peakVO₂ during adolescence resulted in a significant lower maximum peakVO₂ of 1209 mL/min at 25 years (65% predicted, p<0.001). A linear decline after 25 years was observed in patients and references, although patients showed an accelerated decline, with a -0.24% point of predicted (95% CI 0.11 to 0.38) per year without differences between sexes (p=0.263).

CONCLUSIONS

This study provides a context for peakVO₂ across ages in patients with rTOF under contemporary treatment strategies. It showed that the reduction in peakVO₂ originates from childhood and declines over time. Sex differences in patients with rTOF were similar to natural existing sex differences.

Analysis of the recovery phase after maximal exercise in children with repaired tetralogy of Fallot and the relationship with ventricular function

Background

Few studies demonstrate delayed recovery after exercise in children and adults with heart disease. We assess the recovery patterns of gas exchange parameters and heart rate (HR) in children with repaired Tetralogy of Fallot (rToF) compared to healthy peers and investigate the correlation with ventricular function and QRS duration.

Methods

45 children after rToF and 45 controls performed a maximal incremental cardiopulmonary exercise test. In the subsequent recovery period, patterns of VO₂, VCO₂ and HR were analysed. Half-life time (T_1/2) of the exponential decay and drop per minute (Rec_min) were compared between groups. In the rToF group, correlations were examined between the recovery parameters and QRS-duration and ventricular function, described by fractional shortening (FS) and tricuspid annular plane systolic excursion (TAPSE) measured at baseline prior to exercise.

Results

Recovery of VO₂ and VCO₂ was delayed in rToF patients, half-life time values were higher compared to controls (T_1/2VO₂ 52.51 ±11.29 s vs. 44.31 ± 10.47 s; p = 0.001 and T_1/2VCO₂ 68.28 ± 13.84 s vs. 59.41 ± 12.06 s; p = 0.002) and percentage drop from maximal value was slower at each minute of recovery (p<0.05). Correlations were found with FS (T_1/2VO₂: r = -0.517; p<0.001; Rec_1minVO₂: r = -0.636, p<0.001; Rec_1minVCO₂: r = -0.373, p = 0.012) and TAPSE (T_1/2VO₂: r = -0.505; p<0.001; Rec_1minVO₂: r = -0.566, p<0.001; T_1/2VCO₂: r = -0.466; p = 0.001; Rec_1minVCO₂: r = -0.507, p<0.001), not with QRS-duration. No difference was found in HR recovery between patients and controls.

Conclusions

Children after rToF show a delayed gas exchange recovery after exercise. This delay correlates to ventricular function, demonstrating its importance in recovery after physical activity.

Predictors of low exercise cardiac output in patients with severe pulmonic regurgitation

BACKGROUND AND OBJECTIVES

Chronic pulmonic regurgitation (PR) following repair of congenital heart disease (CHD) impairs right ventricular function that impacts peak exercise cardiac index (pCI). We aimed to estimate in a non-invasive way pCI and peak oxygen consumption (pVO₂) and to evaluate predictors of low pCI in patients with significant residual pulmonic regurgitation after CHD repair.

METHOD

We included 82 patients (median age 19 years (range 10-54 years)) with residual pulmonic regurgitation fraction >40%. All underwent cardiac MRI and cardiopulmonary testing with measurement of pCI by thoracic impedancemetry. Low pCI was defined <7 L/min/m².

RESULTS

Low pCI was found in 18/82 patients. Peak indexed stroke volume (pSVi) tended to compensate chronotropic insufficiency only in patients with normal pCI (r=-0.31, p=0.01). Below 20 years of age, only 5/45 patients had low pCI but near-normal (≥6.5 L/min/m²). pVO₂ (mL/kg/min) was correlated with pCI (r=0.58, p=0.0002) only in patients aged >20 years. Left ventricular stroke volume in MRI correlated with pSVi only in the group of patients with low pCI (r=0.54, p=0.02). No MRI measurements predicted low pCI. In multivariable analysis, only age predicted a low pCI (OR=1.082, 95% CI 1.035 to 1.131, p=0.001) with continuous increase of risk with age.

CONCLUSIONS

In patients with severe PR, pVO₂ is a partial reflection of pCI. Risk of low pCI increases with age. No resting MRI measurement predicts low haemodynamic response to exercise. Probably more suitable to detect ventricular dysfunction, pCI measurement could be an additional parameter to take into account when considering pulmonic valve replacement.

4-D flow magnetic-resonance-imaging-derived energetic biomarkers are abnormal in children with repaired tetralogy of Fallot and associated with disease severity

BACKGROUND

Cardiac MRI plays a central role in monitoring children with repaired tetralogy of Fallot (TOF) for long-term complications. Current risk assessment is based on volumetric and functional parameters that measure late expression of underlying physiological changes. Emerging 4-D flow MRI techniques promise new insights.

