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Evaluation of suspected congenital heart disease
SYMPOSIUM: CARDIOVASCULAR MEDICINE
Evaluation of suspected congenital heart disease
Despite this, congenital heart disease (CHD) still accounts for over 40% of deaths from congenital malformations and 3% of all infant deaths. Notably one third of all children born with CHD become critically ill in the first year of life and either die or receive surgical treatment. Early diagnosis and appropriate management are essential to improve outcome.
Anjum Gandhi Srividya Sreekantam
Aetiology Causation of CHD is thought to be multi-factorial resulting from combination of genetic predisposition and environmental stimuli. Having a child with CHD confers a 2% risk in a subsequent pregnancy. A mother with CHD has 6% risk of having an affected offspring while an affected father has a 2% risk. The proportion of congenital heart defects associated with chromosomal anomalies varies between 4 and 12% but can be as high as 22% if antenatal deaths in foetuses are included. Most common heart defects noted in foetal autopsies are ventricular septal defect, atrioventricular septal defect; hypoplastic left heart and double outlet right ventricle which together make up to 72% of all defects. Although hereditary and genetic factors play a major role in causing cardiac malformations some known teratogens are also associated. Table 1 illustrates the common genetic and environmental factors associated with congenital heart disease.
Abstract Congenital heart disease {CHD} still accounts for significant morbidity and mortality, despite major advances in diagnosis and management. It predominantly manifests in the neonatal period and early infancy. Presentation is protean ranging from a well baby with a heart murmur to a baby in extremis. Although advances in antenatal ultrasonography and foetal echocardiography continue to improve detection rates a significant proportion of CHD is still undiagnosed at birth emphasizing the need for a detailed history and meticulous clinical examination. No reliable screening tool exists but pulse oximetry can be quite useful despite its relatively low sensitivity. Limb blood pressure values are quite variable in the newborn and hence should be interpreted with caution. Chest X-ray with a focus on cardiac size and pulmonary vascularity can be useful in the evaluation of cyanotic heart conditions. ECG can provide additional information about axis and chamber hypertrophy. Echocardiography is the gold standard but not always available. Once a diagnosis of CHD is suspected the priority is to stabilize the infant. This usually involves initiation of advanced life support and commencement of Prostaglandins to keep the duct open. As clinical presentation of CHD is broad and similar to other conditions such as sepsis and metabolic disorders a high index of suspicion and systematic approach remain vital to make a timely diagnosis.
Antenatal diagnosis and management of heart disease The increasing use of obstetric ultrasound and foetal echocardiography means that the opportunity to provide optimal care to a newborn with CHD begins in the antenatal period. Current UK practice is to undertake a four chamber cardiac view as a part of antenatal screening ultrasound at 18e20 weeks gestation. This has a relatively low detection rate of 25%. Table 2 illustrates the high-risk categories that fit the criteria for foetal echocardiography. The purpose of antenatal screening is to detect major congenital heart defects which have significant impact on postnatal survival. Examples would include Coarctation of aorta, Transposition of great arteries and Hypoplastic left heart syndrome. Studies looking at the benefits of antenatal screening in detecting these conditions have clearly demonstrated better outcomes in terms of mortality although there was no major effect on morbidity. Based on severity of heart defect and its prognosis parents can be counselled antenatally regarding management options which include planned delivery in a tertiary cardiac centre and sadly in some cases termination of pregnancy. Such decision making however remains a complex issue influenced heavily by cultural/ religious back ground, ethical issues, perceived quality of life and parental choice. Clearly the advantages of antenatal screening are manifold. However a review of 20-year trends in the diagnosis of life-threatening cardiovascular malformations revealed that a significant proportion still remains undiagnosed. These include Coarctation of aorta, interrupted aortic arch, aortic stenosis and TAPVD. The detection rate of cardiovascular malformations could be improved by additional view of outflow tracts on antenatal scans which is currently not a requirement but would count as good practice. The review also clearly highlighted that the prevalence of lifethreatening cardiovascular malformations remains unaltered at
Keywords congenital heart disease; infant; neonate
Introduction Congenital heart defects are the most common of all congenital malformations in the UK, with moderate to severe defects having an incidence of 5e8 per 1000 live births, with similar figures worldwide. Major developments in diagnosis and management over the last decade have led to dramatic improvements in survival with more than 85% of children diagnosed with heart disease now surviving into adulthood. Review of NHS hospital episode statistics (HES) database from 1995e2004 showed a decrease in case fatality rate by 29% and a decrease in mortality rates by 26% in the last decade.
Anjum Gandhi MBBS MD MRCP MRCPCH is a Consultant Paediatrician with Expertise in Cardiology at the Good Hope Hospital, Sutton Coldfield, UK. Srividya Sreekantam MBBS MRCPCH is a Speciality Trainee Year4 in the Department of Paediatrics at the Good Hope Hospital, Sutton Coldfield, UK.
PAEDIATRICS AND CHILD HEALTH 21:1
7
Ó 2010 Elsevier Ltd. All rights reserved.
