Chapter 72. Pediatric Heart Disease

There are 6 common clinical presentations of pediatric heart disease: cyanosis, shock, congestive heart failure (CHF), pathologic murmur, hypertension, and syncope. Table 72-1 lists the most common lesions in each category. While cyanosis and shock typically appear in the first weeks of life and are often dramatic in their presentation, the symptoms of CHF may be subtle and include respiratory distress or feeding intolerance, which may be misdiagnosed as viral upper respiratory tract illness, especially in winter months. A high index of suspicion must therefore be maintained in order to make the correct diagnosis. This chapter focuses on conditions producing cardiovascular symptoms seen in the emergency department (ED) that require immediate recognition, therapeutic intervention, and prompt referral to a pediatric cardiologist.

The evaluation of an asymptomatic murmur is a nonemergent diagnostic workup that can be done on an outpatient basis. Innocent murmurs, often described as flow murmurs, are of low intensity, are brief, and occur during systole. In general, common pathologic murmurs in children are typically harsh, holosystolic, continuous, or diastolic in timing and often radiate. They may be associated with abnormal pulses or symptoms such as syncope or CHF.

The treatment of dysrhythmias is discussed in Chapter 3, pediatric hypertension is discussed in Chapter 26, and syncope is discussed in Chapter 78. Chest pain is usually of benign etiology in children, though may occasionally represent congenital (eg, aberrant left coronary artery) or acquired (eg, Kawasaki disease, myocarditis, pericarditis, cardiomyopathy) heart disease. Myocarditis and cardiomyopathy are covered in Chapter 24, chest pain and acute coronary syndrome in Chapters 17 and 18, and Kawasaki disease in Chapter 83.

Cardiac causes of cyanosis and shock typically present in the first 2 weeks of life and present in the critically ill neonate. The differential diagnosis, however, is broad at this age, and, in addition to congenital heart disease, the clinician should consider infection (sepsis, pneumonia), metabolic disease (see Chapter 79) and nonaccidental trauma. For the neonate presenting with cyanosis, the hyperoxia test helps to differentiate respiratory disease from cyanotic congenital heart disease (although imperfectly). When placed on 100% oxygen, the infant with cyanotic congenital heart disease will fail to demonstrate an increase in Pao2, while those with respiratory causes will often respond with an improvement in pulse oximetry.

Clinical Features

Acral cyanosis (blue discoloration of the distal extremities) can be normal in the neonate, but central cyanosis (including the mucus membranes of the mouth) is the cardinal feature of cyanotic congenital heart disease. Appreciation of cyanosis in dark-skinned neonates may be difficult, and an accurate set of vital signs including pulse oximetry and 4-extremity blood pressures is essential. Cyanosis associated with a heart murmur strongly suggests congenital heart disease, but the absence of a murmur does not exclude a structural heart lesion. The cyanotic infant may be tachypnic, as well, though the increased respiratory rate in cyanotic heart disease is often effortless and shallow unless associated with congestive heart failure, which is rare in the first weeks of life.

Shock with or without cyanosis, especially during the first 2 weeks of life, should alert the clinician to the possibility of ductal-dependent congenital heart disease in which systemic (shock) or pulmonary (cyanosis) blood flow depends on patency of the fetal ductus arteriosis. Shock in the neonate is recognized by inspection of the patient's skin for pallor (or, more often, an “ashen grey” appearance), mottling, and cyanosis, and assessment of the mental status appropriate for age. Mental status changes include apathy, irritability, or frank lethargy. Tachycardia and tachypnea may be the initial signs of impending cardiovascular collapse. Distal pulses should be assessed for quality, amplitude, and duration, and a differential between preductal (right brachial) and postductal (femoral) pulses or blood pressure is classic for ductal-dependent lesions such as coarctation of the aorta.

Diagnosis and Differential

The workup for congenital heart disease begins with chest radiograph and electrocardiogram (ECG) with pediatric analysis. Chest radiographs are assessed for heart size, shape, and pulmonary blood flow. An abnormal right position of the aortic arch may be a clue to the diagnosis of congenital cardiac lesion. Increased pulmonary vascularity may be seen with significant left-to-right shunting or left-sided failure. Decreased pulmonary blood flow is seen with right-sided outflow lesions such as pulmonic stenosis. Cyanotic heart lesions often demonstrate right axis deviation and right ventricular hypertrophy on ECG while left outflow obstruction (eg, coarctation of the aorta) may show left ventricular hypertrophy. Echocardiography is generally required to define the diagnosis.

