The incidence of congenital heart disease is 0.6% to 0.8% of all live births.
The most serious congenital heart lesions are usually symptomatic in the newborn period.
Prompt recognition and treatment of critical congenital heart disease can be lifesaving.
I. INTRODUCTION. Pediatric cardiology is a relatively young field. In an early 20th century textbook of medicine, Dr. William Osler dismissed congenital heart disease as “limited clinical interest as in a large proportion of cases the anomaly is not compatible with life, and in others, nothing can be done to remedy the defect or even relieve the symptoms.” This would change dramatically in 1938, when Dr. Robert Gross successfully ligated a patent ductus arteriosus (PDA) in a 7-year-old girl at Children’s Hospital, Boston. In the years since, the capabilities of medical therapy, procedural, and surgical interventions have improved dramatically, with the ability to treat increasingly complex diseases and defects with decreasing morbidity and mortality.
In critical congenital heart disease, patient outcomes are dependent on (i) early and accurate identification of the cardiac lesion and (ii) evaluation and treatment of secondary organ damage. Therefore, an important mantle of responsibility rests on the neonatologists and pediatricians who often first evaluate and manage these patients. Thereafter, a multidisciplinary team of several subspecialty services is frequently required to avoid the deleterious effects of the cardiac disease on the heart, lung, and brain. Such effects include failure to thrive, increased infection risk, pulmonary vascular disease, cognitive developmental delay, and neurologic deficits. This chapter is an overview of the initial evaluation and management, by neonatologists and pediatricians, of neonates and infants suspected of having congenital heart disease. Additional details about specific heart defects and conditions can be found in current textbooks of pediatric cardiology and pediatric cardiac surgery.
II. INCIDENCE AND SURVIVAL. The reported incidence of congenital heart defects in live born infants varies between 0.6% and 0.8% of live births, resulting in 25,000 to 35,000 infants with congenital heart disease each year in the United States alone. This incidence has remained constant over the past several decades. Some reports indicate as high as 1.2% incidence that may be due to inclusion of minor defects that will resolve spontaneously, but are identified by improvements in diagnostic modalities, and the inclusion of such findings as bicuspid aortic valve without stenosis or insufficiency but indicate a higher risk of developing disease later in life. Data from large population studies suggest that approximately 1 per 110 live births have congenital heart disease, and approximately 25% of congenital heart defects are considered critical congenital heart disease, requiring intervention in the first year of life. Most of these infants with congenital heart disease are identified by the end of the neonatal period. The most common congenital heart lesions presenting in the first weeks of life are summarized in Table 41.1. Advances in diagnostic imaging, cardiac surgery, and intensive care have reduced the operative risks of many complex lesions; the hospital mortality following all forms of neonatal cardiac surgery has significantly decreased in the past decade.
Table 41.1. Top Five Diagnoses Presenting at Different Ages*
Diagnosis
Percentage of Patients
Age on admission: 0-6 d (n = 537)
D-Transposition of great arteries
19
Hypoplastic left ventricle
14
Tetralogy of Fallot
8
Coarctation of aorta
7
Ventricular septal defect
3
Others
49
Age on admission: 7-13 d (n = 195)
Coarctation of aorta
16
Ventricular septal defect
14
Hypoplastic left ventricle
8
D-Transposition of great arteries
7
Tetralogy of Fallot
7
Others
48
Age on admission: 14-28 d (n = 177)
Ventricular septal defect
16
Coarctation of aorta
12
Tetralogy of Fallot
7
D-Transposition of great arteries
7
Patent ductus arteriosus
5
Others
53
*Reprinted with permission from Flanagan MF, Yeager SB, Weindling SN. Cardiac disease. In: MacDonald MG, Mullett MD, Seshia MMK, eds. Avery’s Neonatology: Pathophysiology and Management of the Newborn. 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005.
III. CLINICAL PRESENTATIONS OF CONGENITAL HEART DISEASE IN THE NEONATE. The timing of presentation is dependent on three primary elements: (i) the type and severity of the congenital defect; (ii) alterations in the cardiovascular physiology secondary to the effects of the transitional circulation, principally closure of the ductus arteriosus and the decrease in pulmonary vascular resistance; and (iii) any in utero effects of the defect.
Overall, cardiac emergencies are uncommon in children. Nevertheless, more serious cardiac disease and symptoms are more likely to present earlier in life. The first 72 hours are particularly important because many of the most severe and acutely life-threatening lesions present in this time frame.