SYMPOSIUM: CARDIOVASCULAR MEDICINE
Aetiology & associations in congenital cardiac defects Association Genetic Chromosomal anomalies
Single gene defects Environmental Maternal alcohol abuse Maternal Lithium ingestion Maternal Rubella
Causation
Cardiac defect
Down’s syndrome 22q11 deletion syndrome Trisomy 18 Trisomy 13 Noonan’s syndrome Williams syndrome
AVSD, VSD, ASD, TOF Aortic arch defects, TOF VSD, ASD, PDA VSD PS, HOCM, ASD Supra valvular AS, peripheral PS
Foetal alcohol syndrome Ebstein’s anomaly Congenital Rubella syndrome
VSD, ASD, PDA Hypoplastic right ventricle PS, PDA
Table 1
1 in 1000 live births despite improved antenatal detection and termination of pregnancies with these defects. Only 8% of the life-threatening congenital heart defects were diagnosed antenatally, 62% postnatally before discharge from hospital, about 25% diagnosed after discharge from hospital and 5% at autopsy. Most of these defects continue to be a diagnostic challenge in view of their asymptomatic nature at birth. This is precisely the reason why the discharge check an initial screening tool to identify congenital heart defects is known to perform poorly, missing nearly 50% of them. Opportunity to diagnose is missed further by recent trend towards drive through deliveries and the resultant short stay in the hospital. Parents should be made
aware that a normal neonatal examination does not exclude serious congenital heart disease. An ideal screening method with survival prospective would be the one which can identify heart defects with potential to cause neonatal collapse or sudden death. Obstructive lesions of the left heart namely Coarctation of aorta and Hypoplastic left heart syndrome constitute a significant proportion of these and can present at anytime during the first 1 month of life. While no such tool exists, several recent studies have recognized the potential of pulse oximetry in this regard. The accuracy of pulse oximetry as a screening tool has been extensively researched. It is highly specific in identifying aortic arch abnormalities and cyanotic congenital heart disease but has a low sensitivity. However in conjunction with clinical examination this could be a promising strategy in detecting lifethreatening cardiovascular malformations and thereby influence outcome. As heart defects have a varied presentation any realistic hope of making a timely diagnosis relies on the health professionals having a high index of suspicion and a mental check list of pointers to CHD. Majority of the heart defects present during the neonatal period and infancy, with only a small proportion presenting after the age of 1 year.
Indications for foetal echocardiography Maternal factors C Maternal medications - Women on anticonvulsants, Lithium C Maternal diseases - Insulin dependent diabetes mellitus - Mother with Phenylketonuria - Mother exposed to Rubella C Increased Maternal risk for Down’s syndrome and other defects - Advanced maternal age - Increased nuchal thickness on first trimester scans - Increased risk of Down’s syndrome on serum screening
Pointers to CHD in a neonate Unwell neonate. Neonate with feeble pulses. Cyanotic episodes in an infant. Collapse/sudden death in an infant. Neonate with heart murmur. Neonate with dysmorphism or other congenital abnormalities. Neonate with arrhythmias. Neonate with heart failure. Neonate with respiratory distress. Preterm neonate.
Foetal factors Trisomy (21, 18, 13) C Turners syndrome C 22q11 deletion syndrome C Presence of other congenital defects C Non immune hydrops C
Familial risk factors CHD (left heart obstructive disease) Genetic syndromes (Noonan, Marfan, Tuberous sclerosis)
C
Table 2
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Ó 2010 Elsevier Ltd. All rights reserved.
SYMPOSIUM: CARDIOVASCULAR MEDICINE
Congenital heart defects presenting as neonatal collapse/sudden death in infancy Congenital heart defects associated with duct-dependant systemic circulation namely e Coarctation of aorta, Hypoplastic left heart syndrome, Interrupted aortic arch and critical aortic valve stenosis belong to this group. These malformations which require continuing ductal patency to perfuse the whole or even just lower body cause progressive acidosis and impalpable pulses as the duct constricts. Hence timing of presentation is in the first 2e3 weeks of life and usually before the 6-week check. Bearing this in mind it has been recommended that infants should be reassessed by a senior paediatrician perhaps more than once in first 3 weeks of life. Whether this can be adopted in UK clinical practice is debatable. Infants with these defects often remain asymptomatic until the duct closes resulting in shock. Conversely they can have a more insidious onset with symptoms of poor feeding, lethargy, breathlessness, hypothermia and blue episodes. Difficulty in feeding is an important symptom which is often neglected. Though rare, facial palsy secondary to hypertension in Coarctation of aorta has been reported. The infant might show signs of circulatory compromise with metabolic acidosis or might present in heart failure. Even though sepsis and metabolic disorders remain important differential diagnoses in these situations, the clue to a cardiac cause would be weak/absent femoral pulses, significant difference between pre and postductal saturations and decreased lower limb blood pressure.
Congenital heart disease presenting as the blue baby Wide spectrum of heart defects cause cyanosis in infancy and they constitute about 20% of congenital heart disease. Examples include Tetralogy of Fallot (TOF), Pulmonary atresia, severe pulmonary stenosis, Truncus arteriosus, Transposition of great arteries and Total anomalous pulmonary venous connection. These defects depend on ductal patency to maintain pulmonary blood flow and consequently cause cyanosis when duct closes. Timing of presentation can vary from first few days of life to late infancy depending on the presence of associated heart defects and in accordance with variable ductal physiology in neonates. Most dramatic feature would be cyanosis as a result of pulmonary oligaemia or admixture of arterial and venous circulations. Transposition of great arteries is the most common heart defect causing cyanosis in the first week of life. TOF presents with variable cyanosis depending on the severity of outflow tract obstruction and size of VSD. The “hypercyanotic” spells or “tet” spells characteristic of TOF reflect an increase in severity of obstruction. Detection of cyanosis is influenced by its severity, presence of anaemia or polycythaemia and ethnicity. Blue babies with congenital heart disease are usually not breathless unless there is accompanying acidosis or pulmonary oedema. Cyanotic heart disease should always be suspected in the absence of clear cut evidence of a primary respiratory cause of cyanosis. In a neonate with cyanosis and respiratory distress, obstructed total anomalous pulmonary venous connection should always be considered.
Characteristics of pulses in obstructive left heart lesions
Pulse oximetry plays a vital role in the evaluation of cyanosis. Saturations less than 95% in air or a difference of more than 3% between pre and postductal saturations is significant. The appearances of cardiac silhouette on chest X-ray thought to be diagnostic are often not reliable and are dependent on the interpreters skills. The most useful information is regarding cardiac size and pulmonary vascularity. ECG can be useful in some cases. Echocardiography would confirm the diagnosis and help differentiate from Persistent Primary Hypertension of the Newborn (PPHN), a condition which can present similarly. Commencement of prostaglandins and correction of metabolic acidosis forms the main stay of initial stabilization and management. Catheter based emergency procedures like balloon atrial septostomy in TGA to allow interatrial mixing help to improve the patients’ condition prior to definitive surgery. TGA is usually repaired in infancy but most other defects are palliated prior to surgical correction.