OBJECTIVE

To assess whether 4-D flow MRI-derived measures of blood kinetic energy (1) differentiate children and young adults with TOF from controls and (2) are associated with disease severity.

MATERIALS AND METHODS

Pediatric patients post TOF repair (n=21) and controls (n=24) underwent 4-D flow MRI for assessment of time-resolved 3-D blood flow. Data analysis included 3-D segmentation of the right ventricle (RV) and pulmonary artery (PA), with calculation of peak systolic and diastolic kinetic energy (KE) maps. Total KE_RV and KE_PA were determined from the sum of the KE of all voxels within the respective time-resolved segmentations.

RESULTS

KE_PA was increased in children post TOF vs. controls across the cardiac cycle, with median 12.5 (interquartile range [IQR] 10.3) mJ/m² vs. 8.2 (4.3) mJ/m², P<0.01 in systole; and 2.3 (2.7) mJ/m² vs. 1.4 (0.9) mJ/m², P<0.01 in diastole. Diastolic KE_PA correlated with systolic KE_PA (R² 0.41, P<0.01) and with pulmonary regurgitation fraction (R² 0.65, P<0.01). Diastolic KE_RV showed similar relationships, denoting increasing KE with higher cardiac outputs and increased right heart volume loading. Diastolic KE_RV and KE_PA increased with RV end-diastolic volume in a non-linear relationship (R² 0.33, P<0.01 and R² 0.50, P<0.01 respectively), with an inflection point near 120 mL/m².

CONCLUSION

Four-dimensional flow-derived KE is abnormal in pediatric patients post TOF repair compared to controls and has a direct, non-linear relationship with traditional measures of disease progression. Future longitudinal studies are needed to evaluate utility for early outcome prediction in TOF.

Functional outcome in contemporary children and young adults with tetralogy of Fallot after repair

OBJECTIVE

Functional outcome measures are of growing importance in the aftercare of patients with congenital heart disease. This study addresses the functional status with regard to exercise capacity, health-related physical fitness (HRPF) and arterial stiffness in a recent cohort of children, adolescents and young adults with tetralogy of Fallot (ToF) after repair.

DESIGN

Single-centre, uncontrolled and prospective cohort study.

SETTING

Outpatient department of the German Heart Centre Munich; July 2014-January 2018.

PATIENTS

One hundred and six patients with ToF after repair (13.5±3.7 years, 40 females) were included. Data were compared with a recent cohort of healthy controls (HCs) (n=1700, 12.8±2.6 years, 833 females).

MAIN OUTCOME MEASURES

Patients underwent a symptom-limited cardiopulmonary exercise test, performed an HRPF test (FitnessGram) and had an assessment of their arterial stiffness (Mobil-O-Graph).

RESULTS

Compared with HC, patients with ToF showed lower predicted [Formula: see text]O₂ peak (ToF: 80.4% ± 16.8% vs HC: 102.6% ± 18.1%, p<0.001), impaired ventilatory efficiency (ToF: 29.6 ± 3.6 vs HC: 27.4 ± 2.9, p<0.001), chronotropic incompetence (ToF: 167 ± 17 bpm vs HC: 190 ± 17 bpm, p<0.001) and reduced HRPF (ToF z-score: -0.65 ± 0.87 vs HC z-score: 0.03 ± 0.65, p<0.001). Surrogates of arterial stiffness, central and peripheral systolic blood pressure, did not differ between the two groups.

CONCLUSIONS

Contemporary children, adolescents and young adults with ToF still have functional limitations. How impaired HRPF and limited exercise capacity interact and how they can be modified needs to be evaluated in further intervention studies.

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.

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.

Reliability of Peak Exercise Stroke Volume Assessment by Impedance Cardiography in Patients with Residual Right Outflow Tract Lesions After Congenital Heart Disease Repair

Global ventricular response to exercise may be useful in follow-up of patients with residual right outflow tract lesions after congenital heart disease repair. In this context, impedance cardiography is considered accurate for stroke volume (SV) measurement during exercise testing, however, to date, only partial assessment of its reliability has been reported. We retrospectively evaluated relative and absolute reliability of peak SV by impedance cardiography during exercise using intraclass correlation (ICC) and standard error of measurement (SEM) in this population. Peak SV was measured in 30 young patients (mean age 14.4 years ± 2.1) with right ventricular outflow tract reconstruction who underwent two cardiopulmonary exercise tests at a mean one-year interval. SV was measured using a signal morphology impedance cardiography analysis device (PhysioFlow^®) and was indexed to body surface area. ICC of peak indexed SV measurement was 0.80 and SEM was 10.5%. High heterogeneity was seen when comparing patients according to peak indexed SV; in patients with peak SV < 50 ml/m² (15 patients), ICC rose to 0.95 and SEM dropped to 2.7%, while in patients with a peak SV > 50 ml/m² relative and absolute reliability decreased (ICC = 0.45, SEM = 12.2%). Peak exercise SV assessment by a PhysioFlow^® device represents a highly reliable method in patients with residual right outflow tract lesions after congenital heart disease repair, especially in patients with peak SV < 50 ml/m². In this latter group, a peak SV decrease > 7.3% (corresponding to the minimum "true" difference) should be considered a clinically-relevant decrease in global ventricular performance and taken into account when deciding whether to perform residual lesion removal.

