Edward J. Hickey

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.

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.

Jugular venous valved conduit (Contegra®) matches allograft performance in infant truncus arteriosus repair

OBJECTIVE Limited availability and durability of allograft conduits require that alternatives be considered. We compared bovine jugular venous valved (JVV) and allograft conduit performance in 107 infants who survived truncus arteriosus repair. METHODS Children were prospectively recruited between 2003 and 2007 from 17 institutions. The median z-score for JVV (n=27, all 12 mm) was +2.1 (range +1.2 to +3.2) and allograft (n=80, 9-15mm) was +1.7 (range -0.4 to +3.6). Propensity-adjusted comparison of conduit survival was undertaken using parametric risk-hazard analysis and competing risks techniques. All available echocardiograms (n=745) were used to model deterioration of conduit function in regression equations adjusted for repeated measures. RESULTS Overall conduit survival was 64+/-9% at 3 years. Conduit replacement was for conduit stenosis (n=16) and/or pulmonary artery stenosis (n=18) or regurgitation (n=1). The propensity-adjusted 3-year freedom from replacement for in-conduit stenosis was 96+/-4% for JVV and 69+/-8% for allograft (p=0.05). The risk of intervention or replacement for branch pulmonary artery stenosis was similar for JVV and allograft. Smaller conduit z-score predicted poor conduit performance (p<0.01) with best outcome between +1 and +3. Although JVV conduits were a uniform diameter, their z-score more consistently matched this ideal. JVV exhibited a non-significant trend towards slower progression of conduit regurgitation and peak right ventricular outflow tract (RVOT) gradient. In addition, catheter intervention was more successful at slowing subsequent gradient progression in children with JVV versus those with allograft (p<0.01). CONCLUSIONS JVV does match allograft performance and may be advantageous. It is an appropriate first choice for repair of truncus arteriosus, and perhaps other small infants requiring RVOT reconstruction.

Percutaneous pulmonary valve implantation within bioprosthetic valves

AIMS Replacement of bioprosthetic valves in the right ventricular (RV) outflow tract (RVOT) is inevitable due to acquired valvar dysfunction. Percutaneous pulmonary valve implantation (PPVI) may result in acceptable clinical improvement avoiding surgical reintervention. To report outcomes of PPVI in dysfunctional surgically implanted bioprosthetic valves. METHODS AND RESULTS All children undergoing PPVI into a bioprosthetic pulmonary valve between October 2005 and February 2008 were reviewed. Acute haemodynamic changes were compared and an analysis of variance applied to assess changes in ventricular geometry and pressure over time. Fourteen children (seven males), median weight 57.8 kg and 14.7 years of age were identified, with an echocardiographic RVOT gradient of 59.6 +/- 26.8 mmHg and a pulmonary regurgitation (PR) grade of 3.6 +/- 0.8 (out of 4). Implantation was successful in all. Twenty-four hours after implantation, there was a significant improvement in RV pressure (RVP) (from 82.2 +/- 15.6 to 59.4 +/- 9.9 mmHg, P < 0.001) and degree of PR to 0.6 +/- 0.9 (P < 0.001). Mean hospital stay was 2.0 +/- 0.4 days. Freedom from reintervention was 92 and 89% at 1 and 2 years, respectively. Follow-up echocardiography (mean 12.9 +/- 9.8 months) revealed a further reduction in RVP (P < 0.001) and RVOT gradients (P < 0.001) and an increase in left ventricular end-diastolic volume (P= 0.01) and aortic valve annulus diameters (P < 0.001). CONCLUSIONS Percutaneous pulmonary valve implantation for RVOT dysfunction in a previously implanted prosthetic valve is feasible and safe. Short-term follow-up data are encouraging, yet longer-term information is required to determine if this form of palliation has a significant impact on management strategies.

Very low-birth-weight infants with congenital cardiac lesions: Is there merit in delaying intervention to permit growth and maturation?

