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Evaluation of suspected congenital heart disease in the neonatal period
Current Paediatrics (2000) 10, 229–235 © 2000 Harcourt Publishers Ltd doi: 10.1054/ cupe.2000.0086, available online at http://www.idealibrary.com on
Symposium: Cardiology
Evaluation of suspected congenital heart disease in the neonatal period
R. M. Blumberg, H. M. Gardiner
disease. The presentation of congenital heart disease in this period has been the subject of study in the Northern health region of England; the authors recommend early referral of infants with symptoms or a murmur to a paediatric cardiologist.2–4
INTRODUCTION Congenital heart disease (CHD) is the commonest single group of structural malformations with an incidence of 0.5%–0.8% live births. Although much remains unknown about the genetic aetiology of CHD, exogenous teratogens, chromosomal abnormalities and many syndromes are associated with cardiac defects (Table 1). The risk of recurrence in a family with a previously affected child is about 2%, whilst it is approximately 5% in children of parents with a major cardiac abnormality.1 The current recommendations for screening for CHD are examination within 24 h of birth and a second review at 6–8 weeks of age. The first examination takes place at a time of rapid adaptation of the cardiopulmonary circulation and may both miss, or incorrectly suggest congenital heart disease, as only half the murmurs detected are pathological. Indeed, severe heart disease may have no signs in the immediate neonatal period. Specifically, left ventricular outflow tract obstruction presenting after discharge from hospital in the interval before the second review carries significant mortality if unrecognized. The trend to early discharge means that more infants are likely to develop symptoms at home and emphasizes the need for recognition of heart disease by community midwives, health visitors and general practitioners. Parents too, should be aware that a normal neonatal examination does not exclude heart
CARDIOPULMONARY CHANGES IN THE PERINATAL PERIOD The fetal circulation has systemic and pulmonary components operating in parallel. Normally, oxygenated blood reaching the right heart bypasses the high resistance pulmonary circulation and flows through the arterial duct to the aorta. Pre-natal survival is not endangered even by severe cardiac abnormality as long as one side of the heart can deliver blood from the caval veins to the aorta, bypassing non-functioning chambers. Successful neonatal adaptation depends on expansion of the lungs and remodelling of the thick walled pulmonary vessels, reducing pulmonary vascular pressure and increasing flow. Systemic vascular resistance rises with clamping of the cord and separation from the low resistance placental circulation. The increase in pulmonary blood flow raises left atrial pressure and closes the oval foramen. A rise in arterial oxygen content further dilates pulmonary capillaries and initiates closure of the arterial duct. Thus two vascular circuits connected in series are established, one receiving deoxygenated blood and delivering it to the lungs, and the other receiving oxygenated blood and delivering it to the peripheral tissues. In term infants, functional closure of the arterial duct occurs by contraction of smooth muscle and is complete by 10–15 h. Anatomical closure takes place by 2–3 weeks and the duct is completely closed by 8 weeks in 90% of infants without other cardiac anomalies.
Raoul M. Blumberg, Senior Registrar, Department of Paediatrics and Neonatal Medicine, Hammersmith Hospital, London, UK Helena M. Gardiner, Senior Lecturer in Perinatal Cardiology, Department of Maternofetal Medicine, Division of Paediatrics, Obstetrics & Gynaecology, Queen Charlotte’s and Chelsea Hospital, Imperial College School of Medicine, London, UK Correspondence to HMG
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Current Paediatrics Table 1 Common teratogens and chromosomal anomalies related to congenital heart disease Rubella SLE Alcohol Diabetes Phenytoin Lithium Down syndrome (Trisomy 21) Turner syndrome (45XO) Patau syndrome (Trisomy 13) Edward syndrome (Trisomy 18) Ch 22 microdeletion
Table 2
PDA, Peripheral pulmonary stenosis Complete heart block PDA, VSD, Tetralogy of Fallot Cardiomyopathy, TGA, VSD VSD, ASD, Coarctation Ebstein’s anomaly AVSD, VSD, ASD, Tetralogy of Fallot Coarctation, Aortic stenosis VSD, Various defects VSD, Various defects Conotruncal abnormalities (or any defect)
Categories and percentage incidence of congenital heart disease Cyanotic congenital heart disease
Decreased pulmonary blood flow Tetralogy of Fallot and PS Tricuspid atresia Ebstein’s anomaly Pulmonary valve stenosis Pulmonary atresia with VSD
Increased pulmonary blood flow 5–10% 1–3% <1% 1–2% 1%
Transposition of the great arteries Common arterial trunk TAPVC Double outlet right ventricle Tetralogy of Fallot
5–15% 1–2% 1–2% 1–2%
Acyanotic congenital heart disease Left heart obstruction Coarctation of aorta Aortic stenosis Hypoplastic left heart syndrome Interruption of the aortic arch
Left-to-right shunts 3–5% 2–3% 1–2% <1%
PRESENTATION OF CONGENITAL HEART DISEASE Antenatal Routine anomaly scanning around 20 weeks gestation may detect hypoplasia of the right or left ventricle or abnormalities of the pulmonary trunk or aorta, but currently only identifies about 25% of children with significant cardiac problems. Detailed fetal cardiac assessment should be performed on those with abnormal scan findings, a family history of previous cardiac anomaly or in high risk pregnancies (e.g. maternal systemic lupus erythematosus, diabetes mellitus, or multifetal pregnancies). In the neonatal period CHD (Table 2) can present as • cyanosis with or without respiratory distress • asymptomatic murmur • low output states following closure of the arterial duct • left heart overload with pulmonary congestion • high output states Cyanosis with or without respiratory distress Distinction of cardiac and respiratory disease in the neonate may be difficult immediately following birth. The chief signs underlying both, are respiratory pattern and cyanosis. Normally the respiratory rate
PDA VSD Secundum ASD AVSD/partial AVSD
10–15% 10–20% 5–15% 1–3%
decreases progressively on the first day of life from 50–60 breaths/min to 35–50 breaths/min and mild recession or brief grunting disappear within hours. Tachypnoea due to intrinsic pulmonary disease or airway obstruction will be accompanied by recession, nasal flaring and grunting. In contrast, intense cyanosis with minimal respiratory distress or increase in depth of respiration suggests congenital cyanotic heart disease with decreased pulmonary blood flow. A chest Xray may be diagnostic of a primary lung disorder (e.g. hyaline membrane disease, pneumonia, aspiration) or mechanical interference with respiratory function (e.g. pneumothorax, tracheo-oesophageal fistula, choanal atresia). As the time increases between birth and the development of symptoms a respiratory diagnosis becomes less likely, particularly after a period of wellbeing. Table 3 shows the likely presentation of CHD chronologically following birth. Persistent pulmonary hypertension of the newborn may present with cyanosis. This should be considered in an infant with corroborative history of suspected sepsis, meconium aspiration with X-ray changes or asphyxia. Arterial oxygen saturation improves with hyperoxygenation, hyperventilation and pulmonary vasodilation using nitric oxide or prostacyclin. An important differential diagnosis is infracardiac total anomalous pulmonary venous connections (TAPVC) with obstructed pulmonary venous circulation, which can only be diagnosed on echocardiogram.