Longitudinal changes in adolescents with TOF: implications for care

Background

We sought to identify predictors of change in right ventricular function and exercise capacity in adolescents following repair for tetralogy of Fallot.

Methods and results

We performed a longitudinal study with serial cardiac magnetic resonance imaging and/or exercise stress tests. Patients with interim intervention on the pulmonary valve were excluded. Paired t-test was used to detect longitudinal changes and multivariable regression models were built to identify predictors of change. Initial and follow up magnetic resonance and exercise stress test studies were available for 65 and 63 subjects, respectively. Age at initial testing was 11.7 ± 2.7 years. Average follow up time was 4.5 ± 1.8 (magnetic resonance) and 4.0 ± 1.6 (exercise test) years. There was a significant increase in right ventricular end diastolic and systolic volume (119 ± 34 to 128 ± 35 ml/m2, P = 0.006; 49 ± 20 to 56 ± 23 ml/m2, P = 0.001, respectively), and a decrease in right ventricular ejection fraction (60 ± 7 to 56 ± 8%, P = 0.001), with no significant change in pulmonary regurgitant fraction or right ventricular cardiac index. Predictors of right ventricular dilation over time included: time elapsed from surgical repair, severity of pulmonary insufficiency and right ventricular dilation at the initial magnetic resonance imaging. Of those, time elapsed from surgical repair had the most significant effect. There was no change in exercise capacity.

Discussion

In the adolescent with tetralogy of Fallot, longer time from surgery, more pulmonary insufficiency and greater right ventricular dilation at initial magnetic resonance imaging are associated with progressive right ventricular dilation. These results suggest early monitoring with magnetic resonance imaging might identify those at highest risk for progressive disease.

Usefulness of maximal oxygen pulse in timing of pulmonary valve replacement in patients with isolated pulmonary regurgitation

Patients with pulmonary regurgitation after tetralogy of Fallot repair have impaired aerobic capacity; one of the reasons is the decreasing global ventricular performance at exercise, reflected by decreasing peak oxygen pulse. The aims of our study were to evaluate the impact of pulmonary valve replacement on peak oxygen pulse in a population with pure pulmonary regurgitation and with different degrees of right ventricular dilatation and to determine the predictors of peak oxygen pulse after pulmonary valve replacement. The mean and median age at pulmonary valve replacement was 27 years. Mean pre-procedural right ventricular end-diastolic volume was 182 ml/m2. Out of 24 patients, 15 had abnormal peak oxygen pulse before pulmonary valve replacement. We did not observe a significant increase in peak oxygen pulse after pulmonary valve replacement (p=0.76). Among cardiopulmonary test/MRI/historical pre-procedural parameters, peak oxygen pulse appeared to be the best predictor of peak oxygen pulse after pulmonary valve replacement (positive and negative predictive values, respectively, 0.94 and 1). After pulmonary valve replacement, peak oxygen pulse was well correlated with left ventricular stroke and end-diastolic volumes (r=0.67 and 0.68, respectively). Our study confirms the absence of an effect of pulmonary valve replacement on peak oxygen pulse whatever the initial right ventricular volume, reflecting possible irreversible right and/or left ventricle lesions. Pre-procedural peak oxygen pulse seemed to well predict post-procedural peak oxygen pulse. These results encourage discussions on pulmonary valve replacement in patients showing any decrease in peak oxygen pulse during their follow-up.

Assessing Late Cardiopulmonary Function in Patients with Repaired Tetralogy of Fallot Using Exercise Cardiopulmonary Function Test and Cardiac Magnetic Resonance

BACKGROUND

Patients with repaired tetralogy of Fallot (TOF) usually experience progressive right ventricle (RV) dysfunction due to pulmonary regurgitation (PR). This could further worsen the cardiopulmonary function. This study aimed to compare the changes in patient exercise cardiopulmonary test and cardiac magnetic resonance imaging, and consider the implication of these changes.