The differential diagnosis for cyanosis or shock due to congenital heart disease typically includes cyanotic lesions: transposition of the great vessels, tetralogy of Fallot, and other forms of right ventricular outflow tract obstruction or abnormalities of right heart formation. Acyanotic lesions that can present with shock include severe coarctation of the aorta, critical aortic stenosis, and hypoplastic left ventricle. It should be noted that cyanosis may accompany shock of any cause.

Transposition of the great vessels represents the most common cyanotic defect presenting in the first week of life. This entity is easily missed due to the absence of cardiomegaly or murmur (unless there is a coexistent ventricular septal defect [VSD]). Symptoms (before shock) include central cyanosis, increase respiratory rate, and/or feeding difficulty. There is usually a loud and single S2. Chest radiographs may show an “egg on a string” shaped heart with a narrow mediastinum and increased pulmonary vascular markings. ECG may show right-axis deviation and right ventricular hypertrophy.

Tetralogy of Fallot is the most common cyanotic congenital heart disease overall, and can present with cyanosis later in infancy or childhood. Physical examination reveals a holosystolic murmur of ventricular septal defect, a diamond-shape murmur of pulmonary stenosis, and cyanosis. Cyanotic spells in the toddler may be relieved by squatting. Chest radiograph may show a boot-shape heart with decreased pulmonary vascular markings or a right-sided aortic arch. The ECG often demonstrates right ventricular hypertrophy and right axis deviation.

Hypercyanotic episodes, or “tet spells,” may bring children with tetralogy of Fallot to the ED in dramatic fashion. Symptoms include paroxysmal dyspnea, labored respirations, increased cyanosis, and syncope. Episodes frequently follow exertion due to feeding, crying, or straining with stools and last from minutes to hours.

Left ventricular outflow obstruction syndromes may present with shock, with or without cyanosis. Several congenital lesions fall into this category, but in all these disorders, systemic blood flow is dependent on a large contribution of shunted blood through a patent ductus arteriosus. When the ductus closes, infants present with decreased or absent perfusion, pallor or an ashen appearance, hypotension, tachypnea, and severe lactic acidosis. Diminished lower extremity pulses and BP, particularly compared to right brachial pulse and BP, is classic for coarctation of the aorta.

Emergency Department Care and Disposition

1. Cyanosis and respiratory distress are first managed with high-flow oxygen, cardiac and oxygen monitoring, and a stable intravenous or intraosseous line. Caveat: Neonates tolerate low oxygen saturations well due to oxygen-avid fetal hemoglobin; oxygen is a potent pulmonary vasodilator and may lead to “pulmonary steal” of systemic blood flow, worsening systemic shock in ductal-dependent systemic blood flow such as coarctation of the aorta. Treatment with prostaglandins (see below) is critical in these instances.

2. For severe shock in infants suspected of having shunt-dependent lesions, prostaglandin E1 should be given in an attempt to reopen the ductus. Treatment begins with 0.05 to 0.1 microgram/kilogram/min; this may be increased to 0.2 microgram/kilogram/min if there is no improvement. Side effects include fever, skin flushing, diarrhea, and periodic apnea.

3. Immediate consultation should be obtained with a pediatric cardiologist and, if the patient is in shock, a pediatric intensivist.

4. Management of hypercyanotic spells consists of positioning the patient in the knee-to-chest position and administration of morphine sulfate 0.2 milligram/kilogram SC, IM, or IO. Resistant cases should prompt immediate consultation with a pediatric cardiologist for consideration of phenylephrine for hypotension or propranolol for tachycardia.

5. Noncardiac causes of symptoms should be considered and treated appropriately, including a fluid challenge of 10 to 20 mL/kg of normal saline solution, and empiric administration of antibiotics as indicated. Fluids should be administered more judiciously to neonates with congenital heart disease, typically in 10 mL/kg boluses.

6. Epinephrine is the initial drug of choice for hypotension. An infusion is started at 0.05 to 0.5 microgram/kilogram/min and titrated to the desired blood pressure.

By definition, these children are critically ill and require admission, usually to the neonatal or pediatric intensive care unit.