Heart defect Hypoplastic left heart syndrome Critical aortic stenosis Interrupted aortic arch Coarctation of aorta
Nature of pulse Weak brachials and femorals Absent brachials and reasonable femorals Good right brachial pulse, absent left brachial pulse and weak femorals Weak femorals, sometimes weak brachials
Traditionally it has been accepted that a finding of lower limb blood pressure less than that of upper limb would indicate aortic arch abnormalities. Limb blood pressure alone has a low positive predictive value in identifying these abnormalities, as blood pressure values are quite variable and erratic even in normal newborns. ECG is often normal. Chest X-ray may be normal or reveal cardiomegaly which should prompt further evaluation. Echocardiography is the diagnostic investigation of choice but depends on the availability of paediatric cardiologists/paediatrician with expertise in cardiology which is often not the scenario in district general hospitals. In this regard development of telemedicine facilities with link to the tertiary cardiac centre has an important role. It is crucial to recognize that echo-cardiographic confirmation while desirable is by no means mandatory and should not be allowed to delay treatment in the form of prostaglandin infusion.
Heart murmur and the risk of having a heart defect Heart murmur a common finding in paediatric population constitutes a major part of referrals to paediatric specialists. Nearly 80% of infants and children are found to have a heart murmur. Majority of them do not have an underlying structural heart defect and the murmur is an incidental finding on examination. Implications and assessment strategies of heart murmur in neonatal period and infancy differ from those in childhood. Although the normal physiological changes occurring in the first few days of life account for some murmurs in the neonatal period, majority of murmurs (up to 54%) in this age group have a pathological basis. Also life-threatening cardiac malformations which are duct dependent often present in the neonatal period
Management involves initial stabilization of the infant with correction of metabolic acidosis if any and commencement of Prostaglandin E1 (Prostin) while awaiting definitive surgical repair.
PAEDIATRICS AND CHILD HEALTH 21:1
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Ó 2010 Elsevier Ltd. All rights reserved.
SYMPOSIUM: CARDIOVASCULAR MEDICINE
and early infancy. Wren et al reported that around 25% of murmurs noted at the 6-week check are due to structural heart defects. For these reasons murmurs in this age group need scrupulous evaluation and early referral to paediatric specialists. Almost any structural heart defect can present as a murmur. Conversely the absence of a murmur does not exclude the presence of congenital heart disease. A methodical approach in evaluation of murmurs focussing on relevant history, thorough cardiovascular examination, appropriate investigations and referral pathways would help us distinguish the innocent from pathological.
a careful physical examination along with a chest X-ray and ECG can be invaluable. Chest X-ray with a focus on cardiac size and pulmonary vascularity can help in differentiating various cyanotic heart diseases. Massive cardiomegaly usually indicates a diagnosis of Ebstein’s anomaly. In the absence of massive cardiomegaly the appearance of cardiac silhouette, though traditionally described to be diagnostic is of doubtful use in practice. Instead evaluation of pulmonary vascularity can be quite useful. Increased pulmonary blood flow suggests the presence of TGA with intact ventricular septum while pulmonary oedema points to a diagnosis of TAPVD with obstruction. All other cyanotic heart disease (pulmonary atresia, tricuspid atresia, TOF) all have decreased pulmonary vascularity and normal or only slightly increased heart size. An ECG can provide further differentiation because of the change in QRS axis. Tricuspid atresia is likely to have a superior QRS axis while pulmonary atresia and TOF often have right axis deviation. Once a diagnosis of CHD is suspected the priority should be to stabilize the infant before making arrangements for a definitive diagnosis. Whether the infant presents with cyanosis, heart failure or shock the priority is to initiate advanced life support as well as keep the arterial duct patent. A stable airway must be maintained to ensure adequate ventilation. Intravenous access should be secured and if necessary an arterial line placed. In the neonate the umbilical vessels are the preferred choice. Depending on the child’s presentation fluid resuscitation and inotropic support may be required. Antibiotic cover for possible sepsis should also be provided. If respiratory distress or severe cyanosis is present the infant requires intubation and ventilation which should be done using adequate sedation and paralyzing agents. Intubation should not be attempted without sedation and paralysis in these fragile infants because of the real risk of inducing serious arrhythmias and even vagally induced asystole. Prostaglandin E1 (Prostin) is needed to keep the arterial duct open. It can be started at an initial dose of 5 ng/kg/min and doubled after 20 min if there is no improvement in saturations. Neonates on low dose Prostin for suspected heart disease do not usually require mechanical ventilation unless clinically indicated. A retrospective population based audit over a 10-year period conducted by New South Wales transport service in Australia highlighted this. However much larger doses (up to 100 ng/kg/min) of Prostin may be needed if the duct has already closed. Failure to respond to Prostin indicates either that the diagnosis is incorrect, or the duct is unresponsive to Prostin, or there is obstruction to pulmonary venous return (obstructed TAPVD). Urgent echocardiography needs to be arranged in this situation. Prostaglandin infusion can cause apnoea and hypotension e continuous cardio respiratory monitoring is therefore indicated. Below is a flow chart (Figure 1) which attempts to summarize this approach.
