congenital heart disease ( chd ) , still placed first among common birth defects , occurs approximately 1 in 125 live births . thirty percent among these might require surgery during the first year of life due to extracardiac anomalies such as tracheoesophageal fistula , anorectal anomalies , cleft lip and palate , and renal and skeletal pathologies , and 85% of these chd patients are expected to survive to adulthood in usa . the challenge for anaesthesiologists in handling patients with chd coming for extracardiac surgery relies on the patients age , complexity of the heart lesion , coupled with patients capacity to compensate , urgency of surgery and multiple coexisting diseases . in a clinical review of 191,261 patients less than 18 years old having one or more non - cardiovascular procedures , a diagnosis of chd increases the mortality risk for both minor and major surgery , regardless of whether mortality is measured in a few days or after a month . furthermore , with the same clinical group , neonates and infants with chd are associated with two fold increase in mortality from non - cardiac surgery . anaesthesia - related paediatric cardiac arrest , according to a review , occurred in 75% of patients under 2 years of age with chd during non - cardiac surgery . nevertheless , under the experienced hands , anaesthesia for neonates with complex heart diseases like hypoplastic left heart syndrome ( hlhs ) , unbalanced atrioventricular septal defects ( avsd ) , unstable tetralogy of fallot ( tof ) and truncus arteriosus ( ta ) presenting to us for treatment of general surgical emergencies can still be conducted with manageable complications . children with chd presenting for non - cardiac surgery can be grouped into three categories : non - operated patient , with previous palliative surgery and with previous corrective surgery . apart from categorising , to fully optimise the patient , it is a must for anaesthetist to obtain information about the cardiac lesion , its altered physiology and its implications under anaesthesia . this includes knowledge about whether the patient is on parallel or single ventricle physiology and relies deeply on relative resistance between systemic and pulmonary circulation . effects of respiratory infection on pulmonary vascular resistance are more deleterious in patients with pulmonary hypertension ( htn ) or cavopulmonary anastomosis . the decision on whether to delay the surgery must be discussed with the surgeon to weigh the risk benefit issues . poor exercise tolerance is indicated by fatigue and dyspnoea on feeding , irritability and inability to gain weight . previous cardiac and non - cardiac surgeries and prolonged intubation should be enquired about as they may suggest difficult iv insertion and subglottic stenosis , respectively . right ventricular function is equally important as the left ventricular function in the paediatric chd patient , and thus should also be assessed . patients with high pulmonary flow may present with tachycardia , tachypnoea , irritability , cardiomegaly and hepatomegaly . associated non - cardiac congenital anomalies include musculoskeletal abnormalities 8.8% , neurological defects 6.9% and genitourinary irregularities 5.3% . down 's syndrome patients may have atlanto - occipital subluxation that will warrant airway management precautions . medication history must be elicited . in patients with chd who may be on of aspirin , warfarin , antidepressants , diuretics , angiotensin converting enzyme ( ace ) inhibitors , and antiarrhythmics , all cardiac medications should be given on the morning of surgery , with exemption of ace inhibitors due to their hypotensive effects during anaesthetic induction as seen in adult cases . however , for major surgeries , aspirin is commonly discontinued 7 - 10 days prior to surgery . children on warfarin must be admitted for anticoagulant monitoring and change over to intravenous heparin prior to surgery . if timing of surgery is uncertain , then an iv line should be placed and fluids started . sympathetic stimulation due to crying of an anxious and distressed patient can increase oxygen consumption and myocardial work ; this might be poorly tolerated in a child with limited cardiac reserve . midazolam is the preferred premedication to reduce oxygen consumption in the dose of 0.5 mg / kg orally half an hour before surgery . if iv line is present , then incremental doses of 0.1 - 0.25 mg / kg midazolam can be given , provided airway and breathing issues were addressed accordingly . in the recent guidelines from american college of cardiology / american heart association ( acc / aha ) , underlying cardiac rhythm modes and settings of patients with implanted pacemakers and/or automated defibrillator must be investigated prior to and after operation . aha recommends antibiotic prophylaxis for following patients : 
 when gingival tissue is manipulated , or periapical region of teeth or perforation of oral mucosaprior history of infective endocarditisnon - repaired cyanotic chd , including shunts and conduitcomplete chd repair within the previous 6 monthsrepaired chd with residual defects . 
