The reported incidence of congenital heart disease (CHD) is eight cases per 1,000 live births.1 Family physicians must know how to screen for cardiac defects in infants, how to stabilize infants with these problems and how to manage their problems in teamwork with a pediatric cardiologist and a cardiac surgeon. As patient advocates, we also must be prepared to help the parents and other family members cope with the psychosocial aspects of chronic disease in a child.
Studies suggest that 30 to 60 percent of congenital heart defects can be detected prenatally by four-chamber screening.2 High-resolution four-chamber transvaginal echocardiography can provide detailed imaging of the cardiac anatomy in the fetus and can detect major abnormalities,2 although routine prenatal screening for CHD remains controversial. In one large study,3 however, reliance on only a four-chamber view would have resulted in overlooking 23 percent of the defects. More detailed fetal echocardiography with outflow-tract views can be particularly helpful in detecting anomalies of the great arteries3 and is indicated in pregnancies in which the risk of CHD is increased.2
Women at high risk of having an infant with CHD include those with diabetes, a family history of CHD or exposure to drugs such as indomethacin (Indocin).2 In addition, first-trimester rubella exposure and residence at high altitudes are associated with an increased incidence of patent ductus arteriosus.4 Other infants at high risk for CHD include those with abnormalities of other systems and those with syndromes related to abnormal karyotypes.2,4 If a cardiac malformation is identified, complete evaluation of other systems is warranted. Karyotyping is also recommended.3 Although early prenatal diagnosis is advantageous, lesions can also develop later in pregnancy. Thus, some anomalies may be missed entirely.2 The timing of scanning is controversial. In most studies, scanning has been performed between 18 and 22 weeks' gestation.2
One third of infants born with CHD develop life-threatening symptoms within the first few days of life. The infant mortality rate in these cases is as high as 90 percent.5 In as many as 80 percent of infants with critical disease, congestive heart failure is the presenting symptom.5 Difficulty in feeding is common and is often associated with tachypnea, sweating and subcostal retraction.6 Suspicion of CHD should be raised if feeding takes more than 30 minutes. A history of feeding difficulty often precedes overt congestive heart failure, even if only by six to 12 hours.6 On examination, signs of congestive heart failure include an S3 gallop and pulmonary rales. Failure to recognize congestive heart failure as the cause of symptoms in infants with CHD often leads to misdiagnosis and treatment for septicemia.6
The presence or absence of a heart murmur is unreliable as a basis for the diagnosis of CHD. Transient murmurs are often heard in infants without cardiac abnormalities. Furthermore, a murmur is not present in many severe forms of CHD, such as tricuspid atresia, coarctation of the aorta and transposition of the great vessels. When a murmur is associated with a cardiac defect, the intensity of the murmur is unrelated to the severity of the abnormality. However, the nature of the murmur (harsh, blowing or musical), along with other heart sounds, is useful in differentiating mild defects from severe abnormalities.7 The infant's age at the time a murmur is first heard is also helpful. If a murmur is detected within 24 hours of birth, the risk of CHD is one in 12; in this situation, patent ductus arteriosus is usually the underlying cardiac defect, and it usually closes before the infant is discharged from the hospital. If a murmur is first heard when the infant is six months of age, the chance of CHD is one in seven; at 12 months of age, the risk of CHD is one in 50.1
Femoral and brachial pulses should be palpated. In infants with some obstructive lesions of the left side of the heart, femoral pulses may be palpable, but one or both brachial pulses may not be palpable.6 In infants with patent ductus arteriosus, femoral pulses may be present at birth but may become diminished or absent with closure of the ductus arteriosus at three to 14 days of age.6,7
Suspicion of cyanosis should be confirmed by pulse oximetry. When pulmonary disorders are the cause of cyanosis, administration of 100 percent oxygen usually increases the arterial oxygen saturation to at least 95 percent. In patients with cyanotic CHD, oxygen saturation will only increase to 80 to 85 percent.5
An electrocardiogram (ECG) is indicated if CHD or an arrhythmia is suspected. If the index of suspicion is high on the basis of other findings, a normal ECG does not exclude the presence of CHD.6 Chest radiographs of an infant with congestive heart failure demonstrate cardiomegaly and increased pulmonary vascular markings.1 A serious underlying heart defect is unlikely if the infant is clinically well and electrocardiographic and radiographic findings are normal.1
Definitive evaluation requires cardiac imaging. Echocardiography remains the primary diagnostic modality, but magnetic resonance imaging provides excellent anatomic evaluation and often yields even more information than angiography.8
Common Congenital Heart Defects
Congenital heart defects are classified into two broad categories: acyanotic and cyanotic. In acyanotic defects, congestive heart failure is the most common symptom. The most common acyanotic lesions are ventricular septal defect, atrial septal defect, atrioventricular canal, pulmonary stenosis, patent ductus arteriosus, aortic stenosis and coarctation of the aorta. In infants with cyanotic defects, the primary concern is hypoxia. The most common defects associated with cyanosis are tetralogy of Fallot and transposition of the great arteries. These nine lesions constitute 85 percent of all congenital heart defects.9 Table 1 highlights some of the features of these lesions. The remaining 15 percent are often cyanotic defects9 and include tricuspid atresia, total anomalous pulmonary venous return, truncus arteriosus and hypoplastic left heart.
