Garth D. Meckler
This chapter covers common presentations of congenital heart disease as they present to the emergency department (ED): cyanosis, shock, and congestive heart failure.
Other cardiovascular topics such as dysrhythmias (Chapter 4), syncope and sudden death (Chap. 80), myocarditis, pericarditis, and cardiomyopathies (Chapter 26), endocarditis (Chapter 95) and Kawasaki’s disease (Chapter 85) are discussed elsewhere.
There are six common clinical presentations of pediatric heart disease: cyanosis, shock, congestive heart failure (CHF), pathologic murmur in an asymptomatic patient, hypertension, and syncope or palpitations. Table 74-1 lists the most common lesions in each category.
The evaluation of an asymptomatic murmur is a non-emergent 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. Common benign pediatric murmurs are listed in Table 74-2.
TABLE 74-1 Clinical Presentation of Pediatric Heart Disease
TABLE 74-2 Benign Pediatric Murmurs
EPIDEMIOLOGY
Pediatric cardiac conditions are relatively rare. Congenital heart disease is a broad term encompassing a multitude of anatomic abnormalities. Congenital heart disease is the most common form of pediatric heart disease and is present in only 8 cases per 1000 live births in all forms.
Ventricular septal defects (VSDs) are the most common congenital heart defect, comprising 25% of all such lesions. Transposition of the great arteries (TGA) and tetralogy of Fallot (TOF) are the most common cyanotic lesions presenting in the neonatal and post-infancy period, respectively.
Acquired heart disease is less common and includes complications secondary to rheumatic fever (now quite uncommon), Kawasaki’s disease, cardiomyopathies, severe chronic anemia, myocarditis, pericarditis, and endocarditis.
CYANOSIS
PATHOPHYSIOLOGY
Cyanosis results from deoxygenation of hemoglobin.
Congenital heart lesions produce cyanosis through one of three mechanisms: decreased pulmonary blood flow, mixing or shunting of deoxygenated blood (ie, right-to-left shunts), or poor cardiac output causing deoxygenation in peripheral capillary beds.
CLINICAL FEATURES
Central cyanosis (a blue discoloration of the skin and mucus membranes) is the cardinal sign of cyanotic congenital heart disease (Fig. 74-1A), and may be associated with a murmur. Acral cyanosis (limited to the distal extremities, Fig. 74-1B) can be a normal finding in neonates.
Cyanosis may present in the immediate neonatal period (eg, transposition of the great arteries, critical pulmonary stenosis, TOF) or later in infancy (eg, total anomalies venous return, TOF, Eisenmenger complex).
Hypercyanotic episodes associated with TOF (“tet spells”) typically present with an inconsolable infant with deep central cyanosis.
Effortless tachypnea may be associated with cyanotic congenital heart disease.
FIG. 74-1. Cyanosis of the mucous membranes (A) and nail beds (B). [Reproduced with permission from Shah BR, Lucchesi M (eds): Atlas of Pediatric Emergency Medicine. New York, NY, McGraw-Hill, 2006.]
DIAGNOSIS AND DIFFERENTIAL
The most common congenital heart lesions causing cyanosis are transposition of the great arteries (TGA), TOF, tricuspid atresia, truncus arteriosus, and total anomalous venous return (“the five Ts”).
Cyanosis in the neonate or infant resulting from congenital heart disease must be differentiated from that caused by noncardiac causes such as lung disease and sepsis.
A full set of vital signs including four-extremity blood pressure, and oxygen saturations measured in both the right arm (pre-ductal) and left arm (post-ductal) is essential.
The “hyperoxia test” may help distinguish cyanotic heart disease from noncardiac causes of cyanosis: administer 100% oxygen; infants with cyanotic heart disease will not increase their Pao2 by more than 20 mm Hg.
A chest radiograph should be obtained in all cyanotic neonates and infants, both to exclude pulmonary causes, and to evaluate the size and shape of the heart as well as pulmonary blood flow, which may provide clues to the diagnosis.
An ECG should also be obtained. The typical ECG and chest radiograph findings associated with various cyanotic heart lesions are described in Table 74-3.
Echocardiography and occasionally cardiac catheterization provide definitive diagnosis of cyanotic congenital heart disease, but are rarely performed in the ED and require pediatric sonographers and cardiologists.
Transposition of the great vessels represents the most common cyanotic defect presenting with symptoms during the first week of life. This entity is easily missed due to the absence of cardiomegaly or murmur. Symptoms (prior to shock) include dusky lips, increased respiratory rate, and/or feeding difficulty. ECG may show right-sided-force dominance.