BACKGROUND Low birth weight and prematurity and are known risks for mortality in congenital heart lesions. It is not known whether risks of delayed intervention are offset by benefits of growth and maturation. We explored this question. METHODS All 1618 infants admitted to our institution within 30 days after birth for a congenital heart defect since 2000 were analyzed. Birth details and admission progress notes were detailed on all. For infants requiring cardiac interventions, clinical conference records and progress notes enabled their management to be classified as either USUAL (normal timing and mode of intervention) or DELAYED (intentional delay for growth/maturation). The survival implications of birth weight and prematurity were examined via parametric multiphase methodology with bootstrap resampling. Subsequently, the impact of DELAYED management was sought in propensity-adjusted and multivariable time-related models. RESULTS Low birth weight is a strong, robust and independent predictor of death within the first year of life (P < .0001; 99.6% bootstrap resamples). The relationship is nonlinear with an inflection point at approximately 2.0 kg, below which decrements in survival are increasingly pronounced. Prematurity is also associated with poor outcome but less reliably so (P < .0001; 53% resamples); its variance appears partially mitigated by colinearity with multiple factors including diagnosis and chromosomal aneuploidy. Of the 149 infants with birth weight less than 2.0 kg (highest risk and most likely to receive delayed care in this cohort), care was USUAL in 34 and DELAYED in 46. The remaining children received comfort care only (27), were not considered for intervention owing to severe noncardiac problems (12) or were routinely observed for nonurgent lesions (30). Survival between the children weighing less than 2.0 kg and receiving USUAL or DELAYED care was identical (78% ± 2% at 1 year; P = .88), even when adjusted via propensity score (P = 0.65) or multivariable analysis (P = 0.55). Major determinants of death in this very low-birth-weight population were antenatal diagnosis (P = .01), presence of congenital gastrointestinal defects (P = .07), or lesion type (all higher risk: anomalous pulmonary venous drainage, P = .03; pulmonary atresia and intact septum, P = .05; and truncus, P = .01). CONCLUSIONS For very low-birth-weight neonates (<2.0 kg) with congenital heart defects, imposed delays in intervention neither compromise nor improve survival. Other factors instead appear to account for survival differences, including lesion type, associated noncardiac congenital defects, and antenatal diagnosis.

Congenital Supravalvular Aortic Stenosis: Defining Surgical and Nonsurgical Outcomes

BACKGROUND Supravalvular aortic stenosis is a rare stenotic lesion of the left ventricular outflow tract (LVOT). We characterized the natural history of the disease and the effect of surgical intervention. METHODS Ninety-five children diagnosed with supravalvular aortic stenosis between 1976 and 2006 were studied. Procedural and repeated echocardiography reports were analyzed. RESULTS Stenosis morphology (localized, 82%; diffuse, 18%) was independent of Williams syndrome (n = 59, 62%). The risk of open operation (n = 47) was 46% +/- 6% at 10 years. Increased risk of operation was associated with higher baseline LVOT peak gradients (p < 0.001), smaller minimum LVOT z scores (p < 0.01; thresholds > 50 mm Hg and < -3, respectively), and the absence of Williams syndrome (p = 0.01). Patients who did not undergo operations had gradually reducing LVOT gradients and enlarging ascending aorta z scores over time. Persistently small minimum LVOT z scores and higher gradients were associated with children who required an operation. Operation resulted in persistent relief of LVOT obstruction and accelerated increases in ascending aorta dimensions. Overall survival was 94% +/- 3% and 85% +/- 7% at 10 and 15 years and was similar for surgical and nonsurgical groups. No independent risk factors for death were identified on univariate or multivariable analysis. CONCLUSIONS Many children-particularly those with Williams syndrome-show regression of stenosis without intervention. Children who undergo operation have high LVOT gradients and smaller LVOT z scores that do not improve over time. Surgical intervention alters the natural history: LVOT obstruction is relieved and does not recur, and ascending aortic dimensions progressively enlarge towards normal values.

Lipopolysaccharide-Induced Preconditioning Against Ischemic Injury Is Associated With Changes in Toll-Like Receptor 4 Expression in the Rat Developing Brain

Lipopolysaccharide (LPS) preconditioning reduces ischemic injury in adult brain by activating Toll-like receptor 4 (TLR-4). We sought to investigate the effect of brain maturity on the efficacy of LPS preconditioning against hypoxic-ischemic (HI) injury in the developing rat brain. Rat pups at the specified age were randomly assigned to LPS-treated (0.1 mg/kg) or saline-treated groups. HI injury was induced 48 h later by occluding the right common carotid artery followed by transient hypoxia. Brains were removed 1 wk after HI injury, and infarct volumes were compared between the two groups. TLR-4 expression was also compared among different ages. We found that LPS treated P7, P9, and P14 rat pups had significantly smaller infarct volume compared with saline-treated pups (p = 0.006, 0.03, and 0.01, respectively). This significant reduction in infarct volume was not observed in P3 and P5 rats. TLR-4 expression was significantly higher in older rats compared with P3 and P5 rats (p < 0.01). These findings indicate that LPS-induced preconditioning is a robust neuroprotective phenomenon in the ischemic developing brain that is age dependent. Pattern of TLR-4 expression is also affected by brain maturity and likely to be responsible for differences in the efficacy of LPS preconditioning.