METHODS

Our study examined repaired TOF patients who underwent cardiopulmonary exercise test (CPET) to obtain maximal (peak oxygen consumption, peak VO2) and submaximal parameters (oxygen uptake efficiency plateau, oxygen uptake efficiency plateau (OUEP), and ratio of minute ventilation to carbon dioxide production, VE/VCO2 slope). Additionally, the hemodynamic status was assessed by using cardiac magnetic resonance. Criteria for exclusion included TOF patients with pulmonary atresia, atrioventricular septal defect, or absence of pulmonary valve syndrome.

RESULTS

We enrolled 158 patients whose mean age at repair was 7.8 ± 9.1 years (range 0.1-49.2 years) and the mean patient age at CPET was 29.5 ± 12.2 years (range 7.0-57.0 years). Severe PR (PR fraction ≥ 40%) in 53 patients, moderate in 55, and mild (PR fraction < 20%) in 50 patients were noted. The mean RV end-diastolic volume index (RVEDVi) was 113 ± 35 ml/m(2), with 7 patients observed to have a RVEDVi > 163 ml/m(2). The mean left ventricular ejection fraction (LVEF) was 63 ± 8%, left ventricular end-diastolic volume index (LVEDVi) was 65 ± 12 ml/m(2), and LVESVi was 25 ± 14 ml/m(2). CPET revealed significantly decreased peak VO2 (68.5 ± 14.4% of predicted), and fair OUEP (90.3 ± 14.1% of predicted) and VE/VCO2 slope (27.1 ± 5.3). PR fraction and age at repair were negatively correlated with maximal and submaximal exercise indicators (peak VO2 and OUEP). Left ventricular (LV) function and size were positively correlated with peak VO2 and OUEP.

CONCLUSIONS

The results of CPET showed that patients with repaired TOF had a low maximal exercise capacity (peak VO2), but a fair submaximal exercise capacity (OUEP and VE/VCO2 slope), suggesting limited exercise capability in high intensity circumstances. PR, LV function and age at total repair were the most important determinants of CPET performance.

KEY WORDS

Cardiac magnetic resonance; Cardiopulmonary exercise function; Pulmonary regurgitation; Surgical age; Tetralogy of Fallot.

Comparison of the Degree of Exercise Tolerance in Children After Surgical Treatment of Complex Cardiac Defects, Assessed Using Ergospirometry and the Level of Brain Natriuretic Peptide

Children who underwent surgery for complex congenital heart defects present worse exercise capacity than their healthy peers. In adults and adolescents, heart failure is assessed on the basis of clinical symptoms using the New York Heart Association (NYHA) score, while in an infant Ross scale; heart failure can also be evaluated by other parameters. The purpose of this study was to compare the degree of exercise tolerance in children after surgery for complex heart defects, assessed by the ratio of maximum oxygen uptake (VO2max) and the brain natriuretic peptide (N-terminal fragment of the prohormone brain-type natriuretic peptide [NT-proBNP]) concentration.The study group consisted of 42 children, ages 9 to 17 years (mean 14.00 ± 2.72). Among them there were 22 children with tetralogy of Fallot (ToF) after total correction, 18 children with transposition of the great arteries (d-TGA) after the arterial switch operation, and 2 children with single ventricle (SV) after the Fontan operation. All but 1 child were in NYHA class I. The control group consisted of 20 healthy children. Outcomes of interest were the ratio of VO2max, determined during ergospirometry, and the level of NT-proBNP. The statistical analysis was performed and the groups were considered significantly different for P < 0.05.There was no statistically significant correlation between NT-proBNP and maximum oxygen uptake (VO2) kg min in the study group compared with the control group.The VO2max in the test group had a mean value less (34.6 ± 8.0) than controls (38.4 ± 7.7), and the differences were statistically significant (P = 0.041). In contrast, the average concentration of NT-proBNP in the study group was higher than controls (117.9 ± 74.3 vs 18.0 ± 24.5), and these differences were statistically significant (P < 0.001).After operations for complex heart defects (ToF, TGA, and SV), children have worse heart function parameters and exercise capacity than the healthy population. To control this, we recommend postoperative ergospirometry and determination of NT-proBNP concentrations.

