Table 41.1 Top Five Diagnoses Presenting at Different Agesa | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Cyanosis
Clinical findings. Cyanosis (bluish tinge of the skin and mucous membranes) is one of the most common presenting signs of congenital heart disease in the neonate. Although cyanosis usually indicates underlying hypoxemia (diminished level of arterial oxygen saturation), there are a few instances when cyanosis is associated with a normal arterial oxygen saturation. 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) desaturated hemoglobin and be more easily appreciated to be cyanotic than the anemic infant (hemoglobin of 10 g/dL) who will only have 1.5 g/dL (15% of 10) desaturated hemoglobin. An additional note, 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).
Because determining cyanosis by visual inspection can be challenging for the reasons mentioned, there has been recent interest in adding routine lower extremity pulse oximetry measurement as a screening test for otherwise asymptomatic congenital heart disease. There is conflicting data on the efficacy and costeffectiveness of this screening method, but it would appear that it is most effective when the pulse oximetry reading is done in a lower extremity in infants >24 hours old with further evaluation by echocardiogram for readings <95% in room air.
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 to 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.
Cyanosis due to congenital heart disease can be broadly grouped into those lesions with (i) decreased pulmonary blood flow and intracardiac rightto-left shunting and (ii) normal to increased pulmonary blood flow with intracardiac mixing (complete or incomplete) of the systemic and pulmonary venous return. Specific lesions and lesion-specific management are covered in more detail in section V.
Congestive heart failure
Clinical findings. CHF in the neonate (or in a patient of any age) is a clinical diagnosis made based on the existence of certain signs and symptoms rather than on radiographic or laboratory findings (although these may be supportive evidence for 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 tachycardiac 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. Finally, CHF may present acutely with cardiorespiratory collapse, particularly in “left-sided” lesions (see V.A.). Hydrops fetalis is an extreme form of intrauterine CHF (see Chap. 26).
Differential diagnosis. The age when CHF develops depends on the hemodynamics 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.
Heart murmur. Heart murmurs are not uncommonly heard when examining neonates. Estimates of the prevalence of heart murmurs in neonates vary widely from <1% to >50% depending on the study. 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.
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 (systolic regurgitant 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 41.2 Differential Diagnosis of Cyanosis in the Neonate
Primary cardiac lesions
Decreased pulmonary blood flow, intracardiac right-to-left shunt
Critical pulmonary stenosis
Tricuspid atresia
Pulmonary atresia/intact ventricular septum
Tetralogy of Fallot
Ebstein anomaly
Total anomalous pulmonary venous connection with obstruction
Normal or increased pulmonary blood flow, intracardiac mixing
Hypoplastic left heart syndrome
Transposition of the great arteries
Truncus arteriosus
Tetralogy of Fallot/pulmonary atresia
Complete common atrioventricular canal
Total anomalous pulmonary venous connection without obstruction
Other single-ventricle complexes
Pulmonary lesions (intrapulmonary right-to-left shunt) (see Chaps. 32, 33, 34, 35, 36, 37 and 38)
Primary parenchymal lung disease
Aspiration syndromes (e.g., meconium and blood)
Respiratory distress syndrome
Pneumonia
Airway obstruction
Choanal stenosis or atresia
Pierre Robin syndrome
Tracheal stenosis
(continued)
Pulmonary sling
Absent pulmonary valve syndrome
Extrinsic compression of the lungs
Pneumothorax
Pulmonary interstitial or lobar emphysema
Chylothorax or other pleural effusions
Congenital diaphragmatic hernia
Thoracic dystrophies or dysplasia
Hypoventilation
Central nervous system lesions
Neuromuscular diseases
Sedation
Sepsis
Pulmonary arteriovenous malformations
Persistent pulmonary hypertension (see Chap. 36)
Cyanosis with normal PO2
Methemoglobinemia
a 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).
Arrhythmias. See section VIII (Arrhythmias) of this chapter for a detailed description of identification and management of the neonate with an arrhythmia.
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, total anomalous pulmonary venous return, and mild aortic or pulmonary stenosis are abnormalities that may be missed by fetal echocardiography. 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.
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 valvar obstruction (e.g., aortic stenosis)
Premature closure of the ductus arteriosus
Fetal tachyarrhythmias or bradyarrhythmias (intermittent or persistent) may be detected on routine obstetric screening and ultrasonographic examinations; this should prompt more complete fetal echocardiography to rule out associated structural heart disease, assess fetal ventricular function, and further define the arrhythmia.
Fetal echocardiography has allowed for improved understanding of the in utero evolution of some forms of congenital heart disease. This, in turn, has opened up the possibility of fetal cardiac intervention. Recent successes in limited, selected cases of fetal cardiac intervention suggest that this is a promising new method of treatment for congenital heart disease.