CHD in neonates Table 3
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Likely presentation of congenital heart disease by age
Time
Condition
Features
0–3 days
Transposition with intact septum Tricuspid atresia Pulmonary atresia/critical PS Infracardiac TAPVC Hypoplastic left heart Critical aortic stenosis Coarctation Interrupted aortic arch Severe PS Supracardiac/cardiac TAPVC Tetralogy of Fallot (RVOT obstruction) Common arterial trunk
Cyanosis Cyanosis Cyanosis Tachypnoea, cyanosis
0–7 days
7–14 days 14 days–3 months
3 months +
}
Coarctation Transposition/VSD Tetralogy of Fallot (minimal RVOT) Atrioventricular septal defects Double outlet right ventricle (no PS) Missed transposition with pulmonary hypertension Anomalous left coronary artery
}
Dilated cardiomyopathy Left to right shunts (VSD, PDA, ASD)
Asymptomatic murmur Asymptomatic murmurs in newborns may be due to the changing circulation (closing patent arterial duct), small ventricular septal defects, or moderate semilunar valve obstruction (arterial or pulmonary stenosis). Low output states Obstructed or inadequate systemic circulation resulting from hypoplastic left heart syndrome, critical aortic stenosis, mitral valve abnormalities, coarctation or interruption of the aortic arch produce a low output state. Symptoms occur following closure of the arterial duct. Systemic blood pressure is poor with decreased pulses and peripheral perfusion leading to increasing hypoxaemia and acidosis. Significant left to right shunts A significant left to right shunt presents with left heart volume overload and pulmonary venous congestion with interstitial oedema and reduced lung compliance, increasing the work of breathing and reducing gas transfer. Symptoms include breathlessness, poor feeding and sweating. Clinically there is tachycardia, with a murmur or gallop rhythm, tachypnoea, hepatomegaly, cool peripheries and failure to thrive.
Low output state & Discordant brachial pulses Cyanosis, murmur Cyanosis, tachypnoea Cyanosis, murmur Bounding pulses ± Cyanosis, tachypnoea Low output state Cyanosis, tachypnoea Tachypnoea Left to right shunt Cyanosis, loud P2 Small heart Ischaemia (‘colic’) Episodic tachypnoea, LVF Biventricular failure Left heart overload
INVESTIGATION OF CONGENITAL CARDIAC DISEASE Diagnostic algorithms and Tables 4 and 5 provide guidelines to aid diagnosis of CHD. However, the availability of good echocardiographic equipment on neonatal units and education to improve echocardiographic skills of neonatologists are essential to provide early assessment of suspected heart disease and to guide emergency management. CYANOTIC CONGENITAL HEART DISEASE The classic mnemonic of the 5 Ts remains useful, Tetralogy of Fallot, Tricuspid valve abnormalities, Transposition of the great arteries, common arterial Trunk and Total anomalous pulmonary venous connections), but critical pulmonary stenosis and atresia also form part of this group. Clinically it is more useful to approach the problem physiologically: • right to left shunt • inadequate pulmonary blood flow • common mixing lesions with increased pulmonary blood flow Cyanotic heart disease with decreased pulmonary blood flow
High output states
Tetralogy of Fallot
High output states (e.g. arteriovenous malformation) are rare but may present with intractable heart failure and a bruit over the head should be sought and cranial ultrasound performed to exclude vein of Galen aneurysm.
There is a spectrum of presentation from severe cyanosis with duct-dependent blood flow to ‘pink’ with high pulmonary blood flow and breathlessness. More commonly, infants are cyanosed and the chest X-ray may show decreased pulmonary vascularity.
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Pulmonary valve stenosis/atresia Abnormalities of the pulmonary valve are common and form a spectrum of severity. The mildest forms present later in childhood but, if severe or critical, present in the neonatal period as forward flow to the lungs is obstructed and pulmonary blood flow is therefore ductdependent. Severe tricuspid regurgitation (TR) may cause a right to left atrial shunt. If the patent oval foramen (PFO) is restrictive then right atrial enlargement is followed by hepatic venous engorgement. In pulmonary atresia with intact ventricular septum the right ventricle is hypoplastic with or without sinusoids (fistulae from the coronary artery to the right ventricular cavity). Management of this condition is difficult, but right ventricular (RV) growth may occur if forward flow can be established. Tricuspid valve abnormalities Tricuspid valve abnormalities may prevent normal growth of the right heart and reduce pulmonary blood flow. The valve may be either atretic, hypoplastic, or displaced (Ebstein’s anomaly). In tricuspid atresia there is no communication between the right atrium and right ventricle (‘absent right connection’) and there must be an obligatory right-to-left shunt for survival. Physiological consequences are dependent upon the presence of a ventricular septal defect (VSD), pulmonary stenosis and the relationship of the great arteries. If the VSD is small then there is always a small right ventricular cavity with obstruction to outflow. Ebstein’s anomaly Ebstein’s anomaly is a malformation of the tricuspid valve with a continuum of severity related to the
degree of displacement of the tricuspid valve into the cavity of the right ventricle. More severe displacement critically reduces the volume of the cavity, narrowing the right ventricular outlet and restricting forward flow. Severe forms present with cyanosis, reduced pulmonary blood flow and massive cardiomegaly, compromising lung development. A high proportion will die during fetal life or in the neonatal period from pulmonary hypoplasia. Management is aimed at augmenting pulmonary blood flow and treating arrhythmias arising from the atrial enlargement. Cyanotic congenital heart disease with increased pulmonary blood flow Some circulations do not permit adequate mixing, resulting in cyanosis even though pulmonary blood flow may be increased: • transposition of the great arteries (TGA) • common arterial trunk • total anomalous pulmonary venous connections Transposition of the great arteries In TGA, the right ventricle pumps deoxygenated blood to the aorta and LV pumps oxygenated blood to the lungs in parallel circuits. Postnatally this is not compatible with life unless there is adequate mixing of the circulations through a patent arterial duct (PDA) or PFO. If the left to right flow through the PFO is restrictive then left atrial pressure rises and pulmonary vascular pressure increases putting these infants at risk of fatal pulmonary haemorrhage and early death before transfer to a cardiac unit. Clinically, profound cyanosis is present after birth. Respiration is initially not laboured. A murmur is heard in the presence of a VSD or pulmonary stenosis.