Exercise Performance in Patients with D-Loop Transposition of the Great Arteries After Arterial Switch Operation: Long-Term Outcomes and Longitudinal Assessment

The first patients to undergo a successful arterial switch operation (ASO) for d-transposition of the great arteries (D-TGA) are now entering their fourth decade of life. Past studies of ASO survivors' exercise function have yielded conflicting results. We therefore undertook this study to describe the current function of ASO survivors, to identify factors related to inferior exercise performance and to determine whether their exercise function tends to deteriorate over time. A retrospective cohort study was designed examining all patients with D-TGA after the ASO who underwent comprehensive cardiopulmonary exercise testing (CPET). Patients with palliative surgery prior to ASO, ventricular hypoplasia or severe valvar dysfunction were excluded from the study. Data from CPETs in which the peak respiratory exchange ratio was <1.09 were also excluded. We identified 113 patients who met entry criteria and had 186 CPX at our institution between 1/2002 and 1/2013; 41 patients had at least 2 qualifying CPX. Mean age at the time of the initial test was 17 ± 1 year. Peak oxygen consumption (VO2) averaged 84 ± 2 % predicted. Peak VO2 was lower among patients with repaired ventricular septal defects (82 ± 4 vs. 86 ± 3 % predicted; p < 0.05) and among patients with ≥ moderate right-sided obstructive lesions (77 ± 5 vs. 87 ± 3 % predicted; p < 0.05). Surgery prior to 1991 was also associated with a lower peak VO2 (81 ± 3 vs. 87 ± 3 % predicted; p < 0.01). The mean % predicted peak heart rate was 92 ± 1 %, with no significant difference between any of the subgroups. Non-diagnostic exercise-induced STT changes developed in 10 patients (12 studies). In the subgroup with at least 2 exercise tests, the annual decline in % predicted peak VO2 was quite slow (-0.3 % points/year; p < 0.01 vs. expected normal age-related decline). The exercise capacity of ASO survivors is well preserved and is only mildly reduced compared to normal subjects. Moreover, there is only a slight deterioration in exercise capacity over time. VSD repair, residual right-sided obstructive lesions, and earlier surgical era are associated with worse exercise performance. Peak heart rate was preserved with no significant change in follow up testing.

Exercise Performance in Children and Young Adults After Complete and Incomplete Repair of Congenital Heart Disease

Few previous studies have addressed exercise capacity in patients with corrected congenital heart disease (CHD) and significant anatomical residua. The aim of this study was to determine the aerobic fitness and peak cardiac function of patients with corrected CHD with complete or incomplete repairs, as determined by resting echocardiography. Children, adolescents and young adults (<40 years) with CHD from both sexes, who had previously undergone biventricular corrective therapeutic interventions (n = 73), and non-CHD control participants (n = 76) underwent cardiopulmonary exercise testing. The CHD group was further divided according to the absence/presence of significant anatomical residua on a resting echocardiogram ("complete"/"incomplete" repair groups). Aerobic fitness and cardiac function were compared between groups using linear regression and analysis of covariance. Peak oxygen consumption, O2 pulse and ventilatory threshold were significantly lower in CHD patients compared with controls (all p < 0.01). Compared with the complete repair group, the incomplete repair group had a significantly lower mean peak work rate, age-adjusted O2 pulse (expressed as % predicted) and a higher VE/VCO2 ratio (all p ≤ 0.05). Peak oxygen consumption was comparable between the subgroups. Patients after corrected CHD have lower peak and submaximal exercise parameters. Patients with incomplete repair of their heart defect had decreased aerobic fitness, with evidence of impaired peak cardiac function and lower pulmonary perfusion. Patients that had undergone a complete repair had decreased aerobic fitness attributed only to deconditioning. These newly identified differences explain why in previous studies, the lowest fitness was seen in patients with the most hemodynamically significant heart malformations.

Resting heart rate influences right ventricular volume in repaired tetralogy of Fallot

The aim of this study is to examine the impact of heart rate (HR) on right ventricular end-diastolic volume indexed to body surface area (RVEDVi) in patients with repaired tetralogy of Fallot (TOF). In this cross-sectional study, an institutional database search identified all patients with repaired TOF who underwent cardiac magnetic resonance (CMR) and had a Holter study within 3 months. The association of HR on Holter, HR at the time of CMR, and other clinical and CMR parameters on RVEDVi was explored with univariate and then multivariable models. In the study group (n = 161, median age 23 years), a lower mean Holter HR was associated with a larger RVEDVi (p = 0.004). In a model that also included pulmonary regurgitation fraction, tricuspid regurgitation grade, RV ejection fraction, age at CMR, and gender, mean Holter HR remained associated with RVEDVi (p < 0.0001); for a decrease of 1 bpm, mean RVEDVi increased by 1.09 ml/m(2). When limiting to those with a Holter within 5 days of CMR (n = 70), the impact of mean Holter HR on RVEDVi was stronger (-1.9 ml/m(2)/bpm). HR at time of CMR had a significant but less pronounced relationship to RVEDVi (-0.58 ml/m(2)/bpm, p = 0.002). In conclusion, in repaired TOF patients, a lower HR was significantly associated with a larger RVEDVi. This relationship was stronger with a shorter time interval between the Holter and CMR, and stronger for the mean HR on Holter than for the HR at CMR. Accounting for HR in the interpretation of RVEDVi may impact decisions regarding pulmonary valve replacement and the interpretation of serial CMR data.

