Chapter 39: Congenital Heart Disease

• Ductal-dependent lesions typically present with sudden-onset cardiogenic shock at 1 to 2 weeks of life and require immediate prostaglandin E₁ infusion.

• Congestive heart failure (CHF) typically presents in the first 6 months of infancy in children with left-to-right shunting lesions and requires immediate stabilization and medical management.

• Aortic coarctation may present with hypertension and the complications of hypertension. Blood pressure will be higher in the upper extremities compared with the lower extremities.

• The number of survivors of cardiac surgery for congenital heart lesions is rapidly increasing, and emergency physicians should be aware of common complications, such as arrhythmias, residual or recurrent lesions, and endocarditis.

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. 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, which 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 39-1).^1,2 Most patients present during infancy (Fig. 39-1).

Fetal Circulation

Oxygenated blood from the placenta enters the fetus through the single umbilical vein (Fig. 39-2). 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 Although pulse oximetry is recommended as a screening test in the newborn nursery, it varies in its sensitivity to detect critical CHD. In a U.S. study of 7962 newborns, there were 12 postnatal diagnoses of critical CHD; none were detected on routine pulse oximetry.⁴ A larger German study of 42,240 newborns found a sensitivity of 77.8% in detecting critical CHD in the newborn nursery.⁵

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:

• Pink: CHF, L → R shunt

• Blue: cyanotic heart disease, R → L shunt

• 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 seen in normal newborns. 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 39-2). In general, normal murmurs are never diastolic, late systolic, or pansystolic. Examine the abdomen for hepatomegaly. A normal infant's liver is palpable 1 to 3 cm below the right subcostal margin. Examine the child for dysmorphic features suggestive of a genetic or teratogenic syndrome.

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 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. Ideally, blood is sampled from both preductal (right upper extremity) and postductal sites (preferably the lower extremities)⁷ 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. For example, a markedly higher oxygen level in the right upper extremity versus the lower extremities may indicate aortic arch obstruction.

Regardless of site used, the hyperoxia test should be conducted on all neonates with suspected CHD, not just those who appear cyanotic. Pulse oximetry is not a substitute for an arterial blood gas; 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 immediately until a definitive anatomic diagnosis is made.

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 normals 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 Tables 39-3 and 39-4). 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 suspected⁸ (Fig. 39-3).

Sinus bradycardia must be recognized in the sick infant. Intervals should be analyzed for drug effects and for long QT syndrome. Neonatal right-sided forces such as RAD and right ventricular hypertrophy (RVH) will transition gradually to adult form by age 3 to 4 years. Right bundle-branch block is common, 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.

Echocardiogram often provides the definitive diagnosis, but may not be able to be performed in the emergency department (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*, 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. 39-4). 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. 39-5). 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) and where the veins terminate (Fig. 39-6). 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. 39-7). 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. 39-8). 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. 39-9). 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. 39-10). 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. 39-11). 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.

Atrial septal defect (ASD) accounts for 12% of congenital heart lesions. Many patients are asymptomatic and undiagnosed until childhood or even adulthood. A soft systolic ejection murmur from increased pulmonic flow is heard in the left upper sternal border, and S2 is widely split and fixed (does not close with respiration) (Fig. 39-12). CXR shows right-sided chamber enlargement and increased PBF, and ECG shows an RSR′ in lead V1, often right bundle-branch block, and an increased PR interval.

Ventricular septal defect (VSD) is the most common congenital heart lesion. Small VSDs have a high rate of spontaneous closure. A harsh pansystolic murmur is heard in the left lower sternal border. If the defect is large, respiratory symptoms and CHF develop in the first 3 months of life. As pulmonary vascular resistance decreases, left-to-right shunting via the VSD increases (Fig. 39-13). CXR may be normal or show signs of CHF. ECG may show LVH, RVH, and left atrial enlargement (LAE) if the defect is large.

Patent ductus arteriosus (PDA) occurs in 8:1000 premature infants and 2:1000 full-term infants. A continuous machinery-like murmur is heard in the left second intercostal space, first appearing at 2 to 5 days of age. Prior to this, the pulmonary vascular resistance is high enough that there is no significant left-to-right shunting through the ductus. The diastolic runoff into the PDA generates bounding pulses. Infants may develop CHF, or may compensate with myocardial hypertrophy and present later with exercise intolerance. CXR shows increased PBF and sometimes cardiomegaly (Fig. 39-14). ECG is normal or shows LVH. Premature infants often respond to indomethacin with closure of the PDA.

Aortic stenosis (AS), often associated with a bicuspid aortic valve, may be asymptomatic; however, severe AS can present as shock in an infant (Fig. 39-15). Once symptomatic, patients complain of dyspnea on exertion, fatigue, abdominal pain, increased sweating, and exertional syncope (indicative of critical AS). An ejection click is heard before the systolic ejection murmur in the right upper sternal border, radiating into the neck. There may be a left ventricular thrill or heave. CXR may be normal and ECG reflects LVH.

