Cedric Manlhiot

Late risk of outcomes for adults with repaired tetralogy of Fallot from an inception cohort spanning four decades

BACKGROUND Adult survivors with tetralogy of Fallot constitute a growing population with congenital heart disease. We investigated an inception cohort who underwent surgical repair. We aimed to characterize late hazard or risk for death, and determine the time-related risk of late re-operation and pulmonary valve replacement (PVR). METHODS All children (n=1181) with tetralogy of Fallot born before 1984 who underwent surgical repair at our institution were included. Follow-up (median 20 years after repair) was obtained from 2003 to 2006 via chart review, clinic consultation and telephone interview. Outcomes were analyzed using parametric and competing risks techniques with bagging. RESULTS Corrective repair performed from 1960 to 1998 included transannular patch (n=370), right ventricular outflow tract patch (n=326), no patch (n=333) and right ventricular-pulmonary artery conduit (n=54). Overall, 85+/-1% survived to adulthood (age >18 years). Thirty years after repair, survival was 80+/-1%, instantaneous hazard or risk of death was 0.5+/-0.07% per year and half of survivors had undergone surgical re-operation. Surgical era of repair did not influence late risk of death. Therefore, with early surgical mortality <2% since 1985, 20-year survival has improved to 94+/-1%. If trends in late risks match those of the earliest repairs, 40-year survival will be approximately 90% for children repaired in the modern era. Pulmonary atresia variant (n=88) was associated with three-fold higher late risk of death than classic tetralogy of Fallot (n=1069). Presence of associated branch pulmonary artery stenosis or atrioventricular septal defects conferred a less optimal late prognosis. Risk of PVR was low, constant (0.8% per year) and independent of surgical era. Both pulmonary atresia and absent pulmonary valve (n=15) variants were associated with higher risk of late re-operation or PVR. Survival after re-operation or PVR (88+/-3% and 94+/-3% at 20 years, respectively) was excellent. CONCLUSIONS Surgical progress has not influenced late risks for death, re-operation or PVR in adults with repaired tetralogy of Fallot. Instead, reduction of early surgical mortality to <2% is responsible for excellent late survival >90% overall. The constant risk of PVR is low and independent of repair type. Baseline morphologic features are important determinants of late outcome.

Comparison between Different Speckle Tracking and Color Tissue Doppler Techniques to Measure Global and Regional Myocardial Deformation in Children

BACKGROUND Myocardial deformation parameters obtained by speckle-tracking echocardiography (STE) and color Doppler tissue imaging (CDTI) using two different ultrasound systems and three different software packages were compared. METHODS Apical four-chamber, short-axis grayscale, and color Doppler tissue images were prospectively acquired using Vivid 7 and iE33 ultrasound systems in 34 children and then analyzed using EchoPAC and QLAB (STE) and SPEQLE (CDTI). RESULTS Measurement of myocardial deformation was feasible for all three modalities. Longitudinal strain (epsilon) measurements showed the lowest intraobserver and interobserver variability (intraobserver and interobserver coefficients of variation, 9% and 8% for EchoPAC, 5% and 6% for QLAB, and 14% and 16% for SPEQLE). In addition, longitudinal epsilon had a small bias and narrow limits of agreement when comparing different techniques. The coefficients of variation of circumferential epsilon by EchoPAC and QLAB were 12% and 11% (intraobserver) and 9% and 13% (interobserver), respectively. Circumferential epsilon by STE had a small systematic bias but relatively narrow limits of agreement. The reproducibility of radial epsilon measurements using STE was low, while CDTI epsilon provided better performance (intraobserver and interobserver coefficients of variation for radial posterior epsilon, 12% and 24% for EchoPAC, 39% and 56% for QLAB, and 12% and 14% for SPEQLE). Radial epsilon was on average 50% lower using QLAB compared with EchoPAC and SPEQLE. Systolic strain rate values obtained by STE were lower compared with CDTI-derived values. The limits of agreement for strain rate values among the three modalities were wide, and intraobserver and interobserver variability was poor for all three modalities. CONCLUSIONS Some deformation measurements (e.g., longitudinal and circumferential epsilon) are comparable among different ultrasound machines and software packages, whereas others are significantly different (e.g., radial epsilon and strain rate). This study stresses the need for an industry standard for these techniques.

