Excluding patent ductus arteriosus of the premature infant, congenital heart disease is estimated to occur in about 0.8% of all children.1 Fortunately, most of these problems are minor or self-limited and do not require intervention. Congenital heart disease requiring intervention is less common—about 3 to 4/1000.2 For this important group of patients with heart disease, the past 70 years have witnessed a remarkable advance in diagnostic and therapeutic techniques such that many of these children with previously lethal defects may now lead relatively normal lives. Congenital heart disease ranks ninth in cause of death of infants <1 year at 2.1 per 100,000 live births in the United States, and is comparable to the death rate for sepsis and respiratory distress syndrome.3
Children with congenital heart disease may be hospitalized at the time of diagnosis if they present with critical heart disease, after cardiac interventions (surgery or transcatheter), or for acute illness related or unrelated to their heart condition. While some congenital cardiac disease has straightforward anatomy, the hospitalist may care for children with the most complex cardiac anatomy, as these children typically spend the most time in hospital. The pediatric hospitalist frequently plays an important role in the care of children with congenital heart disease—especially when it coexists with other disease processes.
While the anatomic variation of congenital heart disease is vast, the four main elements of pathophysiology in congenital heart disease are desaturation, pulmonary overcirculation, pulmonary vascular disease, and compromised systemic perfusion. The interventions we undertake for patients with congenital heart disease are done to address or prevent one or more of these issues. These pathologies are discussed more fully in the context of the more common examples of congenital heart disease.
Congenital heart disease typically presents in one of three time frames: the newborn period, in early infancy, or in childhood. The newborn period usually sees most presentations of critical congenital heart disease. What defines these lesions as “critical” is that survival depends on ductal patency, or emergent surgical or catheter intervention. Typical clues to suggest critical heart disease in the newborn include cyanosis or signs and symptoms of decreased perfusion. Increasingly, newborns with congenital heart disease are born with detailed anatomic diagnoses due to prenatal screening by fetal echocardiography. In some centers, more than half of infants born with serious congenital heart disease have been diagnosed antenatally. Antenatal diagnosis allows for appropriate and anticipatory management of these infants and has led to a measure of improved outcome for complex heart disease.4 One other important presentation for newborns with critical congenital heart disease is the screening program for critical congenital heart disease endorsed by the Centers for Disease Control (CDC) and now adpoted by legislation in over half of the states in the US. This simple screening uses a pulse oximeter to check saturations in the right hand and foot in newborns more than 24 hours old or immediately pre-discharge. Any reading <90%, three readings 90% to 94%, or a more than 3% difference between the hand and the foot triggers the recommendation for a diagnostic echocardiogram. This test will detect most cyanotic congenital heart disease as well as hypoplastic left heart syndrome, and other mixing lesions. A recent meta-analysis of several published studies shows a high sensitivity of this test (76%) for critical congenital heart disease and a low false positive rate (0.05%) when done >24 hours after birth.5
A second group of patients with congenital heart disease presents in the weeks after birth as the pulmonary resistance falls to its nadir at 8 to 12 weeks of life. This group may present with a murmur, or with symptoms of congestive heart failure (tachypnea, hepatomegaly) if there is significant pulmonary overcirculation. Late presentations associated with closure of the ductus arteriosus may also present in this time frame with cyanosis, shock, or decreased femoral pulses.
The third common time frame for diagnosis of congenital heart disease is during childhood, with a less-intense heart murmur. This often happens between age 2 and 5 years when the child finally is cooperative to remain still for a minute or two it takes to get a good quiet listen with a stethoscope.
In addition to the more usual presentations of congenital heart disease, there are infants and children with serious cardiovascular malformations that masquerade as more common illnesses such as lung disease or laryngomalacia (Table 53-1).