Does this baby have a congenital heart defect? A simplified approach to answer this question The initial evaluation of the neonate/infant with suspected CHD should include a detailed history, a thorough physical examination including preductal and postductal oxygen saturations, upper and lower limb blood pressures, hyperoxia test and an ECG. A chest X-ray may also be indicated. An echocardiogram is diagnostic but may not always be available and is not mandatory in the initial evaluation. The history should focus not only on the infant’s presentation but should also include detailed obstetric history and family history of CHD. Careful examination for dysmorphic features and other congenital anomalies is equally important. Clinical detection of cyanosis is unreliable and it is vital to check both preductal and postductal saturations. If preductal saturations are higher than postductal saturations it indicates that deoxygenated blood from the pulmonary circulation is being shunted into the descending aorta via a patent arterial duct. This is known as differential cyanosis and suggests a diagnosis of either Persistent Pulmonary Hypertension of the Newborn (PPHN) or Left Heart abnormality (Coarctation of aorta, hypoplastic aortic arch or critical aortic stenosis). Occasionally reversed differential cyanosis (postductal saturation higher than preductal saturation) is seen. While in theory this should only happen when the infant has TGA as well as one of the conditions causing differential cyanosis, in the author’s personal experience it can be noted transiently in well neonates without any CHD. The blood pressure should be measured in the right arm and one of the legs to check for a systolic pressure gradient. If the systolic pressure in the arm is more than 10 mm higher than in the leg it suggests an aortic arch abnormality. However a patent arterial duct may not allow this gradient to manifest. Therefore the absence of a systolic pressure gradient alone does not rule out aortic arch abnormalities. Moreover this should be interpreted with caution because of the inherent variability in the neonatal blood pressure measurements. Hyperoxia test is particularly useful in the neonatal period. It works on the assumption that when there is a right to left shunt in cyanotic heart disease no amount of oxygenation in the pulmonary circulation will alter the desaturating effect of the shunt. Instead if the cyanosis is because of a respiratory cause it can be corrected by increasing the inspired oxygen. Any neonate with oxygen saturations less than 85% in both air and 100% oxygen is very likely to have an intracardiac shunt and treatment for presumed cyanotic heart disease should be commenced. When the hyperoxia test suggests the possibility of cyanotic heart disease and echocardiography is not immediately available
PAEDIATRICS AND CHILD HEALTH 21:1
Future The future is likely to see advances in antenatal diagnosis of congenital heart defects with a larger proportion being detected during pregnancy. Neonatologists and paediatricians with expertise in echocardiography would be increasingly available
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SYMPOSIUM: CARDIOVASCULAR MEDICINE
Infant with suspected CHD 1
2
Collapse
Blue baby
3 Heart murmur
• Weak pulses • ›3% difference between pre- and post-ductal saturations • Abnormal limb BP
• Abnormal saturations • Hyperoxia test +ve Massive heart • CXR Pulmonary oligaemia • ECG – abnormal axis
Blue baby or collapsed infant
Asymptomatic
Aortic arch abnormality
Cyanotic CHD
If abnormal findings as in 1 or 2
Check pre- and post-ductal sats Limb BP ECG
Advanced life support Prostin Transfer to Tertiary centre
If normal then discharge with f/u a local clinic
Figure 1 Algorithm for managing an infant with suspected congenital heart disease.
Dastgiri S, Stone DH, Le-Ha C, et al. Prevalence and secular trend of congenital anomalies in Glasgow, UK. Arch Dis Child 2002; 86: 257e63. ¨m-Westas L, Hanse´us K, et al. Long-distance transports of Hellstro newborn infants with congenital heart disease. Pediatr Cardiol 2001 SepeOct; 22: 380e4. Johnson R, Holzer R. Evaluation of asymptomatic heart murmurs. Current Pediatrics 2005 Dec; 15: 532e8. Liske MR, Greeley CS, et al. Report of the Tennessee Task Force on screening newborn infants for critical congenital heart disease. Pediatrics 2006 Oct; 118: e1250e6. Morris G, Wilson DG. Management of asymptomatic heart murmurs. Current Pediatrics 2000 Dec; 10: 242e7. Sadowski SL, et al. Congenital cardiac disease in the newborn infant: past, present, and future. Crit Care Nurs Clin North Am 2009 Mar; 21: 37e48. vi. Sharland G. Fetal cardiac screening e why bother? Arch Dis Child Fetal Neonatal Ed 2010 Jan; 95: F64e8. Silove ED. Assessment and management of congenital heart disease in newborn by district paediatrician. Arch Dis Child Fetal Neonatal Ed 1994 Jan; 70: F71e4. Thangaratinam S, Daniels J, Ewer AK, et al. Accuracy of pulse oximetry in screening for congenital heart disease in asymptomatic newborns: a systematic review. Arch Dis Child Fetal Neonatal Ed 2007 May; 92: F176e80. Epub 2007 Mar 7. Wray J, Sensky T. Congenital heart disease and cardiac surgery in childhood: effects on cognitive function and academic abilities. Heart 2001; 85: 687e99. Wren C, Richmond S, Donaldson L. Presentation of congenital heart disease in infancy; implications for routine examination. Arch Dis Child Fetal Neonatal Ed 1999; 80: F49e53.
facilitating timely diagnosis and intervention. Increasing availability of telemedicine should also help with early diagnosis.
Conclusion Despite increase in antenatal detection CHD continues to be a diagnostic challenge in neonatal period and infancy. Clinical presentation is broad and overlaps with that of sepsis or metabolic conditions. Consequently high index of suspicion leading to careful detailed evaluation is mandatory to make a timely diagnosis. A stepwise approach focussing on thorough history, comprehensive physical examination and appropriate use of investigations are crucial. While echocardiography is the gold standard one should be able to successfully evaluate and manage suspected CHD in its absence. A
FURTHER READING Abu-Harb M, et al. Presentation of obstructive left heart malformations in infancy. Arch Dis Child 1994; 71: F179e83. Browning Carmo KA, Barr P, et al. Transporting newborn infants with suspected duct dependent congenital heart disease on low-dose prostaglandin E1 without routine mechanical ventilation. Arch Dis Child Fetal Neonatal Ed 2007 Mar; 92: F117e9. Epub 2006 Aug 11. Chaoui R, Korner H, et al. Prenatal diagnosis of heart defects and associated chromosomal aberrations. Ultraschall Med 1999; Oct; 20: 177e84. Clarke E, Kumar M. Evaluation of suspected congenital heart disease in the neonatal period. Current Pediatrics 2005 Dec; 15: 523e31.
PAEDIATRICS AND CHILD HEALTH 21:1
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Ó 2010 Elsevier Ltd. All rights reserved.
SYMPOSIUM: CARDIOVASCULAR MEDICINE
C
Practice points C
C
C
Antenatal screening is a useful tool in detecting major congenital heart defects allowing better planned management. A child with congenital heart disease should be carefully examined for dsysmorphic features and if necessary a karyotype and/or specific genetic tests should be arranged. Life-threatening congenital heart defects are often asymptomatic at birth and should be part of differential diagnosis in any unwell neonate.
PAEDIATRICS AND CHILD HEALTH 21:1
C
C
12
Cyanosis can be difficult to detect, therefore Pulse Oximetry to measure the pre and postductal saturations should always be performed in any infant who is unwell or presenting with non-specific symptoms and signs. Information about pulmonary vascularity can be more useful than appearances of cardiac silhouette in a chest X-ray in the evaluation of CHD. Commencement of Prostaglandins can be life saving intervention while awaiting a definitive diagnosis.
