Transplantation-free survival after Norwood surgery for hypoplastic left heart syndrome with aortic atresia: A Swedish national cohort study.

BACKGROUND: Norwood surgery has been available in Sweden since 1993. In this national cohort study, we analysed transplantation-free survival after Norwood surgery for hypoplastic left heart syndrome with aortic atresia. METHODS: Patients were identified from the complete national cohort of live-born with hypoplastic left heart syndrome/aortic atresia 1993-2010. Analysis of survival after surgery was performed using Cox proportional hazards models for the total cohort and for birth period and gender separately. Thirty-day mortality and inter-stage mortality were analysed. Patients were followed until September 2016. RESULTS: The 1993-2010 cohort consisted of 208 live-born infants. Norwood surgery was performed in 121/208 (58%). The overall transplantation-free survival was 61/121 (50%). The survival was higher in the late period (10-year survival 63%) than in the early period (10-year survival 40%) (p = 0.010) and lower for female (10-year survival 34%) than for male patients (10-year survival 59%) (p = 0.002). Inter-stage mortality between stages I and II decreased from 23 to 8% (p = 0.008). For male patients, low birthweight in relation to gestational age was a factor associated with poor outcome. CONCLUSION: The survival after Norwood surgery for hypoplastic left heart syndrome/aortic atresia improved by era of surgery, mainly explained by improved survival between stages I and II. Female gender was a significant risk factor for death or transplantation. For male patients, there was an increased risk of death when birthweight was lower than expected in relation to gestational age.

Changing Epidemiology of Hypoplastic Left Heart Syndrome: Results of a National Swedish Cohort Study.

Background Norwood surgery provides a palliative surgical option for hypoplastic left heart syndrome and has been available in Sweden since 1993. The practice of prenatal ultrasound screening was gradually implemented in the same era, resulting in an increased prenatal detection rate. Our primary aims were to study changes in the incidence of live births, prenatal detection rate, and the termination of pregnancies over time. The secondary aims were to study the proportion of live-borns undergoing surgery and to identify factors that influenced whether surgery was or was not performed. Methods and Results Neonates with hypoplastic left heart syndrome with aortic atresia born 1990-2010 were identified through national databases, surgical files, and medical records. The fetal incidence was estimated from the period when prenatal screening was rudimentary. The study period was divided into the presurgical, early surgical, and late surgical periods. The incidence was calculated as the overall yearly incidence for each time period and sex separately. Factors influencing whether surgery was performed were analyzed using Cox-logistic regression. The incidence at live birth decreased from 15.4 to 8.4 per 100 000. The prenatal detection rate increased from 27% to 63%, and terminations increased from 19% to 56%. The odds of having surgery was higher in the late period and higher in the group with prenatal diagnosis. Conclusions We observed a decrease in incidence of live-borns with hypoplastic left heart syndrome aortic atresia. There was in increase in prenatal detection rate and an increase in termination of pregnancy. The proportion of live-borns who underwent surgery increased between time periods.

Excellent Outcome With Extracorporeal Membrane Oxygenation After Accidental Profound Hypothermia (13.8°C) and Drowning.

OBJECTIVE: To report outcome and intensive care strategy in a 7-year-old girl with accidental profound hypothermia and drowning. DATA SOURCES AND EXTRACTION: Patient records and interviews with search-and-rescue personnel. STUDY SELECTION: Case report. DATA SYNTHESIS: The girl was rescued after an estimated submersion time of at least 83 minutes in icy sea water. She presented with cardiac arrest, ice in her upper airways, a first-documented nasopharyngeal temperature of 13.8°C, and a serum potassium of 11.3 mmol/L. The patient was slowly rewarmed with extracorporeal membrane oxygenation and made an exceptional recovery after intensive care and a long rehabilitation time. CONCLUSION: Excellent outcome is possible in children with body temperature and serum potassium reaching the far limits of previously reported human survival and prolonged submersion time.

No evidence for mosaic pathogenic copy number variations in cardiac tissue from patients with congenital heart malformations.

The aim of this study was to investigate if pathogenic copy number variations (CNVs) are present in mosaic form in patients with congenital heart malformations. We have collected cardiac tissue and blood samples from 23 patients with congenital heart malformations that underwent cardiac surgery and screened for mosaic gene dose alterations restricted to cardiac tissue using array comparative genomic hybridization (array CGH). We did not find evidence of CNVs in mosaic form after array CGH analysis. Pathogenic CNVs that were present in both cardiac tissue and blood were detected in 2/23 patients (9%), and in addition we found several constitutional CNVs of unclear clinical significance. This is the first study investigating mosaicism for CNVs in heart tissue compared to peripheral blood and the results do not indicate that pathogenic mosaic copy number changes are common in patients with heart malformations. Importantly, in line with previous studies, our results show that constitutional pathogenic CNVs are important factors contributing to congenital heart malformations.