22q11.2 deletion status and disease burden in children and adolescents with tetralogy of Fallot

BACKGROUND

Patients with repaired tetralogy of Fallot experience variable outcomes for reasons that are incompletely understood. We hypothesize that genetic variants contribute to this variability. We sought to investigate the association of 22q11.2 deletion status with clinical outcome in patients with repaired tetralogy of Fallot.

METHODS AND RESULTS

We performed a cross-sectional study of tetralogy of Fallot subjects who were tested for 22q11.2 deletion, and underwent cardiac magnetic resonance, exercise stress test, and review of medical history. We studied 165 subjects (12.3±3.1 years), of which 30 (18%) had 22q11.2 deletion syndrome (22q11.2DS). Overall, by cardiac magnetic resonance the right ventricular ejection fraction was 60±8%, pulmonary regurgitant fraction was 34±17%, and right ventricular end-diastolic volume was 114±39 cc/m(2). On exercise stress test, maximum oxygen consumption was 76±16% predicted. Despite comparable right ventricular function and pulmonary regurgitant fraction, on exercise stress test the 22q11.2DS had significantly lower percent predicted: forced vital capacity (61.5±16 versus 80.5±14; P<0.0001), maximum oxygen consumption (61±17 versus 80±12; P<0.0001), and work (64±18 versus 86±22, P=0.0002). Similarly, the 22q11.2DS experienced more hospitalizations (6.5 [5-10] versus 3 [2-5]; P<0.0001), saw more specialists (3.5 [2-9] versus 0 [0-12]; P<0.0001), and used ≥1 medications (67% versus 34%; P<0.001).

CONCLUSIONS

22q11.2DS is associated with restrictive lung disease, worse aerobic capacity, and increased morbidity, and may explain some of the clinical variability seen in tetralogy of Fallot. These findings may provide avenues for intervention to improve outcomes, and should be re-evaluated longitudinally because these associations may become more pronounced with time.

Tricuspid annular plane systolic excursion in the assessment of right ventricular function in children and adolescents after repair of tetralogy of Fallot

BACKGROUND

Assessing right ventricular (RV) performance is essential for patients with tetralogy of Fallot (TOF). The aim of this study was to investigate the reliability and validity of tricuspid annular plane systolic excursion (TAPSE) against cardiac magnetic resonance imaging measures and cardiopulmonary exercise testing.

METHODS

A retrospective study was performed in 125 outpatients with repaired TOF with available protocol-driven echocardiography, cardiac magnetic resonance imaging, and exercise stress testing obtained as part of a cross-sectional study. TAPSE was measured on the two-dimensional apical four-chamber view on echocardiography by two readers. Multivariate linear regression was used to examine the association between TAPSE and measures of RV function and exercise capacity.

RESULTS

The mean age was 12.6 ± 3.3 years, 41 patients (33%) were female, and 104 (83%) were white. TAPSE averaged 1.6 ± 0.37 cm, with an interreader intraclass correlation coefficient of 0.78 (n = 18). TAPSE was significantly associated with cardiac magnetic resonance-based RV stroke volume after adjustment for gender and body surface area (β = 13.8; 95% confidence interval, 2.25-25.30; P = .02). TAPSE was not associated with cardiac magnetic resonance-based RV ejection fraction (P = .77). On exercise testing, TAPSE was not associated with peak oxygen consumption, percentage of predicted oxygen consumption, oxygen pulse, or the ventilatory equivalent for carbon dioxide in patients with maximal exercise stress testing (n = 73 [58%]).

CONCLUSIONS

TAPSE is reproducibly measured by echocardiography in patients with TOF. It is not associated with RV ejection fraction or exercise performance, and its association with RV stroke volume may be confounded by body size. On the basis of these results, TAPSE is not representative of global RV performance in patients with TOF.

Functional analysis of the anatomical right ventricular components: should assessment of right ventricular function after repair of tetralogy of Fallot be refined?

OBJECTIVE

Follow-up after tetralogy of Fallot (ToF) repair is directed to detect timely right ventricular (RV) dysfunction by following pulmonary regurgitation and global RV size, with little attention for the effective contribution of regional RV dysfunction. This study investigates the contribution of regional RV dysfunction on exercise capacity after ToF repair.

METHODS

Forty-two patients were investigated with cardiac magnetic resonance imaging for regional RV dysfunction in relation to global RV function by functional quantification of the sinus and outflow part of the RV. The impact of regional and global RV dysfunction on clinical status was studied by exercise testing.