|Ventricular septal defect||Size of defect dictates hemodynamic presentation. In 30 to 40% of cases, spontaneous closure occurs within the first 6 months.|
|Surgical repair required if infant exhibits failure to thrive, pulmonary hypertension or right-to-left shunt > 2:1.|
|Atrial septal defect||Often asymptomatic; 87% of secundum types close by age 4. Primary and sinus types require surgery. Late sequelae include mitral valve prolapse, atrial fibrillation or flutter, and pulmonary hypertension.|
|Atrioventricular canal||Combination of the primum type of atrial septal defect, ventricular septal defect and common atrioventricular valve. Presentation similar to that of ventricular septal defect. Palliative pulmonary artery banding in refractory congestive heart failure.|
|Pulmonary stenosis||May be asymptomatic or may result in severe congestive heart failure. Prostaglandin E1 infusion at birth may be helpful. Valvular type may require balloon valvuloplasty.|
|Patent ductus arteriosus||In premature infants, spontaneous closure or indomethacin-induced closure may occur. In term infants, spontaneous closure is less likely, and indomethacin is not helpful. Recurrent pneumonia may occur. Surgical ligation usually required. No long-term sequelae if adequately treated.|
|Aortic stenosis||May be asymptomatic. Valve replacement and anticoagulation may be required.|
|Coarctation of the aorta||98% of cases occur at origin of left subclavian artery. Blood pressure higher in arms than legs. Bounding pulses in arms and decreased pulses in legs. Surgical repair usually required between 2 and 4 years of age.|
|Tetralogy of Fallot||Most common CHD beyond infancy. Defects include ventricular septal defect, right ventricular hypertrophy, right outflow obstruction and overiding aorta. Intermittent episodes of hyperpnea, irritability, cyanosis with decreased intensity of murmur. Palliative shunting may be necessary. Surgical repair required before age 4.|
|Transposition of the great arteries||Transposition of pulmonary artery and aorta. Ductus-dependent. Consider palliative balloon atrial septostomy, but definitive surgical switch of aorta and pulmonary artery required as soon as possible. Late complications include pulmonary stenosis, mitral regurgitation, aortic stenosis, coronary artery obstruction, ventricular dysfunction and arrhythmias.|
VENTRICULAR SEPTAL DEFECT
Ventricular septal defect is the most common CHD, accounting for 15 to 20 percent of all cases of isolated CHD.10 It may occur in any septal location. The hemodynamic significance of a ventricular septal defect is related to the size of the defect and ranges from insignificant to severe. Spontaneous closure within the first six months of life occurs in 30 to 40 percent of membranous and muscular defects10 and is more likely to occur in smaller defects than in larger defects.
Congestive heart failure, which may begin to develop at six to eight weeks of age, is managed with diuretics and digoxin (Lanoxin). Indications for surgical closure include growth failure that is nonresponsive to medical management, evidence of impending pulmonary hypertension or a pulmonary-to-systemic flow ratio of greater than 2:1 as determined by cardiac catheterization. Postoperative complications include conduction defects, such as transient right bundle branch block.
ATRIAL SEPTAL DEFECT
Atrial septal defects may occur as sinus venosus, secundum or primum type. The overall rate of spontaneous closure of the secundum type of atrial septal defect is 87 percent in the first four years of life.10 Primum and sinus venosus types with defects greater than 8 mm rarely close spontaneously, and surgical intervention is usually required. Most children with an atrial septal defect remain asymptomatic, but in those who develop congestive heart failure, medical management with diuretics and digoxin usually suffices.
