The term “congenital heart disease” (CHD) encompasses a wide variety of lesions. The emergency physician must not only recognize and manage previously undiagnosed CHD but also anticipate complications in a rapidly growing population of survivors of congenital heart surgery.

Congenital heart lesions occur in approximately 8 in 1000 live births in the United States, with lesions ranging from mild to severe; this number does not include common lesions such as bicuspid aortic valve (1%–2% of the population) or mitral valve prolapse.¹ Overall, neither gender is predominant, but individual lesions may be more common in either males or females. The vast majority of patients will have isolated congenital heart lesions that are multifactorial in origin. Approximately 10% of cases can be attributed to genetic causes. Many genetic syndromes (e.g., the trisomies, connective tissue disorders) and teratogens (e.g., congenital rubella infection) are associated with a higher risk of specific congenital heart lesions (Table 40-1).^1,2 Most patients present during infancy (Fig. 40-1).

FETAL CIRCULATION

Oxygenated blood from the placenta enters the fetus through the single umbilical vein (Fig. 40-2). Approximately half of this blood bypasses the liver via the ductus venosus, flowing directly into the inferior vena cava (IVC). The majority is then directed from the IVC across the foramen ovale into the left atrium, bypassing the right heart and pulmonary circulation. This highly oxygenated blood in the left atrium mixes with pulmonary venous return, enters the left ventricle and the ascending aorta, and perfuses the cerebral circulation. Deoxygenated blood from the cerebral circulation drains into the superior vena cava, entering the right atrium, right ventricle, and pulmonary artery. Since pulmonary vascular resistance is high in the fetus, most of this blood bypasses the pulmonary circulation by way of the ductus arteriosus and enters the descending aorta. Two-thirds of this descending aorta outflow returns to the placenta via the umbilical arteries, and one-third perfuses the lower part of the fetus.

NEONATAL CIRCULATION

In the first hours of life, the newborn’s pulmonary arterioles dilate and pulmonary vascular resistance begins to fall, resulting in increased pulmonary blood flow (PBF). Separation from the low-resistance placental circuit results in increased systemic blood pressure, which also reduces blood flow through the ductus arteriosus. The smooth muscle of the ductus arteriosus constricts in response to increased blood PO₂; it is functionally closed by 15 hours of life. In the normal infant, the ductus arteriosus becomes the ligamentum arteriosum by 2 to 3 weeks of age. The foramen ovale closes by 3 months of age.

The neonatal myocardium is inefficient in extracting oxygen at the cellular level; its baseline oxygen requirement is high and it is unable to increase its contractility in response to demand. When increased cardiac output is needed, the neonate responds with an increasing heart rate. Thus, the physiology in the young infant is one of rate-dependent cardiac output, increased oxygen consumption, and a lower systolic reserve. These factors predispose children with CHD to congestive heart failure (CHF). In addition, neonates and young infants may be slow to transition from in utero physiology and may still shunt blood via the foramen ovale or a patent ductus arteriosus (PDA). This may present as high pulmonary vascular resistance, which is responsive to oxygen (i.e., oxygen decreases resistance), and a prominent right ventricle, seen as right-axis deviation (RAD) on electrocardiogram (ECG).

HISTORY

General health, including growth, development, and susceptibility to respiratory illnesses, should be assessed. Pregnancy, birth, and family history may provide valuable clues to specific genetic or teratogenic etiologies. Symptoms of CHF should be sought: poor feeding, longer feeding times than the average infant, poor growth or failure to thrive, sweating with feeding, irritability or lethargy, weak cry, increased respiratory effort, dyspnea, tachypnea, and coughing. Ask about cyanosis or cyanotic episodes, which may be more noticeable during crying or exercise.

Although eliciting a thorough history is essential, it is important to note the limitations of prenatal and perinatal diagnosis of CHD. Significant congenital heart lesions may go undetected by prenatal ultrasound and may not present immediately after birth.³ Pulse oximetry measurement is increasingly recognized as a useful screening tool to identify potential critical congenital heart disease in the newborn nursery.⁴ Birth medical records may disclose routine pulse oximetry screening, which has a high specificity, and when done at age <24 hours is approximately 85% sensitive.⁵ Measuring both preductal (right upper extremity) and postductal (preferably lower extremity) O₂ saturation and screening at age <24 hours improves sensitivity but results in a higher false positive rate. A common cutoff for abnormal is SpO₂ <95% in either limb or a difference of >2% between limbs.⁴ Further research is needed to define cutoffs for high-altitude locations.