Reduced Fetal Cerebral Oxygen Consumption is Associated With Smaller Brain Size in Fetuses With Congenital Heart Disease

Background— Fetal hypoxia has been implicated in the abnormal brain development seen in newborns with congenital heart disease (CHD). New magnetic resonance imaging technology now offers the potential to investigate the relationship between fetal hemodynamics and brain dysmaturation. Methods and Results— We measured fetal brain size, oxygen saturation, and blood flow in the major vessels of the fetal circulation in 30 late-gestation fetuses with CHD and 30 normal controls using phase-contrast magnetic resonance imaging and T2 mapping. Fetal hemodynamic parameters were calculated from a combination of magnetic resonance imaging flow and oximetry data and fetal hemoglobin concentrations estimated from population averages. In fetuses with CHD, reductions in umbilical vein oxygen content (P<0.001) and failure of the normal streaming of oxygenated blood from the placenta to the ascending aorta were associated with a mean reduction in ascending aortic saturation of 10% (P<0.001), whereas cerebral blood flow and cerebral oxygen extraction were no different from those in controls. This accounted for the mean 15% reduction in cerebral oxygen delivery (P=0.08) and 32% reduction cerebral VO2 in CHD fetuses (P<0.001), which were associated with a 13% reduction in fetal brain volume (P<0.001). Fetal brain size correlated with ascending aortic oxygen saturation and cerebral VO2 (r=0.37, P=0.004). Conclusions— This study supports a direct link between reduced cerebral oxygenation and impaired brain growth in fetuses with CHD and raises the possibility that in utero brain development could be improved with maternal oxygen therapy.

A Multicenter, Randomized Trial Comparing Heparin/Warfarin and Acetylsalicylic Acid as Primary Thromboprophylaxis for 2 Years After the Fontan Procedure in Children

OBJECTIVES The purpose of this study was to compare the safety and efficacy of acetylsalicylic acid (ASA) and warfarin for thromboprophylaxis after the Fontan procedure. BACKGROUND Fontan surgery is the definitive palliation for children with single-ventricle physiology. Thrombosis is an important complication; the optimal thromboprophylaxis strategy has not been determined. METHODS We performed a multicenter international randomized trial of primary prophylactic anticoagulation after Fontan surgery. Patients were randomized to receive for 2 years either ASA (5 mg/kg/day, no heparin phase) or warfarin (started within 24 h of heparin lead-in; target international normalized ratio: 2.0 to 3.0). Primary endpoint (intention to treat) was thrombosis, intracardiac or embolic (all events adjudicated). At 3 months and 2 years after the Fontan procedure, transthoracic and transesophageal echocardiograms were obtained as routine surveillance. Major bleeding and death were primary adverse outcomes. RESULTS A total of 111 eligible patients were randomized (57 to ASA, 54 to heparin/warfarin). Baseline characteristics for each group were similar. There were 2 deaths unrelated to thrombosis or bleeding. There were 13 thromboses in the heparin/warfarin group (3 clinical, 10 routine echo) and 12 thromboses in the ASA group (4 clinical, 8 routine echo). Overall freedom from thrombosis 2 years after Fontan surgery was 19%, despite thrombosis prophylaxis. Cumulative risk of thrombosis was persistent but varying and similar for both groups (p = 0.45). Major bleeding occurred in 1 patient in each group. CONCLUSIONS There was no significant difference between ASA and heparin/warfarin as primary thromboprophylaxis in the first 2 years after Fontan surgery. The thrombosis rate was suboptimal for both regimens, suggesting alternative approaches should be considered. (International Multi Centre Randomized Clinical Trial Of Anticoagulation In Children Following Fontan Procedures; NCT00182104).

Role of the Waist/Height Ratio in the Cardiometabolic Risk Assessment of Children Classified by Body Mass Index

