neonatal surgical emergencies carry the risk of mortality and co - existing unpalliated congenital heart defects make the anaesthetic management a formidable challenge . until the surgical palliation by norwood and allograft cardiac transplantation by bailey in the 1980s , mortality of hypoplastic left heart syndrome ( hlhs ) was 100% . hlhs is the abnormal development of the left - sided cardiac structures , resulting in obstruction to blood flow from the left ventricle . necrotising enterocolitis ( nec ) , one of the common neonatal gastrointestinal emergencies , is characterised by ischaemic necrosis of the intestinal mucosa , invasion of organisms and dissection of gas into the muscularis and portal system . hlhs neonates who develop nec belong to a unique group of term babies with reasonable birth weights , unlike the common nec patient . these children require meticulous preoperative evaluation and with thorough preparation they tolerate general anaesthesia well . we have reported a neonate with unpalliated hlhs who underwent an emergency laparotomy for nec . a 4 kg term male with normal apgar scores and blood investigations at birth , developed respiratory distress , acidosis and abdominal distention following initiation of oral feeds . echocardiogram reported hlhs with atrial septal defect ( asd ) . with a diagnosis of nec , the baby was scheduled for emergency laparotomy . in the neonatal intensive care unit ( nicu ) , the baby was intubated , ventilated , umbilical vessels were catheterised and infusion of dopamine and prostaglandin e1 was started . the post - operative course was marked with cardiovascular instability following sepsis . on day seven , the fourth post - operative day , the baby died following a cardiac arrest . children with severe uncorrected heart defects presenting with non - cardiac surgical emergencies are a major challenge to the anaesthetist and only few case reports are available in the medical literature . nec and hlhs though inter - related , are two distinct entities and to understand the anaesthetic implications of both , we need to know the pathophysiology of each . hlhs is the most common form of functional single ventricle heart disease with a prevalence rate of 2 - 3 cases per 1000 live births.,it is characterised by underdevelopment of the left heart with hypoplasia of the left ventricle and ascending aorta with atresia , stenosis or hypoplasia of the aortic or mitral valve ; resulting in the right ventricle supporting the pulmonary and systemic circulation . survival depends on a patent ductus arteriosus ( pda ) for systemic perfusion and an adequate asd for mixing of oxygenated and deoxygenated blood . neonates with a non - restrictive asd , are asymptomatic after delivery and become symptomatic with pda closure . initial management is providing adequate systemic perfusion by maintaining a pda with prostaglandin e1 ( 0.01 - 0.05 ug / kg / min ) and if necessary , creating a transcatheter atrial septoplasty . the incidence of nec varies between 1 and 8% with a mortality rate between 20% and 40% . treatment is by nasogastric decompression , antibiotics , fluids , parenteral nutrition and insertion of a peritoneal drain . plain abdominal x - ray on the left shows pneumatosis intestinalis ( large arrow ) a specific characteristic finding in necrotising enterocolitis . x - ray on the right is a follow - up film , which shows free air indicating perforation of the bowel ( small arrow ) immaturity of the gut is an important predisposing factor . reports where nec has been described in term infants with congenital heart disease have attributed all deaths to nec . among patients with hlhs , with decreasing pulmonary vascular resistance ( pvr ) , left to right shunting at the ductal level may decrease mesenteric flow , resulting in bowel ischaemia . prostaglandin use , indwelling umbilical catheters and cardiac catheterisation have been implicated in nec , but the underlying circulatory physiology may be more contributory . after birth , three factors affect the haemodynamic status : decrease in pvr , size of the asd and closure of pda . the ratio of pulmonary blood flow to systemic blood flow ( qp / qs ) describes how the cardiac output from the single ventricle is partitioned . with the ductus open , most infants with hlhs can maintain a balance between pvr and systemic vascular resistance . however , a marked discrepancy in blood flow to the pulmonary and systemic circulations causes rapid onset of haemodynamic instability . an increase in qp / qs ratio results in excessive pulmonary flow at the expense of systemic flow . the ductus provides blood to the coronary arteries and the descending aorta and as it constricts , hypoperfusion occurs , resulting in shock . because of this unique parallel circulation and propensity for systemic hypoperfusion , neonates with hlhs frequently develop nec . a prolonged period of stabilisation in the nicu before transfer to theatre needs to be balanced against the requirement for early surgical intervention . anaesthetic management of such infants include a strategy to maintain qp : qs slightly < 1 . kang et al . described the anaesthetic management of two neonates with hlhs with a tracheoesophageal fistula in one and meningomyelocele in the other . in both cases , they minimised excessive qp by prostaglandin e1 in the first case and by adding nitrogen for a hypoxic mixture in the second case . walker et al . reviewed the notes of children with complex cardiac anomalies presenting for non - cardiac surgeries , including laparotomies for nec . our patient tolerated general anaesthesia well , but developed sepsis resulting in fatal cardiovascular collapse . measures that induce pulmonary vasoconstriction , such as permissive hypercarbia or low inspired oxygen concentration , maybe utilised to counteract the presence of high qp . as recent advances allow for the palliation of hlhs , the incidence of these patients presenting with nec is likely to increase and hence , we made an attempt to review the literature about the perioperative management of this rare group patients .
necrotising enterocolitis ( nec ) and congenital heart disease are two distinct disease processes , but they appear to be inter - related , particularly in patients with the congenital heart condition known as hypoplastic left heart syndrome ( hlhs ) . 
 both nec and hlhs are causes of significant morbidity and mortality in the neonatal population . as medical and surgical advances 
 allow for the palliation and correction of complex heart lesions at an earlier gestational age and lower birth weight , the already high - risk of nec in this population is likely to increase . in this article 
 , we report a case of a neonate with unpalliated hlhs who underwent emergency laparotomy for nec . 
 we also discuss the pathophysiology of these two diseases and the perioperative care of this rare group of patients .