  when gingival tissue is manipulated , or periapical region of teeth or perforation of oral mucosa prior history of infective endocarditis non - repaired cyanotic chd , including shunts and conduit complete chd repair within the previous 6 months repaired chd with residual defects . antibiotics for infective endocarditis prophylaxis is no longer indicated in patients with 
 aortic stenosis , mitral stenosis , or symptomatic or asymptomatic mitral valve prolapse.genitourinary and gastrointestinal tract procedures ( transoesophageal echocardiography , oesophagogastroduodenoscopy , colonoscopy , etc . ) genitourinary and gastrointestinal tract procedures ( transoesophageal echocardiography , oesophagogastroduodenoscopy , colonoscopy , etc . ) polycythemia increases blood viscosity which leads to thrombosis and infarction in cerebral , renal and pulmonary regions . prothrombin time ( pt ) and partial thromboplastin time ( ptt ) are usually deranged in a polycythemic patient . preoperative phlebotomy is performed in symptomatic hyperviscosity and hematocrit ( hct ) more than 65% . however , dehydration must be corrected first before deciding about phlebotomy . on the other hand , wbc count and c - reactive protein ( crp ) measurement provide potential diagnosis of infection . echo is used for doppler and colour flow mapping , while catheterisation is used for information about pressures in different chambers , magnitude of shunt and coronary anatomy . the chest x - ray shows the heart position and size , atelectasis , acute respiratory infection , vascular markings and elevated hemidiaphragm . the need for cardiologist evaluation depends on the complexity of the lesion . in a patient with simple or moderately complex lesion that has been completely corrected and is well compensated , a standard pre - anaesthetic visit without moderately complex lesions accompanied with inability to compensate will warrant cardiologist evaluation and optimisation , but clearance must always be given by anaesthesiologist . effects of respiratory infection on pulmonary vascular resistance are more deleterious in patients with pulmonary hypertension ( htn ) or cavopulmonary anastomosis . the decision on whether to delay the surgery must be discussed with the surgeon to weigh the risk benefit issues . poor exercise tolerance is indicated by fatigue and dyspnoea on feeding , irritability and inability to gain weight . previous cardiac and non - cardiac surgeries and prolonged intubation should be enquired about as they may suggest difficult iv insertion and subglottic stenosis , respectively . right ventricular function is equally important as the left ventricular function in the paediatric chd patient , and thus should also be assessed . patients with high pulmonary flow may present with tachycardia , tachypnoea , irritability , cardiomegaly and hepatomegaly . associated non - cardiac congenital anomalies include musculoskeletal abnormalities 8.8% , neurological defects 6.9% and genitourinary irregularities 5.3% . down 's syndrome patients may have atlanto - occipital subluxation that will warrant airway management precautions . medication history must be elicited . in patients with chd who may be on of aspirin , warfarin , antidepressants , diuretics , angiotensin converting enzyme ( ace ) inhibitors , and antiarrhythmics , all cardiac medications should be given on the morning of surgery , with exemption of ace inhibitors due to their hypotensive effects during anaesthetic induction as seen in adult cases . however , for major surgeries , aspirin is commonly discontinued 7 - 10 days prior to surgery . children on warfarin must be admitted for anticoagulant monitoring and change over to intravenous heparin prior to surgery . if timing of surgery is uncertain , then an iv line should be placed and fluids started . sympathetic stimulation due to crying of an anxious and distressed patient can increase oxygen consumption and myocardial work ; this might be poorly tolerated in a child with limited cardiac reserve . midazolam is the preferred premedication to reduce oxygen consumption in the dose of 0.5 mg / kg orally half an hour before surgery . if iv line is present , then incremental doses of 0.1 - 0.25 mg / kg midazolam can be given , provided airway and breathing issues were addressed accordingly . in the recent guidelines from american college of cardiology / american heart association ( acc / aha ) , underlying cardiac rhythm modes and settings of patients with implanted pacemakers and/or automated defibrillator must be investigated prior to and after operation . aha recommends antibiotic prophylaxis for following patients : 
 when gingival tissue is manipulated , or periapical region of teeth or perforation of oral mucosaprior history of infective endocarditisnon - repaired cyanotic chd , including shunts and conduitcomplete chd repair within the previous 6 monthsrepaired chd with residual defects . 