Table 4 Hyperoxia test. Ideally set up a preductal transcutaneous oxygen probe and pulse oximetry. Sample right radial artery gases to provide a baseline and increase the inspired oxygen to as close to 100% for at least 5 and not longer than 20 min before rechecking the gases. Pulse oximetry is less reliable but arterial oxygen saturations <85% in an FiO2 of 100% are suggestive of cyanotic heart disease. Cyanotic duct dependent lesions will improve temporarily before falling again as the duct begins to close but will not override a prostaglandin E1 or E2 infusion. Arterial pO2<12 kPa (90 mmHg) Arterial pO2 > 33 kPa (250 mmHg) Arterial pO2 > 46 kPa (350 mmHg) Arterial pO2 <3.3 kPa (25 mmHg)
Suggests cyanotic heart disease Cyanotic heart disease unlikely (except high flow common mixing lesions e.g. CAT and AVSD) Excludes cyanotic heart disease <0.7 kPa (5 mmHg) rise suggests simple TGA with intact septum
Table 5. ECG changes in congenital heart disease AVSD Tricuspid atresia HLHS Aortic stenosis TGA Common arterial trunk Pulmonary atresia Tetralogy of Fallot
Superior or left QRS axis and normal right ventricular forces Incomplete RBBB Superior axis with absent or reduced right ventricular forces Left axis deviation Atypical RVH Normal or LVH Right axis deviation, RVH or normal RA enlargement, BVH Normal QRS and prominent left ventricular forces RA enlargement, RVH and right axis deviation
CHD in neonates Chest X-ray shows a narrow superior mediastinum with normal or minimally enlarged heart (egg-on-side) and pulmonary vascular markings may be increased. Acute management is aimed at maintaining the patency of the duct and correcting acidosis, hypercarbia and hypovolaemia. Systemic oxygen saturations of 60% are sufficient for tissue oxygenation until atrial septostomy is performed, indeed supplemental oxygen may be hazardous. The preferred surgical procedure is the arterial switch operation within the first 2 weeks, the greatest difficulty being the transfer of the coronary arteries without kinking or stretching. Common arterial trunk (CAT) A single great artery arises from the heart because of failure of septation of the fetal arterial trunk. There is a single truncal valve, which may be regurgitant or stenotic and the pulmonary arteries arise from this common trunk. A large VSD is always present and pulmonary blood flow is unrestrictive in the absence of stenotic lesions. There is no arterial duct. Clinically there is only mild cyanosis and an early murmur secondary to high flow and bounding pulses if there is truncal regurgitation. There is a RV impulse and a single second sound with mid-systolic ejection click. Chest X-ray shows cardiomegaly with increased vascular markings. As pulmonary vascular resistance falls, pulmonary blood flow increases with clinical decompensation manifested by tachypnoea and sweating with feeding. Total anomalous pulmonary venous connections In TAPVC the pulmonary veins empty into a variety of sites other than the left atrium • supracardiac—draining into the brachiocephalic or superior vena cava • cardiac—draining into the coronary sinus and right atrium • infracardiac—into the portal and hepatic veins beneath the diaphragm • mixed—left pulmonary veins into the left brachiocephalic and right pulmonary veins into coronary sinus In all forms an ASD is mandatory to permit satisfactory mixing. Infracardiac defects cause severe respiratory distress often requiring ventilation, and can be confused with persistent pulmonary hypertension of the newborn (PPHN), but may show hepatomegaly with venous engorgement. Clinically both supracardiac and infracardiac TAPVC present with cyanosis and tachypnoea. There is a RV impulse and a widely split second sound. An ejection systolic murmur and a tricuspid diastolic rumble may be present secondary to the increased flow. In supracardiac TAPVC the chest X-ray shows a dilated superior mediastinum, an enlarged right heart and pulmonary venous congestion (‘snowman’ or
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‘cottage loaf’ appearance). Management may require positive pressure ventilation with supplementary oxygen and early transfer for surgery. LEFT HEART OBSTRUCTION • • • • •
Coarctation of the aorta Interrupted aortic arch Critical aortic stenosis Hypoplastic left heart syndrome Shone’s anomaly
This group of conditions form a spectrum of left heart obstructive lesions that may be completely asymptomatic in the immediate neonatal period but present with critical illness within days to weeks of life. As the duct constricts flow is reduced to the systemic circulation resulting in organ and tissue hypoperfusion and increasing pulmonary vascular resistance. Prostaglandin use Initial management of these conditions utilizes prostaglandin E1 or E2. On balance, they should also be employed in the initial treatment of an infant with congenital cyanotic heart disease. It may, however, exacerbate the clinical condition in transposition of the great arteries (TGA) and TAPVC because of obstruction to adequate mixing and should not be used concurrently with oxygen unless there is significant lung pathology. Respiratory apnoea is the most important side effect of PG E1 or E2 infusion with an incidence of 10% and will improve with decrease of infusion rate. Other side effects include mild fever, hypotension, flushing, diarrhoea and bradycardia. The usual dosage range for PGE1 (Alprostadil) and PGE2 (Dinoprostone) is 10–20 nanograms/kg.min–1, but a lower dose (5 ng/kg.min–1) may be sufficient. Coarctation of the aorta Coarctation may exist alone or in association with other intracardiac anomalies and syndromes. The position of narrowing is usually just beyond the origin of the left subclavian artery and may be discrete or long-segment. The diagnosis is suspected clinically with poor lower limb pulses and is confirmed on echocardiogram. Management is directed at reperfusion of tissues distal to the obstruction and correction of the acidosis. Prostaglandin E1 or E2 may reopen the duct and mechanical ventilation may be necessary whilst awaiting surgical repair. The presentation of an interrupted aortic arch is similar to coarctation but the left brachial arterial pulse may be difficult to feel, or weaker than the right depending on the site of interruption. Aortic stenosis Narrowing at the aortic outflow of the left ventricle is most commonly valvular. Presentation is dependent