Table 41.4 Indications for Fetal Echocardiography | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Initial evaluation
Physical examination. A complete physical examination provides important clues to the anatomic diagnosis. Inexperienced examiners frequently focus solely on the presence or absence of cardiac murmurs, but much more additional information should be obtained during a complete examination. A great deal may be learned from simple visual inspection of the infant. Cyanosis may first be apparent on inspection of the mucous membranes and/or nail beds (see III.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.
Before auscultation, palpation of the distal extremities with attention to temperature and capillary refill is imperative. The cool neonate with delayed capillary refill should always be evaluated for the possibility of severe congenital heart disease. While palpating the distal extremities, note the presence and character of the distal pulses. Diminished or absent distal pulses are highly suggestive of obstruction of the aortic arch. Palpation of the precordium may provide an important clue to the presence of congenital heart disease. The presence of a precordial thrill usually indicates at least moderate pulmonary or aortic outflow obstruction, although a restrictive ventricular septal defect with low right ventricular (RV) pressure may present with a similar finding. A hyperdynamic precordium suggests a sizeable left-to-right shunt.
During auscultation, the examiner should first pay particular attention to the heart rate, noting its regularity and/or variability. The heart sounds, particularly the second heart sound, can be helpful clues to the ultimate diagnosis as well. A split-second heart sound is a particularly important marker of the existence of two semilunar valves, although it is often difficult to be sure of S2 splitting with the rapid heart rate of a neonate. Differentiating an S3 from an S4 heart sound is challenging in a tachycardic newborn; however, a gallop rhythm of either type is unusual and suggests the possibility of a significant left-to-right shunt or myocardial dysfunction. Ejection clicks suggest pulmonary or aortic valvar stenosis.
The presence and intensity of systolic murmurs can be very helpful in suggesting the type and severity of the underlying anatomic diagnosis; systolic murmurs are usually due to (i) semilunar valve or outflow tract stenosis, (ii) atrioventricular valve regurgitation, or (iii) shunting through a septal defect. Diastolic murmurs are always indicative of cardiovascular pathology. For a more complete description of auscultation of the heart, refer to one of the cardiology texts listed at the end of the chapter.
A careful search for other anomalies is essential because congenital heart disease is accompanied by at least one extracardiac malformation 25% of the time. Table 41.5 summarizes malformation and chromosomal syndromes commonly associated with congenital heart disease.
Four-extremity blood pressure. Measurement of blood pressure should be taken in both arms and in both legs. Usually, an automated Dinamap is used, 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 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 systolic pressure gradient is diagnostic of an aortic arch abnormality.
Chest x-ray. A frontal and lateral view (if possible) of the chest should be obtained. In infants, particularly in newborns, the size of the heart may be difficult to determine due to 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) can frequently 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.
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).
Table 41.5 Chromosomal Anomalies, Syndromes, and Associations Commonly Associated with Congenital Heart Disease
Approximate incidence or mode of inheritance
Extracardiac features
Cardiac features
Chromosomal anomalies
Trisomy 13 (Patau syndrome)
1/5,000
SGA; facies (midfacial hypoplasia, cleft lip and palate, microophthalmia, coloboma, low-set ears); brain anomalies (microcephaly, holoprosencephaly); aplasia cutis congenita of scalp; polydactyly
≥80% have cardiac defects, VSD most common
Trisomy 18 (Edward syndrome)
1/3,000 (female-male = 3:1)
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 valvar tissue with regurgitation often affecting more than one valve (polyvalvar 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; short webbed 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 valvar pulmonary stenosis, also ASD, hypertrophic CM
Holt-Oram syndrome
AD
Spectrum of upper limb and shoulder girdle anomalies
≥50% have cardiac defect, usually ASD or VSD
Alagille syndrome
AD
Cholestasis; facies (micrognathism, broad forehead, deep-set eyes); vertebral anomalies, ophthalmologic abnormalities
Cardiac findings in 90% peripheral pulmonic stenosis, 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 supravalvar 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
Associations
VACTERL
Vertebral defects; anal atresia; TE fistula; radial and renal anomalies; limb defects
Approximately 50% have cardiac defect, most commonly VSD
CHARGE
Coloboma; 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)
AD = autosomal dominant; AR = autosomal recessive; CM = cardiomyopathy; CoA = coarctation of the aorta; CAVC = complete atrioventricular canal; DORV = double outlet right ventricle; FIT = failure to thrive; IAA = interrupted aortic arch; PDA = patent ductus arteriosus; PPS = peripheral pulmonary stenosis; SGA = small-for-gestational-age; TOF = tetralogy of Fallot; TEF = tracheoesophageal fistula; VSD = ventricular septal detect.
Table 41.6 ECG Standards in Newborns
Measure
Age (D)
0-1
1-3
3-7
7-30
Term infants
Heart rate (beats/mm)
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 (beats/mm)
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 (116.0)
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)
Sources: 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, Karemperis S. Comparative study of the electrocardiograms of healthy fullterm and premature newborns. Acta Paediatr Scand 1988;77(5):653-657.
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 recent disease.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