  when gingival tissue is manipulated , or periapical region of teeth or perforation of oral mucosa prior history of infective endocarditis non - repaired cyanotic chd , including shunts and conduit complete chd repair within the previous 6 months repaired chd with residual defects . antibiotics for infective endocarditis prophylaxis is no longer indicated in patients with 
 aortic stenosis , mitral stenosis , or symptomatic or asymptomatic mitral valve prolapse.genitourinary and gastrointestinal tract procedures ( transoesophageal echocardiography , oesophagogastroduodenoscopy , colonoscopy , etc . ) genitourinary and gastrointestinal tract procedures ( transoesophageal echocardiography , oesophagogastroduodenoscopy , colonoscopy , etc . ) polycythemia increases blood viscosity which leads to thrombosis and infarction in cerebral , renal and pulmonary regions . prothrombin time ( pt ) and partial thromboplastin time ( ptt ) are usually deranged in a polycythemic patient . preoperative phlebotomy is performed in symptomatic hyperviscosity and hematocrit ( hct ) more than 65% . however , dehydration must be corrected first before deciding about phlebotomy . on the other hand , wbc count and c - reactive protein ( crp ) measurement provide potential diagnosis of infection . echo is used for doppler and colour flow mapping , while catheterisation is used for information about pressures in different chambers , magnitude of shunt and coronary anatomy . the chest x - ray shows the heart position and size , atelectasis , acute respiratory infection , vascular markings and elevated hemidiaphragm . the need for cardiologist evaluation depends on the complexity of the lesion . in a patient with simple or moderately complex lesion that has been completely corrected and is well compensated , a standard pre - anaesthetic visit without moderately complex lesions accompanied with inability to compensate will warrant cardiologist evaluation and optimisation , but clearance must always be given by anaesthesiologist . whether or not the patients with complex heart disease are coming for minor day surgery or major operation , the anaesthetist must assure that the hospital is equipped to answer all potential problems the case might bring . if not working in a specialty institution , communication with other specialists and back - up support from other centres should be assured if complications arise . all commonly used induction agents are well tolerated depending on the rate and dose of the drug , whether it is inhalational or intravenous . systemic vascular resistance ( svr ) and peripheral vascular resistance ( pvr ) balance should be considered when using intravenous agents . patients with poor cardiac function , who require inotropes preoperatively , may not tolerate inhalational induction , and favour the use of ketamine . in a review of 18 neonates with complex cardiac defects undergoing major general surgery , ketamine was the most common induction agent in those not intubated at the time of surgery . inotropes should be continued and iv induction agents titrated . the need for invasive monitoring should depend on the type of surgery and cardiac lesion . left to right shunts are the most common lesions representing over 50% of children with chd . examples include atrial septal defects , ventricular septal defects , patent ductus arteriosus , av canal defects , pavd and blalock taussig shunt ( bt shunt ) . they have minimal effect on inhalation or intravenous induction and decrease with the drop in svr or an increase in pvr . 1 - 1.5 minimum alveolar concentration ( mac ) of isoflurane , halothane and sevoflurane has no effect on qpqs ratio in patients with isolated asd or vsd during mechanical ventilation . r shunt will result in pulmonary vasodilation , which in turn will further increase pulmonary congestion , and thus should be avoided . spell under anaesthesia responds to volume , increase in svr with alpha agonists such as phenylephrine or ephedrine and ceasing infundibular spasm with beta blockade . another significant caveat in managing these patients is to be aware that pulse oximetry overestimates arterial oxygen saturation as saturation decreases , end - tidal carbon dioxide readings underestimate paco2 , and discrepancy worsens with hypoxemia . mean pulmonary artery pressure greater than 25 mmhg at rest and 35 mmhg during exercise is defined as pulmonary hypertension . initially pulmonary htn is reactive and responds to hypothermia , stress , pain , acidosis , hypercarbia , hypoxia and elevated intrathoracic pressure , but later pulmonary htn becomes fixed . the anaesthetic goals in managing such a patient are to prevent increase in pvr and depression of myocardial function . pulmonary htn crisis intervention measures such