Preoperative risk-of-death prediction model in heart surgery with deep hypothermic circulatory arrest in the neonate

Periventricular leukomalacia is common after neonatal cardiac surgery

OBJECTIVES

Periventricular leukomalacia is necrosis of the cerebral white matter adjacent to the lateral ventricles and results from injury to immature oligodendroglia. In infants without congenital heart disease, periventricular leukomalacia is associated with an increased incidence of developmental delay and attention deficit/hyperactivity disorder. The incidence of periventricular leukomalacia and the risk factors for development of periventricular leukomalacia after infant cardiac surgery are not known.

METHODS

Magnetic resonance imaging of the brain was performed 6 to 14 days after cardiac surgery utilizing cardiopulmonary bypass with or without deep hypothermic circulatory arrest in 105 neonates and infants < or = 6 months of age.

RESULTS

Median age at surgery was 6 days (range 1-178), with 82 neonates (age < or = 30 days). Periventricular leukomalacia was found in 44 of the neonates (54%) compared with 1 of 23 infants (4%). Forward logistic regression using age at surgery as a continuous variable identified a model containing longer total support time (cardiopulmonary bypass plus deep hypothermic circulatory arrest), lower systolic blood pressure at cardiac intensive care unit admission postoperatively, lower minimum diastolic blood pressure, and Po(2) in the first 48 hours after surgery. When age at surgery was considered as a dichotomous variable (neonate versus infant), younger age at surgery replaced systolic blood pressure, Po(2), and total support time in the model. Lower minimum diastolic blood pressure was a significant risk factor in both models.

CONCLUSIONS

Periventricular leukomalacia was found in >50% of neonates after cardiac surgery but rarely in older infants. Hypoxemia and hypotension in the early postoperative period, particularly diastolic hypotension, may be important risk factors for periventricular leukomalacia.

Achieving resonance in a programme for congenital cardiac surgery

In 1995, Miami Children's Hospital recognized an institutional problem with its programme providing surgical treatment for congenital cardiac malformations. There was a high rate of mortality for neonatal surgery, and no patients had survived attempted first stage palliation for hypoplastic left heart syndrome. The hospital enlisted nationally recognized consultants in congenital cardiac surgery and cardiology to review the existing programme, and to make recommendations for improvement. Based on these recommendations, a new team was recruited. The recruits were a young attending surgeon, an interventional cardiologist, and a cardiac intensivist, attracted from recognized centers of excellence in Boston and Toronto.

Apolipoprotein E genotype and neurodevelopmental sequelae of infant cardiac surgery

BACKGROUND

There has been increasing recognition of adverse neurodevelopmental sequelae in some children after repair of congenital heart defects. Even among children with the same cardiac defect, significant interindividual variation exists in developmental outcome. Polymorphisms of apolipoprotein E have been identified as a risk factor for worse neurologic recovery after central nervous system injury.

METHODS

A single-institution prospective study of patients <or=6 months of age undergoing cardiopulmonary bypass for repair of congenital heart defects was undertaken to evaluate the association between apolipoprotein E genotype and postoperative neurodevelopmental dysfunction. Developmental outcomes were evaluated at 1 year of age by using the Bayley Scales of Infant Development.

RESULTS

One-year evaluation was performed in 244 patients. After adjustment for preoperative and postoperative covariates-including gestational age, age at operation, sex, race, socioeconomic status, cardiac defect, and use of deep hypothermic circulatory arrest-the apolipoprotein E epsilon2 allele was associated with a worse neurologic outcome as assessed by the Psychomotor Developmental Index of the Bayley Scales of Infant Development (P =.036). Patients with the apolipoprotein E epsilon2 allele had approximately a 7-point decrease in the Psychomotor Developmental Index.

CONCLUSIONS

Apolipoprotein E epsilon2 allele carriers had significantly lower Psychomotor Development Index scores at 1 year of age after infant cardiac surgery. The effect was independent of ethnicity, socioeconomic status, cardiac defect, and use of deep hypothermic circulatory arrest. An effect of the apolipoprotein E epsilon4 allele was not detected. Genetic polymorphisms that decrease neuroresiliency and impair neuronal repair after central nervous system injury are important risk factors for neurodevelopmental dysfunction after infant cardiac surgery.

Risk of seizures in survivors of newborn heart surgery using deep hypothermic circulatory arrest

OBJECTIVE

To identify pre- and intraoperative variables associated with postoperative acute neurologic events (ANEs), including seizures and coma, in newborn survivors of congenital heart surgery undergoing deep hypothermic circulatory arrest (DHCA), and to risk-stratify this population on the basis of preoperative risk variables for the purpose of designing future neuroprotection trials.