A. Parallel, nonmixing circulations. The primary diagnosis of this description is D-transposition of the great arteries (D-TGA). D-TGA is defined as the aorta arising from the morphologically right ventricle, wherein the systemic venous blood returns to the right cardiac chambers and returns to the systemic arterial system without passing through the pulmonary vasculature. The pulmonary artery arises from the morphologically left ventricle, leading to the fully oxygen-saturated blood from the pulmonary venous system returning to the left cardiac chambers, and then returning to the pulmonary vasculature. As such, the two circulations work in parallel, with oxygen-saturated blood not reaching the systemic circulation.
The two locations where oxygen-saturated blood can enter the systemic circulation are (i) the PDA and (ii) the patent foramen ovale (PFO). As the PDA closes as part of the transitional circulatory changes, the sole source of oxygenated blood becomes the PFO, which commonly becomes increasingly restrictive. Without intervention, the neonate will become increasingly cyanotic and develop a metabolic acidosis, and subsequent circulatory shock.
Palliative interventions are urgent to prevent this clinical presentation. These include initiation of a prostaglandin E1 (PGE1) infusion that maintains patency of the ductus arteriosus. Frequently, this is insufficient, or becomes insufficient, and a balloon atrial septostomy is necessary via cardiac catheterization techniques. These interventions allow time to stabilize the patient in anticipation of neonatal reparative surgery via the arterial switch procedure.
B. Critically obstructed left heart lesions. This group of cardiac defects includes those in which patency of the ductus arteriosus is necessary to maintain systemic blood flow. As a result of the expected ductal constriction and closure, the neonate will become acidotic and develop cardiogenic shock. Some of these lesions can present later in life; however, those that present in the first 72 hours are of a more severe nature.
1. Hypoplastic left heart syndrome. This defect comprises underdevelopment of left heart structures including the mitral and aortic valve (either stenotic or atretic), small or absent left ventricular chamber, and hypoplasia of the ascending aorta, including coarctation.
2. Critical aortic valve stenosis. In its most severe form, systemic output is dependent on the PDA because sufficient blood flow does not cross the aortic valve to sustain the body. Less severe forms can be monitored beyond the neonatal period and may not require intervention for months or years.
3. Coarctation of the aorta. The most common site of coarctation is near the ductus arteriosus, and as the ductus arteriosus closes, the inadequate systemic output manifests. Again, less severe forms may not be discovered until months or years after the neonatal period. Those requiring early and urgent intervention are those with the most severe disease.
4. Interrupted aortic arch. In this lesion, there is absence of continuity between the ascending and descending aorta. The different types are distinguished by the location of discontinuity relative to the head and neck vessels. Without the PDA, there is no blood flow to the lower body.
C. Critically obstructed right heart lesions. This group of cardiac defects includes those in which patency of the ductus arteriosus is necessary to maintain pulmonary blood flow. As a result, the neonate will become cyanotic without appropriate intervention. Milder forms of these lesions may present later in life; however, those that present in the first 72 hours are of a more severe nature.
1. Pulmonary atresia (PA). This defect occurs as a result of the pulmonary valve not achieving patency during fetal life. As a result, pulmonary blood flow is entirely dependent on the ductus arteriosus. This lesion presents in multiple forms:
a. PA with intact ventricular septum. In this variant, blood flow in the right ventricle has no outlet other than via tricuspid regurgitation and subsequent right-to-left shunt across the foramen ovale. The high pressure generated in the right ventricle, in the absence of outflow, is correlated with coronary artery fistulas that can be dependent on the high pressure in the ventricle for coronary blood flow. This presents an independent risk factor for this disease.
b. PA with ventricular septal defect. In this variant, systemic venous blood entering the right ventricle will mix with pulmonary venous blood entering the left ventricle and enter the systemic circulation via the aortic valve.
c. PA with major aortopulmonary collateral arteries (MAPCAs). This variant is not dependent on ductal circulation for pulmonary blood flow. Native pulmonary arteries may or may not be present and are uniformly hypoplastic. Collateral vessels form off the descending aorta and provide pulmonary blood flow.
2. Critical pulmonary valve stenosis. In its most severe form, pulmonary blood flow is dependent on the PDA because sufficient blood does not cross the pulmonary valve to provide effective pulmonary blood flow. Less severe forms can be monitored beyond the neonatal period and may not require intervention for months or years.