TABLE 53-1Examples of Congenital Heart Disease that Masquerade as Other Diseases ||Download (.pdf) TABLE 53-1 Examples of Congenital Heart Disease that Masquerade as Other Diseases
|Masquerading Disease ||Congenital Heart Disease ||Hint/Clue ||Definitive Diagnostic Test |
Frequent lower respiratory illnesses
Asthma / bronchiolitis
Failure to thrive
Ventricular septal defect
Patent ductus arteriosus
Atrioventricular canal defect
Aortopulmonary window with elevated pulmonary vascular resistance
Loud, single second heart sound
|Vascular ring ||Often right aortic arch on chest x-ray || |
|Anomalous left coronary artery from the pulmonary artery (ALCAPA) || |
Cardiomegaly on CXR
Abnormal ECG (infarction pattern)
|Echocardiogram (looking specifically at origin of coronary arteries) |
|Hypertension ||Coarctation of the aorta ||Decreased intensity of femoral pulses and/or radio-femoral delay || |
Four extremity blood pressures
|Severe neonatal respiratory distress ||Total anomalous pulmonary venous return (with obstruction) ||History not suggestive for infant at-risk for pulmonary disease ||Echocardiogram (complete, but especially focusing on pulmonary veins) |
For infants who are critically ill with low oxygen saturation and/or hypotension, the more common diagnoses of infancy are usually first to be considered. Respiratory distress syndrome, sepsis, meconium aspiration syndrome, pneumonia, and others are usually first considered because their incidence is much higher. Critical heart disease should especially be suspected when cyanosis is present without accompanying respiratory distress, or there are signs of decreased systemic perfusion such as weak or absent femoral pulses and/or metabolic acidosis (Table 53-2). A high index of suspicion for heart disease should be maintained for infants who appear to have severe respiratory disease but who are not improving with conventional management.
TABLE 53-2Critical Newborn Heart Disease Dependence on a Patent Ductus Arteriosus (PDA) ||Download (.pdf) TABLE 53-2 Critical Newborn Heart Disease Dependence on a Patent Ductus Arteriosus (PDA)
|PDA Required to Support Pulmonary Flow ||PDA Required to Support Systemic Flow ||PDA Increases Mixing |
Critical pulmonary stenosis
Pulmonary atresia/intact ventricular septum
Tricuspid atresia (normally related great arteries)
Tetralogy of Fallot (some)
Complex single ventricle with pulmonary stenosis/atresia
Critical aortic stenosis
Critical coarctation/Interrupted aortic arch
Tricuspid atresia (transposed great arteries)
Hypoplastic left heart syndrome
Complex single ventricle with systemic outflow obstruction
|d-Transposition of great arteries (d-TGA) |
When critical heart disease is suspected in the neonate, diagnostic and empiric interventions need to be performed simultaneously. For diagnosis, consultation with a pediatric cardiologist and full transthoracic echocardiogram is indicated. With such evaluation, the diagnosis of virtually all congenital heart disease in the newborn period is possible. Where the index of suspicion for heart disease is lower, a chest radiograph, electrocardiogram, and hyperoxic test should be performed. The hyperoxic test is performed by placing the infant on 100% FiO2 and measuring a post-ductal arterial PO2. A value of >200 Torr almost always excludes cyanotic congenital heart disease. A value lower than that or an infant who has poor perfusion or remains critically ill despite the usual treatment measures for these other conditions should have a complete echocardiogram performed and interpreted by a physician qualified to diagnose complex congenital cardiac disease.
In those infants suspected of having critical heart disease, empiric therapy with intravenous prostaglandin E-1 should be commenced immediately at a dose of between 0.01 μg/kg/min and 0.05 μg/kg/min. Prostaglandin E-1 will reopen a closing ductus arteriosus and restore pulmonary or systemic flow in critical heart disease, temporizing the situation and allowing time for diagnosis and planned intervention. Side effects of prostaglandin include apnea, hypotension, tachycardia, and fever.
Two points are important to make at this juncture:
A “normal” fetal ultrasound or even an echocardiogram should not be reason to exclude the consideration of serious congenital heart disease. The fetal diagnosis of congenital heart disease is a very operator-dependent test. There are many instances where infants with hearts diagnosed as “normal” in-utero turn out to have critical congenital heart disease.