Atrioventricular septal defect or AV canal is associated with Trisomy 21 (Fig. 39-16). Symptoms include those of CHF, poor growth, and frequent respiratory infections. CXR shows increased PBF and cardiomegaly. ECG shows an increased PR interval, RAE and/or LAE, and RVH. The axis is often superior (extreme left-axis deviation).

Rather than memorizing a multitude of individual lesions, the emergency physician should concentrate on a few scenarios: the undifferentiated sick infant, ductal-dependent lesions, CHF, hypoxemic “tet” spells, and presentations seen in older children. These scenarios require rapid emergency management to prevent further decompensation and cardiac arrest. Knowledge of the exact lesion is often not necessary to provide the critical management needed in these cases.

Undifferentiated Sick Infant

Patients present in two main categories: the “H&P patient” and the “ABC patient.” The “H&P patient” is typically stable, with a chronic or subacute presentation; the emergency physician has some time to examine, run tests, observe, and come to a diagnosis. The “ABC patient” presents in acute distress or in extremis and the emergency physician must be ready to diagnose and treat simultaneously.

The sick infant is the prototype of the “ABC” patient, often presenting with little available information and a palpable need to intervene. As there is significant similarity in presentation between CHD and other life-threatening disorders, a systematic approach is needed for the wide differential diagnosis (Fig. 39-17). The mnemonic “THE MISFITS” outlines the broad and varied causes of acute illness in very young children.⁹

• T—Trauma (accidental and nonaccidental)

• H—Heart disease and hypovolemia

• E—Endocrine (congenital adrenal hyperplasia and thyrotoxicosis)

• M—Metabolic (electrolyte abnormalities)

• I—Inborn errors of metabolism

• S—Sepsis (meningitis, pneumonia, and pyelonephritis)

• F—Formula problems (over- or underdilution)

• I—Intestinal disasters (intussusception, necrotizing enterocolitis, and volvulus)

• T—Toxins

• S—Seizures

As with any sick infant, assessment and intervention in airway, breathing, and circulation is critical, with close attention to vital signs, such as tachycardia and tachypnea. Always check bedside blood glucose and keep the infant warm during the course of evaluation and treatment. Even with a detailed differential diagnosis, final diagnosis may not be possible until much later in the child's management because conditions such as sepsis and CHD have significant overlap. Concomitant treatment with fluids, antibiotics, and possibly prostaglandin E₁ (PGE₁) to cover the most common causes is often appropriate in these circumstances.

The most important mantra in the care for the sick newborn is that neonates who present in shock with cyanosis in the first few weeks of life are presumed to have ductal-dependent systemic flow until proven otherwise. Resuscitation depends on opening the ductus arteriosus with PGE₁. Start PGE₁ before a definitive anatomic diagnosis is made.³

This dictum should be balanced with an even more basic tenet of emergency medicine: perform an intervention and carefully evaluate its effect. This is true for any patient, but essential in treating critically ill newborns. An algorithmic approach reminds the emergency physician of possible pathways, not to usurp clinical judgment. For example, some children with CHD may worsen with supplemental oxygen; at baseline, an infant with CHD may have preexisting pulmonary hypertension that shunts blood to the systemic circulation, maintaining adequate blood pressure. Overoxygenation can dilate the pulmonary vasculature to the point where it shunts blood away from the systemic circulation, causing sustained hypotension and either no improvement or worsening of the patient's condition with oxygen therapy.¹⁰ Oxygen is a cornerstone of therapy in sick infants and the physician should not hesitate to begin treatment with oxygen. However, this rare adverse effect serves to illustrate the importance of assessment, intervention, and reassessment.

Ductal-Dependent Lesions and Cardiogenic Shock

Lesions, which are completely dependent on a PDA for systemic or PBF, present with acute onset cyanotic circulatory failure and shock when the ductus closes, typically within the first week of life. Such lesions include HLHS, severe aortic coarctation, interrupted aortic arch, and lesions such as pulmonary atresia or TGA without a mixing lesion (e.g., a VSD). No symptoms or signs of CHD may have been noted in the newborn nursery or at home prior to presentation. Ductal-dependent cardiac failure should be suspected in any infant in the first week of life with sudden-onset circulatory collapse and cyanosis leading to hypoperfusion, hypotension, and severe acidosis. Infants may present in the second week of life, but rarely present beyond 4 weeks of age.