3. Ebstein’s anomaly. This disease is a product of distal displacement of the tricuspid valve into the right ventricle. The result is a large right atrium with an “atrialized” right ventricle and a limited, functional right ventricular (RV) chamber. In its severe form, the tricuspid valve displacement can cause an outflow tract obstruction, requiring a PDA. Milder forms have been found incidentally in adulthood and may not require intervention.
D. Total anomalous pulmonary venous return (TAPVR). Anomalous pulmonary venous connections can present similar to a large left-to-right shunt, similar to an atrial septal defect, however, in its obstructed form, represents a surgical emergency. Obstructed TAPVR has an initial clinical manifestation similar to pulmonary hypertension but should be considered when traditional pulmonary hypertension therapies are ineffective. There is no medical management that will improve this condition. There are some reports of interventional cardiologists placing percutaneous stents to relieve the obstruction, but this is a palliative intervention meant to allow time for somatic growth, or for a critically ill patient to recover prior to undergoing surgery.
Without acute intervention, many of the heart lesions described earlier can have significant morbidity and mortality. Fortunately, currently, many diagnoses are made prenatally due to improvements in ultrasound technology and the availability of fetal echocardiography. In the absence of prenatal diagnoses, these and other forms of heart disease present in the neonatal period that, although not requiring short-term intervention, require early recognition for proper therapy.
Important clinical findings should alert the clinician to the possibility of congenital heart disease. Key findings that require additional evaluation include (i) cyanosis, (ii) congestive heart failure (CHF), (iii) cardiovascular collapse or shock, (iv) heart murmur, and (v) arrhythmia.
IV. CLINICAL MANIFESTATIONS OF CONGENITAL HEART DISEASE
A. Cyanosis
1. Clinical findings. Cyanosis (bluish tinge of the skin and mucous membranes) is a common presenting sign of congenital heart disease in the neonate. In the setting of congenital heart disease, cyanosis is an indication of hypoxemia or decreased arterial oxygen saturation. However, depending on the underlying skin complexion, clinically apparent cyanosis is usually not visible until there is >3 g/dL of desaturated hemoglobin in the arterial system. Therefore, the degree of visible cyanosis depends on both the severity of hypoxemia (which determines the percentage of oxygen saturation) as well as the hemoglobin concentration. For example, consider two infants with similar degrees of hypoxemia—each having an arterial oxygen saturation of 85%. The polycythemic newborn (hemoglobin of 22 g/dL) will have 3.3 g/dL (15% of 22 g/dL) desaturated hemoglobin and have more visibly apparent cyanosis than the anemic infant (hemoglobin of 10 g/dL) who will only have 1.5 g/dL (15% of 10 g/dL) desaturated hemoglobin. Also, there are a few instances when cyanosis is associated with normal arterial oxygen saturation. True central cyanosis should be a generalized finding (i.e., not acrocyanosis, blueness of the hands and feet only, which is a normal finding in a neonate) and can often best be appreciated in the mucous membranes.
Because determining cyanosis by visual inspection can be challenging for the reasons mentioned, adding routine pre- and postductal extremity pulse oximetry has been proposed as an additional screening test in the first 48 hours of life. A 2009 prospective study in Sweden demonstrated an improved total detection rate of ductal-dependent circulation to 92%. Importantly, the combination of physical exam and pulse oximetry screening demonstrated better sensitivity than either screen alone. In 2011, the U.S. Secretary of Health and Human Services recommended that critical congenital heart defects be added to the U.S. Recommended Uniform Screening Panel for newborns. Implementation of this would entail pulse oximetry screening after 24 hours of life, with further evaluation by echocardiogram for oxygen saturations below 95%. Multiple states have included it in their screening mandates, with additional studies to validate its clinical and cost-effectiveness underway.