METHODS

Survivors of newborn heart surgery who were enrolled in a neuroprotection trial provided a comprehensive database for the evaluation of pre- and intraoperative variables that influence the postoperative occurrence of ANEs (seizures or coma). Patients with hypoplastic heart syndrome were excluded. After characterization of the study population, stepwise logistic regression, combined with clinical judgment, was used to identify variables that were most likely to be associated with an increased risk of seizures in the study sample and that were most likely to be generalized to other populations.

RESULTS

Data were available on 164 nonhypoplastic left heart syndrome survivors who underwent newborn heart surgery using DHCA. ANEs occurred in 31 (18.9%) including "seizures alone" (n = 28), "coma alone" (n = 2) or "seizures and coma" (n = 1). A preoperative risk model was constructed demonstrating that infants with a genetic condition and aortic arch obstruction had a 47.8% risk of ANEs compared with all other remaining infants, who had a 9.9% risk. It was also found that prolonged DHCA time (>or=60 minutes) can be a significant risk for infants who have a preexisting genetic condition; however, infants who have genetic conditions and do not undergo prolonged DHCA time or have an aortic arch obstruction are not at increased risk of ANEs.

CONCLUSIONS

This study provides new information about the occurrence of ANEs after newborn heart surgery. Seizures or coma, which appeared in approximately 19% of all non-hypoplastic left heart syndrome survivors, were not random events but were significantly associated with specific types of congenital heart disease, the presence of genetic conditions, and prolonged DHCA time. The 3 identified variables permitted individual cases to be assigned to low-, intermediate-, or high-risk categories. Because neonatal seizures are a good surrogate marker of long-term neurologic outcome, these models provide useful information to stratify individual patients for risk of seizures in future neuroprotection trials.

Risk factors for mortality after the Norwood procedure

OBJECTIVES

Recent studies have suggested that survival following the Norwood procedure is influenced by anatomy and is worse for patients with hypoplastic left heart syndrome (HLHS), particularly aortic atresia (AA), as compared to other forms of functional single ventricle and systemic outflow tract obstruction. The current study was undertaken to evaluate our recent experience with the Norwood procedure and to evaluate potential predictors of operative and 1-year mortality.

METHODS

A retrospective study of risk factors for operative and 1-year mortality in 158 patients undergoing the Norwood procedure between January 1, 1998 and June 30, 2001.

RESULTS

HLHS was present in 102 patients (70 with AA) and other forms of functional single ventricle with systemic outflow tract obstruction in the remaining 56. Operative survival was 77% (122/158), 78% for patients with HLHS and 75% for patients with other diagnoses. Multivariable analysis identified birth weight (odds ratio (OR) 0.18/kg, 95% confidence limit (CL) 0.08-0.42, P<0.001), associated cardiac anomalies (OR 4.45, 95% CL 1.50-13.2, P=0.001), total support time (OR 1.02/min, 95% CL 1.01-1.03, P=0.004), and extracorporeal membrane oxygenation (ECMO) or ventricular assist device (VAD) support (OR 17.8, 95% CL 4.40-71.0, P<0.001) as predictors of operative mortality. The anatomic diagnosis (HLHS versus non-HLHS) was not a predictor of mortality, P=0.6). The Kaplan-Meier survival estimate at 1 year was 66% (95% CL 58-73%) and was not different for patients with HLHS compared to non-HLHS, P=0.5. For patients who have survived the Norwood procedure, survival to 1 year was 86% (95% CL 78-91%). Presence of an extra-cardiac anomaly or genetic syndrome (OR 2.70, 95% CL 0.98-7.41%, P=0.05) and presence of an additional cardiac defect (OR 3.99, 95% CL 1.67-9.57, P=0.002) were predictors of worse survival in the first year of life.

CONCLUSIONS

The Norwood procedure is currently being applied to a heterogeneous group of patients. Operative and 1-year survival are equivalent for patients with HLHS and those with other cardiac defects. The presence of additional cardiac or extra-cardiac anomalies are predictors of poor outcome.

Consensus-based method for risk adjustment for surgery for congenital heart disease

OBJECTIVE

The aim was to develop a consensus-based method of risk adjustment for in-hospital mortality among children younger than 18 years after surgery for congenital heart disease (designated RACHS-1).

METHODS

An 11-member national panel of pediatric cardiologists and cardiac surgeons used clinical judgment to place surgical procedures into six risk categories. Categories were refined after review of information from the Pediatric Cardiac Care Consortium and three statewide hospital discharge data sets. The effects of including additional clinical variables were explored by comparing areas under receiver-operator characteristic curves.