The mainstay of therapy for suspected ductal-dependent cardiogenic shock is PGE₁ infusion to maintain the patency of the ductus arteriosus. It is infused initially at 0.05 to 0.1 μg/kg/min and advanced to 0.2 to 0.4 μg/kg/min if necessary.¹¹ When an increase in PaO₂ is noted, titrate down to the lowest effective dose; the usual dose needed is 0.01 to 0.4 μg/kg/min. Potential adverse effects include hyperthermia, apnea, hypotension, rash, tremors, focal seizures, and bradycardia. Nevertheless, PGE₁ is critical for infants in ductal-dependent cardiac shock and should be initiated in the ED. Be prepared to provide definitive airway management in the case of apnea, and to add inotropic medications as needed for circulatory support. Other etiologies for shock must be entertained and treated as well, such as sepsis. A pediatric cardiologist must be consulted immediately and the patient admitted to the pediatric or neonatal intensive care unit.

Congestive Heart Failure

Children differ from adults both in the causes and in the presentation of CHF. A common scenario is that of an infant 2 to 6 months old with a left-to-right shunting lesion (VSD, PDA, AV canal defect, or less commonly, an ASD alone) resulting in volume overload and CHF (Fig. 39-18). Excessive pressure load from left-sided obstruction (e.g., aortic coarctation, AS) may also result in CHF. Causes other than congenital heart lesions include myocardial dysfunction (e.g., cardiomyopathies) and dysrhythmias.

Symptoms are gradual in onset and may be subtle. They include poor feeding (increased time to feed) or sweating while feeding; poor growth; irritability, lethargy, or a weak cry; increased respiratory effort, dyspnea, tachypnea, chronic cough, or wheezing; and increased frequency of respiratory infections.

Physical examination may reveal tachypnea, retractions, nasal flaring, grunting, wheezing, or rales (although less commonly than in adults). One may also find tachycardia, a gallop rhythm, hyperactive precordium, murmur, poor peripheral pulses with delayed capillary refill, and hepatomegaly (a cardinal sign of CHF in infants). Jugular venous distension and peripheral edema, often seen in adults with CHF, are rarely seen in young children. If present, edema is best appreciated in the eyelids, sacrum, and legs. More commonly, children will present with hepatic congestion or hepatomegaly, as the relatively pliable liver becomes congested with venous blood. It is important to start palpation for hepatomegaly low in the abdomen, just above the pelvic bones. CXR shows cardiomegaly (cardiothoracic ratio >0.55 in infants, >0.50 for children older than 1 year) and increased pulmonary vascularity. When evaluating for cardiomegaly, remember that infants often have a prominent thymus shadow overlying the heart; the thymus gives an appearance of an enlarged mediastinum and will be apparent as anterior to the heart on the lateral film. ECG findings depend on the specific lesion.

Treatment includes oxygen to keep saturations near 95%. Overoxygenating the patient may lead to pulmonary vascular dilation and worsened failure. Keep the infant in a semi-reclining position (such as when in an infant car seat) if possible. Fluid and sodium restriction is necessary, and furosemide should be given at 1 mg/kg intravenously. Nitrates are not first-line emergent therapy in children. In consultation with a pediatric cardiologist, the patient should be started on digoxin. Consult a pediatric drug handbook for digitalization doses. Patients may require sedation, but closely monitor the airway and ventilatory efforts. Make preparations for endotracheal intubation and ventilatory support in the event that they are needed. If a patient's respiratory status allows, a trial of continuous positive airway pressure (CPAP) may be applied nasally in an attempt to avoid intubation. If the child is in shock, fluids must be used cautiously (boluses of only 5–10 mL/kg, if at all); inotropic support with norepinephrine, dopamine, or dobutamine may be more appropriate. Milrinone may be added to the traditional vasopressors for its inotropic and chronotropic effects, typically in consultation with a cardiologist or pediatric intensivist; expect peripheral vasodilation and afterload reduction. The loading dose of milrinone is 50 μg/kg, followed by a 0.25 to 1 μg/kg/min infusion.¹² Complete blood count, chemistry panel, calcium level, rapid bedside glucose test, and arterial blood gas should be assessed. Monitor vital signs, including blood pressure, cardiac rhythm, and oxygen saturation continuously.

B-type Natriuretic Peptide Assay

The role of B-type natriuretic peptide (BNP) is well described in specific congenital heart lesions in children. Traditionally used in adults as an indirect marker of atrial chamber stretch from volume overload, it may be used judiciously in the ED as an ancillary screening tool in the evaluation of the dyspneic young child. BNP levels spike at birth with the physiologic transition from fetal to neonatal circulation, reaching a plateau at day 3 to 4; BNP levels subsequently fall to a constant level during infancy.¹³ As natriuretic peptides do not cross the placenta, BNP measurements will reflect the neonate's own production and clearance.