2. Differential diagnosis. Differentiation of cardiac from respiratory causes of cyanosis in the neonatal intensive care unit (NICU) is a common problem. Pulmonary disorders are frequently the cause of cyanosis in the newborn due to intrapulmonary right-to-left shunting. Primary lung disease (pneumonia, hyaline membrane disease, pulmonary arteriovenous malformations, etc.), pneumothorax, airway obstruction, extrinsic compression of the lungs (congenital diaphragmatic hernia, pleural effusions, etc.), and central nervous system abnormalities may produce varying degrees of hypoxemia manifesting as cyanosis in the neonate. For a more complete differential diagnosis of pulmonary causes of cyanosis in the neonate, see Chapters 33, 34, 35, 36, 37, 38. Finally, clinical cyanosis may occur in an infant without hypoxemia in the setting of methemoglobinemia or pronounced polycythemia. Table 41.2 summarizes the differential diagnosis of cyanosis in the neonate.
B. Congestive heart failure
1. Clinical findings. CHF in the neonate (or in a patient of any age) is a clinical diagnosis made based on the presence of certain signs and symptoms rather than on radiographic or laboratory findings, which may corroborate the diagnosis. Signs and symptoms of CHF occur when the heart is unable to meet the metabolic demands of the tissues. Clinical findings are frequently due to homeostatic mechanisms attempting to compensate for this imbalance. In early stages, the neonate may be tachypneic and tachycardic with an increased respiratory effort, rales, hepatomegaly, and delayed capillary refill. In contrast to adults, edema is rarely seen. Diaphoresis, feeding difficulties, and growth failure may be present. Diaphoresis during feeding is a common scenario that this symptom manifests. Finally, CHF may present acutely with cardiorespiratory collapse, particularly in “left-sided” lesions (see section VI.A). Hydrops fetalis is an extreme form of intrauterine CHF (see Chapter 5).
2. Differential diagnosis. The age when CHF develops depends on the physiologic effects of the responsible lesion. When heart failure develops in the first weeks of life, the differential diagnosis includes (i) a structural lesion causing severe pressure and/or volume overload, (ii) a primary myocardial lesion causing myocardial dysfunction, or (iii) arrhythmia. Table 41.3 summarizes the differential diagnoses of CHF in the neonate.
Table 41.2. Differential Diagnosis of Cyanosis in the Neonate
* In the case of polycythemia, these infants have plethora and venous congestion in the distal extremities, which gives the appearance of distal cyanosis; these infants actually are not hypoxemic (see text).
C. Heart murmur. Heart murmurs are not uncommonly heard when examining neonates. It is estimated that >50% of children have a murmur at some point during childhood, with the majority presenting in the neonatal period. Murmurs heard in newborns in the first days of life are often associated with structural heart disease of some type, and therefore may need further evaluation, particularly if there are any other associated clinical symptoms. Nevertheless, it is not uncommon for an innocent murmur to be heard during the transition from fetal circulation, specifically the closing of the PDA. Other transient murmurs may be heard, including a very small muscular ventricular septal defect that is closing or peripheral branch pulmonary artery stenosis that is due to blood flow turbulence at the pulmonary artery branches that disappears as the branches grow.
Pathologic murmurs tend to appear at characteristic ages. Semilunar valve stenosis (systolic ejection murmurs) and atrioventricular valvular insufficiency (systolic regurgitant murmurs) tend to be noted very shortly after birth, on the first day of life. In contrast, murmurs due to left-to-right shunt lesions (a ventricular septal defect murmur or continuous PDA murmur) may not be heard until the second to fourth week of life, when the pulmonary vascular resistance has decreased and the left-to-right shunt increases. Therefore, the age of the patient when the murmur is first noted and the character of the murmur provide important clues to the nature of the malformation.
Table 41.3. Differential Diagnosis of Congestive Heart Failure in the Neonate
Pressure overload
Aortic stenosis
Coarctation of the aorta
Volume overload
Left-to-right shunt at level of great vessels
Patent ductus arteriosus
Aorticopulmonary window
Truncus arteriosus
Tetralogy of Fallot, pulmonary atresia with multiple aorticopulmonary collaterals
Left-to-right shunt at level of ventricles
Ventricular septal defect
Common atrioventricular canal
Single ventricle without pulmonary stenosis (includes hypoplastic left heart syndrome)
Arteriovenous malformations
Combined pressure and volume overload
Interrupted aortic arch
Coarctation of the aorta with ventricular septal defect
Aortic stenosis with ventricular septal defect
Myocardial dysfunction
Primary
Cardiomyopathies
Inborn errors of metabolism
Genetic
Myocarditis
Secondary
Sustained tachyarrhythmias
Perinatal asphyxia
Sepsis
Severe intrauterine valvular obstruction (e.g., aortic stenosis)
Premature closure of the ductus arteriosus
D. Arrhythmias. See section IX (Arrhythmias) of this chapter for a detailed description of the identification and management of the neonate with an arrhythmia.