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upon the severity of the obstruction. If the stenosis is critical infants present within days to weeks with a low output state similar to hypoplastic left heart syndrome (below) and coarctation. If there is left ventricular dysfunction the classical ejection systolic murmur may be absent and the infant pale, with a low output. Hypoplastic left heart syndrome (HLHS) HLHS is characterized by mitral and aortic atresia and hypoplastic aortic arch secondary to arrested normal heart development. The timing and severity of presentation after birth depends upon the arterial duct, the size of the left-to-right atrial shunt through the oval foramen and the ratio of the pulmonary to systemic vascular resistance. When the duct closes early there is severe respiratory distress and cardiogenic shock. Chest X-ray shows mild cardiomegaly and increased pulmonary vascularity. Urgent resuscitation, ventilation and re-establishment of ductal flow are required. Overventilation with low pCO2 and high pO2 will lower pulmonary vascular resistance exacerbating the condition, so SaO2 should not exceed 90% and the pCO2 should be kept relatively high. Definitive management includes three stage surgical palliation, or transplantation. Without other congenital malformations (standard risk) there is currently an approximately 55% survival at 5 years. Shone’s anomaly This defect consists of multiple levels of left heart obstruction. Classically there is a parachute mitral valve or supravalvar mitral ring, subaortic stenosis and coarctation of the aorta, but in practice valvar mitral and aortic stenosis are included. Presentation is variable depending on the dominant obstructive component but can be severe when management is similar to HLHS. LEFT TO RIGHT SHUNTS • • • •
Atrial septal defect Ventricular septal defect Patent arterial duct Atrioventricular septal defects
Left-to-right shunt lesions form the commonest category of congenital heart disease. Fully oxygenated blood from the left atrium, left ventricle or aorta reenters the right side increasing pulmonary blood flow and venous return to the left side producing both volume and pressure overload. Atrial septal defects Atrial septal defects are rarely life threatening in the neonatal period, are diagnosed infrequently and will not be discussed.
Ventricular septal defects Ventricular septal defects become more prominent as pulmonary vascular resistance decreases. Small muscular and perimembraneous defects may be managed expectantly in the outpatient department. The size of the physiological shunt does not depend only on morphological size, but on ventricular and pulmonary compliance. However, a large defect will usually be associated with a large shunt and usually no murmur.
Atrioventricular septal defects (AVSD) An AVSD may be asymptomatic initially but present after the first few weeks with a large left to right shunt. The murmurs of A-V valve regurgitation or pulmonary stenosis may or may not be present. There is an association with Trisomy 21 in 40% of cases and these babies all need an early echocardiogram.
Patent arterial duct (PDA) The duct is physically open during the first four postnatal days in 80% of premature newborns with hyaline membrane disease, although only one third will develop symptomatic shunts.5 In this setting it presents from day 5 onwards with a systolic murmur, wide pulse pressure, a hyperdynamic precordial impulse of left-sided overload, pulmonary congestion with worsening respiratory status and hepatomegaly. Indomethacin is probably indicated only for symptomatic PDA because of its attendant risks, and is more successful if employed early. Failed medical therapy is an indication for surgical ligation in the ventilator dependent neonate.
Cardiomyopathies Hypertrophic cardiomyopathies present with reduced output or episodic cyanosis and an active praecordium. The dilated cardiomyopathies present with biventricular heart failure and a big heart, pulmonary oedema and hepatomegaly. The latter may require inotropes, diuretics and urgent transfer to a cardiac unit. Both require echocardiography to confirm the diagnosis and metabolic and genetic investigations to determine the aetiology.
SUMMARY The wide range of congenital heart disease may be simplified by: • • • •
considering the likely timing of presentation a careful examination and attention to basic tests use of a diagnostic algorithm developing good on-site echocardiography skills
CHD in neonates REFERENCES 1. 2. 3. 4. 5.
Burn J, Brennan P, Little J, Holloway S et al. Recurrence risks in offspring of adults with major heart defects: results from first cohort of British collaborative study. Lancet 1998; 351: 311–316. Gregory J, Emslie A, Wyllie JP, Wren C. Examination for cardiac malformations at six weeks of age. Arch Dis Child Fetal Neonatal Ed 1999; 80: F46–F48. Ainsworth SB, Wyllie JP, Wren C. Prevalence and clinical significance of cardiac murmurs in neonates. Arch Dis Child Fetal Neonatal Ed 1999; 80: F43–F45. Abu-Harb M, Wyllie J, Richmond S, Wren C. Presentation of obstructive left heart malformations in infancy. Arch Dis Child Fetal Neonatal Ed 1994; 71: F179–F183. Evans N. Diagnosis of patent ductus arteriosus in the preterm newborn. Arch Dis Child 1993; 68: 58–61.
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FURTHER READING Berger Stuart. Pediatric Cardiology. Pediatr Clin North Am. 1999 April; 46: (2) Franklin RC, Spiegelhalter DJ, Macartney FJ, Bull K. Evaluation of a diagnostic algorithm for heart disease in neonates. BMJ 1991; 302: 935–939. Burch M. Hypertrophic cardiomyopathy. Arch Dis Child 1994; 71: 488–489. Burch M, Runciman M. Dilated cardiomyopathy. Arch Dis Child 1996; 74: 479–481. Anderson RA, et al. Paediatric Cardiology. Harcourt Brace, 2000; 2.