PHYSICAL EXAMINATION

As with any patient encounter, evaluation begins with a first impression of the patient. The pediatric assessment triangle (PAT) is used to assess rapidly a child’s severity of illness and to determine urgency for life support. Its three components—appearance, work of breathing, and circulation to skin—give powerful information across the room using only visual and auditory clues.⁶ This rapid global assessment is especially useful in the undifferentiated patient who may be suffering from CHD.

Check vital signs, including four-extremity blood pressures and pulse quality, in the upper and lower extremities in the sick infant. Color and general appearance may be significant clues for classifying the lesion into one of three categories:

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  Pink: CHF, L → R shunt

  
  
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  Blue: cyanotic heart disease, R → L shunt

  
  
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  Gray: outflow obstruction, hypoperfusion, and shock

For cyanosis to be clinically apparent, 3 to 5 g/dL of deoxygenated hemoglobin must be present (correlating to an oxygen saturation of 80%–85%). If the child is anemic, cyanosis may be less easily recognized. Peripheral cyanosis, acrocyanosis, and mottling may be normal newborn variants. Nail beds (look also for clubbing) and mucous membranes are the best locations to assess for central cyanosis. Auscultate for murmurs, S1 and S2, and extra sounds. If the child is quiet and comfortable when you first enter the room, take advantage of the situation to auscultate the heart and lungs before upsetting the child with other elements of the physical examination. Murmurs are commonly heard in normal children (Table 40-2). In general, normal murmurs are never diastolic, late systolic, or pansystolic. Examine the abdomen for hepatomegaly. The liver is palpable no more than 1 to 3 cm below the right subcostal margin in normal infants. Examine the child for dysmorphic features suggestive of a genetic or teratogenic syndrome.

PULSE OXIMETRY

Although pulse oximetry screening programs have been found to be cost effective and useful adjuncts in the detection of critical CHD in the newborn nursery, neonatal screening is not applicable to the acutely ill infant in the emergency department (ED). It can be useful as a screening tool in the presumably well infant, and readings obtained after the first 24 hours of life, which is when infants are likely to be seen in the ED, result in lower false positive rates. Consider referring otherwise well infants with SpO₂ <95% unexplainable by respiratory or other acute illness, or a difference of >2% between preductal and postductal O₂ saturations, for further evaluation to rule out CHD.^4,5

HYPEROXIA TEST

The hyperoxia test is the single most sensitive and specific test in the initial evaluation of a neonate with suspected CHD (in the absence of readily available echocardiography). An arterial blood gas (ABG) is sampled with the patient on room air (if tolerated), and repeated after a few minutes of high-flow oxygen. When a child breathes high-flow oxygen (“100%” O₂), an arterial PO₂ of greater than 250 torr virtually excludes hypoxia due to cyanotic CHD (a “passed” hyperoxia test).³ An arterial PO₂ of less than 100 torr in a patient without obvious lung disease is indicative of a right-to-left shunt and extremely predictive of cyanotic CHD (a “failed” hyperoxia test). A value of 100 to 250 torr may indicate structural heart disease with complete intracardiac mixing (“indeterminate” hyperoxia test). Ideally, blood is sampled from both preductal (right upper extremity) and postductal sites (preferably the lower extremities) and carefully labeled as to site and FiO₂. When done at both sites, valuable information about the possible lesion may be obtained, such as differential cyanosis, e.g. a markedly higher preductal oxygen level compared to postductal, may indicate aortic arch obstruction.

Regardless of site used, the hyperoxia test is useful in all neonates with suspected CHD, not just those who appear cyanotic. Pulse oximetry is an imperfect substitute for an ABG; it is not sensitive enough to determine “pass or fail” because a child breathing high-flow O₂ and registering 100% on pulse oximetry may actually have an arterial PO₂ of anywhere from 80 to 680 torr. Most importantly, a neonate who fails the hyperoxia test should be presumed to have critical CHD and should receive prostaglandin E1 (PGE1) immediately until a definitive anatomic diagnosis is made.