OBJECTIVES The aim of this study was to determine the utility of waist/height ratio (WHtR) in the specification of cardiometabolic risk in children already stratified by body mass index (BMI). BACKGROUND Reflective of its association with cardiometabolic risk, BMI is a commonly used indirect indicator of adiposity in children. The WHtR, a marker of central adiposity, has been advocated as a possibly superior indicator of cardiometabolic risk. METHODS Cross-sectional analysis of 5 National Health and Nutrition Examination Surveys from 1999 to 2008 (ages 5 to 18 years of age). The BMI percentile categories (normal, overweight, and obese) were further stratified on the basis of WHtR (<0.5, 0.5 to <0.6, ≥ 0.6). Outcome measures were lipid and glycemic profiles, C-reactive protein, liver transaminases, prevalence of hypertension, and metabolic syndrome. RESULTS Data were available for 14,493 subjects. Overweight and obese subjects with a WHtR <0.5 had a cardiometabolic risk approaching that of subjects with a normal BMI percentile category. Increasing WHtR was significantly associated with increased cardiometabolic risk in overweight and obese subjects, with the greatest associations observed in the obese population. Of obese subjects with WHtR ≥ 0.6, 26% had elevated non-high-density lipoprotein levels, 18% had elevated C-reactive protein levels, 69% had an elevated homeostatic model assessment-insulin resistance, and 32% had metabolic syndrome. CONCLUSIONS The WHtR further specifies cardiometabolic risk within classifications stratification on the basis of BMI percentile. A significant proportion of obese children with increased WHtRs have abnormal cardiometabolic risk factor levels. The WHtR should be included in the routine screening and assessment of overweight and obese children, and those with an elevated WHtR should undergo a further cardiometabolic risk assessment.

Remote preconditioning improves maximal performance in highly trained athletes.

BACKGROUND Remote ischemic preconditioning (RIPC) induced by transient limb ischemia releases a dialysable circulating protective factor that reduces ischemia-reperfusion injury. Exercise performance in highly trained athletes is limited by tissue hypoxemia and acidosis, which may therefore represent a type of ischemia-reperfusion stress modifiable by RIPC. METHODS AND RESULTS National-level swimmers, 13-27 yr, were randomized to RIPC (four cycles of 5-min arm ischemia/5-min reperfusion) or a low-pressure control procedure, with crossover. In study 1, subjects (n=16) performed two incremental submaximal swimming tests with measurement of swimming velocity, blood lactate, and HR. For study 2, subjects (n=18) performed two maximal competitive swims (time trials). To examine possible mechanisms, blood samples taken before and after RIPC were dialysed and used to perfuse mouse hearts (n=10) in a Langendorff preparation. Infarct sizes were compared with dialysate obtained from nonathletic controls. RIPC released a protective factor into the bloodstream, which reduced infarct size in mice (P<0.05 for controls and swimmers). There was no statistically significant difference between the effect of RIPC and the low-pressure control protocol on submaximal exercise performance. However, RIPC was associated with a mean improvement of maximal swim time for 100 m of 0.7 s (P=0.04), an improvement in swim time relative to personal best time (-1.1%, P=0.02), and a significant improvement in average International Swimming Federation points (+22 points, P=0.01). CONCLUSIONS RIPC improves maximal performance in highly trained swimmers. This simple technique may be applicable to other sports and, more importantly, to other clinical syndromes in which exercise tolerance is limited by tissue hypoxemia or ischemia.

Improved Classification of Coronary Artery Abnormalities Based Only on Coronary Artery z-Scores After Kawasaki Disease

Competing definitions and classifications of coronary artery abnormalities (CAAs) after Kawasaki disease (KD) have been arbitrarily defined based on clinical experience. We sought to propose a classification system for CAAs based only on coronary artery z-scores. All echocardiograms performed between 1990 and 2007 on patients with a previous history of KD were reviewed. Coronary artery luminal dimensions were converted to body-surface-area-adjusted z-scores and compared to current classification systems. A total of 1356 patients with a previous history of KD underwent 4379 echocardiograms. There was important overlap in the distributions of coronary artery z-scores between the different CAA classes as defined by the American Heart Association (AHA). The AHA classification underestimated the severity of CAAs in 19–32% of small CAAs and 35–78% of medium CAAs. We determined the optimal definition of CAA to be small if the z-score is ≥2.5 to <5.0, large if the z-score is ≥5.0 to <10.0, and giant if the z-score is ≥10.0. This classification seems to appropriately apply to the circumflex branch despite a lack of normal values for this branch. The current AHA classification might not accurately classify CAAs in KD patients. Accurate classification is important for defining management and prognosis consistently across patient age and size.