Symposium: Cardiology
Evaluation of suspected congenital heart disease in the neonatal period
R. M. Blumberg, H. M. Gardiner
disease. The presentation of congenital heart disease in this period has been the subject of study in the Northern health region of England; the authors recommend early referral of infants with symptoms or a murmur to a paediatric cardiologist.2–4
INTRODUCTION Congenital heart disease (CHD) is the commonest single group of structural malformations with an incidence of 0.5%–0.8% live births. Although much remains unknown about the genetic aetiology of CHD, exogenous teratogens, chromosomal abnormalities and many syndromes are associated with cardiac defects (Table 1). The risk of recurrence in a family with a previously affected child is about 2%, whilst it is approximately 5% in children of parents with a major cardiac abnormality.1 The current recommendations for screening for CHD are examination within 24 h of birth and a second review at 6–8 weeks of age. The first examination takes place at a time of rapid adaptation of the cardiopulmonary circulation and may both miss, or incorrectly suggest congenital heart disease, as only half the murmurs detected are pathological. Indeed, severe heart disease may have no signs in the immediate neonatal period. Specifically, left ventricular outflow tract obstruction presenting after discharge from hospital in the interval before the second review carries significant mortality if unrecognized. The trend to early discharge means that more infants are likely to develop symptoms at home and emphasizes the need for recognition of heart disease by community midwives, health visitors and general practitioners. Parents too, should be aware that a normal neonatal examination does not exclude heart
CARDIOPULMONARY CHANGES IN THE PERINATAL PERIOD The fetal circulation has systemic and pulmonary components operating in parallel. Normally, oxygenated blood reaching the right heart bypasses the high resistance pulmonary circulation and flows through the arterial duct to the aorta. Pre-natal survival is not endangered even by severe cardiac abnormality as long as one side of the heart can deliver blood from the caval veins to the aorta, bypassing non-functioning chambers. Successful neonatal adaptation depends on expansion of the lungs and remodelling of the thick walled pulmonary vessels, reducing pulmonary vascular pressure and increasing flow. Systemic vascular resistance rises with clamping of the cord and separation from the low resistance placental circulation. The increase in pulmonary blood flow raises left atrial pressure and closes the oval foramen. A rise in arterial oxygen content further dilates pulmonary capillaries and initiates closure of the arterial duct. Thus two vascular circuits connected in series are established, one receiving deoxygenated blood and delivering it to the lungs, and the other receiving oxygenated blood and delivering it to the peripheral tissues. In term infants, functional closure of the arterial duct occurs by contraction of smooth muscle and is complete by 10–15 h. Anatomical closure takes place by 2–3 weeks and the duct is completely closed by 8 weeks in 90% of infants without other cardiac anomalies.
Raoul M. Blumberg, Senior Registrar, Department of Paediatrics and Neonatal Medicine, Hammersmith Hospital, London, UK Helena M. Gardiner, Senior Lecturer in Perinatal Cardiology, Department of Maternofetal Medicine, Division of Paediatrics, Obstetrics & Gynaecology, Queen Charlotte’s and Chelsea Hospital, Imperial College School of Medicine, London, UK Correspondence to HMG
229
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Current Paediatrics Table 1 Common teratogens and chromosomal anomalies related to congenital heart disease Rubella SLE Alcohol Diabetes Phenytoin Lithium Down syndrome (Trisomy 21) Turner syndrome (45XO) Patau syndrome (Trisomy 13) Edward syndrome (Trisomy 18) Ch 22 microdeletion
Table 2
PDA, Peripheral pulmonary stenosis Complete heart block PDA, VSD, Tetralogy of Fallot Cardiomyopathy, TGA, VSD VSD, ASD, Coarctation Ebstein’s anomaly AVSD, VSD, ASD, Tetralogy of Fallot Coarctation, Aortic stenosis VSD, Various defects VSD, Various defects Conotruncal abnormalities (or any defect)
Categories and percentage incidence of congenital heart disease Cyanotic congenital heart disease
Decreased pulmonary blood flow Tetralogy of Fallot and PS Tricuspid atresia Ebstein’s anomaly Pulmonary valve stenosis Pulmonary atresia with VSD
Increased pulmonary blood flow 5–10% 1–3% <1% 1–2% 1%
Transposition of the great arteries Common arterial trunk TAPVC Double outlet right ventricle Tetralogy of Fallot
5–15% 1–2% 1–2% 1–2%
Acyanotic congenital heart disease Left heart obstruction Coarctation of aorta Aortic stenosis Hypoplastic left heart syndrome Interruption of the aortic arch
Left-to-right shunts 3–5% 2–3% 1–2% <1%
PRESENTATION OF CONGENITAL HEART DISEASE Antenatal Routine anomaly scanning around 20 weeks gestation may detect hypoplasia of the right or left ventricle or abnormalities of the pulmonary trunk or aorta, but currently only identifies about 25% of children with significant cardiac problems. Detailed fetal cardiac assessment should be performed on those with abnormal scan findings, a family history of previous cardiac anomaly or in high risk pregnancies (e.g. maternal systemic lupus erythematosus, diabetes mellitus, or multifetal pregnancies). In the neonatal period CHD (Table 2) can present as • cyanosis with or without respiratory distress • asymptomatic murmur • low output states following closure of the arterial duct • left heart overload with pulmonary congestion • high output states Cyanosis with or without respiratory distress Distinction of cardiac and respiratory disease in the neonate may be difficult immediately following birth. The chief signs underlying both, are respiratory pattern and cyanosis. Normally the respiratory rate
PDA VSD Secundum ASD AVSD/partial AVSD
10–15% 10–20% 5–15% 1–3%
decreases progressively on the first day of life from 50–60 breaths/min to 35–50 breaths/min and mild recession or brief grunting disappear within hours. Tachypnoea due to intrinsic pulmonary disease or airway obstruction will be accompanied by recession, nasal flaring and grunting. In contrast, intense cyanosis with minimal respiratory distress or increase in depth of respiration suggests congenital cyanotic heart disease with decreased pulmonary blood flow. A chest Xray may be diagnostic of a primary lung disorder (e.g. hyaline membrane disease, pneumonia, aspiration) or mechanical interference with respiratory function (e.g. pneumothorax, tracheo-oesophageal fistula, choanal atresia). As the time increases between birth and the development of symptoms a respiratory diagnosis becomes less likely, particularly after a period of wellbeing. Table 3 shows the likely presentation of CHD chronologically following birth. Persistent pulmonary hypertension of the newborn may present with cyanosis. This should be considered in an infant with corroborative history of suspected sepsis, meconium aspiration with X-ray changes or asphyxia. Arterial oxygen saturation improves with hyperoxygenation, hyperventilation and pulmonary vasodilation using nitric oxide or prostacyclin. An important differential diagnosis is infracardiac total anomalous pulmonary venous connections (TAPVC) with obstructed pulmonary venous circulation, which can only be diagnosed on echocardiogram.