RESULTS

Global RV function was lower than sinus function (ejection fraction (EF) 52±12% vs 58±10%, P<0.001), attributable to the adverse influence of right ventricular outflow tract (RVOT) dysfunction (EF 34±17%). Percent predicted peak VO2 correlated better with the RV sinus ejection fraction compared with the global RV ejection fraction (r=0.51, P=0.001 vs r=0.44, P=0.004). Multivariate analysis revealed the EF of RV sinus (β=0.34, 95% CI 0.07-0.61, P=0.013) and the extent of RVOT akinesia (β=-0.28, 95% CI -0.50; -0.06, P=0.015) as significant determinants of exercise capacity. Impaired exercise performance occurred in 43% of the patients, and was independently determined by the type of repair (transventricular vs transatrial: OR 6.0, 95% CI 1.31-17.3, P=0.02) by associating greater sinus and RVOT dysfunction.

CONCLUSION

Functional analysis of the RV components shows that exercise capacity after repair of ToF is better predicted by systolic function of the RV sinus as the extent of RVOT dysfunction commonly leads to underestimation of global RV function. This method of differential quantification of regional RV function might be more appropriate than assessment of global RV function during the long-term follow-up of repaired ToF patients.

Poorer right ventricular systolic function and exercise capacity in women after repair of tetralogy of fallot: a sex comparison of standard deviation scores based on sex-specific reference values in healthy control subjects

BACKGROUND

In repaired congenital heart disease, there is increasing evidence of sex differences in cardiac remodeling, but there is a lack of comparable data for specific congenital heart defects such as in repaired tetralogy of Fallot.

METHODS AND RESULTS

In a prospective multicenter study, a cohort of 272 contemporary patients (158 men; mean age, 14.3±3.3 years [range, 8-20 years]) with repaired tetralogy of Fallot underwent cardiac magnetic resonance for ventricular function and metabolic exercise testing. All data were transformed to standard deviation scores according to the Lambda-Mu-Sigma method by relating individual values to their respective 50th percentile (standard deviation score, 0) in sex-specific healthy control subjects. No sex differences were observed in age at repair, type of repair conducted, or overall hemodynamic results. Relative to sex-specific controls, repaired tetralogy of Fallot in women had larger right ventricular end-systolic volumes (standard deviation scores: women, 4.35; men, 3.25; P=0.001), lower right ventricular ejection fraction (women, -2.83; men, -2.12; P=0.011), lower right ventricular muscle mass (women, 1.58; men 2.45; P=0.001), poorer peak oxygen uptake (women, -1.65; men, -1.14; P<0.001), higher VE/VCO2 (ventilation per unit of carbon dioxide production) slopes (women, 0.88; men 0.58; P=0.012), and reduced peak heart rate (women, -2.16; men -1.74; P=0.017). Left ventricular parameters did not differ between sexes.

CONCLUSIONS

Relative to their respective sex-specific healthy control subjects, derived standard deviation scores in repaired tetralogy of Fallot suggest that women perform poorer than men in terms of right ventricular systolic function as tested by cardiac magnetic resonance and exercise capacity. This effect cannot be explained by selection bias. Further outcome data are required from longitudinal cohort studies.

The results of cardiopulmonary exercise test in healthy Korean children and adolescents: single center study

PURPOSE

The cardiopulmonary exercise test (CPET) is an important clinical tool for evaluating exercise capacity and is frequently used to evaluate chronic conditions including congenital heart disease. However, data on the normal CPET values for Korean children and adolescents are lacking. The aim of this study was to provide reference data for CPET variables in children and adolescents.

METHODS

From August 2006 to April 2009, 76 healthy children and adolescents underwent the CPET performed using the modified Bruce protocol. Here, we performed a medical record review to obtain data regarding patient' demographics, medical history, and clinical status.

RESULTS

The peak oxygen uptake (VO2Peak) and metabolic equivalent (METMax) were higher in boys than girls. The respiratory minute volume (VE)/CO2 production (VCO2) slope did not significantly differ between boys and girls. The cardiopulmonary exercise test data did not significantly differ between the boys and girls in younger age group (age, 10 to 14 years). However, in older age group (age, 15 to 19 years), the boys had higher VO2Peak and METMax values and lower VE/VCO2 values than the girls.

CONCLUSION

This study provides reference data for CPET variables in case of children and adolescents and will make it easier to use the CPET for clinical decision-making.