Ó 2010 Elsevier Ltd. All rights reserved.
Evaluation of suspected congenital heart disease
Despite this, congenital heart disease (CHD) still accounts for over 40% of deaths from congenital malformations and 3% of all infant deaths. Notably one third of all children born with CHD become critically ill in the first year of life and either die or receive surgical treatment. Early diagnosis and appropriate management are essential to improve outcome.
Anjum Gandhi Srividya Sreekantam
Aetiology Causation of CHD is thought to be multi-factorial resulting from combination of genetic predisposition and environmental stimuli. Having a child with CHD confers a 2% risk in a subsequent pregnancy. A mother with CHD has 6% risk of having an affected offspring while an affected father has a 2% risk. The proportion of congenital heart defects associated with chromosomal anomalies varies between 4 and 12% but can be as high as 22% if antenatal deaths in foetuses are included. Most common heart defects noted in foetal autopsies are ventricular septal defect, atrioventricular septal defect; hypoplastic left heart and double outlet right ventricle which together make up to 72% of all defects. Although hereditary and genetic factors play a major role in causing cardiac malformations some known teratogens are also associated. Table 1 illustrates the common genetic and environmental factors associated with congenital heart disease.
Abstract Congenital heart disease {CHD} still accounts for significant morbidity and mortality, despite major advances in diagnosis and management. It predominantly manifests in the neonatal period and early infancy. Presentation is protean ranging from a well baby with a heart murmur to a baby in extremis. Although advances in antenatal ultrasonography and foetal echocardiography continue to improve detection rates a significant proportion of CHD is still undiagnosed at birth emphasizing the need for a detailed history and meticulous clinical examination. No reliable screening tool exists but pulse oximetry can be quite useful despite its relatively low sensitivity. Limb blood pressure values are quite variable in the newborn and hence should be interpreted with caution. Chest X-ray with a focus on cardiac size and pulmonary vascularity can be useful in the evaluation of cyanotic heart conditions. ECG can provide additional information about axis and chamber hypertrophy. Echocardiography is the gold standard but not always available. Once a diagnosis of CHD is suspected the priority is to stabilize the infant. This usually involves initiation of advanced life support and commencement of Prostaglandins to keep the duct open. As clinical presentation of CHD is broad and similar to other conditions such as sepsis and metabolic disorders a high index of suspicion and systematic approach remain vital to make a timely diagnosis.
Antenatal diagnosis and management of heart disease The increasing use of obstetric ultrasound and foetal echocardiography means that the opportunity to provide optimal care to a newborn with CHD begins in the antenatal period. Current UK practice is to undertake a four chamber cardiac view as a part of antenatal screening ultrasound at 18e20 weeks gestation. This has a relatively low detection rate of 25%. Table 2 illustrates the high-risk categories that fit the criteria for foetal echocardiography. The purpose of antenatal screening is to detect major congenital heart defects which have significant impact on postnatal survival. Examples would include Coarctation of aorta, Transposition of great arteries and Hypoplastic left heart syndrome. Studies looking at the benefits of antenatal screening in detecting these conditions have clearly demonstrated better outcomes in terms of mortality although there was no major effect on morbidity. Based on severity of heart defect and its prognosis parents can be counselled antenatally regarding management options which include planned delivery in a tertiary cardiac centre and sadly in some cases termination of pregnancy. Such decision making however remains a complex issue influenced heavily by cultural/ religious back ground, ethical issues, perceived quality of life and parental choice. Clearly the advantages of antenatal screening are manifold. However a review of 20-year trends in the diagnosis of life-threatening cardiovascular malformations revealed that a significant proportion still remains undiagnosed. These include Coarctation of aorta, interrupted aortic arch, aortic stenosis and TAPVD. The detection rate of cardiovascular malformations could be improved by additional view of outflow tracts on antenatal scans which is currently not a requirement but would count as good practice. The review also clearly highlighted that the prevalence of lifethreatening cardiovascular malformations remains unaltered at
Keywords congenital heart disease; infant; neonate
Introduction Congenital heart defects are the most common of all congenital malformations in the UK, with moderate to severe defects having an incidence of 5e8 per 1000 live births, with similar figures worldwide. Major developments in diagnosis and management over the last decade have led to dramatic improvements in survival with more than 85% of children diagnosed with heart disease now surviving into adulthood. Review of NHS hospital episode statistics (HES) database from 1995e2004 showed a decrease in case fatality rate by 29% and a decrease in mortality rates by 26% in the last decade.
Anjum Gandhi MBBS MD MRCP MRCPCH is a Consultant Paediatrician with Expertise in Cardiology at the Good Hope Hospital, Sutton Coldfield, UK. Srividya Sreekantam MBBS MRCPCH is a Speciality Trainee Year4 in the Department of Paediatrics at the Good Hope Hospital, Sutton Coldfield, UK.
PAEDIATRICS AND CHILD HEALTH 21:1
7
Ó 2010 Elsevier Ltd. All rights reserved.