CHD in neonates Table 3
231
Likely presentation of congenital heart disease by age
Time
Condition
Features
0–3 days
Transposition with intact septum Tricuspid atresia Pulmonary atresia/critical PS Infracardiac TAPVC Hypoplastic left heart Critical aortic stenosis Coarctation Interrupted aortic arch Severe PS Supracardiac/cardiac TAPVC Tetralogy of Fallot (RVOT obstruction) Common arterial trunk
Cyanosis Cyanosis Cyanosis Tachypnoea, cyanosis
0–7 days
7–14 days 14 days–3 months
3 months +
}
Coarctation Transposition/VSD Tetralogy of Fallot (minimal RVOT) Atrioventricular septal defects Double outlet right ventricle (no PS) Missed transposition with pulmonary hypertension Anomalous left coronary artery
}
Dilated cardiomyopathy Left to right shunts (VSD, PDA, ASD)
Asymptomatic murmur Asymptomatic murmurs in newborns may be due to the changing circulation (closing patent arterial duct), small ventricular septal defects, or moderate semilunar valve obstruction (arterial or pulmonary stenosis). Low output states Obstructed or inadequate systemic circulation resulting from hypoplastic left heart syndrome, critical aortic stenosis, mitral valve abnormalities, coarctation or interruption of the aortic arch produce a low output state. Symptoms occur following closure of the arterial duct. Systemic blood pressure is poor with decreased pulses and peripheral perfusion leading to increasing hypoxaemia and acidosis. Significant left to right shunts A significant left to right shunt presents with left heart volume overload and pulmonary venous congestion with interstitial oedema and reduced lung compliance, increasing the work of breathing and reducing gas transfer. Symptoms include breathlessness, poor feeding and sweating. Clinically there is tachycardia, with a murmur or gallop rhythm, tachypnoea, hepatomegaly, cool peripheries and failure to thrive.
Low output state & Discordant brachial pulses Cyanosis, murmur Cyanosis, tachypnoea Cyanosis, murmur Bounding pulses ± Cyanosis, tachypnoea Low output state Cyanosis, tachypnoea Tachypnoea Left to right shunt Cyanosis, loud P2 Small heart Ischaemia (‘colic’) Episodic tachypnoea, LVF Biventricular failure Left heart overload
INVESTIGATION OF CONGENITAL CARDIAC DISEASE Diagnostic algorithms and Tables 4 and 5 provide guidelines to aid diagnosis of CHD. However, the availability of good echocardiographic equipment on neonatal units and education to improve echocardiographic skills of neonatologists are essential to provide early assessment of suspected heart disease and to guide emergency management. CYANOTIC CONGENITAL HEART DISEASE The classic mnemonic of the 5 Ts remains useful, Tetralogy of Fallot, Tricuspid valve abnormalities, Transposition of the great arteries, common arterial Trunk and Total anomalous pulmonary venous connections), but critical pulmonary stenosis and atresia also form part of this group. Clinically it is more useful to approach the problem physiologically: • right to left shunt • inadequate pulmonary blood flow • common mixing lesions with increased pulmonary blood flow Cyanotic heart disease with decreased pulmonary blood flow
High output states
Tetralogy of Fallot
High output states (e.g. arteriovenous malformation) are rare but may present with intractable heart failure and a bruit over the head should be sought and cranial ultrasound performed to exclude vein of Galen aneurysm.
There is a spectrum of presentation from severe cyanosis with duct-dependent blood flow to ‘pink’ with high pulmonary blood flow and breathlessness. More commonly, infants are cyanosed and the chest X-ray may show decreased pulmonary vascularity.
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Pulmonary valve stenosis/atresia Abnormalities of the pulmonary valve are common and form a spectrum of severity. The mildest forms present later in childhood but, if severe or critical, present in the neonatal period as forward flow to the lungs is obstructed and pulmonary blood flow is therefore ductdependent. Severe tricuspid regurgitation (TR) may cause a right to left atrial shunt. If the patent oval foramen (PFO) is restrictive then right atrial enlargement is followed by hepatic venous engorgement. In pulmonary atresia with intact ventricular septum the right ventricle is hypoplastic with or without sinusoids (fistulae from the coronary artery to the right ventricular cavity). Management of this condition is difficult, but right ventricular (RV) growth may occur if forward flow can be established. Tricuspid valve abnormalities Tricuspid valve abnormalities may prevent normal growth of the right heart and reduce pulmonary blood flow. The valve may be either atretic, hypoplastic, or displaced (Ebstein’s anomaly). In tricuspid atresia there is no communication between the right atrium and right ventricle (‘absent right connection’) and there must be an obligatory right-to-left shunt for survival. Physiological consequences are dependent upon the presence of a ventricular septal defect (VSD), pulmonary stenosis and the relationship of the great arteries. If the VSD is small then there is always a small right ventricular cavity with obstruction to outflow. Ebstein’s anomaly Ebstein’s anomaly is a malformation of the tricuspid valve with a continuum of severity related to the
degree of displacement of the tricuspid valve into the cavity of the right ventricle. More severe displacement critically reduces the volume of the cavity, narrowing the right ventricular outlet and restricting forward flow. Severe forms present with cyanosis, reduced pulmonary blood flow and massive cardiomegaly, compromising lung development. A high proportion will die during fetal life or in the neonatal period from pulmonary hypoplasia. Management is aimed at augmenting pulmonary blood flow and treating arrhythmias arising from the atrial enlargement. Cyanotic congenital heart disease with increased pulmonary blood flow Some circulations do not permit adequate mixing, resulting in cyanosis even though pulmonary blood flow may be increased: • transposition of the great arteries (TGA) • common arterial trunk • total anomalous pulmonary venous connections Transposition of the great arteries In TGA, the right ventricle pumps deoxygenated blood to the aorta and LV pumps oxygenated blood to the lungs in parallel circuits. Postnatally this is not compatible with life unless there is adequate mixing of the circulations through a patent arterial duct (PDA) or PFO. If the left to right flow through the PFO is restrictive then left atrial pressure rises and pulmonary vascular pressure increases putting these infants at risk of fatal pulmonary haemorrhage and early death before transfer to a cardiac unit. Clinically, profound cyanosis is present after birth. Respiration is initially not laboured. A murmur is heard in the presence of a VSD or pulmonary stenosis.