TOF produces the following features: a holosystolic murmur of a VSD, a diamond-shaped murmur of pulmonary stenosis, and cyanosis. Chest radiograph may reveal a boot-shaped heart with decreased pulmonary vascular markings or a right-sided aortic arch (Fig. 74-2). The ECG may reveal right ventricular hypertrophy and right axis deviation.
Hypercyanotic episodes, or “tet spells,” may bring children with TOF to the ED with dramatic presentations. Symptoms include paroxysmal dyspnea, labored respiration, increased cyanosis, and possibly syncope. These episodes frequently follow exertion due to feeding, crying, or straining at stool, and last from minutes to hours.
TABLE 74-3 Cyanotic Congenital Cardiac Lesions: Typical Chest Radiograph and ECG Findings
FIG. 74-2. Chest radiograph revealing the classic “boot-shaped heart” of tetralogy of Fallot. [Reproduced with permission from Shah BR, Lucchesi M (eds): Atlas of Pediatric Emergency Medicine. New York, NY, McGraw-Hill, 2006.]
EMERGENCY DEPARTMENT CARE AND DISPOSITION
The ED management is primarily focused on stabilization, and definitive diagnosis (if not known); most cyanotic congenital defects are treated surgically.
Though high-flow oxygen should be placed initially and maintained until noncardiac causes of cyanosis such as pneumonia or sepsis have been excluded, it is important to remember that neonates have significant amounts of oxygen-avid fetal hemoglobin and tolerate saturations in the 70s without tissue hypoxia. Oxygen is a potent pulmonary vasodilator and may lead to pulmonary over circulation in some lesions, and should be reserved for those with signs of inadequate tissue perfusion.
Noncardiac causes should be considered and treated appropriately including a fluid challenge (10 mL/kg in neonates, 20 mL/kg in infants) and antibiotics if indicated.
Management of hypercyanotic spells from TOF include placing the patient in the knee-chest position, administration of high-flow oxygen, and calming the infant; if these measures fail, morphine sulfate (0.2 milligram/kg SC or IM) may be given and refractory cases can be treated with IV phenylephrine or propranolol.
Immediate consultation with a pediatric cardiologist and intensivist should be obtained for neonates and infants with suspected undiagnosed cyanotic heart disease or hemodynamic instability.
While new diagnoses and unstable patients require hospitalization (usually to intensive care), hypercyanotic spells that have been successfully treated may be discharged safely.
SHOCK
PATHOPHYSIOLOGY
Congenital heart disease presenting with shock has two main causes: inadequate left-ventricular outflow (eg, critical aortic stenosis, hypoplastic left heart syndrome) or closure of a patent ductus arteriosus upon which systemic circulation depends (eg, coarctation of the aorta). Both of these mechanisms lead to inadequate systemic perfusion with resultant tissue hypoxia and acidosis.
CLINICAL FEATURES
The presentation of congenital heart defects resulting in shock is usually quite dramatic and infants may arrive in the ED in extremis. Most patients present in the first or second week of life as the ductus arteriosus closes.
Early symptoms include poor feeding or sweating with feeds, vomiting, and parents may note rapid breathing, irritability, or lethargy.
Tachycardia, tachypnea, pallor, mottling of skin, and sometimes cyanosis (from inadequate tissue perfusion) are typically noted on presentation to the ED.
Mental status changes including profound lethargy are common with severe shock.
DIAGNOSIS AND DIFFERENTIAL
The congenital heart defects most commonly associated with shock in the neonate are hypoplastic left heart syndrome, coarctation of the aorta, and interrupted aortic arch.
Noncardiac causes of shock such as sepsis, inborn errors of metabolism, abdominal catastrophes, non-accidental trauma, and congenital adrenal hyperplasia must be considered.
A full set of vital signs including four-extremity blood pressures should be obtained. Extreme tachycardia, tachypnea, and differential upper extremity and lower extremity blood pressures with delayed or absent femoral pulses strongly suggest ductal dependent congenital heart disease.
A chest radiograph and ECG may help exclude noncardiac causes of shock such as pneumonia with sepsis and suggest a cardiac lesion.
Routine blood tests are not helpful to diagnose ductal dependent heart lesions, but may be useful to guide management and exclude other causes and may include a complete blood count (for infectious causes), electrolytes (for metabolic and endocrine disease), venous blood gas, and lactate. Cultures may be helpful to exclude infection.
Echocardiography and occasionally cardiac catheterization provide definitive diagnosis of congenital heart disease, but are rarely performed in the ED and require pediatric sonographers and cardiologists.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Neonates presenting with shock from congenital heart disease require urgent resuscitation, continuous monitoring, and pharmacologic treatment.
Provide high-flow oxygen to improve delivery to tissues, though recognize that oxygen may hasten closure of the ductus arteriosus or cause pulmonary steal of systemic blood flow through dilation of pulmonary vasculature.