Although pulse oximetry is an imperfect substitute for ABG, in many situations rapid and accurate ABG results are not possible, particularly in the acute setting. Pulse oximetry can still be a useful tool at the bedside while awaiting ABG results. An acutely cyanotic child whose low pulse oximetry is completely unresponsive to supplemental oxygen has a high likelihood of CHD, and as previously discussed, a trial of PGE1 may be initiated while awaiting further diagnostics.

OTHER ANCILLARY TESTS

Chronically cyanotic children usually compensate with polycythemia. A cyanotic child’s oxygen-carrying capacity will be further compromised by anemia. Obtain a chest radiograph (CXR) to evaluate cardiomegaly, chamber enlargement, and pulmonary vascularity. Evaluate an ECG for conduction and rhythm disturbances, chamber forces, and rare ischemic changes. Consult a pediatric handbook, as ECG normal ranges vary greatly by age. Age and chamber force differences may seem intimidating to the clinician, but a few basic principles may provide a guide (see also Table 40-3). For example, one striking difference between adult and pediatric ECGs is the inclusion of additional leads such as the right ventricular (RV) leads V3R or V4R (and less frequently the posterior left ventricular lead V7). Neonates and young children have a natural RAD, which may obscure the typical findings of right-sided disease; the addition of leads V3R or V4R increases the yield in detecting right atrial or ventricular hypertrophy when CHD is suspected.⁷

Sinus bradycardia must be recognized in the sick infant. Intervals should be analyzed for drug effects and for long QT syndrome. The upper limit of abnormal for the QTc is 450 msec, except in infants aged 0 to 6 months, when it is 490 msec.^7,8 Neonatal right-sided forces such as RAD and right ventricular hypertrophy (RVH) will transition gradually to adult form by age 3 to 4 years. Incomplete right bundle-branch block (rSr′) is common (Fig. 40-3), and left bundle-branch block is rare. Ischemic changes are rare and differ from those in adults. However, Q waves greater than 35 ms, ST elevation greater than 2 mm, or ventricular arrhythmia in the context of a worrisome clinical picture may indicate ischemia. T-wave changes, especially T-wave inversions, are common in children and are rarely ischemic (juvenile T waves). The T wave is normally inverted in V1 between age 1 week and adolescence; an upright T in V1 in this age range may reflect RVH. Other common ECG findings in children include first-degree AV block, pronounced sinus arrhythmia, and isolated premature atrial and ventricular complexes.⁸

Echocardiogram often provides the definitive diagnosis, but may not be able to be performed in the ED. Do not withhold appropriate therapy for the critically ill child while awaiting confirmatory echocardiography. Bedside ultrasound is sometimes performed by emergency practitioners to assess cardiac contractility and ventricular size in adults, but these methods have not yet been validated in children.

Lesions are usually classified as cyanotic or acyanotic and further subclassified according to whether or not the lesion is ductal-dependent; that is, whether the lesion depends on a PDA to deliver partially oxygenated blood to the systemic circulation.

Cyanotic lesions: “The Six Terrible (Turquoise) Ts” include Truncus arteriosus, Transposition of the great arteries (TGA), Total anomalous pulmonary venous return, Tetralogy of Fallot (TOF)*, Tricuspid abnormalities* (tricuspid atresia, Ebstein’s anomaly), and “Tons” of others* (“Tiny Heart”—hypoplastic left heart syndrome [HLHS], “Terminated Aorta”—interrupted aortic arch) (*ductal-dependent lesions).

Acyanotic lesions: “PiCk A Very Powerful Approach to Acyanosis” include Pulmonic stenosis*, Coarctation of the aorta*, Atrioseptal defect, Ventriculoseptal defect, Patent ductus arteriosus, Aortic stenosis, Atrioventriculoseptal defects (*ductal-dependent lesions).