Left ventricular morphology influences mortality after the Norwood operation

Background: Within the spectrum of congenital heart disease referred to as hypoplastic left heart syndrome (HLHS), there is variation in the morphology and function of the left ventricle which could influence outcomes after stage I Norwood palliation. Objective: To determine if left ventricular (LV) morphology is associated with outcome after stage I Norwood palliation for HLHS. Methods: Echocardiograms were reviewed from 108 patients who had undergone Norwood palliation at our institution over the past 11 years. Total cardiac diameter, thickness of the interventricular septum (IVS), LV area and LV myocardial area were calculated. Competing risk analysis was performed for survival to a stage II operation and to determine potential predictors. Results: From the Norwood operation up to stage II operation, mortality was predicted by IVS thickness, while the absence of right ventricular (RV) dysfunction was predictive of survival to stage II operation. For the complete pathway, from Norwood to the Fontan operation, mortality was predicted by IVS, a lower RV fractional area change and the presence of significant tricuspid regurgitation. Cardiac transplantation during this period was predicted by a lower RV fractional area change (p = 0.02) and a larger LV area in diastole. Conclusions: These results indicate that LV hypertrophy and decreased RV function adversely effect survival after the Norwood operation. They suggest that LV morphology, especially septal hypertrophy, can influence outcomes in HLHS and should be considered when evaluating treatment options.

Survival and right ventricular performance for matched children after stage-1 Norwood: Modified Blalock-Taussig shunt versus right-ventricle-to-pulmonary-artery conduit

OBJECTIVE Early survival advantages after Norwood with right-ventricle-(RV)-to-pulmonary-artery conduit (NW-RVPA) over Norwood-operation with a Blalock-Taussig shunt (NW-BT) are offset by concerns regarding delayed RV dysfunction. We compared trends in survival, RV dysfunction, and tricuspid valve regurgitation (TR) between NW-RVPA and NW-BT for propensity-matched neonates with critical left ventricular outflow tract obstruction (LVOTO). METHODS In an inception cohort (2005-2014; 21 institutions), 454 neonates with critical LVOTO underwent Norwood stage 1. Propensity-score matching paired 169 NW-RVPA patients with 169 NW-BT patients. End-states were compared between NW-RVPA and NW-BT using competing-risks, multiphase, parametric, hazard analysis. Post-Norwood echocardiogram reports (n = 2993) were used to grade RV dysfunction and TR. Time-related prevalence of ≥moderate RV dysfunction and TR were characterized using nonlinear mixed-model regression, and compared between groups via multiphase, parametric models. RESULTS Overall 6-year survival was better after NW-RVPA (70%) versus NW-BT (55%; P < .001). Additionally, transplant-free survival during this time was better after NW-RVPA (64%) versus NW-BT (53%; P = .004). Overall prevalence of ≥moderate RV dysfunction reached 11% within 3 months post-Norwood. During this time, RV dysfunction after NW-BT was 16% versus 6% after NW-RVPA (P = .02), and coincided temporally with an increased early hazard for death. For survivors, late RV dysfunction was <5% and was not different between groups (P = .36). Overall prevalence of ≥moderate TR reached 13% at 2 years post-Norwood and was increased after NW-BT (16%) versus NW-RVPA (11%; P = .003). Late TR was similar between groups. CONCLUSIONS Among propensity-score-matched neonates with critical LVOTO, NW-RVPA offers superior 6-year survival with no greater prevalence of RV dysfunction or TR than conventional NW-BT operations.

Functional Health Status in Adult Survivors of Operative Repair of Tetralogy of Fallot

We aimed to determine late functional health status of the growing adult population with repaired tetralogy of Fallot (TOF). We studied all 840 patients with TOF born from 1927 through 1984 who survived to adulthood (> 18 years of age). Clinical follow-up was by chart review, telephone interview (n = 706), and echocardiographic reports (n = 339). Functional health status was assessed using Short Form-36 (SF-36) surveys (n = 396) indexed to normative data. Risk of reoperation was low (≈ 1%/year) but increased beyond age 40 years. At latest follow-up moderate or severe pulmonary regurgitation was common (54%) and right ventricular outflow tract stenosis presented in 1/3. Consequently, evidence of right ventricular dilatation and dysfunction and tricuspid regurgitation was typical. Left-sided abnormalities were also common: hypertrophy (p < 0.0001) and outflow tract dilation (p < 0.0001) with at least mild aortic regurgitation in > 50%. Cardiorespiratory symptoms were reported in 45% (palpitations 27%, dyspnea 21%, chest pain 17%). SF-36 scores were significantly below normal for 4 physical domains (p < 0.001). Decrements in physical functioning were associated particularly with older age at follow-up (p < 0.0001), associated syndromes/lesions, reoperations, ventricular dysfunction, tricuspid regurgitation, residual septal defects, and cardiorespiratory symptomatology. Echocardiographic abnormalities were more common in older patients (p < 0.0001). All 3 SF-36 domains specific to psychosocial well-being were normal. In conclusion, despite excellent survival prospects, physical compromise is common in adults with repaired TOF. Greater decrements in older patients may reflect late deterioration with advancing age or cohort effects related to historical management. Efforts to limit ventricular and outflow tract dysfunction may translate into improved late functional status.