The interpretation of normal BNP ranges is under continued investigation, with variability by age of patient, kits used, units reported, and specific cardiac lesions. Nonetheless, multiple studies have attempted to provide normal mean BNP values in children (Table 39-5).¹⁴ There are as of yet no established BNP “cutoff” values in children to support definitively or to rule out acute CHF. Currently, BNP values can be interpreted as either consistent with the normal mean value or not. The standard deviations are reported as a reference, and not as a diagnostic tool. As always, the physician should note the normal laboratory values used at each institution.

In the case of CHF in children, just as in adults, the patient's clinical presentation will often provide an adequate basis to make the diagnosis. No single laboratory test should replace or supersede a clinician's judgment. However, in the undifferentiated dyspneic child, a screening BNP level may help to exclude the diagnosis if very low and support the diagnosis if markedly high.

In children with known cardiomyopathy or CHD, there is recent evidence to suggest higher mortality with increasing BNP values. In a sub-group analysis of a large, multi-center study, stable, outpatient, euvolemic children with cardiomyopathy or CHD and a BNP value of ≥140 pg/mL on routine draw were almost four times more likely to die within a 9-month period (hazard ratio of 3.69; 95% CI: 1.61–8.44).¹⁵ Although exact numbers have not been established in the acute setting, knowledge of the patient's overall status and trajectory may aid in management, disposition, counseling, and follow-up.

Hypoxemic “Tet” Spells

Sudden-onset spells of increased cyanosis may occur in young children with tetralogy of Fallot and less commonly in other complex lesions with decreased PBF, such as tricuspid atresia. Various theories exist regarding the initiation of a spell. The classic teaching is a precipitous “clamping down” of the pulmonary infundibular RV outflow tract, leading to increased right-to-left shunting; although not a complete explanation, this provides a useful model to understand spell physiology. The increased right-to-left shunting leads to hypoxemia, cyanosis, and acidosis. Attempts at compensation occur via hyperventilation and decreased systemic vascular resistance (SVR) to increase cardiac output. Decreased SVR and increased venous return result in further right-to-left shunting, perpetuating a cycle of ongoing shunting and hypoxemia.

Spells are most common in children younger than 2 years and often occur when SVR is naturally decreased: in the morning after awakening, after a feed, after defecation, and after a bout of crying. Symptoms include restlessness, irritability, or lethargy. Signs include a sudden increase in cyanosis and occasional syncope. Hyperpnea is a cardinal sign of hypoxemic spells. Previously appreciated murmurs of left-to-right shunting may disappear during a spell. The “tet spell” may occur in a previously acyanotic patient and may be the first presentation of a child with previously unrecognized CHD. Spells must be differentiated from seizures, CHF, and respiratory disease. Differentiating factors include history of CHD, profound cyanosis unresponsive to oxygen, and presence of features consistent with tetralogy of Fallot (Fig. 39-19).

Keep the child as calm as possible, in a position of comfort with a parent present. Avoid unnecessary painful or stressful procedures. Provide oxygen, although it will have little effect in shunt-induced hypoxemia. Place the child in a knee-chest position (to simulate squatting) to increase SVR (older children may even have a history of squatting on their own to abort spells). Morphine, 0.05 to 0.2 mg/kg intravenously or intramuscularly is the traditional first-line medical therapy, although the exact mechanism by which it “breaks” the spell is unknown. Administer a fluid bolus of 10 mL/kg normal saline intravenously to counteract the vasodilatory effects of morphine and to ensure adequate preload, on which pulmonary flow is dependent. Ketamine may be used to decrease agitation and to increase SVR.¹⁶ If metabolic acidosis is suspected or confirmed, sodium bicarbonate may be administered to help to break the cycle of hypoxemia, acidosis, and worsening hypotension and perfusion.

Successful therapy will be evidenced by improved pulse oximetry, decreased cyanosis, decreased hyperpnea, and a calmer child. If the above therapies are unsuccessful, propranolol 0.1 to 0.25 mg/kg (mechanism of action unclear) by a slow intravenous route may be given and repeated once after 15 minutes. Phenylephrine 5 to 20 μg/kg/dose (alpha-agonist resulting in increased SVR) intravenously may be used and repeated every 10 to 15 minutes as necessary. Propranolol and phenylephrine are customarily given in consultation with a cardiologist. If these interventions fail, general anesthesia may be necessary.