Table 4 Hyperoxia test. Ideally set up a preductal transcutaneous oxygen probe and pulse oximetry. Sample right radial artery gases to provide a baseline and increase the inspired oxygen to as close to 100% for at least 5 and not longer than 20 min before rechecking the gases. Pulse oximetry is less reliable but arterial oxygen saturations <85% in an FiO2 of 100% are suggestive of cyanotic heart disease. Cyanotic duct dependent lesions will improve temporarily before falling again as the duct begins to close but will not override a prostaglandin E1 or E2 infusion. Arterial pO2<12 kPa (90 mmHg) Arterial pO2 > 33 kPa (250 mmHg) Arterial pO2 > 46 kPa (350 mmHg) Arterial pO2 <3.3 kPa (25 mmHg)
Suggests cyanotic heart disease Cyanotic heart disease unlikely (except high flow common mixing lesions e.g. CAT and AVSD) Excludes cyanotic heart disease <0.7 kPa (5 mmHg) rise suggests simple TGA with intact septum
Table 5. ECG changes in congenital heart disease AVSD Tricuspid atresia HLHS Aortic stenosis TGA Common arterial trunk Pulmonary atresia Tetralogy of Fallot
Superior or left QRS axis and normal right ventricular forces Incomplete RBBB Superior axis with absent or reduced right ventricular forces Left axis deviation Atypical RVH Normal or LVH Right axis deviation, RVH or normal RA enlargement, BVH Normal QRS and prominent left ventricular forces RA enlargement, RVH and right axis deviation
CHD in neonates Chest X-ray shows a narrow superior mediastinum with normal or minimally enlarged heart (egg-on-side) and pulmonary vascular markings may be increased. Acute management is aimed at maintaining the patency of the duct and correcting acidosis, hypercarbia and hypovolaemia. Systemic oxygen saturations of 60% are sufficient for tissue oxygenation until atrial septostomy is performed, indeed supplemental oxygen may be hazardous. The preferred surgical procedure is the arterial switch operation within the first 2 weeks, the greatest difficulty being the transfer of the coronary arteries without kinking or stretching. Common arterial trunk (CAT) A single great artery arises from the heart because of failure of septation of the fetal arterial trunk. There is a single truncal valve, which may be regurgitant or stenotic and the pulmonary arteries arise from this common trunk. A large VSD is always present and pulmonary blood flow is unrestrictive in the absence of stenotic lesions. There is no arterial duct. Clinically there is only mild cyanosis and an early murmur secondary to high flow and bounding pulses if there is truncal regurgitation. There is a RV impulse and a single second sound with mid-systolic ejection click. Chest X-ray shows cardiomegaly with increased vascular markings. As pulmonary vascular resistance falls, pulmonary blood flow increases with clinical decompensation manifested by tachypnoea and sweating with feeding. Total anomalous pulmonary venous connections In TAPVC the pulmonary veins empty into a variety of sites other than the left atrium • supracardiac—draining into the brachiocephalic or superior vena cava • cardiac—draining into the coronary sinus and right atrium • infracardiac—into the portal and hepatic veins beneath the diaphragm • mixed—left pulmonary veins into the left brachiocephalic and right pulmonary veins into coronary sinus In all forms an ASD is mandatory to permit satisfactory mixing. Infracardiac defects cause severe respiratory distress often requiring ventilation, and can be confused with persistent pulmonary hypertension of the newborn (PPHN), but may show hepatomegaly with venous engorgement. Clinically both supracardiac and infracardiac TAPVC present with cyanosis and tachypnoea. There is a RV impulse and a widely split second sound. An ejection systolic murmur and a tricuspid diastolic rumble may be present secondary to the increased flow. In supracardiac TAPVC the chest X-ray shows a dilated superior mediastinum, an enlarged right heart and pulmonary venous congestion (‘snowman’ or
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‘cottage loaf’ appearance). Management may require positive pressure ventilation with supplementary oxygen and early transfer for surgery. LEFT HEART OBSTRUCTION • • • • •
Coarctation of the aorta Interrupted aortic arch Critical aortic stenosis Hypoplastic left heart syndrome Shone’s anomaly
This group of conditions form a spectrum of left heart obstructive lesions that may be completely asymptomatic in the immediate neonatal period but present with critical illness within days to weeks of life. As the duct constricts flow is reduced to the systemic circulation resulting in organ and tissue hypoperfusion and increasing pulmonary vascular resistance. Prostaglandin use Initial management of these conditions utilizes prostaglandin E1 or E2. On balance, they should also be employed in the initial treatment of an infant with congenital cyanotic heart disease. It may, however, exacerbate the clinical condition in transposition of the great arteries (TGA) and TAPVC because of obstruction to adequate mixing and should not be used concurrently with oxygen unless there is significant lung pathology. Respiratory apnoea is the most important side effect of PG E1 or E2 infusion with an incidence of 10% and will improve with decrease of infusion rate. Other side effects include mild fever, hypotension, flushing, diarrhoea and bradycardia. The usual dosage range for PGE1 (Alprostadil) and PGE2 (Dinoprostone) is 10–20 nanograms/kg.min–1, but a lower dose (5 ng/kg.min–1) may be sufficient. Coarctation of the aorta Coarctation may exist alone or in association with other intracardiac anomalies and syndromes. The position of narrowing is usually just beyond the origin of the left subclavian artery and may be discrete or long-segment. The diagnosis is suspected clinically with poor lower limb pulses and is confirmed on echocardiogram. Management is directed at reperfusion of tissues distal to the obstruction and correction of the acidosis. Prostaglandin E1 or E2 may reopen the duct and mechanical ventilation may be necessary whilst awaiting surgical repair. The presentation of an interrupted aortic arch is similar to coarctation but the left brachial arterial pulse may be difficult to feel, or weaker than the right depending on the site of interruption. Aortic stenosis Narrowing at the aortic outflow of the left ventricle is most commonly valvular. Presentation is dependent