E. Fetal echocardiography. It is increasingly common for infants to be born with a diagnosis of probable congenital heart disease due to the widespread use of obstetric ultrasonography and fetal echocardiography. This may be quite valuable to the team of physicians caring for mother and baby, guiding plans for prenatal care, site and timing of delivery, as well as immediate perinatal care of the infant. The recommended timing for fetal echocardiography is 18 to 20 weeks’ gestation, although reasonable images can be obtained as early as 16 weeks, and transvaginal ultrasonography may be used for diagnostic purposes in fetuses in the first trimester. Indications for fetal echocardiography are summarized in Table 41.4. It is important to note, however, that most cases of prenatally diagnosed congenital heart disease occur in pregnancies without known risk factors. Most severe forms of congenital heart disease can be accurately diagnosed by fetal echocardiography. Coarctation of the aorta, small ventricular and atrial septal defects, TAPVR, and mild aortic or pulmonary stenosis are abnormalities that may be missed by fetal echocardiography. It is important to consider that the expected PDA can mask a coarctation, and the fetal circulation requires a PFO for survival that can make the presence of an atrial septal defect uncertain. In general, in complex congenital heart disease, the main abnormality is noted; however, the full extent of cardiac malformation may be better determined on postnatal examinations.
Fetal tachyarrhythmias or bradyarrhythmias (intermittent or persistent) may be detected on routine obstetric screening ultrasound examinations; this should prompt more complete fetal echocardiography to rule out associated structural heart disease, assess fetal ventricular function, and further define the arrhythmia.
Table 41.4. Indications for Fetal Echocardiography
Fetus-related indications
Suspected congenital heart disease on screening ultrasonography
Fetal chromosomal anomaly
Fetal extracardiac anatomic anomaly
Fetal cardiac arrhythmia
Persistent bradycardia
Persistent tachycardia
Irregular rhythm
Nonimmune hydrops fetalis
Mother-related indications
Congenital heart disease
Maternal metabolic disease
Diabetes mellitus
Phenylketonuria
Maternal rheumatic disease (such as systemic lupus erythematosus)
Maternal environmental exposures
Alcohol
Cardiac teratogenic medications
Amphetamines
Anticonvulsants
Phenytoin
Trimethadione
Carbamazepine
Valproate
Isotretinoin
Lithium carbonate
Maternal viral infection
Rubella
Family-related indications
Previous child or parent with congenital heart disease
Previous child or parent with genetic disease associated with congenital heart disease
Fetal echocardiography has allowed for improved understanding of the in utero evolution of some forms of congenital heart disease. This, in turn, has led to the development of fetal cardiac intervention. Several institutions have begun intervening in semilunar valve stenosis, as well as select other defects. This progress represents a promising new method of treatment for congenital heart disease, however, further research is needed to assess outcomes.
V. EVALUATION OF THE NEONATE WITH SUSPECTED CONGENITAL HEART DISEASE. The most time-sensitive presentation of the neonate with congenital heart disease is circulatory collapse. In this scenario, emergency treatment of circulatory shock should precede cardiac diagnostic studies. Low cardiac output should generate a suspicion for congenital heart disease.
A. Initial evaluation
1. Physical examination. The physical examination should extend beyond the heart. Inexperienced examiners frequently focus solely on the presence or absence of cardiac murmurs, but many other findings can guide diagnostic decision making.
a. Inspection. Cyanosis may first be apparent on inspection of the mucous membranes and/or nail beds (see section IV.A.1). Mottling of the skin and/or an ashen, gray color are important clues to severe cardiovascular compromise and incipient shock. While observing the infant, particular attention should be paid to the pattern of respiration including the work of breathing and use of accessory muscles.
b. Palpation. Palpation of the distal extremities with attention to temperature and capillary refill is imperative. Although cool extremities with delayed capillary refill would indicate a suspicion for sepsis, it should also raise suspicion of congenital heart disease. While palpating the distal extremities, note the presence and character of the distal pulses. Diminished or absent distal pulses are suggestive of aortic arch obstruction. Palpation of the precordium may provide important information suggesting congenital heart disease. A precordial thrill may be present in the setting of at least moderate pulmonary or aortic outflow obstruction. A restrictive ventricular septal defect with low RV pressure could also generate a thrill; however, it is less likely in the early neonatal period. A hyperdynamic precordium suggests a significant left-to-right shunt.