Presentations in Older Children and Adults

Clinically unapparent lesions are frequently discovered by recognition of a murmur during routine physical examination. Common lesions include ASD, small VSD, PDA, PS, AS, and aortic coarctation. Patients with an ASD will also be noted to have a fixed, split S2. Adult patients with unrepaired ASD may present with atrial arrhythmias, often in the fourth decade of life. Patients with PDA and AS may present with dyspnea on exertion and fatigue. Patients with critical AS may present with syncope. Patients with critical PS may present with cyanosis on exertion, right-sided heart failure, or syncope. Patients with aortic coarctation (Fig. 39-20) are often diagnosed during evaluation for hypertension. They may present with symptoms resulting from hypertension such as headache, intracranial hemorrhage, dizziness, palpitations, or epistaxis. Occasionally, they may complain of claudication due to decreased perfusion of the lower extremities.

Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a genetic disorder of sarcomeric proteins that results in varying degrees of LVH, found in 1:500 of the general population.¹⁷ It is a primary myopathy, not secondary to hypertension or AS. The term hypertrophic cardiomyopathy (HCM) includes both hypertrophic obstructive cardiomyopathy (HOCM) and idiopathic hypertrophic subaortic stenosis (IHSS). The distinction is made depending on the degree of outflow obstruction and/or asymmetric hypertrophy found in each case. The shared feature is diastolic dysfunction, with resultant impaired cardiac output on exertion.

Approximately half of patients with HCM have a family history of the same. Young children may be asymptomatic, and the first clinical manifestation may be cardiac arrest. Children and young adults may complain of dyspnea, angina, fatigue, or syncope, especially after strenuous exercise. Patients often have a harsh systolic murmur increasing after the first heart sound (diamond-shaped) best heard at the lower left sternal border or apex; this may be accompanied by an S4. The murmur may be more prominent with tachycardia or Valsalva maneuver, which both reduce ventricular volume, mimicking the conditions of exercise in these patients. Conversely, the murmur may decrease with squatting, hand grip, or leg raise, which augment venous return and increase ventricular volume. Patients may also demonstrate a prominent apical impulse and rapidly rising carotid impulse on physical examination.

ECG may show LVH and/or wide Q waves. Although an athlete may have LVH on ECG due to normal physiologic changes in left ventricular wall thickness (LVWT) from training, this cannot be assumed in the ED; an echocardiogram is needed in the symptomatic patient to measure LVWT (typically, less than 12 mm in an athlete) to rule out HCM (greater than 16 mm in HCM).¹⁸ CXR may be normal or reflect a mild-to-moderate increase in the size of the cardiac silhouette. Echocardiography is the mainstay of diagnosis.

Treatment options span from medication such as β-blockers or calcium-channel blockers to septal myomectomy to placement of an automated implantable cardioverter-defibrillator. Any child with a history consistent with arrhythmia and syncope warrants inpatient investigation, including urgent echocardiography and possibly electrophysiology studies. If the clinician has high suspicion of HCM in a currently asymptomatic child without high-risk historical features such as arrhythmia or syncope, nonemergent referral to a cardiologist is recommended.¹⁹ The child should avoid dehydration and refrain from strenuous activity until a definitive diagnosis is made.

Arrhythmogenic Right Ventricular Dysplasia

Arrhythmogenic right ventricular dysplasia (ARVD) is a disorder in which normal heart muscle is progressively replaced by fibrous fatty tissue in a triangular configuration in the right ventricle. The true prevalence is unknown but estimated at 6 in 10,000 in the general population and up to 44 in 10,000 in certain Mediterranean and southern U.S. populations; it is an inherited condition in up to 50% of cases.²⁰ ARVD is the second most common cause of sudden cardiac death in young people, after HCM.²¹

The clinical presentation of ARVD may vary from palpitations and syncope to sudden cardiac arrest. There may be a history of sudden cardiac or unexplained death in a young relative. Physical examination is usually unremarkable.²² The ECG is an important screening tool: more than 90% of cases of ARVD will have some ECG abnormality, such as right bundle branch block or prolonged right precordial QRS duration (>110 ms).²³ The distinguishing ECG finding in ARVD is the epsilon wave, which is a terminal upward deflection at the end of the QRS complex in any of the precordial leads, typically V1–V3 (Fig. 39-21). Echocardiography often readily reveals the diagnosis, but cardiac MRI may also be used to confirm.

ARVD is a progressive disease and a prime goal in management is to prevent a lethal dysrhythmia. Treatment options include lifestyle modifications (no strenuous activity), antiarrhythmic medications, radiofrequency ablation, and/or placement of an automated implantable cardioverter-defibrillator.²⁴

Left Ventricular Noncompaction Syndrome

During normal embryonic development, trabeculations allow the myocardium to expand quickly and grow without an epicardial arterial supply; later, epicardial vessels penetrate and vascularize the myocardium, and replace the spongy trabecular network with thicker, stronger myocytes. If this process is halted early in the first trimester, this loosely interwoven spongiform mesh of muscle fibers results in weakened myocardium and left ventricular noncompaction syndrome (LVNC).²⁵