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upon the severity of the obstruction. If the stenosis is critical infants present within days to weeks with a low output state similar to hypoplastic left heart syndrome (below) and coarctation. If there is left ventricular dysfunction the classical ejection systolic murmur may be absent and the infant pale, with a low output. Hypoplastic left heart syndrome (HLHS) HLHS is characterized by mitral and aortic atresia and hypoplastic aortic arch secondary to arrested normal heart development. The timing and severity of presentation after birth depends upon the arterial duct, the size of the left-to-right atrial shunt through the oval foramen and the ratio of the pulmonary to systemic vascular resistance. When the duct closes early there is severe respiratory distress and cardiogenic shock. Chest X-ray shows mild cardiomegaly and increased pulmonary vascularity. Urgent resuscitation, ventilation and re-establishment of ductal flow are required. Overventilation with low pCO2 and high pO2 will lower pulmonary vascular resistance exacerbating the condition, so SaO2 should not exceed 90% and the pCO2 should be kept relatively high. Definitive management includes three stage surgical palliation, or transplantation. Without other congenital malformations (standard risk) there is currently an approximately 55% survival at 5 years. Shone’s anomaly This defect consists of multiple levels of left heart obstruction. Classically there is a parachute mitral valve or supravalvar mitral ring, subaortic stenosis and coarctation of the aorta, but in practice valvar mitral and aortic stenosis are included. Presentation is variable depending on the dominant obstructive component but can be severe when management is similar to HLHS. LEFT TO RIGHT SHUNTS • • • •
Atrial septal defect Ventricular septal defect Patent arterial duct Atrioventricular septal defects
Left-to-right shunt lesions form the commonest category of congenital heart disease. Fully oxygenated blood from the left atrium, left ventricle or aorta reenters the right side increasing pulmonary blood flow and venous return to the left side producing both volume and pressure overload. Atrial septal defects Atrial septal defects are rarely life threatening in the neonatal period, are diagnosed infrequently and will not be discussed.
Ventricular septal defects Ventricular septal defects become more prominent as pulmonary vascular resistance decreases. Small muscular and perimembraneous defects may be managed expectantly in the outpatient department. The size of the physiological shunt does not depend only on morphological size, but on ventricular and pulmonary compliance. However, a large defect will usually be associated with a large shunt and usually no murmur.
Atrioventricular septal defects (AVSD) An AVSD may be asymptomatic initially but present after the first few weeks with a large left to right shunt. The murmurs of A-V valve regurgitation or pulmonary stenosis may or may not be present. There is an association with Trisomy 21 in 40% of cases and these babies all need an early echocardiogram.
Patent arterial duct (PDA) The duct is physically open during the first four postnatal days in 80% of premature newborns with hyaline membrane disease, although only one third will develop symptomatic shunts.5 In this setting it presents from day 5 onwards with a systolic murmur, wide pulse pressure, a hyperdynamic precordial impulse of left-sided overload, pulmonary congestion with worsening respiratory status and hepatomegaly. Indomethacin is probably indicated only for symptomatic PDA because of its attendant risks, and is more successful if employed early. Failed medical therapy is an indication for surgical ligation in the ventilator dependent neonate.
Cardiomyopathies Hypertrophic cardiomyopathies present with reduced output or episodic cyanosis and an active praecordium. The dilated cardiomyopathies present with biventricular heart failure and a big heart, pulmonary oedema and hepatomegaly. The latter may require inotropes, diuretics and urgent transfer to a cardiac unit. Both require echocardiography to confirm the diagnosis and metabolic and genetic investigations to determine the aetiology.
SUMMARY The wide range of congenital heart disease may be simplified by: • • • •
considering the likely timing of presentation a careful examination and attention to basic tests use of a diagnostic algorithm developing good on-site echocardiography skills
CHD in neonates REFERENCES 1. 2. 3. 4. 5.
Burn J, Brennan P, Little J, Holloway S et al. Recurrence risks in offspring of adults with major heart defects: results from first cohort of British collaborative study. Lancet 1998; 351: 311–316. Gregory J, Emslie A, Wyllie JP, Wren C. Examination for cardiac malformations at six weeks of age. Arch Dis Child Fetal Neonatal Ed 1999; 80: F46–F48. Ainsworth SB, Wyllie JP, Wren C. Prevalence and clinical significance of cardiac murmurs in neonates. Arch Dis Child Fetal Neonatal Ed 1999; 80: F43–F45. Abu-Harb M, Wyllie J, Richmond S, Wren C. Presentation of obstructive left heart malformations in infancy. Arch Dis Child Fetal Neonatal Ed 1994; 71: F179–F183. Evans N. Diagnosis of patent ductus arteriosus in the preterm newborn. Arch Dis Child 1993; 68: 58–61.
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FURTHER READING Berger Stuart. Pediatric Cardiology. Pediatr Clin North Am. 1999 April; 46: (2) Franklin RC, Spiegelhalter DJ, Macartney FJ, Bull K. Evaluation of a diagnostic algorithm for heart disease in neonates. BMJ 1991; 302: 935–939. Burch M. Hypertrophic cardiomyopathy. Arch Dis Child 1994; 71: 488–489. Burch M, Runciman M. Dilated cardiomyopathy. Arch Dis Child 1996; 74: 479–481. Anderson RA, et al. Paediatric Cardiology. Harcourt Brace, 2000; 2.