Right Ventricular Mass is Associated with Exercise Capacity in Adults with Repaired Tetralogy of Fallot.

The relationship between exercise capacity and right ventricular (RV) structure and function in adult repaired tetralogy of Fallot (TOF) is poorly understood. We therefore aimed to examine the relationships between cardiac MRI and cardiopulmonary exercise test variables in adult repaired TOF patients. In particular, we sought to determine the role of RV mass in determining exercise capacity. Eighty-two adult repaired TOF patients (age at evaluation 26 ± 10 years; mean age at repair 2.5 ± 2.8 years; 23.3 ± 7.9 years since repair; 53 males) (including nine patients with tetralogy-type pulmonary atresia with ventricular septal defect) were prospectively recruited to undergo cardiac MRI and cardiopulmonary exercise testing. As expected, these repaired TOF patients had RV dilatation (indexed RV end-diastolic volume: 153 ± 43.9 mL/m(2)), moderate-severe pulmonary regurgitation (pulmonary regurgitant fraction: 33 ± 14 %) and preserved left (LV ejection fraction: 59 ± 8 %) and RV systolic function (RV ejection fraction: 51 ± 7 %). Exercise capacity was near-normal (peak work: 88 ± 17 % predicted; peak oxygen consumption: 84 ± 17 % predicted). Peak work exhibited a significant positive correlation with RV mass in univariate analysis (r = 0.45, p < 0.001) and (independent of other cardiac MRI variables) in multivariate analyses. For each 10 g higher RV mass, peak work was 8 W higher. Peak work exhibits a significant positive correlation with RV mass, independent of other cardiac MRI variables. RV mass measured on cardiac MRI may provide a novel marker of clinical progress in adult patients with repaired TOF.

Detection of serious complications by MR imaging in asymptomatic young adults with repaired coarctation of the aorta.

BACKGROUND: Despite early repair, patients with aortic coarctation (CoA) continue to have a reduced life expectancy due to the development of late complications. We sought to define the rate of aortic abnormalities in patients with previous CoA repair, referred for surveillance magnetic resonance (MR) imaging. METHODS: We evaluated 59 asymptomatic adults consecutively for repaired CoA with MR imaging between 2008 and 2012. RESULTS: Patients were aged 29 ± 8 (16-49) years; 34 males (58%) and 34 with bicuspid aortic valve (58%). Median age at the time of initial repair was two years. Surveillance MR imaging was performed 23 ± 8 years post-procedure. The three most common interventions performed were subclavian-flap repair (25%), end-to-end repair (33%) and patch aortoplasty (33%). Re-intervention with balloon angioplasty or repeat surgery had been performed in 22% of subjects. There were 28 cases of recoarctation (48%), of which seven were at least moderate in severity. Repair site and ascending aortic aneurysm occurred in eight (14%) and four (7%) subjects, respectively. Freedom from any degree of recoarctation and other aortic complications was observed in eight subjects (14%). CONCLUSION: MR imaging detected a high rate of aortic abnormalities in asymptomatic adults after CoA repair, including 27% with clinically significant recoarctation and/or local aneurysm formation.

Right ventricular outflow tract enlargement prior to pulmonary valve replacement is associated with poorer structural and functional outcomes, in adults with repaired Tetralogy of Fallot.

BACKGROUND: Pulmonary valve replacement (PVR) is commonly performed late after Tetralogy of Fallot (TOF) repair. We examined the effects of PVR on cardiac structure, function and exercise capacity in adults with repaired TOF. METHODS: Eighteen adult patients with repaired TOF and severe pulmonary regurgitation (PR) with right ventricular (RV) dilatation requiring PVR for clinical reasons (age; 25±8 years) were recruited to undergo cardiac MRI (1.5T) and cardiopulmonary exercise testing before and 14±3 months after PVR. RESULTS: Reduced indexed RV end-diastolic volume (RVEDVi; 186±32mL/m(2) pre-op vs 114±20mL/m(2) post-op, p<0.001) was observed after PVR. "Normalisation" of RVEDVi (≤108mL/m(2)) was achieved in only seven of 18 patients. Pre-PVR RVEDVi correlated with post-operative change in RVEDVi (change=-72.1±20.4mL/m(2), r=-0.815, p<0.001). Exercise capacity remained high-normal post-PVR (% predicted maximal workload: 93±16% vs 91±12%, p=0.5). Regional RV volumes were assessed; RV outflow tract (RVOT) volumes were compared to the RV muscular corpus. Large pre-PVR RVOT volumes correlated negatively with post-surgical RV ejection fraction, peak VO2 and delta VO2 at anaerobic threshold (p<0.05 for all). CONCLUSIONS: Normalisation of RV volume is unlikely to be achieved above a pre-PVR RVEDVi of 165mL/m(2) or more. In particular, an enlarged RVOT prior to PVR predicts suboptimal structural and functional outcomes.

Progress of right ventricular dilatation in adults with repaired tetralogy of Fallot and free pulmonary regurgitation.