SYMPOSIUM: CARDIOVASCULAR MEDICINE
Aetiology & associations in congenital cardiac defects Association Genetic Chromosomal anomalies
Single gene defects Environmental Maternal alcohol abuse Maternal Lithium ingestion Maternal Rubella
Causation
Cardiac defect
Down’s syndrome 22q11 deletion syndrome Trisomy 18 Trisomy 13 Noonan’s syndrome Williams syndrome
AVSD, VSD, ASD, TOF Aortic arch defects, TOF VSD, ASD, PDA VSD PS, HOCM, ASD Supra valvular AS, peripheral PS
Foetal alcohol syndrome Ebstein’s anomaly Congenital Rubella syndrome
VSD, ASD, PDA Hypoplastic right ventricle PS, PDA
Table 1
1 in 1000 live births despite improved antenatal detection and termination of pregnancies with these defects. Only 8% of the life-threatening congenital heart defects were diagnosed antenatally, 62% postnatally before discharge from hospital, about 25% diagnosed after discharge from hospital and 5% at autopsy. Most of these defects continue to be a diagnostic challenge in view of their asymptomatic nature at birth. This is precisely the reason why the discharge check an initial screening tool to identify congenital heart defects is known to perform poorly, missing nearly 50% of them. Opportunity to diagnose is missed further by recent trend towards drive through deliveries and the resultant short stay in the hospital. Parents should be made
aware that a normal neonatal examination does not exclude serious congenital heart disease. An ideal screening method with survival prospective would be the one which can identify heart defects with potential to cause neonatal collapse or sudden death. Obstructive lesions of the left heart namely Coarctation of aorta and Hypoplastic left heart syndrome constitute a significant proportion of these and can present at anytime during the first 1 month of life. While no such tool exists, several recent studies have recognized the potential of pulse oximetry in this regard. The accuracy of pulse oximetry as a screening tool has been extensively researched. It is highly specific in identifying aortic arch abnormalities and cyanotic congenital heart disease but has a low sensitivity. However in conjunction with clinical examination this could be a promising strategy in detecting lifethreatening cardiovascular malformations and thereby influence outcome. As heart defects have a varied presentation any realistic hope of making a timely diagnosis relies on the health professionals having a high index of suspicion and a mental check list of pointers to CHD. Majority of the heart defects present during the neonatal period and infancy, with only a small proportion presenting after the age of 1 year.
Indications for foetal echocardiography Maternal factors C Maternal medications - Women on anticonvulsants, Lithium C Maternal diseases - Insulin dependent diabetes mellitus - Mother with Phenylketonuria - Mother exposed to Rubella C Increased Maternal risk for Down’s syndrome and other defects - Advanced maternal age - Increased nuchal thickness on first trimester scans - Increased risk of Down’s syndrome on serum screening
Pointers to CHD in a neonate Unwell neonate. Neonate with feeble pulses. Cyanotic episodes in an infant. Collapse/sudden death in an infant. Neonate with heart murmur. Neonate with dysmorphism or other congenital abnormalities. Neonate with arrhythmias. Neonate with heart failure. Neonate with respiratory distress. Preterm neonate.
Foetal factors Trisomy (21, 18, 13) C Turners syndrome C 22q11 deletion syndrome C Presence of other congenital defects C Non immune hydrops C
Familial risk factors CHD (left heart obstructive disease) Genetic syndromes (Noonan, Marfan, Tuberous sclerosis)
C
Table 2
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Ó 2010 Elsevier Ltd. All rights reserved.
SYMPOSIUM: CARDIOVASCULAR MEDICINE
Congenital heart defects presenting as neonatal collapse/sudden death in infancy Congenital heart defects associated with duct-dependant systemic circulation namely e Coarctation of aorta, Hypoplastic left heart syndrome, Interrupted aortic arch and critical aortic valve stenosis belong to this group. These malformations which require continuing ductal patency to perfuse the whole or even just lower body cause progressive acidosis and impalpable pulses as the duct constricts. Hence timing of presentation is in the first 2e3 weeks of life and usually before the 6-week check. Bearing this in mind it has been recommended that infants should be reassessed by a senior paediatrician perhaps more than once in first 3 weeks of life. Whether this can be adopted in UK clinical practice is debatable. Infants with these defects often remain asymptomatic until the duct closes resulting in shock. Conversely they can have a more insidious onset with symptoms of poor feeding, lethargy, breathlessness, hypothermia and blue episodes. Difficulty in feeding is an important symptom which is often neglected. Though rare, facial palsy secondary to hypertension in Coarctation of aorta has been reported. The infant might show signs of circulatory compromise with metabolic acidosis or might present in heart failure. Even though sepsis and metabolic disorders remain important differential diagnoses in these situations, the clue to a cardiac cause would be weak/absent femoral pulses, significant difference between pre and postductal saturations and decreased lower limb blood pressure.
Congenital heart disease presenting as the blue baby Wide spectrum of heart defects cause cyanosis in infancy and they constitute about 20% of congenital heart disease. Examples include Tetralogy of Fallot (TOF), Pulmonary atresia, severe pulmonary stenosis, Truncus arteriosus, Transposition of great arteries and Total anomalous pulmonary venous connection. These defects depend on ductal patency to maintain pulmonary blood flow and consequently cause cyanosis when duct closes. Timing of presentation can vary from first few days of life to late infancy depending on the presence of associated heart defects and in accordance with variable ductal physiology in neonates. Most dramatic feature would be cyanosis as a result of pulmonary oligaemia or admixture of arterial and venous circulations. Transposition of great arteries is the most common heart defect causing cyanosis in the first week of life. TOF presents with variable cyanosis depending on the severity of outflow tract obstruction and size of VSD. The “hypercyanotic” spells or “tet” spells characteristic of TOF reflect an increase in severity of obstruction. Detection of cyanosis is influenced by its severity, presence of anaemia or polycythaemia and ethnicity. Blue babies with congenital heart disease are usually not breathless unless there is accompanying acidosis or pulmonary oedema. Cyanotic heart disease should always be suspected in the absence of clear cut evidence of a primary respiratory cause of cyanosis. In a neonate with cyanosis and respiratory distress, obstructed total anomalous pulmonary venous connection should always be considered.
Characteristics of pulses in obstructive left heart lesions
Pulse oximetry plays a vital role in the evaluation of cyanosis. Saturations less than 95% in air or a difference of more than 3% between pre and postductal saturations is significant. The appearances of cardiac silhouette on chest X-ray thought to be diagnostic are often not reliable and are dependent on the interpreters skills. The most useful information is regarding cardiac size and pulmonary vascularity. ECG can be useful in some cases. Echocardiography would confirm the diagnosis and help differentiate from Persistent Primary Hypertension of the Newborn (PPHN), a condition which can present similarly. Commencement of prostaglandins and correction of metabolic acidosis forms the main stay of initial stabilization and management. Catheter based emergency procedures like balloon atrial septostomy in TGA to allow interatrial mixing help to improve the patients’ condition prior to definitive surgery. TGA is usually repaired in infancy but most other defects are palliated prior to surgical correction.