c. Auscultation. This part of the exam should be performed systematically and not be rushed to identify heart murmurs. Many severe congenital heart defects will not have a murmur in the neonatal period. First, listen to the heart rate to determine if it is regular. Second, listen carefully to the heart sounds. The second heart sound is important because its split indicates the presence of two semilunar valves. Hearing this can be difficult in neonates that have fast heart rates. However, the presence of a S3 or S4 is more obvious and more indicative of a neonate in crisis. Distinguishing them may be difficult, but the presence of either is abnormal and should prompt further study and consultation. A systolic ejection click suggests aortic or pulmonary valve stenosis.
The presence and intensity of systolic murmurs suggest the type and severity of the underlying anatomic diagnosis. When associated with pathology, they are associated with (i) semilunar valve or outflow tract stenosis, (ii) shunting through a septal defect, or (iii) atrioventricular valve regurgitation. Diastolic murmurs are always indicative of cardiovascular pathology. For a more complete description of auscultation of the heart, refer to the cardiology texts from the chapter reference list.
A careful search for other anomalies is essential because congenital heart disease is accompanied by at least one extracardiac malformation in 25% of these patients. Table 41.5 summarizes malformation and chromosomal syndromes commonly associated with congenital heart disease.
2. Four-extremity blood pressure. Measurement of blood pressure should be taken in bilateral upper and lower extremities. The lower extremities should be equivalent because both are located distal to any aortic arch obstruction. A difference between leg blood pressures is likely due to sampling and not indicative of disease. Automated blood pressure cuffs are most commonly used today, but in a small neonate with pulses that are difficult to palpate, manual blood pressure measurement with Doppler amplification may be necessary for an accurate measurement. A systolic pressure that is 10-15 mm Hg higher in the upper body compared to the lower body is abnormal and suggests coarctation of the aorta, aortic arch hypoplasia, or interrupted aortic arch. It should be noted that a systolic blood pressure gradient is quite specific for an arch abnormality but not sensitive; a systolic blood pressure gradient will not be present in the neonate with an arch abnormality in whom the ductus arteriosus is patent and nonrestrictive. Therefore, the lack of a systolic blood pressure gradient in newborn does not conclusively rule out coarctation or other arch abnormalities, but the presence of a significant systolic pressure gradient is diagnostic of an aortic arch abnormality.
3. Pulse oximetry. Multiple studies indicate improved detection of congenital heart disease with the implementation of routine pulse oximetry screening. As such, many countries include this as part of the neonatal evaluation. The primary approach includes pre- and postductal extremity pulse oximetry measurement >24 hours after birth. Values <95% would result in further evaluation with echocardiography. Some investigators suggest that the threshold may need to be adjusted for patients born at altitude.
Table 41.5. Chromosomal Anomalies, Syndromes, and Associations Commonly Associated with Congenital Heart Disease
SGA; facies (dolichocephaly, prominent occiput, short palpebral fissures, low-set posteriorly rotated ears, small mandible); short sternum; rocker bottom feet; overlapping fingers with “clenched fists”
≥95% have cardiac defects, VSD most common (sometimes multiple); redundant valvular tissue with regurgitation often affecting more than one valve (polyvalvular disease)
Trisomy 21 (Down syndrome)
1/660
Facies (brachycephaly, flattened occiput, midfacial hypoplasia, mandibular prognathism, upslanting palpebral fissures, epicanthal folds, Brushfield spots, large tongue); simian creases, clinodactyly with short fifth finger; pronounced hypotonia
40%-50% have cardiac defects, CAVC, VSD most common, also TOF, ASD, PDA; complex congenital heart disease is very rare
45,X (Turner syndrome)
1/2,500
Lymphedema of hands, feet; short stature; shortwebbed neck; facies (triangular with downslanting palpebral fissures, low-set ears); shield chest
25%-45% have cardiac defects, coarctation, bicuspid aortic valve most common
Single-gene defects
Noonan syndrome
AD
Facies (hypertelorism, epicanthal folds, downslanting palpebral fissures, ptosis); low-set ears; short webbed neck with low hairline; shield chest, cryptorchidism in men
50% have cardiac detect, usually pulmonary valve stenosis, also ASD, hypertrophic CM
Holt-Oram syndrome
AD
Spectrum of upper limb and shoulder girdle anomalies
Cardiac findings in 90%. Peripheral pulmonic stenosis is most common.