Risk, Clinical Features, and Outcomes of Thrombosis Associated With Pediatric Cardiac Surgery

Background— Thrombosis, usually considered a serious but rare complication of pediatric cardiac surgery, has not been a major clinical and/or research focus in the past. Methods and Results— We noted 444 thrombi (66% occlusive, 60% symptomatic) in 171 of 1542 surgeries (11%). Factors associated with increased odds of thrombosis were age <31 days (odds ratio [OR], 2.0; P=0.002), baseline oxygen saturation <85% (OR, 2.0; P=0.001), previous thrombosis (OR, 2.6; P=0.001), heart transplantation (OR, 4.1; P<0.001), use of deep hypothermic circulatory arrest (OR, 1.9 P=0.01), longer cumulative time with central lines (OR, 1.2 per 5-day equivalent; P<0.001), and postoperative use of extracorporeal support (OR, 5.2; P<0.001). Serious complications of thrombosis occurred with 64 of 444 thrombi (14%) in 47 of 171 patients (28%), and were associated with thrombus location (intrathoracic, 45%; extrathoracic arterial, 19%; extrathoracic venous, 8%; P<0.001), symptomatic thrombi (OR, 8.0; P=0.02), and partially/fully occluding thrombi (OR, 14.3; P=0.001); indwelling access line in vessel (versus no access line) was associated with lower risk of serious complications (OR, 0.4; P=0.05). Thrombosis was associated with longer intensive care unit (+10.0 days; P<0.001) and hospital stay (+15.2 days; P<0.001); higher odds of cardiac arrest (OR, 4.9; P<0.001), catheter reintervention (OR, 3.3; P=0.002), and reoperation (OR, 2.5; P=0.003); and increased mortality (OR, 5.1; P<0.001). Long-term outcome assessment was possible for 316 thrombi in 129 patients. Of those, 197 (62%) had resolved at the last follow-up. Factors associated with increased odds of thrombus resolution were location (intrathoracic, 75%; extrathoracic arterial, 89%; extrathoracic venous, 60%; P<0.001), nonocclusive thrombi (OR, 2.2; P=0.01), older age at surgery (OR, 1.2 per year; P=0.04), higher white blood cell count (OR, 1.1/109 cells per 1 mL; P=0.002), and lower fibrinogen (OR, 1.4/g/L; P=0.02) after surgery. Conclusions— Thrombosis affects a high proportion of children undergoing cardiac surgery and is associated with suboptimal outcomes. Increased awareness and effective prevention and detection strategies are needed.

Comparison of Transplacental Treatment of Fetal Supraventricular Tachyarrhythmias With Digoxin, Flecainide, and Sotalol Results of a Nonrandomized Multicenter Study

Background— Fetal tachyarrhythmia may result in low cardiac output and death. Consequently, antiarrhythmic treatment is offered in most affected pregnancies. We compared 3 drugs commonly used to control supraventricular tachycardia (SVT) and atrial flutter (AF). Methods and Results— We reviewed 159 consecutive referrals with fetal SVT (n=114) and AF (n=45). Of these, 75 fetuses with SVT and 36 with AF were treated nonrandomly with transplacental flecainide (n=35), sotalol (n=52), or digoxin (n=24) as a first-line agent. Prenatal treatment failure was associated with an incessant versus intermittent arrhythmia pattern (n=85; hazard ratio [HR]=3.1; P<0.001) and, for SVT, with fetal hydrops (n=28; HR=1.8; P=0.04). Atrial flutter had a lower rate of conversion to sinus rhythm before delivery than SVT (HR=2.0; P=0.005). Cardioversion at 5 and 10 days occurred in 50% and 63% of treated SVT cases, respectively, but in only 25% and 41% of treated AF cases. Sotalol was associated with higher rates of prenatal AF termination than digoxin (HR=5.4; P=0.05) or flecainide (HR=7.4; P=0.03). If incessant AF/SVT persisted to day 5 (n=45), median ventricular rates declined more with flecainide (−22%) and digoxin (−13%) than with sotalol (−5%; P<0.001). Flecainide (HR=2.1; P=0.02) and digoxin (HR=2.9; P=0.01) were also associated with a higher rate of conversion of fetal SVT to a normal rhythm over time. No serious drug-related adverse events were observed, but arrhythmia-related mortality was 5%. Conclusion— Flecainide and digoxin were superior to sotalol in converting SVT to a normal rhythm and in slowing both AF and SVT to better-tolerated ventricular rates and therefore might be considered first to treat significant fetal tachyarrhythmia.

Variability in tacrolimus blood levels increases the risk of late rejection and graft loss after solid organ transplantation in older children

Pollock‐BarZiv SM, Finkelstein Y, Manlhiot C, Dipchand AI, Hebert D, Ng VL, Solomon M, McCrindle BW, Grant D. Variability in tacrolimus blood levels increases the risk of late rejection and graft loss after solid organ transplantation in older children.
Pediatr Transplantation 2010: 14:968–975.