Heart defect Hypoplastic left heart syndrome Critical aortic stenosis Interrupted aortic arch Coarctation of aorta
Nature of pulse Weak brachials and femorals Absent brachials and reasonable femorals Good right brachial pulse, absent left brachial pulse and weak femorals Weak femorals, sometimes weak brachials
Traditionally it has been accepted that a finding of lower limb blood pressure less than that of upper limb would indicate aortic arch abnormalities. Limb blood pressure alone has a low positive predictive value in identifying these abnormalities, as blood pressure values are quite variable and erratic even in normal newborns. ECG is often normal. Chest X-ray may be normal or reveal cardiomegaly which should prompt further evaluation. Echocardiography is the diagnostic investigation of choice but depends on the availability of paediatric cardiologists/paediatrician with expertise in cardiology which is often not the scenario in district general hospitals. In this regard development of telemedicine facilities with link to the tertiary cardiac centre has an important role. It is crucial to recognize that echo-cardiographic confirmation while desirable is by no means mandatory and should not be allowed to delay treatment in the form of prostaglandin infusion.
Heart murmur and the risk of having a heart defect Heart murmur a common finding in paediatric population constitutes a major part of referrals to paediatric specialists. Nearly 80% of infants and children are found to have a heart murmur. Majority of them do not have an underlying structural heart defect and the murmur is an incidental finding on examination. Implications and assessment strategies of heart murmur in neonatal period and infancy differ from those in childhood. Although the normal physiological changes occurring in the first few days of life account for some murmurs in the neonatal period, majority of murmurs (up to 54%) in this age group have a pathological basis. Also life-threatening cardiac malformations which are duct dependent often present in the neonatal period
Management involves initial stabilization of the infant with correction of metabolic acidosis if any and commencement of Prostaglandin E1 (Prostin) while awaiting definitive surgical repair.
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SYMPOSIUM: CARDIOVASCULAR MEDICINE
and early infancy. Wren et al reported that around 25% of murmurs noted at the 6-week check are due to structural heart defects. For these reasons murmurs in this age group need scrupulous evaluation and early referral to paediatric specialists. Almost any structural heart defect can present as a murmur. Conversely the absence of a murmur does not exclude the presence of congenital heart disease. A methodical approach in evaluation of murmurs focussing on relevant history, thorough cardiovascular examination, appropriate investigations and referral pathways would help us distinguish the innocent from pathological.
a careful physical examination along with a chest X-ray and ECG can be invaluable. Chest X-ray with a focus on cardiac size and pulmonary vascularity can help in differentiating various cyanotic heart diseases. Massive cardiomegaly usually indicates a diagnosis of Ebstein’s anomaly. In the absence of massive cardiomegaly the appearance of cardiac silhouette, though traditionally described to be diagnostic is of doubtful use in practice. Instead evaluation of pulmonary vascularity can be quite useful. Increased pulmonary blood flow suggests the presence of TGA with intact ventricular septum while pulmonary oedema points to a diagnosis of TAPVD with obstruction. All other cyanotic heart disease (pulmonary atresia, tricuspid atresia, TOF) all have decreased pulmonary vascularity and normal or only slightly increased heart size. An ECG can provide further differentiation because of the change in QRS axis. Tricuspid atresia is likely to have a superior QRS axis while pulmonary atresia and TOF often have right axis deviation. Once a diagnosis of CHD is suspected the priority should be to stabilize the infant before making arrangements for a definitive diagnosis. Whether the infant presents with cyanosis, heart failure or shock the priority is to initiate advanced life support as well as keep the arterial duct patent. A stable airway must be maintained to ensure adequate ventilation. Intravenous access should be secured and if necessary an arterial line placed. In the neonate the umbilical vessels are the preferred choice. Depending on the child’s presentation fluid resuscitation and inotropic support may be required. Antibiotic cover for possible sepsis should also be provided. If respiratory distress or severe cyanosis is present the infant requires intubation and ventilation which should be done using adequate sedation and paralyzing agents. Intubation should not be attempted without sedation and paralysis in these fragile infants because of the real risk of inducing serious arrhythmias and even vagally induced asystole. Prostaglandin E1 (Prostin) is needed to keep the arterial duct open. It can be started at an initial dose of 5 ng/kg/min and doubled after 20 min if there is no improvement in saturations. Neonates on low dose Prostin for suspected heart disease do not usually require mechanical ventilation unless clinically indicated. A retrospective population based audit over a 10-year period conducted by New South Wales transport service in Australia highlighted this. However much larger doses (up to 100 ng/kg/min) of Prostin may be needed if the duct has already closed. Failure to respond to Prostin indicates either that the diagnosis is incorrect, or the duct is unresponsive to Prostin, or there is obstruction to pulmonary venous return (obstructed TAPVD). Urgent echocardiography needs to be arranged in this situation. Prostaglandin infusion can cause apnoea and hypotension e continuous cardio respiratory monitoring is therefore indicated. Below is a flow chart (Figure 1) which attempts to summarize this approach.