Gene deletion syndromes
Williams syndrome (deletion 7q11)
1/7,500
SGA, FIT; facies (“elfin” with short palpebral fissures, periorbital fullness or puffiness, flat nasal bridge, stellate iris, long philtrum, prominent lips); fussy infants with poor feeding, friendly personality later in childhood; characteristic mental deficiency (motor more reduced than verbal performance)
50%-70% have cardiac defect, most commonly supravalvular aortic stenosis; other arterial stenoses also occur, including PPS, CoA, renal artery, and coronary artery stenoses.
DiGeorge syndrome (deletion 22q11)
1/6,000
Thymic hypoplasia/aplasia; parathyroid hypoplasia/aplasia; cleft palate or velopharyngeal incompetence
IAA and conotruncal malformations including truncus, TOF
VACTERL
Vertebral defects, anal atresia, cardiac defects, TE fistula, radial and renal anomalies, limb defects
Approximately 50% have cardiac defect, most commonly VSD.
CHARGE
Coloboma, heart defects, choanal atresia, growth and mental deficiency, genital hypoplasia (in men), ear anomalies and/or deafness
50%-70% have cardiac defect, most commonly conotruncal anomalies (TOF, DORV, truncus arteriosus)
SGA, small for gestational age; VSD, ventricular septal defect; CAVC, complete atrioventricular canal; TOF, tetralogy of Fallot; ASD, atrial septal defect; PDA, patent ductus arteriosus; AD, autosomal dominant; CM, cardiomyopathy; FIT, failure to thrive; PPS, peripheral pulmonary stenosis; CoA, coarctation of the aorta; IAA, interrupted aortic arch; TE, tracheoesophageal; DORV, double outlet right ventricle.
4. Chest x-ray. A frontal and lateral view (if possible) of the chest should be obtained. In infants, particularly newborns, the size of the heart may be difficult to determine due to an overlying thymus. Nevertheless, useful information can be gained from the chest x-ray. In addition to heart size, notation should be made of visceral and cardiac situs (dextrocardia and situs inversus are frequently accompanied by congenital heart disease). The aortic arch side (right or left) often can be determined; a right-sided aortic arch is associated with congenital heart disease in >90% of patients. Dark or poorly perfused lung fields suggests decreased pulmonary blood flow, whereas diffusely opaque lung fields may represent increased pulmonary blood flow or significant left atrial hypertension.
5. Electrocardiogram (ECG). The neonatal ECG reflects the hemodynamic relations that existed in utero; therefore, the normal ECG is notable for RV predominance. As many forms of congenital heart disease have minimal prenatal hemodynamic effects, the ECG is frequently “normal for age” despite significant structural pathology (e.g., transposition of the great arteries, tetralogy of Fallot). Throughout the neonatal period, infancy, and childhood, the ECG will evolve due to the expected changes in physiology and the resulting changes in chamber size and thickness that occur. Because most findings on a neonate’s ECG would be abnormal in an older child or adult, it is essential to refer to age-specific charts of normal values for most ECG parameters. Refer to Tables 41.6 and 41.7 for normal ECG values in term and premature neonates.
When interpreting an ECG, the following determinations should be made: (i) rate and rhythm; (ii) P, QRS, and T axes; (iii) intracardiac conduction intervals; (iv) evidence for chamber enlargement or hypertrophy; (v) evidence for pericardial disease, ischemia, infarction, or electrolyte abnormalities; and (vi) if the ECG pattern fits with the clinical picture. When the ECG is abnormal, one should also consider incorrect lead placement; a simple confirmation of lead placement may be done by comparing QRS complexes in limb lead I and precordial lead V6—each should have a similar morphology if the limb leads have been properly placed. The ECG of the premature infant is somewhat different from that of the term infant (Table 41.7).
6. Hyperoxia test. In all neonates with suspected critical congenital heart disease (not just those who are cyanotic), a hyperoxia test should be considered. This single test is perhaps the most sensitive and specific tool in the initial evaluation of the neonate with suspected disease. In sites with timely access to echocardiography, a complete hyperoxia test may not need to be performed; however, it is important to appreciate that this can be a valuable test when echocardiography is not quickly available.