LVNC may occur in isolation, or in conjunction with other CHD. Patients may present with palpitations or nonspecific chest pain from resultant dysrhythmias or CHF. Although the ECG is often nonspecific, the majority (87%) will have some abnormality: intraventricular conduction delay, evidence of left bundle branch block, or LVH.²⁵ In more advanced disease, the classic triad is heart failure, ventricular dysrhythmias, and a systemic embolic event, such as a stroke or renal infarction. Echocardiography may be nondiagnostic; cardiac MRI is increasingly used to make the diagnosis.²⁶

Although an uncommon cause of palpitations or dysrhythmias, LVNC should be included in the differential diagnosis of a young person with unexplained syncope, especially with previous symptoms consistent with heart failure. As ventricular dysrhythmias are reported in up to 20% of patients, most are treated with an automated implantable cardioverter-defibrillator and possibly anticoagulation.

Isolated Coronary Artery Anomalies

Congenital lesions of the coronary arteries are uncommon, occurring in less than 1% of the population.²⁷ During fetal development, abnormalities may form affecting the number (duplication of artery), site of origin (e.g., from pulmonary trunk), anatomic course (e.g., between the aorta and pulmonary trunk), anomalous termination (e.g., fistula formation), or structure (stenosis and atresia) of the coronary arteries. Virtually any coronary artery may be affected. These lesions may be isolated to a single coronary artery or associated with other congenital heart defects.

Depending on the lesion, patients may present from infancy to young adulthood. Neonates with an isolated coronary artery anomaly may demonstrate anginal symptoms such as irritability, episodic diaphoresis, and/or color change when symptomatic. Older infants may have poor feeding, dyspnea, failure to thrive, or unexplained episodes of pallor. Diaphoresis during feeding is an ominous sign, reflecting both a decreased “exercise tolerance” and a splanchnic steal syndrome. Older children and young adults typically present with more familiar ischemic symptoms such as angina and dyspnea. Unfortunately, a child's first presentation may be sudden death.

A rare but serious lesion primarily affects neonates—anomalous origin of the left coronary artery arising from the pulmonary artery (ALCAPA), also called Bland–White–Garland syndrome.^28,29 Most children present within the first few months of life, often with nonspecific complaints such as irritability; they are often misdiagnosed with colic. Signs and symptoms of CHF, such as tachypnea, tachycardia, poor feeding, and weight gain, may ensue. On physical examination, the baby may be completely normal or show signs of CHF. ECG may show an anterolateral infarct pattern with deep and wide Q waves laterally and absent Q waves inferiorly. CXR may be consistent with CHF. Echocardiography with Doppler flow is often diagnostic, especially if retrograde flow from the left coronary artery to the pulmonary trunk is shown.

Surgical correction is necessary to restore blood flow. ED care is supportive, with great attention paid to volume status and very careful use of diuretics and nitrates if needed. Titrate oxygen to effect; 100% oxygen may dilate pulmonary vasculature and create a steal syndrome from the right coronary artery to the pulmonary arteries in this lesion. Although isolated coronary artery anomalies are rare, they should be considered in the child with unexplained age-specific anginal symptoms.

Eisenmenger Syndrome

Patients with a large left-to-right shunt that is left unrepaired, either by choice or because the lesion was never recognized, gradually develop pulmonary vascular disease due to the increased volume overload. When pulmonary hypertension becomes severe enough, the direction of shunting will reverse to right to left, and cyanosis ensues. Typically, this occurs in adolescence to early adulthood. Patients may complain of decreased exercise tolerance, dyspnea on exertion, hemoptysis, palpitations due to atrial arrhythmias, and symptoms of hyperviscosity due to chronic polycythemia (vision disturbances, fatigue, headache, dizziness, paresthesias, and even cerebrovascular accident). Brain abscesses can occur with right-to-left passage of an infected embolus. On examination, the murmur may no longer be present when the left-to-right shunting ends and S2 is loud due to the pulmonary hypertension. CXR shows decreased vasculature (pruned pattern), and ECG shows RVH. Although no definitive therapy exists, other than heart–lung transplant, patients should avoid dehydration, heavy exertion, altitude, vasodilators, and pregnancy (which are associated with a high-mortality rate). Symptoms of hyperviscosity may be treated with phlebotomy and isovolemic replacement. Patients should be medically managed by a cardiologist to optimize cardiac function as long as possible.

Categories of Repair

Patients with true complete repairs generally lead a normal life after repair. True complete repairs are typically performed successfully for ASD, VSD, PDA, aortic coarctation, and TGA (switch procedure). Repairs of tetralogy of Fallot, AV canal, and valve obstructions typically result in anatomic repairs with residual lesions, and late complications may occur (Table 39-6). Repairs requiring prosthetic materials such as pulmonary atresia, truncus arteriosus, and prosthetic valve replacements will require replacement of the prosthetic material due to growth of the child or degeneration of the material. Physiologic repairs improve the patient's blood flow physiology but do not result in normal cardiac anatomy. These palliative repairs, which include the Fontan operation for lesions resulting in a functionally single ventricle and the Mustard operation and Senning procedure for TGA, invariably produce late complications.