RESULTS

Among 4602 surgical patients in the Pediatric Cardiac Care Consortium data set and 4493 in the hospital discharge data, 3767 (81.9%) and 3832 (85.3%), respectively, had a single cardiac procedure, and 98.5% and 89.2%, respectively, were able to be assigned to one of six risk categories defined by the panel. Mortality rates showed expected trends (P <.001). For the Pediatric Cardiac Care Consortium data, mortality rates were 0.4% in category 1, 3.8% in 2, 8.5% in 3, 19.4% in 4, and 47.7% in 6; rates were similar in the hospital discharge data. There were too few cases in category 5 to estimate mortality rates. In multivariable models, younger age, prematurity, and the presence of a major noncardiac structural anomaly added to the risk of in-hospital death predicted by risk category alone. Best performance was obtained when cases with multiple procedures were placed in the risk category of the most complex procedure.

CONCLUSION

The RACHS-1 method should adjust for baseline risk differences and allow meaningful comparisons of in-hospital mortality for groups of children undergoing surgery for congenital heart disease.

First-stage palliation of complex univentricular cardiac anomalies in older infants

BACKGROUND

Poor outcomes have been reported for children older than 30 days of age with cardiac anomalies treated with first-stage palliation.

METHODS

Our institution has offered first-stage palliation for all such patients regardless of age. The results of this policy were reviewed.

RESULTS

Nine patients older than 30 days (median age 67 days, range 36 to 108 days) with diagnoses of hypoplastic left heart syndrome (n = 5), double-outlet right ventricle with hypoplastic aortic arch (n = 2), unbalanced atrioventricular septal defect (n = 1), or single left ventricle with subaortic stenosis (n = 1) underwent surgical palliation. Patients underwent a Norwood (n = 7) or Damus-Kaye-Stancel (n = 2) procedure with a 4- or 5-mm modified Blalock-Taussig shunt; all patients survived the operation. Eight patients underwent a subsequent bidirectional Glenn (2 perioperative deaths, both due to pneumonia; 6 survivors). Two of the 6 surviving patients have undergone Fontan reconstruction and 4 are awaiting Fontan.

CONCLUSIONS

Surgical palliation for complex univentricular cardiac malformations can be performed in older infants with results comparable to those in neonates. The use of a larger shunt may contribute to these improved outcomes.

Regional low-flow perfusion provides somatic circulatory support during neonatal aortic arch surgery

BACKGROUND

Regional low-flow perfusion has been shown to provide cerebral circulatory support during neonatal aortic arch operations. However, its ability to provide somatic circulatory support remains unknown.

METHODS

Fifteen neonates undergoing arch reconstruction with regional perfusion were studied. Three techniques were used to assess somatic perfusion: abdominal aortic blood pressure, quadriceps blood flow (near-infrared spectroscopy), and gastric tonometry.

RESULTS

Twelve patients required operation for hypoplastic left heart syndrome, and 3 required arch reconstruction with a biventricular repair. There was one death (7%). Abdominal aortic blood pressure was higher (12+/-3 mm Hg versus 0+/-0 mm Hg), and quadriceps blood volumes (5+/-24 versus -17+/-26) and oxygen saturations (57+/-25 versus 33+/-12) were greater during regional perfusion than during deep hypothermic circulatory arrest (p < 0.05). During rewarming, the arterial-gastric mucosal carbon dioxide tension difference was lower after circulatory arrest than after regional perfusion (-3.3+/-0.3 mm Hg versus 7.8+/-7.6 mm Hg, p < 0.05).

CONCLUSIONS

Regional low-flow perfusion provides somatic circulatory support during neonatal arch surgical procedures. Support of the subdiaphragmatic viscera should improve the ability of neonates to survive the postoperative period.

Allopurinol neurocardiac protection trial in infants undergoing heart surgery using deep hypothermic circulatory arrest

OBJECTIVE

This pharmacologic protection trial was conducted to test the hypothesis that allopurinol, a scavenger and inhibitor of oxygen free radical production, could reduce death, seizures, coma, and cardiac events in infants who underwent heart surgery using deep hypothermic circulatory arrest (DHCA).

DESIGN

This was a single center, randomized, placebo-controlled, blinded trial of allopurinol in infant heart surgery using DHCA. Enrolled infants were stratified as having hypoplastic left heart syndrome (HLHS) and all other forms of congenital heart disease (non-HLHS). Drug was administered before, during, and after surgery. Adverse events and the clinical efficacy endpoints death, seizures, coma, and cardiac events were monitored until infants were discharged from the intensive care unit or 6 weeks, whichever came first.