Indications for surgical closure are persistence of the defect beyond four years of age, refractory congestive heart failure and the presence of other associated defects, such as ventricular septal defect or valvular anomalies. Cardiac dysrythmias and mitral valve prolapse may be late sequelae of treated or untreated atrial septal defect in children or adults. Pulmonary hypertension may develop in adults with an untreated atrial septal defect. Atrial flutter or fibrillation may also occur in adults with a history of atrial septal defect, regardless of the treatment.
Atrioventricular canal is characterized by a combination of a primum type of atrial septal defect, a common atrioventricular valve and an inlet type of ventricular septal defect. Most of the hemodynamic problems associated with this abnormality are caused by the ventricular septal defect, although mitral regurgitation or left-ventricle-to-right-atrium regurgitation, or both, may add to the pulmonary overload.
The treatment of congestive heart failure in association with atrioventricular canal, the indications for surgical repair and the postoperative complications are similar to those described for ventricular septal defect. Corrective surgery should be performed before the onset of pulmonary vascular occlusive disease. Palliative pulmonary artery banding may be performed in infants who have refractory congestive heart failure and are too small for definitive repair.
Pulmonary stenosis may be valvular, subvalvular or supravalvular. The clinical manifestations of pulmonary stenosis range from an asymptomatic lesion to frank congestive heart failure. Newborns may respond to prostaglandin E1 infusion. Balloon valvuloplasty, performed during cardiac catheterization, is the preferred method of treatment for the valvular type of pulmonary stenosis. If this intervention fails, and in the other types of obstruction, surgery is necessary.
PATENT DUCTUS ARTERIOSUS
Patent ductus arteriosus is a common problem in premature infants. Closure may be spontaneous; if medical closure is required, indomethacin is effective. In term infants, spontaneous closure is unlikely, and indomethacin is not effective. Congestive heart failure and recurrent pneumonia are likely complications if the flow through the ductus is substantial.
Surgical ligation remains the preferred method of closure and should be performed as soon as possible. Cardiopulmonary bypass is not necessary. Nonsurgical techniques for correction of patent ductus arteriosus, such as catheter placement of an embolic device in term infants and indomethacin therapy in premature infants, are gaining in popularity. Patent ductus arteriosus is the only CHD that may be considered surgically “cured,” with no long-term sequelae.
Aortic stenosis may be valvular, subvalvular or supravalvular. It may be asymptomatic or may cause symptoms of congestive heart failure. The pressure gradient across the stenosis increases with the child's growth, as the cardiac output increases.
Surgical correction is the preferred treatment. Timing of the surgery is dependent on the child's cardiopulmonary status, the type of procedure planned (valvulotomy versus valve replacement) and the size of the valve if a graft is needed. Lifelong anticoagulation therapy is required if a prosthetic valve replacement is performed.
COARCTATION OF THE AORTA
Narrowing of the aorta may occur anywhere along its length, but 98 percent of cases occur just below the origin of the left subclavian artery.9 The classic clinical sign of coarctation of the aorta is a higher blood pressure in the arms than in the legs and pulses that are bounding in the arms but decreased in the legs. Surgical repair is usually performed between the ages of two and four years. Urgent surgical repair is performed in cases of circulatory shock, cardiomegaly, severe hypertension or severe congestive heart failure.
TETRALOGY OF FALLOT
Tetralogy of Fallot is the most common CHD seen beyond infancy, with surgical repair usually undertaken when the child reaches three years of age.10 It consists of a large ventricular septal defect, right outflow tract obstruction, right ventricular hypertrophy and overriding of the aorta. The classic clinical presentation is the “tet spell,” characterized by hyperpnea, irritability, cyanosis and decreased murmur intensity.
Squatting decreases systemic venous return by trapping blood in the legs, breaking the overload-hypoxia cycle. If this maneuver is ineffective, pharmacologic treatment may be necessary. Medical management of tetralogy of Fallot includes patient and parent education on ways to treat the “spells,” prevention of anemia and prophylaxis for subacute bacterial endocarditis. Surgical palliation consists of placement of a shunt from the subclavian artery to the ipsilateral pulmonary artery. Several different types of shunt procedures are currently performed. Total repair includes placement of a ventricular septal defect patch and right ventricular outflow tract widening. Total repair is performed before the child is four years of age.