An echocardiogram done on a critically ill newborn is a very difficult test to perform and interpret accurately. The infant may be ventilated on an oscillator, be very labile with blood pressure or saturation to even brief imaging, and a whole other host of hemodynamic factors may make the acquisition and interpretation difficult. In addition, some of the most difficult diagnoses to make by echocardiogram (such as obstructed total anomalous pulmonary venous return) typically present in this fashion. While more neonatologists, radiologists and hospitalists are acquiring advanced training in pediatric echocardiography, it is imperative that the physician caring for the critically ill infant does not overstep his/her degree of expertise when assessing for potential critical heart disease.6
DIAGNOSTIC EVALUATION FOR CONGENITAL HEART DISEASE
The recognition of congenital heart disease rests on the foundation of a good clinical history and physical examination. The electrocardiogram may add supplemental information to the assessment of cardiac anatomy, and is necessary for diagnosis of rhythm problems. The diagnosis of congenital heart disease has been revolutionized by two-dimensional echocardiography. Echocardiography provides a detailed anatomic and physiologic diagnosis of congenital heart disease, is noninvasive, and is performed at the bedside. Coupled with the Doppler technique, blood velocity may also be assessed, and this can be used to estimate chamber pressures and presence of heart or great vessel obstruction or valve regurgitation. Because almost all the ultrasound waves are reflected at tissue–air interfaces, echocardiography is limited to views where the lungs do not obstruct the path between the ultrasound beam and the heart. Factors that limit the usefulness of transthoracic echocardiography include obesity, obstructive lung disease, and certain chest wall deformities. Three-dimensional echocardiography is in the early stages of clinical application and may provide additional understanding of the anatomic information
Magnetic resonance imaging (MRI) is increasingly being used for diagnostic evaluation of congenital heart disease. Advantages of cardiac MRI include excellent anatomic detail that is not limited by lung tissue, and MRI is therefore an especially good modality for imaging the great vessels. A major disadvantage is the requirement for sedation and the relatively long post-processing and interpretation time. Functional assessment of blood flow by MRI is possible and in many instances may be more accurate than echocardiography. Implanted metal such as surgical clips or embolization coils render bothersome imaging artifacts in many patients when performing cardiac/thoracic MRIs.
MRI is generally contraindicated in patients with pacemakers and defibrillators.
Cardiac catheterization with angiography was once considered the gold standard for anatomic diagnosis. However, echocardiography and MRI have now almost completely supplanted cardiac catheterization for anatomic diagnosis. Cardiac catheterization remains the gold standard for hemodynamic assessment, and increasingly cardiac catheterization is being used as an interventional rather than diagnostic tool.
MANAGEMENT OF CONGENITAL HEART DISEASE
Definitive treatment of congenital heart disease is complex due to the wide variety of anatomy, the physiologic changes that occur over time (e.g. fall in pulmonary vascular resistance), and growth. Straightforward heart lesions are approached with surgical or transcatheter techniques that address a single problem (e.g. atrial septal defect). More complex forms of congenital heart disease are approached by cardiologists and cardiovascular surgeons by first attempting to decide if there are enough required cardiac “parts” to immediately or eventually repair the heart in such a way that it is physiologically, if not anatomically, correct. A “complete” or “two-ventricle” repair entails having separate systemic and pulmonary circuits, each with its own ventricle and atrioventricular valve able to pump deoxygenated blood to the lungs and oxygenated blood to the body. Although this type of repair is referred to as a “complete,” the resulting cardiac anatomy is often very different from normal. Where possible, complete repair is generally the preferred option.
If there are insufficient “parts” to perform a complete repair (e.g. hypoplastic left heart syndrome, tricuspid atresia) then a single ventricle pathway must be pursued. The single ventricle pathway typically follows as a series of palliative surgeries that culminate with a Fontan procedure. This staged cardiac surgery ultimately results in a circulation where the venous blood return is passively routed to the lungs without passing though a ventricle, and then returns to a functionally single ventricle that pumps to the body. For this type of repair to succeed, the patient must have a relatively competent atrioventricular valve, good systolic ventricular function, unobstructed outflow from the heart, widely patent pulmonary arteries, and low pulmonary vascular resistance. The vascular resistance of the neonatal pulmonary vascular bed is too high to accept the passive pulmonary flow of a Fontan, and so a series of operations is necessary to ultimately achieve this type of palliation.
STAGE I: SINGLE VENTRICLE PATHWAY
The first stage of the single ventricle pathway provides for adequate pulmonary blood flow and unobstructed systemic flow in the newborn period (Figure 53-1). If the original cardiac anatomy is such that there is insufficient pulmonary flow, a shunt is surgically placed to provide flow from the systemic circulation to the pulmonary circulation taking the place of the ductus arteriosus. One of the more common types of shunt is the modified Blalock-Taussig shunt, which is a synthetic tube, placed from the subclavian artery to the ipsilateral pulmonary artery. There are many types of shunts and modifications of techniques, which depend on the individual anatomy and operator preference.