Pulse oximetry home monitoring in infants with single-ventricle physiology and a surgical shunt as the only source of pulmonary blood flow.

BACKGROUND: Shunt occlusion is a major cause of death in children with single ventricle. We evaluated whether one daily measurement of oxygen saturation at home could detect life-threatening shunt dysfunction. METHODS: A total of 28 infants were included. Parents were instructed to measure saturation once daily and if less than or equal to 70% repeat the measurement. Home monitoring was defined as positive when a patient was admitted to Queen Silvia Children's Hospital because of saturation less than or equal to 70% on repeated measurement at home. A shunt complication was defined as arterial desaturation and a narrowing of the shunt that resulted in an intervention to relieve the obstruction or in death. Parents' attitude towards the method was investigated using a questionnaire. RESULTS: A shunt complication occurred out of hospital eight times in eight patients. Home monitoring was positive in five out of eight patients. In two patients, home monitoring was probably life saving; in one of them, the shunt was replaced the same day and the other had an emergency balloon dilatation of the shunt. In three out of eight patients, home monitoring was negative; one had an earlier stage II and survived, but two died suddenly at home from thrombotic shunt occlusion. On seven occasions in three patients home monitoring was positive but there was no shunt complication. The method was well accepted by the parents according to the results of the questionnaire. CONCLUSION: Home monitoring of oxygen saturation has the potential to detect some of the life-threatening shunt obstructions between stages I and II in infants with single-ventricle physiology.

A study of the physiological consequences of sympathetic denervation of the heart caused by the arterial switch procedure.

BACKGROUND: The arterial switch operation is the corrective operation for transposition of the great arteries, defined as the combination of concordant atrioventricular and discordant ventriculo-arterial connections, but there have been concerns about silent subendocardial ischaemia on exercise and coronary artery growth. The arterial switch divides the majority of the sympathetic nerves entering the heart; we have studied the effects of coronary flow and sensitivity to catecholamine stimulation in an animal model. METHODS: A total of 10 piglets were operated on cardiopulmonary bypass with section and resuturing of aortic trunk, pulmonary artery and both coronary arteries, with 13 sham-operated controls. After 5-7 weeks of recovery, seven simulated switch survivors and 13 controls were studied. RESULTS: Basal heart rate was significantly higher in switch piglets: in vivo mean (standard deviation) 112 (12) versus sham 100 (10) beats per minute, (p = 0.042); in vitro (Langendorff preparation): 89 (9) versus sham 73 (8) beats per minute (p = 0.0056). In vivo maximal heart rate in response to epinephrine was increased in switch piglets, 209 (13) versus 190 (17) beats per minute (p = 0.044). In vitro dose-response curves to norepinephrine were shifted leftward and upwards (p = 0.0014), with an 80% increase in heart rate induced by 0.095 (0.053) norepinephrine micromole per litre perfusate in switch hearts versus 0.180 (0.035) norepinephrine micromole per litre (p = 0.023). Increase in coronary flow on norepinephrine stimulation and maximal coronary flow were significantly reduced in switch hearts: 0.3 (0.2) versus 0.8 (0.4) millilitre per gram heart weight (p = 0.045) and 2.5 (0.4) versus 3.1 (0.4) millilitre per gram heart (p = 0.030), respectively. CONCLUSIONS: A combination of increased intrinsic heart rate, increased sensitivity to chronotropic actions of norepinephrine, and a decreased maximal coronary flow creates potential for a mismatch between perfusion and energy demands.

Results of staged palliation for hypoplastic left heart syndrome: a complete population-based series.

AIM: To study the outcome of staged palliation for classic hypoplastic left heart syndrome. METHODS: Retrospective chart review. Risk factors for mortality were analysed using Cox's proportional hazard regression modelling. RESULTS: From 1993 to 2004, 55 infants underwent Norwood stage I procedure at a median age of 8 d (range 1-19 d). Hospital survival was 39/55 (71%), and there were six late deaths (before stage II). Birthweight, circulatory arrest time and cardiopulmonary bypass time were independent risk factors for stage I hospital mortality (p=0.029, p=0.001 and p=0.003, respectively). Poor right ventricular function prior to stage I was a significant predictor for interstage mortality (p=0.02). Thirty-two patients underwent bidirectional cavopulmonary anastomosis, at a median age of 6.5 mo (range 2.0-9.5 mo), with seven late deaths. Two patients had a heart transplant after stage II. Total cavopulmonary connection (TCPC) was performed in 13 patients, at a median age of 33 mo (range 21-45 mo), without mortality. Kaplan-Meier survival was 58%, 52% and 45% at 6, 12 and 48 mo, respectively. CONCLUSION: Low birthweight, long time on circulatory arrest and cardiopulmonary bypass were risk factors for stage I mortality. Poor right ventricular function was detrimental to intermediate outcome.