There exists a myriad of variations of CHD and procedures for repair (Table 39-6).^30,31 The key concept for care of these children is a careful examination and consideration of complications such as arrhythmias, infective endocarditis, and thromboembolism. Consultation with the child's cardiologist or primary care physician may be helpful in the management and disposition of postoperative patients.

Postoperative Complications

Arrhythmias are the most common problem and may present with symptoms of palpitations, decreased appetite, emesis, and decreased exercise tolerance.^30,32 Arrhythmias may be a result of the surgical repair, the underlying lesion (e.g., Ebstein's anomaly), or medical therapy (e.g., digoxin toxicity). Supraventricular tachycardia (SVT) is the most common clinically significant arrhythmia and is seen in lesions repaired with atriotomy (Senning, Mustard, Fontan, ASD repair, and TAPVR repair). Bradycardia due to sinoatrial nodal disease is seen in 20% of patients, status post-Fontan repair, and first-degree block may occur after AV canal repair. Ventricular arrhythmias occur uncommonly after VSD or TOF repair and are decreasing further, due to increased use of transatrial approaches to repair. Right bundle-branch block is common after VSD, TOF, and AV canal repairs. Premature ventricular contractions are benign if isolated and unifocal (order a 24-hour Holter monitor test); consult a cardiologist if they are frequent, coupled, or multifocal. Postoperative patients with surgical cardiac shunts should be assessed for volume status and work of breathing. Many CHD repairs consist of a series of staged repairs; as the child grows into a new stage, at any given time the shunt may be slightly too large or too small. A shunt that is relatively large for the patient may cause increased PBF and result in pulmonary vascular congestion. In this context, titrating down the inspired oxygen concentration can encourage vasoconstriction of the pulmonary arteries, decrease vascular congestion, and paradoxically improve overall lung function and oxygenation.¹² A shunt that is relatively too small for the patient may cause the pulmonary arterial infundibulum to vasoconstrict, worsening the patient's oxygenation. This patient may present with jugular venous distention and liver enlargement without the expected concomitant pulmonary vascular congestion. These patients are likely to present with worsening cyanosis; give oxygen and reassess for improvement.¹²

Pulmonary shunts do not have valves (as do native veins) and they rely on passive flow back to the heart. Volume depletion from fever, vomiting, or diarrhea will adversely affect preload, and therefore oxygenation. Dehydration is a major risk factor for thrombus formation in the shunt, which may be fatal. Careful consideration of the child's volume status—avoiding overload as well as dehydration—is essential in the care of the postoperative CHD patient.

Residual or recurrent lesions may occur as a complication of repair, due to incomplete success of the repair, outgrowing prosthetic materials, or from conduit stenosis. Coarctation recurs in 10% of repaired patients. Recurrent stenosis after PS or AS repair is common, as is aortic insufficiency after AS repair. Recurrent stenosis may be recognized by a new murmur or a change in exercise tolerance. A residual small VSD around the borders of the patch is present in 15% to 25% of patients after VSD or TOF repair; most close spontaneously within 6 to 12 months.

Endocarditis is a significant complication seen in congenital heart patients before and after surgical repair (Table 39-7).^33,34 The rate in patients with uncorrected CHD is 0.1% to 0.2% per patient-year; this decreases to 0.02% after correction for many lesions. Unrepaired complex CHD carries the highest risk, at 1.5% per patient-year. ASDs of the ostium secundum type are the lowest-risk lesions and do not require prophylaxis for procedures, even if unrepaired. Patients with repaired ASD, VSD, PDA, aortic coarctation, and PS (no mechanical valve) without residual lesions, and patients' status post heart transplantation or pacemaker insertion also carry a low risk and do not require prophylaxis. Patients who are status post AS or TOF repair and those with prosthetic valves remain at high risk. Antibiotic prophylaxis should be given to patients at high risk prior to invasive procedures likely to produce bacteremia, such as dental procedures. See Tables 39-8 and 39-9³³ for procedures requiring prophylaxis and antibiotic regimens used.

Other complications common in patients with CHD include poor growth, electrolyte disturbances due to medications, cerebral embolus in patients with right-to-left shunts (health care workers should be especially careful to avoid air embolus during intravenous line placement), and increased susceptibility to respiratory illnesses. Cardiac patients may have a particularly difficult time with respiratory syncytial virusinfections.