Clinical Features

Congestive heart failure from congenital or acquired heart disease typically presents after the neonatal period, typically in the second or third month of life (congenital) or later in childhood (acquired causes). The distinction between pneumonia and CHF in infants requires a high index of clinical suspicion and is often difficult. Pneumonia can cause a previously stable cardiac condition to decompensate; thus, both problems can present simultaneously. Presenting symptoms include poor feeding, diaphoresis, irritability or lethargy with feeding, weak cry, and, in severe cases, grunting, nasal flaring, and respiratory distress. Note that the early tachypnea of CHF in infants is typically “effortless” and the first manifestation of decompensation, followed by increased work of breathing and rales on examination.

Diagnosis and Differential

Cardiomegaly evident on chest radiograph is universally present except in constrictive pericarditis. A cardiothoracic index greater than 0.6 is abnormal. The primary radiographic signs of cardiomegaly on the lateral chest radiograph are an abnormal cardiothoracic index and lack of retrosternal air space due to the direct abutment of the heart against the sternum.

Once CHF is recognized, age-related categories simplify further differential diagnosis (Table 72-2). Congenital cardiac causes of CHF are best categorized by age of onset. Early-onset CHF is associated with ductal-dependent lesions such as coarctation of the aorta and may be abrupt in onset; persistent patent ductus arteriosis (PDA) may also present in the neonatal period with CHF. Rarely, sustained tachyarrhythmias may present with CHF in the neonatal period. By contrast, lesions that result in pulmonary over-circulation such as VSD or atrial septal defect (ASD) present with gradual development of failure in the second or third month of life. Onset of CHF after age 3 months usually signifies acquired heart disease such as cardiomyopathy or myocarditis. The exception is when pneumonia, endocarditis, or another complication causes a congenital lesion to decompensate.

Cardiomyopathy presents with respiratory distress and feeding difficulties. A pathologic gallop (S3 and or S4) is key to recognition. Rales and organomegally are often present and cardiomegaly and pulmonary vascular congestion are noted on chest radiography.

Myocarditis is often preceded by a viral respiratory illness and needs to be differentiated from pneumonia. As with pneumonia, the infant usually presents in distress with fever, tachypnea, and tachycardia. ECG may show diffuse ST changes, dysrhythmias, or ectopy, which is associated with an increased risk of sudden death. Chest radiograph shows cloudy lung fields from inflammation or pulmonary edema. Cardiomegaly with poor distal pulses and prolonged capillary refill, however, distinguish it from common pneumonia. Once cardiomegaly is discovered, hospital admission and an echocardiogram are indicated.

Usually pericarditis presents with pleuritic and positional chest pain. Muffled heart sounds and a friction rub may be present on physical examination. Cardiomegaly is seen on a chest radiograph. An echocardiogram is performed urgently to distinguish a pericardial effusion from dilated or hypertrophic cardiomyopathy and to determine the need for pericardiocentesis.

If an infant presents in pure right-side CHF, the primary problem is most likely to be pulmonary, such as cor pulmonale. In early stages, periorbital edema is often the first noticeable sign. This may progress to hepatomegaly, jugular venous distention, peripheral edema, and anasarca.

Emergency Department Care and Disposition

1. The infant who presents with mild tachypnea, hepatomegaly, and cardiomegaly should be seated upright in a comfortable position, oxygen should be given, and the child should be kept in a neutral thermal environment to avoid metabolic stresses imposed by hypothermia or hyperthermia.

2. If the work of breathing is increased or CHF is apparent on chest radiograph, 1 to 2 milligrams/kilogram furosemide should be administered parenterally.

3. Hypoxemia is usually corrected by administration of oxygen, fluid restriction, and diuresis, although continuous positive airway pressure is sometimes necessary.

4. Stabilization and improvement of left ventricular function is often first accomplished with inotropic agents. Digoxin is used in milder forms of CHF. The appropriate first digitalizing dose to be given in the ED is 0.02 to 0.03 milligram/kilogram.

5. When CHF progresses to cardiogenic shock (absent distal pulses and decreased end-organ perfusion), continuous infusions of inotropic agents, such as dopamine or dobutamine, are indicated instead of digoxin. The initial starting range is 2 to 10 micrograms/kilogram/min.

6. Aggressive management of secondary derangements, including respiratory insufficiency, acute renal failure, lactic acidosis, disseminated intravascular coagulation, hypoglycemia, and hypocalcaemia should be implemented.

7. Definitive diagnosis and treatment of congenital defects presenting with CHF often requires cardiac catheterization followed by surgical repair. See the previous section for recommendations regarding administration of prostaglandin E1 as a temporizing measure before surgery.