RESULTS

Between July 1992 and September 1997, 350 infants were enrolled and 348 subsequently randomized. A total of 318 infants (131 HLHS and 187 non-HLHS) underwent heart surgery using DHCA. There was a nonsignificant treatment effect for the primary efficacy endpoint analysis (death, seizures, and coma), which was consistent over the 2 strata. The addition of cardiac events to the primary endpoint resulted in a lack of consistency of treatment effect over strata, with the allopurinol treatment group experiencing fewer events (38% vs 60%) in the entire HLHS stratum, compared with the non-HLHS stratum (30% vs 27%). In HLHS surgical survivors, 40 of 47 (85%) allopurinol-treated infants did not experience any endpoint event, compared with 27 of 49 (55%) controls. There were fewer seizures-only and cardiac-only events in the allopurinol versus placebo groups. Allopurinol did not reduce efficacy endpoint events in non-HLHS infants. Treated and control infants did not differ in adverse events.

CONCLUSIONS

Allopurinol provided significant neurocardiac protection in higher-risk HLHS infants who underwent cardiac surgery using DHCA. No benefits were demonstrated in lower risk, non-HLHS infants, and no significant adverse events were associated with allopurinol treatment.congenital heart defects, hypoplastic left heart syndrome, induced hypothermia, ischemia-reperfusion injury, neuroprotective agents, allopurinol, xanthine oxidase, free radicals, seizures, coma.

Impact of prenatal diagnosis on survival and early neurologic morbidity in neonates with the hypoplastic left heart syndrome

BACKGROUND

Prenatal echocardiography can identify the fetus that has complex congenital heart disease and may improve early management and surgical outcome. Prenatal diagnosis may be particularly beneficial to patients who have hypoplastic left heart syndrome (HLHS) and who are at risk for hypoxic-ischemic insult at presentation.

OBJECTIVES

We sought to determine whether prenatal diagnosis reduces neurologic morbidity and operative mortality in patients who undergo palliative surgery for the HLHS.

METHODS

Data from all patients who had HLHS, except for those with lethal genetic anomalies, and who were admitted to our institution between July 1992 and September 1997 were analyzed to assess the impact of prenatal diagnosis on preoperative management, neurologic morbidity, and surgical mortality. The primary outcome measures were hospital mortality and the incidence of adverse neurologic events (seizure or coma).

RESULTS

There were 216 patients who had HLHS and were referred for surgical palliation, 79 (36.6%) of whom had been diagnosed prenatally. All patients who had been diagnosed prenatally were delivered in an advanced nursery and were started on prostaglandin E(1) on the first day of life. Patients whose HLHS was diagnosed postnatally were begun on prostaglandin E(1) later in life (median = day 2 [range = 1-28 days]). There were 4 preoperative deaths and 53 operative or postoperative deaths. Overall hospital mortality was 26.4% and did not differ between patients whose HLHS had been diagnosed prenatally and those whose HLHS had been diagnosed postnatally. With the use of multivariable analysis, prenatal diagnosis was associated with fewer adverse perioperative neurologic events in the patients whose HLHS had been diagnosed prenatally than in those whose HLHS had been diagnosed postnatally (odds ratio = 0.46).

CONCLUSIONS

These data suggest that prenatal diagnosis has a favorable impact on treatment of patients who have HLHS and are undergoing staged palliation and reduces early neurologic morbidity. Prenatal diagnosis was not associated with reduced hospital mortality. It is possible that prenatal diagnosis may improve long-term neurologic outcome.

Neonates with congenital heart disease

Early reparative surgery in neonates and infants with congenital heart disease, as opposed to initial palliation and later repair, is now commonplace. Changes to the conduct of cardiopulmonary bypass, timing of surgery and surgical techniques, and perioperative management substantially have reduced the postoperative mortality and morbidity for these patients. The success of this strategy of early reparative surgery now has been extended to the premature and low-birth-weight newborn, and, along with this, new challenges to postoperative care in the intensive care unit. However, the low mortality associated with two-ventricle repairs has not been the experience in newborns undergoing palliation for single-ventricle defects, in particular, hypoplastic left heart syndrome. A number of articles regarding management of newborns with single-ventricle defects have been published during the past 12 months, ranging from classification, prenatal diagnosis, treatment options, and predictors of both early and late outcome, which may provide a guide for patient management. As mortality has declined, there has been an increased emphasis on identifying indices that may predict outcome or morbidity both before and after surgery, along with possible strategies to attenuate adverse clinical responses. The inflammatory response to bypass is heightened in neonates and infants, and several reports have addressed possible techniques for attenuating the response. In addition, reports regarding the risk for necrotizing enterocolitis, the utility of lactate as an index of systemic perfusion, potential markers of myocardial and neurologic injury, and the use of mechanical support of the circulation in newborns with congenital heart disease are summarized.