Does this baby have a congenital heart defect? A simplified approach to answer this question The initial evaluation of the neonate/infant with suspected CHD should include a detailed history, a thorough physical examination including preductal and postductal oxygen saturations, upper and lower limb blood pressures, hyperoxia test and an ECG. A chest X-ray may also be indicated. An echocardiogram is diagnostic but may not always be available and is not mandatory in the initial evaluation. The history should focus not only on the infant’s presentation but should also include detailed obstetric history and family history of CHD. Careful examination for dysmorphic features and other congenital anomalies is equally important. Clinical detection of cyanosis is unreliable and it is vital to check both preductal and postductal saturations. If preductal saturations are higher than postductal saturations it indicates that deoxygenated blood from the pulmonary circulation is being shunted into the descending aorta via a patent arterial duct. This is known as differential cyanosis and suggests a diagnosis of either Persistent Pulmonary Hypertension of the Newborn (PPHN) or Left Heart abnormality (Coarctation of aorta, hypoplastic aortic arch or critical aortic stenosis). Occasionally reversed differential cyanosis (postductal saturation higher than preductal saturation) is seen. While in theory this should only happen when the infant has TGA as well as one of the conditions causing differential cyanosis, in the author’s personal experience it can be noted transiently in well neonates without any CHD. The blood pressure should be measured in the right arm and one of the legs to check for a systolic pressure gradient. If the systolic pressure in the arm is more than 10 mm higher than in the leg it suggests an aortic arch abnormality. However a patent arterial duct may not allow this gradient to manifest. Therefore the absence of a systolic pressure gradient alone does not rule out aortic arch abnormalities. Moreover this should be interpreted with caution because of the inherent variability in the neonatal blood pressure measurements. Hyperoxia test is particularly useful in the neonatal period. It works on the assumption that when there is a right to left shunt in cyanotic heart disease no amount of oxygenation in the pulmonary circulation will alter the desaturating effect of the shunt. Instead if the cyanosis is because of a respiratory cause it can be corrected by increasing the inspired oxygen. Any neonate with oxygen saturations less than 85% in both air and 100% oxygen is very likely to have an intracardiac shunt and treatment for presumed cyanotic heart disease should be commenced. When the hyperoxia test suggests the possibility of cyanotic heart disease and echocardiography is not immediately available
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Future The future is likely to see advances in antenatal diagnosis of congenital heart defects with a larger proportion being detected during pregnancy. Neonatologists and paediatricians with expertise in echocardiography would be increasingly available
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SYMPOSIUM: CARDIOVASCULAR MEDICINE
Infant with suspected CHD 1
2
Collapse
Blue baby
3 Heart murmur
• Weak pulses • ›3% difference between pre- and post-ductal saturations • Abnormal limb BP
• Abnormal saturations • Hyperoxia test +ve Massive heart • CXR Pulmonary oligaemia • ECG – abnormal axis
Blue baby or collapsed infant
Asymptomatic
Aortic arch abnormality
Cyanotic CHD
If abnormal findings as in 1 or 2
Check pre- and post-ductal sats Limb BP ECG
Advanced life support Prostin Transfer to Tertiary centre
If normal then discharge with f/u a local clinic
Figure 1 Algorithm for managing an infant with suspected congenital heart disease.
Dastgiri S, Stone DH, Le-Ha C, et al. Prevalence and secular trend of congenital anomalies in Glasgow, UK. Arch Dis Child 2002; 86: 257e63. ¨m-Westas L, Hanse´us K, et al. Long-distance transports of Hellstro newborn infants with congenital heart disease. Pediatr Cardiol 2001 SepeOct; 22: 380e4. Johnson R, Holzer R. Evaluation of asymptomatic heart murmurs. Current Pediatrics 2005 Dec; 15: 532e8. Liske MR, Greeley CS, et al. Report of the Tennessee Task Force on screening newborn infants for critical congenital heart disease. Pediatrics 2006 Oct; 118: e1250e6. Morris G, Wilson DG. Management of asymptomatic heart murmurs. Current Pediatrics 2000 Dec; 10: 242e7. Sadowski SL, et al. Congenital cardiac disease in the newborn infant: past, present, and future. Crit Care Nurs Clin North Am 2009 Mar; 21: 37e48. vi. Sharland G. Fetal cardiac screening e why bother? Arch Dis Child Fetal Neonatal Ed 2010 Jan; 95: F64e8. Silove ED. Assessment and management of congenital heart disease in newborn by district paediatrician. Arch Dis Child Fetal Neonatal Ed 1994 Jan; 70: F71e4. Thangaratinam S, Daniels J, Ewer AK, et al. Accuracy of pulse oximetry in screening for congenital heart disease in asymptomatic newborns: a systematic review. Arch Dis Child Fetal Neonatal Ed 2007 May; 92: F176e80. Epub 2007 Mar 7. Wray J, Sensky T. Congenital heart disease and cardiac surgery in childhood: effects on cognitive function and academic abilities. Heart 2001; 85: 687e99. Wren C, Richmond S, Donaldson L. Presentation of congenital heart disease in infancy; implications for routine examination. Arch Dis Child Fetal Neonatal Ed 1999; 80: F49e53.
facilitating timely diagnosis and intervention. Increasing availability of telemedicine should also help with early diagnosis.
Conclusion Despite increase in antenatal detection CHD continues to be a diagnostic challenge in neonatal period and infancy. Clinical presentation is broad and overlaps with that of sepsis or metabolic conditions. Consequently high index of suspicion leading to careful detailed evaluation is mandatory to make a timely diagnosis. A stepwise approach focussing on thorough history, comprehensive physical examination and appropriate use of investigations are crucial. While echocardiography is the gold standard one should be able to successfully evaluate and manage suspected CHD in its absence. A
FURTHER READING Abu-Harb M, et al. Presentation of obstructive left heart malformations in infancy. Arch Dis Child 1994; 71: F179e83. Browning Carmo KA, Barr P, et al. Transporting newborn infants with suspected duct dependent congenital heart disease on low-dose prostaglandin E1 without routine mechanical ventilation. Arch Dis Child Fetal Neonatal Ed 2007 Mar; 92: F117e9. Epub 2006 Aug 11. Chaoui R, Korner H, et al. Prenatal diagnosis of heart defects and associated chromosomal aberrations. Ultraschall Med 1999; Oct; 20: 177e84. Clarke E, Kumar M. Evaluation of suspected congenital heart disease in the neonatal period. Current Pediatrics 2005 Dec; 15: 523e31.
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SYMPOSIUM: CARDIOVASCULAR MEDICINE
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Antenatal screening is a useful tool in detecting major congenital heart defects allowing better planned management. A child with congenital heart disease should be carefully examined for dsysmorphic features and if necessary a karyotype and/or specific genetic tests should be arranged. Life-threatening congenital heart defects are often asymptomatic at birth and should be part of differential diagnosis in any unwell neonate.
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Cyanosis can be difficult to detect, therefore Pulse Oximetry to measure the pre and postductal saturations should always be performed in any infant who is unwell or presenting with non-specific symptoms and signs. Information about pulmonary vascularity can be more useful than appearances of cardiac silhouette in a chest X-ray in the evaluation of CHD. Commencement of Prostaglandins can be life saving intervention while awaiting a definitive diagnosis.
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