TRANSPOSITION OF THE GREAT ARTERIES
Complete transposition of the great arteries occurs in about 5 percent of children with CHD.10 The aorta and pulmonary arteries are transposed, so that the two circulations are separate and parallel rather than in sequence. Infants with transposition of the great arteries are cyanotic at birth and often have congestive heart failure. Associated defects such as an atrial septal defect or patent ductus arteriosus, which permit the mixing of blood from the two circuits, are necessary for the infant's survival. Transposition of the great vessels is called “ductus-dependent,” meaning that the ductus should be kept open by prostaglandin infusion until surgery can be performed. Metabolic abnormalities and severe hypoxia should be corrected before surgical repair is undertaken. Balloon atrial septostomy may be performed palliatively to increase the mixing of blood.
The definitive surgical procedure of choice is the arterial switch operation, in which the aorta and the pulmonary artery are divided and reattached to their proper positions, resulting in a physiologic repair. It should be performed as soon as possible. The five-year survival rate after the arterial switch operation is 82 percent.10 Associated defects, such as ventricular septal defect, pulmonary stenosis and patent ductus arteriosus, may necessitate a staged repair. Late complications of surgical repair include pulmonary or aortic stenosis, coronary artery obstruction, ventricular dysfunction, arrhythmias and mitral regurgitation.
Health Maintenance Issues
Growth impairment of infants with acyanotic CHD is directly proportional to the severity of the hemodynamic disturbance. The most severely affected infants are those with congestive heart failure.11 Acyanotic lesions tend to jeopardize weight gain rather than height, whereas cyanotic lesions tend to affect both height and weight.12 Infants with cyanotic lesions have an earlier fall-off in linear growth and often are smaller than infants without these problems.11 Infants with CHD and growth impairment typically show caloric deprivation and a reduction in adipose stores. Boys are usually more malnourished than girls.11,12 Anorexia and early satiety may be exacerbated by the drugs, such as diuretics, that are administered for the treatment of congestive heart failure.12 However, in the absence of congestive heart failure, a large left-to-right shunt or cyanosis, other causes of failure to thrive should be explored.11
Many factors contribute to growth impairment in infants with CHD, including a lower than normal birth weight, increased caloric requirements and the presence of concomitant musculoskeletal, central nervous system, renal or gastrointestinal malformations. Mild gastrointestinal abnormalities, mild steatorrhea and excess protein loss are common in infants with CHD.11 Up to 30 percent of infants with CHD have features of various genetic syndromes.11 Some of these syndromes, such as fetal alcohol syndrome, are probably underdiagnosed.
Poor nutrition related to anorexia, fatigability, vomiting, fluid restriction and frequent respiratory infections also contributes to growth impairment.11 Systemic and respiratory illnesses increase the body temperature and the metabolic rate. The metabolic rate can increase up to 13 percent for each degree centigrade over normal temperature.12 Hypertrophic cardiac muscle can use up to 30 percent of the total oxygen consumption of the body rather the usual 10 percent. After accounting for other energy needs, infants with CHD may have only one half as much energy available for growth as healthy infants.11
Adequate nutrition is extremely important in infants with CHD. Many infants with CHD are able to breast-feed and gain adequate weight as well as enjoy the other benefits of breast feeding.13 In infants who are unable to gain sufficient weight with breast feeding, supplementation options include a formula with a high caloric density, nocturnal enteral feeding or continuous 24-hour feeding with a nasogastric or duodenal tube. The latter is the most effective form of supplementation. A caloric intake of 140 to 200 calories per kg per day is needed to induce catch-up growth.11 Generally, growth improves with increasing age as a result of the decreased size of a left-to-right shunt, closure of a septal defect or development of pulmonary vascular obstructive disease. In most patients, catch-up growth is largely complete within six to 12 months of surgery.11
Routine childhood health maintenance visits should be scheduled. More frequent evaluations are needed if congestive heart failure or other problems are present. The routine immunization schedule should be followed with a few exceptions: varicella vaccine and measles, mumps and rubella vaccine are indicated at 12 months of age rather than at 15 months; pneumococcal vaccine is recommended at two years of age, and influenza vaccine should be given yearly beginning at age six months in this higher-risk population.