BRIEF SURVEY OF INDIVIDUAL LESIONS

Truncus arteriosus involves a single arterial trunk supplying both the pulmonary and systemic circulations (Fig. 40-4). A ventricular septal defect (VSD) is usually present. Initially, cyanosis may be mild or absent. A murmur is detected in the first few days, pulses are bounding, and there is a single S2. The patient may have symptoms of CHF and recurrent pulmonary infections. CXR shows cardiomegaly and increased PBF. ECG shows left ventricular hypertrophy (LVH), RVH, or both.

Transposition of the great arteries (TGA) is the most common cyanotic lesion to present in the first week of life. The right ventricle feeds the aorta, whereas the left ventricle feeds the pulmonary artery (Fig. 40-5). Mixing must occur to sustain life via an atrial septal defect (ASD) or patent foramen ovale (PFO), VSD, or PDA, as the pulmonary and systemic circulations are in parallel. Symptoms include cyanosis and tachypnea in the first days of life; often there is no murmur. CXR may be normal or may have an “egg on a string” appearance. ECG shows RAD and RVH but may be normal in the first days of life. If the mixing lesion is small, the patient presents early with cyanosis. If there is a large VSD, the infant may present with CHF and cyanosis at 2 to 6 weeks of age.

Total anomalous pulmonary venous return (TAPVR) has many variations depending on whether it is total or partial (one to four veins connecting anomalously to a location other than the left atrium, usually to the right atrium), where the veins terminate, and the degree of pulmonary venous obstruction (Fig. 40-6). Cyanosis is mild to moderate, depending on the degree of mixing of the right and left circulations. There is often little murmur, but the S2 is widely split. CXR may show a “snowman” appearance, and ECG may show RVH, RAD, and right atrial enlargement (RAE).

Tetralogy of Fallot (TOF) is the most common cyanotic CHD seen in children older than 4 years. It consists of RV outflow obstruction with resultant RVH, a large VSD, and an overriding aorta (Fig. 40-7). Patients have a loud, harsh, pansystolic murmur in the left sternal border, and often a single S2. CXR shows a boot-shaped heart (cœur en sabot), decreased PBF, and in 25%, a right-sided aortic arch. ECG shows RAD and RVH. Severity ranges widely, and depends on the degree of RV outflow obstruction.

Tricuspid atresia must be accompanied by an intra-atrial right-to-left shunt (ASD or PFO) (Fig. 40-8). Tricuspid atresia is rare, and findings depend on the presence or absence of a VSD and presence of hypoplasia of the right ventricle. Ebstein’s anomaly is a displacement of the tricuspid valve into the RV. Severity varies widely depending on the degree of displacement.

Hypoplastic left heart syndrome (HLHS) is a rare anomaly in which the right ventricle perfuses both circulations via the pulmonary artery (Fig. 40-9). The systemic circulation is perfused through a PDA. Management spans the entire range of no treatment, palliative surgery, or cardiac transplantation, depending on the parents’ choice and resources available.

Pulmonic stenosis (PS) often produces no symptoms and may be recognized when a murmur is noted during routine physical examination (Fig. 40-10). Once PS is moderate to severe, there may be cyanosis on exertion, syncope, RV failure, and even sudden death. An ejection click is typically heard before the systolic ejection murmur in the left second to third intercostal space. CXR shows a prominent main pulmonary artery and normal to decreased PBF. ECG may be normal or show RVH.

Aortic coarctation accounts for 10% of congenital heart lesions. The narrowing most commonly occurs just distal to the left subclavian artery branch. Symptoms range from ductal-dependent cardiogenic shock or CHF in infancy to hypertension in childhood or adulthood (Fig. 40-11). The median age at referral is 5 to 8 years. Blood pressure is elevated in the upper compared with the lower extremities, and femoral pulses are weak or absent. Children may complain of pain in the legs after exercise. A systolic ejection murmur at the apex radiates to the interscapular back. There may be a diastolic murmur of aortic regurgitation as well. In some patients a thrill is felt in the suprasternal notch. CXR is normal initially, but may show notching of ribs 3 through 8 posteriorly as collateral circulation develops. ECG shows LVH in the severely affected infant. Children may present with complications of hypertension, including intracranial hemorrhage.