Cardiac Disorders

Cardiac Disorders
Stephanie Burns Wechsler
Gil Wernovsky
I. INTRODUCTION.
At the beginning of the 20th century, Dr. William Osler wrote in his textbook of medicine that congenital heart disease was of “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.” In the years since 1938, when Dr. Robert Gross first successfully ligated a patent ductus arteriosus (PDA) in a 7-year-old girl at Children’s Hospital, Boston (with a 17-day postoperative stay, 12 of which were for “general interest in the case”), the outlook for children with congenital heart disease has improved dramatically. This remarkable progress is due to synergistic advances in pediatric and fetal cardiology, cardiac surgery, neonatology, cardiac anesthesia, intensive care, and nursing.
In critical lesions, the ultimate prognosis for the patient depends in part on (i) a timely and accurate assessment of the structural anomaly and (ii) the evaluation and resuscitation of secondary organ damage. It is therefore crucial that pediatricians and neonatologists be able to rapidly evaluate and participate in the initial medical management of neonates with congenital heart disease. A multidisciplinary approach involving several subspecialty services is frequently required, especially because one-fifth of patients with severe congenital heart disease may be premature and/or weigh <2,500 g at birth. Although neonates (as a group) may have a slightly higher surgical mortality than term infants, the secondary effects of the unoperated lesion on the heart, lung, and brain may be quite severe. These secondary changes may include chronic congestive heart failure (CHF), failure to thrive, frequent infections, irreversible pulmonary vascular changes, delayed cognitive development, or focal neurologic deficits. For these reasons, at Children’s Hospital in Boston, primary surgical correction is carried out early in life, often in the neonatal period. This chapter is intended as a practical guide for the initial evaluation and management, by pediatricians and neonatologists, of neonates and infants suspected of having congenital heart disease. For a detailed discussion of the individual lesions, the clinician should consult current textbooks of pediatric cardiology and cardiac surgery.
II. INCIDENCE AND SURVIVAL.
The incidence of moderate to severe structural congenital heart disease in live born infants is 6 to 8 per 1,000 live births. This incidence has been relatively constant over the years and in different areas around the world. More recent higher incidence figures appear to be due to the inclusion of more trivial forms of congenital heart disease, such as tiny ventricular septal defects that are detected more frequently by highly sensitive echocardiography. Data from the New England Regional Infant Cardiac Program suggest that approximately 3 per 1,000 live births have heart disease that results in death or requires cardiac catheterization or surgery during 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. Recent advances in diagnostic imaging, cardiac surgery, and intensive care have reduced the operative risks for 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 Agesa

Diagnosis

Percentage of patients

Age on admission: 0-6 days (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 days (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 days (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

aReprinted 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 and accompanying symptomatology depends on (i) the nature and severity of the anatomic defect, (ii) the in utero effects (if any) of the structural lesion, and (iii) the alterations in cardiovascular physiology secondary to the effects of the transitional circulation: closure of the ductus arteriosus and the fall in pulmonary vascular resistance. This chapter focuses primarily on cardiovascular abnormalities with critical effects in the neonatal period.
In the first few weeks of life, many heterogeneous forms of heart disease present in a surprisingly limited number of ways (in no particular order nor mutually exclusive): (i) cyanosis; (ii) CHF (with the most extreme presentation being cardiovascular collapse or shock); (iii) an asymptomatic heart murmur; and (iv) arrhythmia. With increasing frequency, neonates with congenital heart disease have been diagnosed before delivery by fetal echocardiography and are therefore born with a presumptive diagnosis into an expectant team of physicians and nurses. In many neonates, however, congenital heart disease is not suspected until after birth. The clinician may be diverted away from a diagnosis of heart disease because of the report of a “normal” prenatal ultrasonography performed for screening purposes. Finally, the diagnosis of “heart disease” should never divert the clinician from a complete noncardiac evaluation with a thorough search for additional or secondary medical problems—occasionally, the neonate with complex congenital heart disease and hypoxemia has inadequate attention paid to an initial and continued assessment of an adequate airway and ventilation.
  • 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

    Polycythemiaa (see Chap. 46)

    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.
IV. EVALUATION OF THE NEONATE WITH SUSPECTED CONGENITAL HEART DISEASE.
As noted, the suspicion of congenital heart disease in the neonate typically follows one of a few clinical scenarios. Circulatory collapse is, unfortunately, not an uncommon means of presentation for the neonate with congenital heart disease. It must be emphasized that emergency treatment of shock precedes definitive anatomic diagnosis. Although sepsis may be suspected and treated, the signs of low cardiac output should always alert the examining physician to the likely possibility of congenital heart disease.
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

  • 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.

      Only gold members can continue reading. Log In or Register to continue

      Stay updated, free articles. Join our Telegram channel

Jun 11, 2016 | Posted by in PEDIATRICS | Comments Off on Cardiac Disorders

Full access? Get Clinical Tree

Get Clinical Tree app for offline access