Obtain vascular or osseous access and administer normal saline in 10 to 20 mL/kg boluses repeated as necessary.
Begin infusion of prostaglandin E1 in all patients suspected of ductal dependent congenital heart disease, as this may be lifesaving: start at 0.1 microgram/kg/min and gradually decrease to the lowest effective dose.
Consider epinephrine for further treatment of hypotension (0.05–05.0 microgram/kg/min).
Obtain immediate consultation with a pediatric cardiologist and intensivist.
By definition, these patients require admission to intensive care.
CONGESTIVE HEART FAILURE
PATHOPHYSIOLOGY
Congestive heart failure in infants and children develops because of one of two mechanisms (sometimes a combination of both): poor ventricular outflow or pulmonary vascular over-circulation.
Poor ventricular outflow may be structural (eg, hypoplastic left ventricle, coarctation of the aorta) or functional (eg, cardiomyopathy, severe anemia, sustained tachydysrhythmia).
Pulmonary vascular over-circulation is typically the result of left-to-right shunting, which can occur through a patent ductus arteriosus or a septal defect.
CLINICAL FEATURES
Feeding difficulties (slow feeding, sweating with feeds) are often the first symptoms of congenital heart disease causing congestive heart failure (CHF).
Respiratory symptoms develop as pulmonary edema progresses resulting in tachypnea (usually effortless initially, later with signs of distress), nasal flaring, and grunting. Rales can sometimes be heard on auscultation.
Hepatomegaly and dependent edema (back, scalp, scrotum) can sometimes develop.
The timing and age at which CHF develops may be helpful in determining the likely cause (see Diagnosis and Differential below).
DIAGNOSIS AND DIFFERENTIAL
Diagnosis is made through a combination of physical examination and radiologic findings. Tachypnea, tachycardia, decreased breath sounds, or rales may be the only signs in left-sided CHF, while hepatomegaly and peripheral edema suggest right-sided failure.
Chest radiograph reveals cardiomegaly and pulmonary vascular congestion (see Fig. 74-3), sometimes with an effusion.
The rapidity and age of onset of CHF help determine the differential diagnosis (Table 74-4).
Onset of CHF after the first 6 months of life usually signifies acquired heart disease such as cardiomyopathy, myocarditis, or pericarditis, though acute respiratory infection can precipitate CHF in the setting of underlying structural disease.
Myocarditis is often preceded by a viral respiratory illness and may be difficult to distinguish from pneumonia, though patients with myocarditis may show ECG changes such as ST segment elevations, dysrhythmias, or ectopy.
Pericarditis may be associated with muffled heart sounds and a friction rub and a pericardial effusion may be noted on bedside ultrasound.
Cardiomyopathy is usually more insidious in onset with malaise, gradual progression of respiratory distress, signs of CHF accompanied by weak peripheral pulses, cardiomegaly on chest radiograph, and often chamber enlargement on ECG.
Once CHF is diagnosed, echocardiography is indicated to define anatomy and cardiac function.
FIG. 74-3. Cardiomegaly and pulmonary edema in a 74-day-old infant.
TABLE 74-4 Differential Diagnosis of Congestive Heart Failure Based on age at Presentation
EMERGENCY DEPARTMENT CARE AND DISPOSITION
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 either hypothermia or hyperthermia.
If the work of breathing is increased or CHF is apparent on chest radiograph, 1 to 2 milligrams/kg of furo-semide parenterally is indicated.
Fluid restriction, diuresis, and an increased FiO2 can usually correct hypoxemia, although continuous positive airway pressure is sometimes necessary.
Stabilization and improvement of left ventricular function can often first be accomplished with ino-tropic agents. Digoxin is used in milder forms of CHF. The appropriate loading/digitalizing dose to be given in the ED is 0.02 milligram/kg.
At some point, CHF progresses to cardiogenic shock, in which distal pulses are absent and end-organ perfusion is threatened. In such situations, continuous infusions of inotropic agents, such as dopamine or dobutamine, are indicated instead of digoxin. The initial starting range is 2 to 10 micrograms/kg/min.
Aggressive management is often necessary for secondary derangements, including respiratory insufficiency, acute renal failure, lactic acidosis, disseminated intravascular coagulation, hypoglycemia, and hypocalcemia.
For definitive diagnosis and treatment of congenital lesions presenting in CHF, cardiac catheterization followed by surgical intervention is often necessary. See the previous section for recommendations regarding administration of prostaglandin E1 as a temporizing measure prior to surgery.
For further reading in Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7th ed., see Chapters 122A, “Congenital Heart Defects,” and 122B, “Acquired Heart Disease,” by Linton L. Yee and Garth D. Meckler.