Prophylaxis against bacterial endocarditis should be instituted in patients undergoing certain procedures, in accordance with the American Heart Association recommendations (Tables 2, 3 and 4).14 Children who are already receiving an antibiotic that is used in prophylaxis should be given an alternate antibiotic prophylaxis regimen.14
Guidelines regarding activity levels and sports participation for children with CHD have been developed (Table 5).15 Children should be assessed individually, based on their clinical condition and the type of activity in which they plan to engage. Basic assessment by a pediatric cardiologist includes graded exercise testing on a treadmill or bicycle to measure heart rate, rhythm and blood pres sure. Patients with severe forms of cyanotic CHD, aortic stenosis and coarctation of the aorta with residual hypertension are at risk of sudden death during exercise. In the absence of pulmonary hypertension, patients with an unrepaired atrial septal defect, ventricular septal defect and patent ductus arteriosus are usually asymptomatic with exercise.15
|Category I—No restrictions; interscholastic athletic competition and contact sports allowed|
|Aortic stenosis, mild|
|Atrial septal defect without pulmonary vascular obstructive disease|
|Coarctation of the aorta, surgically repaired, normal blood pressure|
|Patent ductus arteriosus without pulmonary vascular obstructive disease|
|Pulmonary stenosis, mild|
|Tetralogy of Fallot, surgically repaired, right ventricular pressure < 50 mm Hg|
|Ventricular septal defect without pulmonary vascular obstructive disease|
|Category II— Moderate exercise, regular physical education classes, tennis and baseball allowed|
|Transposition of the great arteries, surgically repaired|
|Tricuspid atresia, surgically repaired|
|Category III—Light exercise, nonstrenuous team games, golf, leisure swimming, cycling and jogging allowed|
|Aortic stenosis, moderate|
|Atrial septal defect, mild to moderate pulmonary vascular obstructive disease|
|Coarctation of the aorta, hypertensive|
|Patent ductus arteriosus, mild to moderate pulmonary vascular obstructive disease|
|Pulmonary stenosis, moderate|
|Tetralogy of Fallot, surgically repaired, right ventricular pressure > 50 mm Hg or marked cardiomegaly|
|Tricuspid atresia, palliated or unoperated|
|Ventricular septal defect, mild to moderate pulmonary vascular obstructive disease|
|Category IV—Moderate limitation, no participation in physical education classes|
|Aortic stenosis, severe|
|Atrial septal defect, moderate to severe pulmonary vascular obstructive disease|
|Patent ductus arteriosus, moderate to severe pulmonary vascular obstructive disease|
|Pulmonary stenosis, severe|
|Ventricular septal defect, moderate to severe pulmonary vascular obstructive disease|
|Category V—Extreme limitation. Home- or wheelchair-bound|
The diagnosis of a chronic condition in any family member causes much distress. When an infant is born with a heart defect, the parents may grieve over the loss of the healthy newborn they had anticipated and experience shock, denial, guilt, anger, despair or confusion on learning that their infant has a cardiac defect. Some parents may be unable at first to respond to their newborn. Even greater stress may occur if the condition is one that requires surgical intervention.16(p353)
Many parents develop a narrow, disease-oriented focus. The family physician's main role is to help the family put the diagnosis in perspective by clarifying parental expectations and misconceptions and by answering specific questions. Because the family is ultimately responsible for the child's care, they must be included as part of the health care team. The family physician should remain in close contact with specialists also involved in the patient's care to assure that the parents have accurate information for making decisions about the treatment of their child. Reinforcement of the positive, normal attributes of the child helps the family see the child as an individual with many of the same needs as healthy children.17
Consultation with a mental health professional may enable the family to recognize and build on strengths that will help them cope with this challenge and circumvent those things that might interfere with their coping ability.16(p360)
Unless day care facilities for children with chronic conditions are readily available, caregivers may be forced to give up jobs or careers to stay at home with the child. This may also be true because of the demands of the child's medical treatment. While some caregivers respond positively to the stay-at-home role, others may become depressed and develop lowered self-esteem and somatic symptoms.17 The extreme involvement often required of parents may drain their energy, financial resources and leisure time. If possible, these additional stressors should be prevented.18 Physician awareness of community resources, such as parental support groups and respite care, is helpful to parents. In addition, homemaker services may be important support.
Recognizing and building on the family's strengths and on the child's positive attributes lays the groundwork for normalization. When this process occurs, the family focuses on the child rather than on the condition. Reinforcing the family's successes helps them build the confidence and desire to address and manage future issues.17