Stage I single ventricle pathway for hypoplastic left heart syndrome (see Figure 53-8 for unrepaired anatomy). 1. Right modified Blalock-Taussig shunt. 2. Large (surgically created) atrial septal defect. 3. Main pulmonary artery has been detached form branch pulmonary arteries. 4. Unobstructed egress of blood from the heart to the body has been achieved by using the main pulmonary artery and native aorta with additional patch material. (Reproduced from Sinclair CM. The Report of the Manitoba Pediatric Cardiac Surgery Inquest: An Inquiry Into Twelve Deaths at the Winnipeg Health Sciences Center in 1994. 2000. Available at http://www.pediatriccardiacinquest.mb.ca/pdf/index.html. Accessed March 21, 2017.)
The infant with an “ideal” physiology following a shunt has a systemic oxygen saturation of about 80%. Empirically this saturation has been found to be the best balance between systemic oxygen delivery and pulmonary overcirculation. Because blood circulating to the lungs is already partially saturated, shunt physiology is inefficient, and even with this “ideal” saturation of 80%, there is still about twice as much blood being circulated to the lungs as to the body.
If the original cardiac anatomy dictates the single ventricle pathway but there is too much pulmonary flow such that the pulmonary pressures are high and/or the infant is in congestive heart failure, then the first stage in palliation is a pulmonary artery band (PAB). A PAB is a surgical “noose” placed around the pulmonary artery that creates an artificial stenosis and limits pulmonary flow.
Of great importance in the single ventricle pathway is the provision for an unobstructed pathway for systemic blood flow. The proximal pulmonary artery and aorta are often used together to recreate a single unobstructed outflow from the heart in this first stage.
STAGE II: BIDIRECTIONAL GLENN
At about 4 to 8 months of age, the pulmonary vascular resistance has typically decreased sufficiently to accept a portion of the venous return in a passive manner (Figure 53-2). The second step of cardiac palliation for children proceeding down the single ventricle pathway is the “bidirectional Glenn,” or stage II. This involves connecting the superior vena cava directly to the pulmonary arteries and eliminating any previous shunted source of pulmonary blood flow. The arterial saturations are usually about the same before and after the procedure (~80%); however, this type of circulation is preferable because it is more efficient. In the shunted scenario, the single ventricle pumps blood to both the body and the lungs, and the blood pumped to the lungs is partially saturated—an inefficient type of arrangement. After the stage II repair, the heart is only pumping blood to the body, and only desaturated blood is flowing to the lungs, thereby increasing the efficiency.
Stage II single ventricle pathway for hypoplastic left heart syndrome. 1, 2. The right modified Blalock-Taussig shunt that was created at the stage 1 repair has been removed. The superior vena cava is divided and the proximal portion is attached directly to the right pulmonary artery, allowing the blood from the superior vena cava (SVC) to flow to both lungs (“bidirectional Glenn”). “Bidirectional” refers to the SVC blood flowing to both the right and left lungs. (Reproduced from Sinclair CM. The Report of the Manitoba Pediatric Cardiac Surgery Inquest: An Inquiry Into Twelve Deaths at the Winnipeg Health Sciences Center in 1994. 2000. Available at http://www.pediatriccardiacinquest.mb.ca/pdf/index.html. Accessed March 21, 2017.)
The third stage (Fontan completion) consists of redirecting the blood from the inferior vena cava to the lungs, thereby separating the pulmonary and systemic circuits (Figure 53-3). Directing the inferior vena cava blood to the lungs may be accomplished by use of a synthetic tube lateral to the heart (external conduit) or using part of the right atrium as a wall (lateral tunnel). Often a small communication is left in the tube (fenestration) that may later be closed in the cardiac catheterization lab. After closure of the fenestration, these patients have normal oxygen saturations. Stage III is usually performed between ages 2 to 5 years, depending on center preference and technique.
Stage III –single ventricle pathway for hypoplastic left heart syndrome. 1. A tube has been placed within the right atrium to direct the blood from the inferior vena cava to the superior vena cava. The superior vena cava is reattached to the undersurface of the pulmonary artery. 2. Fenestration: a small hole is left in the tube to allow some of the venous blood to bypass the lungs. The fenestration keeps the venous pressure from rising too high after the Fontan operation, but results in some desaturation. The fenestration may be optional in some patients, but if desired can be easily closed in the cardiac catheterization laboratory afterward. (Reproduced from Sinclair CM. The Report of the Manitoba Pediatric Cardiac Surgery Inquest: An Inquiry Into Twelve Deaths at the Winnipeg Health Sciences Center in 1994. 2000. Available at http://www.pediatriccardiacinquest.mb.ca/pdf/index.html. Accessed March 21, 2017.)