Outcomes of neonates with congenital heart disease

One of the most important advances of the past 10 to 15 years in the field of pediatric cardiology is the improvement in prognosis for neonates with complex congenital heart disease. During the past 18 months, several publications have addressed outcomes in neonates with congenital heart disease. Many of these reports demonstrate continuing improvement in preoperative, early postoperative, and late postoperative survival among patients with complex neonatal heart defects. Other reports shed substantial new light on late functional outcome, especially neurodevelopmental status. In addition to data on survival, morbidity, and functional status, we discuss developments in perioperative evaluation and management that are likely to further the trend toward improved outcome for neonates with complex congenital heart disease.

Survival After Reconstructive Surgery for Hypoplastic Left Heart Syndrome

Background —There are limited data regarding the long-term survival of patients who have undergone reconstructive surgery for hypoplastic left heart syndrome (HLHS). We reviewed the 15-year experience at our institution to examine survival in the context of continued improvements in early operative results.

Methods and Results —Between 1984 and 1999, 840 patients underwent stage I surgery for HLHS. From review of medical records and direct patient contact, survival status was determined. The 1-, 2-, 5-, 10-, and 15-year survival for the entire cohort was 51%, 43%, 40%, 39%, and 39%, respectively. Late death occurred in 14 of the 291 patients discharged to home after the Fontan procedure, although only 1 patient has died beyond 5 years of age. Heart transplantation after stage I reconstruction was performed in 5 patients. Later era of stage I surgery was associated with significantly improved survival ( P <0.001). Three-year survival for patients undergoing stage I reconstruction from 1995 to 1998 was 66% versus 28% for those patients undergoing surgery from 1984 to 1988. Age >14 days at stage I and weight <2.5 kg at stage I were also associated with higher mortality ( P =0.004 and P =0.01, respectively). Other variables, including anatomic subtype, heterotaxia, and age at subsequent staging procedures, were not associated with survival.

Conclusions —Over the 15-year course of this study, early- and intermediate-term survival for patients with HLHS undergoing staged palliation increased significantly. Late death and the need for cardiac transplantation were uncommon.

Inhaled nitric oxide and prevention of pulmonary hypertension after congenital heart surgery: a randomised double-blind study

BACKGROUND

Pulmonary hypertensive crises (PHTC) are a major cause of morbidity and mortality after congenital heart surgery. Inhaled nitric oxide is frequently used as rescue therapy. We did a randomised double-blind study to investigate the role of routinely administered inhaled nitric oxide to prevent pulmonary hypertension in infants at high risk.

METHODS

We enrolled 124 infants (64 male, 60 female; median age 3 months [IQR 1-5]), 76% with large ventricular or atrioventricular septal defects, who had high pulmonary flow, pressure, or both, and were undergoing corrective surgery for congenital heart disease. They were randomly assigned continuous low-dose inhaled nitric oxide (n=63) or placebo (n=61) from surgery until just before extubation. We measured the numbers of PHTC, time on study gas, and hours spent in intensive care. Analysis was done by intention to treat.

FINDINGS

Compared with placebo, infants receiving inhaled nitric oxide had fewer PHTC (median four [IQR 0-12] vs seven [1-19]; relative risk, unadjusted 0.66, p<0.001, adjusted for dispersion 0.65, p=0.045) and shorter times until criteria for extubation were met (80 [38-121] vs 112 h [63-164], p=0.019). Time taken to wean infants off study gas was 35% longer in the nitric oxide group than in the placebo group (p=0.19), but the total time on the study gas was still 30 h shorter for the nitric oxide group (87 [43-125] vs 117 h [67-168], p=0.023). No important toxic effects arose.

INTERPRETATION

In infants at high risk of pulmonary hypertension, routine use of inhaled nitric oxide after congenital heart surgery can lessen the risk of pulmonary hypertensive crises and shorten the postoperative course, with no toxic effects.

Advances in pediatric cardiovascular surgery: anatomic reconstruction of the left ventricular outflow tract in transposition of the great arteries with pulmonic valve abnormalities

In the past years, advances in pediatric cardiovascular surgery have occurred in many areas with some of the greatest strides being made in complex repairs in younger age groups. Aggressive early corrections while higher risk, may in the long run provide a child with a normal anatomic heart, and corresponding myocardial growth and physiology.