Cardiac Transplant Patients

Children with end-stage heart failure or inoperable CHD may undergo orthotopic heart transplantation, in which the patient's heart is removed and replaced with a donor's heart. Emergency physicians will encounter these patients with more frequency in the future, as outcomes improve: the 5-year survival rate currently is 65%.³⁵ Patients who are status post heart transplant are at risk for acute or chronic rejection, posttransplant lymphoproliferative disorder (PTLD), and infectious complications associated with their immunosuppressive or immunomodulating medication regimen.³⁵ In contrast to other types of transplantation, acute and chronic cardiac rejection is not defined by the timing after the operation; rather it is the clinical presentation that delineates them. Acute rejection is defined as a distinct episode that prompts intensification of immunosuppressive therapy, either based on cardiac dysfunction or based on histologic diagnosis. Symptoms of acute rejection vary widely, and may include fever, myalgias, vomiting, and shock. Less commonly, children may experience chest pain and/or have ECG changes, such as decreased R-wave amplitude. Laboratory studies, such as cardiac markers, are often nondiagnostic. An echocardiogram may show diastolic dysfunction, but it may not be present early in the course.

Whereas acute cardiac rejection is a fulminant presentation, chronic rejection is an ongoing process that mostly involves development of atherosclerotic disease. Ischemic symptoms such as decreased exercise tolerance, fatigue, and chest pain may be present. Syncope or sudden death may result from an arrhythmia. As in acute rejection, the diagnosis is clinical.

PTLD is associated with the Epstein–Barr virus and occurs most often within a year of transplant, but may develop many years later. PTLD is a B-cell lymphoma resulting in masses throughout the body, most notably in the abdomen, chest, head, and neck. Symptoms include a mononucleosis-like syndrome of fever, lymphadenopathy, and abdominal pain. The diagnosis is based on clinical suspicion from history and physical examination with radiologic findings consistent with scattered lymphoid masses.

The emergency physician should assess the post-cardiac transplant patient for general appearance and well-being, volume status, potential acute or chronic rejection, and possible occult infection. Volume depletion should be managed aggressively in these patients, as the nephrotoxic immunosuppressants tacrolimus and cyclosporine can cause hyperkalemia, hypophosphatemia, hypomagnesemia, and metabolic acidosis.³⁶ Obtain an ECG and laboratory tests to evaluate for possible ischemia and electrolyte disorders. ECG will invariably show right bundle branch block, left atrial enlargement, and RVH; a comparison ECG is essential in interpretation. Dysrhythmias such as sinus bradycardia, atrial tachycardia, and ventricular tachycardia are especially prevalent in this group.³⁷ A CXR may reveal pulmonary vascular congestion, infiltrates, or hilar masses, as in PTLD.³⁵ A good outpatient candidate would be a well-appearing, euvolemic child with a clear-cut minor and self-limiting illness who has close follow-up. Otherwise, the provider should have a low threshold to admit the patient for continued observation and management.

Prevention of Infective Endocarditis

In 2007, the American Heart Association (AHA) in conjunction with the American Academy of Pediatrics (AAP) and the Infectious Diseases Society of America (IDSA) published revised guidelines for the prevention of infective endocarditis (IE).^33,34 The changes simplify and greatly narrow the recommendations to provide prophylaxis for only higher-risk patients and procedures. Antibiotic prophylaxis solely to prevent IE is no longer indicated for gastrointestinal and genitourinary procedures. The committee found that it is still reasonable to give prophylaxis for procedures on the respiratory tract, infected skin, or musculoskeletal tissue only for high-risk patients (see Tables 39-7 to 39-9).

Outpatient Referral

Children with complications associated with CHD and those with a new diagnosis in the ED are invariably admitted for stabilization and/or investigation of the lesion. A currently asymptomatic child may have high-risk historical features, including symptoms associated with exertion, recurrent episodes, symptoms while recumbent, associated chest pain or palpitations, and family history of sudden death or childhood cardiac disease; children with one or more of these features are also often admitted in consultation with a pediatric cardiologist.³⁸

An otherwise well child with no high-risk historical features and a normal ECG may present to the ED with signs and symptoms necessitating an expedited outpatient workup. Any well child with only unexplained poor feeding may be referred to his/her primary care physician. Appropriate outpatient cardiology referrals from the ED include otherwise well children with diaphoresis with eating, unexplained significant murmur, or exercise intolerance. Parent education is crucial in understanding both the importance of primary care and (if needed) subspecialty follow-up, as well as return precautions to the ED.

Emergency physicians should concentrate on recognition and management of a few common presentations seen in CHD patients, especially ductal-dependent circulatory shock and CHF. Physicians are unlikely to determine the specific lesion in the ED without an echocardiogram, and knowledge of the exact lesion is often unnecessary for appropriate therapy.