To investigate the possibility of a fixed, intracardiac right-to-left shunt, the arterial oxygen tension should be measured in room air (if tolerated) followed by repeat measurements with the patient receiving 100% inspired oxygen (the “hyperoxia test”). If possible, the arterial partial pressure of oxygen (PO2) should be measured directly through arterial puncture, although properly applied transcutaneous oxygen monitor (TCOM) values for PO2 are also acceptable. Pulse oximetry cannot be used for documentation; in a neonate given 100% inspired oxygen, a value of 100% oxygen saturation may be obtained with an arterial PO2 ranging from 80 torr (abnormal) to 680 torr (normal, see section IV.A.1).
Table 41.6. ECG Standards in Newborns
Age (Days)
Measure
0-1
1-3
3-7
7-30
Term infants
Heart rate (bpm)
122 (99-147)
123 (97-148)
128 (100-160)
148 (114-177)
QRS axis (degrees)
135 (91-185)
134 (93-188)
133 (92-185)
108 (78-152)
PR interval, II (s)
0.11 (0.08-0.14)
0.11 (0.09-0.13)
0.10 (0.08-0.13)
0.10 (0.08-0.13)
QRS duration (s)
0.05 (0.03-0.07)
0.05 (0.03-0.06)
0.05 (0.03-0.06)
0.05 (0.03-0.08)
V1, R amplitude (mm)
13.5 (6.5-23.7)
14.8 (7.0-24.2)
12.8 (5.5-21.5)
10.5 (4.5-18.1)
V1, S amplitude (mm)
8.5 (1.0-18.5)
9.5 (1.5-19.0)
6.8 (1.0-15.0)
4.0 (0.5-9.7)
V6, R amplitude (mm)
4.5 (0.5-9.5)
4.8 (0.5-9.5)
5.1 (1.0-10.5)
7.6 (2.6-13.5)
V6, S amplitude (mm)
3.5 (0.2-7.9)
3.2 (0.2-7.6)
3.7 (0.2-8.0)
3.2 (0.2-3.2)
Preterm infants
Heart rate (bpm)
141 (109-173)
150 (127-182)
164 (134-200)
170 (133-200)
QRS axis (degrees)
127 (75-194)
121 (75-195)
117 (75-165)
80 (17-171)
PR interval (s)
0.10 (0.09-0.10)
0.10 (0.09-1.10)
0.10 (0.09-0.10)
0.10 (0.09-0.10)
QRS duration (s)
0.04
0.04
0.04
0.04
V1, R amplitude (mm)
6.5 (2.0-12.6)
7.4 (2.6-14.9)
8.7 (3.8-16.9)
13.0 (6.2-21.6)
V1, S amplitude (mm)
6.8 (0.6-17.6)
6.5 (1.0-16.0)
6.8 (0.0-15.0)
6.2 (1.2-14.0)
V6, R amplitude (mm)
11.4 (3.5-21.3)
11.9 (5.0-20.8)
12.3 (4.0-20.5)
15.0 (8.3-21.0)
V6, S amplitude (mm)
15.0 (2.5-26.5)
13.5 (2.6-26.0)
14.0 (3.0-25.0)
14.0 (3.1-26.3)
Source: Davignon A, Rautaharja P, Boiselle E, et al. Normal ECG standards for infants and children. Pediatr Cardiol 1980;1(2):123-131; Sreenivasan VV, Fisher BJ, Liebman J, et al. Longitudinal study of the standard electrocardiogram in the healthy premature infant during the first year of life. Am J Cardiol 1973;31(1):57-63.
Table 41.7. ECG Findings in Premature Infants (Compared to Term Infants)
Rate
Slightly higher resting rate with greater activity-related and circadian variation (sinus bradycardia to 70, with sleep not uncommon)
Intracardiac conduction
PR and QRS duration slightly shorter
Maximum QTc <0.44 s (longer than for term infants, QTc <0.40 s)
QRS complex
QRS axis in frontal plane more leftward with decreasing gestational age
QRS amplitude lower (possibly due to less ventricular mass)
Less right ventricular predominance in precordial chest leads
Source: Reproduced with permission from Thomaidis C, Varlamis G, Karamperis S. Comparative study of the electrocardiograms of healthy fullterm and premature newborns. Acta Paediatr Scand 1988;77(5):653-657.
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