Noninvasive measurement of cardiac output during exercise in children with tetralogy of Fallot

In patients with surgically repaired tetralogy of Fallot (TOF), reported peak oxygen consumption (VO(2)) is decreased compared with control subjects. The measurement of exercise cardiac output (CO) could be a useful adjunct for assessing cardiovascular fitness. There are few data assessing noninvasive CO, cardiac index (CI), and stroke volume (SV) during exercise for these patients. This study sought to measure noninvasive CI and SV during rest and exercise in children with repaired TOF. The authors compared 21 asymptomatic children with repaired TOF ages 11-17 years during rest and exercise and 42 gender- and age-matched healthy control children without structural heart disease. Using a Bruce exercise protocol, exercise data were measured noninvasively by a novel inert gas rebreathing technique including peak duration and heart rate, as well as VO(2), CO, CI, and SV measured at 90 % of peak predicted theoretical heart rate (90 % ppHR). Statistical correlation between peak VO(2) and CI was performed. At baseline, there was no statistically significant difference in any of the measures between the groups. At 90 % ppHR, there was an increase in CI during exercise of 140 % in the TOF children and 180 % in the control children. During exercise, SV changed minimally in the patient group, whereas it increased more than 30 % in the control children. At 90 % ppHR, the patient group showed an increase in VO(2) during exercise similar to that of their healthy peers. The patients had a significantly shorter peak exercise duration than normal control subjects. The patients had a lower CI during exercise because they were less able to increase SV. Therefore, at similar heart rates, patients who have had TOF repair must rely on increased peripheral muscle extraction, with a higher arteriovenous oxygen difference (SaO(2)-MvO(2)) during exercise, which may limit peak exercise capacity. In this cohort of TOF patients, noninvasive CI measurement was feasible, and correlation with VO(2) was good.

Natural history of exercise function in patients with Ebstein anomaly: A serial study

BACKGROUND

The clinical manifestations of Ebstein anomaly (EA) vary greatly; criteria for surgical intervention remain undefined. Decisions regarding surgical intervention in asymptomatic/mildly symptomatic patients would be helpfully informed by a detailed, quantitative understanding of the natural history of exercise intolerance in these patients. However, past studies of exercise function in EA have been of a cross-sectional, rather than a serial, nature. We, therefore, analyzed serial cardiopulmonary exercise (CPX) tests from patients with unrepaired EA to better appreciate the natural history of their exercise function.

METHODS

All patients with EA who had had at least 2 CPX tests, separated by at least 6 months, between November 2002 and October 2010 were identified. Patients with prior tricuspid valve surgery were excluded from the study.

RESULTS

Cardiopulmonary exercise data from 23 patients (64 CPX tests; 2.8 ± 1.0 tests/patient) were analyzed. The median time interval between the first and last CPX tests was 3.3 (range, 0.6-7.3) years. The percentage of predicted peak oxygen consumption declined slowly (1.87 ± 8.04 percentage points/y) during the follow-up period. The decline was more pronounced (3.04 ± 6.78 percentage points/y) in patients <18 years old. On multivariate modeling, only the change in oxygen pulse at peak exercise (a surrogate for forward stroke volume) and the change in peak heart rate over time emerged as statistically significant correlates of the change in percentage of predicted peak oxygen consumption.

CONCLUSION

The exercise function of patients with EA tends to deteriorate over time. This deterioration appears to be related to a progressive decline in their ability to augment their forward stroke volume and heart rate during exercise.

Cardiopulmonary exercise function among patients undergoing transcatheter pulmonary valve implantation in the US Melody valve investigational trial

OBJECTIVES

We assessed the hypothesis that there is an improvement in clinical and physiologic parameters of cardiopulmonary exercise testing (CPET) after implantation of a transcatheter pulmonary valve (TPV).

BACKGROUND

Transcatheter pulmonary valve provides a new tool for treating conduit stenosis and regurgitation in patients with right ventricle (RV) to pulmonary artery conduit dysfunction.

METHODS

Patients who underwent a TPV placement between January 2007 and January 2010 (N = 150) were investigated with a standardized CPET protocol before and at 6 months after TPV placement. Cardiopulmonary exercise testing was performed on a mechanically braked cycle ergometer with respiratory gas exchange analysis.

RESULTS

Six months post TPV, small but statistically significant improvements were observed in the maximum workload (65.0% ± 18.8% to 68.3% ± 20.3% predicted, P < .001) and the ratio of minute ventilation to CO(2) production at the anaerobic threshold (30.8 ± 4.7 to 29.1 ± 4.1, P < .001). There was no significant change in peak oxygen consumption (VO(2)). Patients with pre-TPV hemodynamics consistent with RV dysfunction and patients with a lower pre-TPV peak VO(2) tended to have the greatest improvement in peak VO(2). The correlation between TPV-related improvements in peak VO(2) and baseline clinical variables were weak, however, and these variables could not be used to reliably identify patients likely to have improved peak VO(2) after TPV.

CONCLUSION

In patients with RV to pulmonary artery conduit dysfunction, TPV is associated with modest improvement in exercise capacity and gas exchange efficiency during exercise.