as 100% oxygen , inhaled nitric oxide , phosphodiesterase inhibitors , prostacyclin analogues , inotropes and other measures to maintain cardiac output and pulmonary blood flow must be prepared and administered accordingly as the need arises . on the other hand , despite the potential airway and ventilatory issues during sedation or anaesthesia , the choice of airway device dictates the incidence of complications in children with pulmonary htn undergoing non - cardiac surgery . reports regarding incidence of pulmonary hypertensive crisis among tracheally intubated adult patients with severe pulmonary htn encourage anaesthetists to use less - invasive airway management if the surgical procedure permits . following completion of bt shunt and glenn shunts , oxygen saturation is expected to be 75 - 85% . always note that after these two stages , residual shunts , increased sensitivity to svr and pvr pressure changes , and arrhythmia are still not uncommon . fontan physiology relies on transpulmonary gradient to direct blood into the pulmonary circulation , and thus dictates cardiac output . therefore , if a patient with fontan physiology comes in for a laparoscopic procedure , one must take into consideration the capacity of the patient to handle the insult of hypercarbia , pnuemoperitoneum and extremes of positions . studies have shown that insufflation pressures less than 8 - 12 cm h2o did not decrease cardiac output , while a decrease in cardiac performance was seen in pressures of 15 - 20 cm h2o . case reports show neonates with well - compensated fontan physiology can have an uneventful laparoscopic abdominal surgery . in another case report , an adolescent with non - fenestrated fontan went through two laparoscopic procedures with 3 years interval and successfully tolerated incision , co2 insufflation and trendelenberg position . on both occasions , intraabdominal pressures were maintained less than10 cm h2o , and there were no significant haemodynamic changes and anaesthetic management alteration . pain management is a critical factor that an anaesthetist must cover during intra- or postoperative management . opioid infusion or patient - controlled analgesia for major operations has been the primary postoperative intervention for pain for patients with chd . the use of regional anaesthesia for well - compensated patients with chd was reported with no complications . in the study by shenkman et al . , 44 unsupplemented spinal anaesthesias for inguinal hernia correction were done with 1 mg / kg of either hyperbaric tetracaine or bupivacaine in premature or former premature infants with non - cyanotic chd ; even when fluid restricted , causes minimal cardio - respiratory complications . in a related investigation , infants undergoing minor non - cardiac surgery under awake spinal anaesthesia were not different from controls without chd in terms of percent decrease in mean arterial pressure and heart rate . fourteen patients in the study group were even classified as high risk , having pulmonary htn , congestive heart failure , combined cardiac lesions , multiple cardiac surgeries , and on drug therapy . even with favourable outcome , patients with chd coming for non - cardiac surgery are still under high - risk category after operation . observing them in high - dependency bed or intensive care unit will warrant assurance of catching arrhythmia , cardiac ischaemia , dehydration , pain , ventilator issues and other complications before they cause detrimental effects . as there are many complex factors involved , anaesthetic management of patients with chd coming in for non - cardiac surgery is based on individual experience , and confidence in handling the case . precision in planning and good foundation in physiological and pharmacological principles will contribute to the successful completion of the procedure .
the objective of this article is to provide an updated and comprehensive review on current perioperative anaesthetic management of paediatric patients with congenital heart disease ( chd ) coming for non - cardiac surgery . 
 search of terms such as  anaesthetic management ,   congenital heart disease  and 
 non - cardiac surgery  was carried out in kkh elibrary , pubmed , medline and google , focussing on significant current randomised control trials , case reports , review articles and editorials . 
 issues on how to tailor perioperative anaesthetic management on cases with left to right shunt , right to left shunt and complex heart disease are discussed in this article . 
 furthermore , the author also highlights special considerations such as pulmonary hypertension , neonates with chd coming for extracardiac surgery and the role of regional anaesthesia in children with chd undergoing non - cardiac operation .