BACKGROUND: The time course of progressive dilatation of the right ventricle (RV) in adults with pulmonary regurgitation (PR) late after repair of tetralogy of Fallot (TOF) is poorly characterized. METHODS: We analysed cardiac MRI data (1.5 T) from 14 adult repaired TOF patients (26 ± 11 years of age) with dilated RVs and known significant PR, on 2 separate visits with a between MRI period of 2.1 ± 1.0 years. RESULTS: Indexed RV end diastolic volume (RVEDVi) increased over 2 years (142 ± 19 to 151 ± 20 mL/m2, p = 0.005; change = 8.4 ± 9.3 mL/m2, range = - 6 to 26 mL/m2; annual mL/m2 increase = 4.3 ± 4.6; annual percentage increase = 3.1 ± 3.3%), whilst RV ejection fraction decreased (53 ± 8 to 49 ± 7 %, p = 0.039). RV muscular corpus (RVMC) EDVi significantly increased (130 ± 19 to 138 ± 20 mL/m2, p = 0.014), whereas RV outflow tract (RVOT) EDVi did not (12 ± 7 vs 13 ± 6 mL/m2, p = 0.390). No other RV or LV measures significantly changed during the inter-MRI period. The change in RVEDVi correlated significantly with LV end diastolic volume (r = - 0.582, p = 0.029), RVEDVi:LVEDVi (r = 0.6, p = 0.023) and RVMC EDVi (r = 0.9, p < 0.001) but not RVOT EDVi (r = 0.225, p = 0.459). CONCLUSIONS: Adult repaired TOF patients with free PR experienced a mean 3.1%, or 4.3 mL/m2, annual increase in RVEDVi, unrelated to the initial RVEDVi or PR fraction. The increase in RVEDVi was due to RVMC rather than RVOT dilatation. This provides a guide to the frequency of MR surveillance and insights into the natural history of progressive RV dilatation in this setting.

Mechanisms of maintained exercise capacity in adults with repaired tetralogy of Fallot.

BACKGROUND: The mechanisms whereby cardiac output is augmented with exercise in adult repaired tetralogy of Fallot (TOF) are poorly characterised. METHODS: 16 repaired TOF patients (25 ± 7 years of age) and 8 age and sex matched controls (25 ± 4 years of age) underwent cardiopulmonary exercise testing and then real-time cardiac MRI (1.5 T) at rest and whilst exercising within the scanner, aiming for 30% heart rate reserve (Level 1) and 60% heart rate reserve (Level 2), using a custom-built MRI compatible foot pedal device. RESULTS: At rest, TOF patients had severely dilated RVs (indexed RV end-diastolic volume: 149 ± 37 mL/m(2)), moderate-severe PR (regurgitant fraction 35 ± 12%), normal RV fractional area change (FAC) (52 ± 7%) and very mildly impaired exercise capacity (83 ± 15% of predicted maximal work rate). Heart rate and RV FAC increased significantly in TOF patients (75 ± 10 vs 123 ± 17 beats per minute, p<0.001; 44 ± 7 vs 51 ± 10%, p=0.025), and similarly in control subjects (70 ± 11 vs 127 ± 12 beats per minute, p<0.001; 49 ± 7 vs 61 ± 9%, p=0.003), when rest was compared to Level 2. PR fraction decreased significantly but only modestly, from rest to Level 2 in TOF patients (37 ± 15 to 31 ± 15%, p=0.002). Pulmonary artery net forward flow was maintained and did not significantly increase from rest to Level 2 in TOF patients (70 ± 19 vs 69 ± 12 mL/beat, p=0.854) or controls (93 ± 9 vs 95 ± 21 mL/beat, p=0.648). CONCLUSIONS: During exercise in repaired TOF subjects with dilated RV and free PR, increased total RV output per minute was facilitated by an increase in heart rate, an increase in RV FAC and a decrease in PR fraction.

Exercise capacity and stroke volume are preserved late after tetralogy repair, despite severe right ventricular dilatation.

OBJECTIVES: To assess if exercise capacity and resting stroke volume are different in tetralogy of Fallot (TOF) repair survivors with indexed RV (right ventricle) end-diastolic volume (RVEDVi) more versus less than 150 ml/m(2), a currently suggested threshold for pulmonary valve replacement (PVR). DESIGN: Cross-sectional study. SETTING: Single-centre adult congenital heart disease unit. PATIENTS: 55 consecutively eligible patients with repaired TOF (age at repair 2.3±1.9 years; age at evaluation 26.2±8.8 years; NYHA Class I or II). INTERVENTIONS: Cardiovascular MRI (1.5T) and cardiopulmonary exercise test. MAIN OUTCOME MEASURES: Biventricular volumes and function; exercise capacity. RESULTS: 20 patients had RVEDVi below, and 35 had RVEDVi above 150 ml/m(2), at time of referral. In the >150 ml/m(2) group, fractional pulmonary regurgitation was higher (41±8 vs 31±8%, p<0.001). Although RV ejection fraction (EF) was lower (47±7 vs 54±6%, p=0.007), indexed RV stroke volume was higher (87±14 vs 64±10 ml/m(2), p<0.001) in the >150 ml/m(2) group. There were no significant differences in LVEF, indexed LV stroke volume or exercise capacity (% predicted peak work: 90±17 vs 89±11% and; % predicted VO(2) peak: 84±17 vs 87±12%). CONCLUSIONS: Exercise capacity and stroke volume are maintained with RVEDVi above compared with below a commonly used cut-off for PVR surgery. Optimal timing for PVR, thus, remains unclear.