Postoperative problems encountered by patients with Fontan-type repairs include early problems such as prolonged pleural effusions, and late problems such as increased risk for stroke and thrombus formation in the Fontan, arrhythmia development (especially atrial flutter), and protein-losing enteropathy.
CRITICAL NEWBORN HEART DISEASE
CRITICAL NEWBORN HEART DISEASE: PATENT DUCTUS ARTERIOSUS AUGMENTS
In this set of lesions, a portion of the normal anatomy supporting pulmonary blood flow (tricuspid valve, right ventricle, pulmonary valve, and pulmonary arteries) is small or absent. The ductus arteriosus provides pulmonary blood flow by shunting systemic blood flow to the lungs. While d-transposition of the great arteries (d-TGA) is also included in this section, the physiology of this lesion is somewhat different, as explained below.
The tricuspid valve is atretic in this lesion and the right ventricle is typically severely hypoplastic (Figure 53-4). The pulmonary artery arises from the right ventricle, and there may be a ventricular septal defect. When the ventricular septal defect and/or pulmonary artery are hypoplastic, pulmonary blood flow is inadequate and the ductus arteriosus is required to support pulmonary blood flow. In some instances, there may be adequate pulmonary flow through the ventricular septal defect, and in other cases the ventricular septal defect and pulmonary artery may be so large that the infant has too much pulmonary blood flow.
Tricuspid atresia (normal great arteries). 1. Patent foramen ovale with flow right to left. 2. Atretic tricuspid valve. 3. Ventricular septal defect (VSD). Size of VSD and amount of restriction is variable. (Reproduced from Sinclair CM. The Report of the Manitoba Pediatric Cardiac Surgery Inquest: An Inquiry Into Twelve Deaths at the Winnipeg Health Sciences Center in 1994. 2000. Available at http://www.pediatriccardiacinquest.mb.ca/pdf/index.html. Accessed March 21, 2017.)
If the pulmonary flow is inadequate, a systemic-to-pulmonary artery shunt is required. If there is too much pulmonary flow, the infant may require a pulmonary artery band to reduce the amount of pulmonary flow. In some instances, nature provides just enough pulmonary stenosis so that the child is not in congestive heart failure with adequate systemic saturations. In any case, the infant with tricuspid atresia also follows a single ventricle pathway. In some instances, tricuspid atresia is also found with transposition of the great arteries. These infants will require a repair similar to hypoplastic left heart syndrome, as the aortic valve and arch are typically hypoplastic when the great arteries are transposed.
This condition arises when the ventricular septal muscle between the aorta and the pulmonary artery is deviated anteriorly (Figure 53-5). This causes the pulmonary outflow area to be stenotic, a special type of ventricular septal defect to be present under the aorta (anterior malalignment), and the aorta to then be aligned over the ventricular septal defect and crest of the ventricular septum (overriding aorta). There is usually accompanying right ventricular hypertrophy, which completes the four parts of the tetralogy. While simple in its description, there is a huge variation in the severity of this disease that is largely dependent upon the pulmonary artery architecture. When there are well-developed pulmonary arteries and mild or moderate pulmonary stenosis, this lesion is not critical. Systemic oxygen saturations from 80% to 95% are possible, and infants may undergo elective complete repair between 3 and 12 months of age. Surgical repair in these cases involves closing the ventricular septal defect and relieving the pulmonary obstruction by patching the right ventricular outflow tract, pulmonary valve, and main pulmonary artery as needed.7
Tetralogy of Fallot. 1. Pulmonary valve and subvalvar stenosis. 2. Hypertrophied right ventricle. 3. Overriding aorta. 4. Ventricular septal defect. (Reproduced from Sinclair CM. The Report of the Manitoba Pediatric Cardiac Surgery Inquest: An Inquiry Into Twelve Deaths at the Winnipeg Health Sciences Center in 1994. 2000. Available at http://www.pediatriccardiacinquest.mb.ca/pdf/index.html. Accessed March 21, 2017.)
More severe obstruction at the pulmonary valve and right ventricular outflow tract may lead to more profound cyanosis and ductal dependency. These infants may require a shunt to increase pulmonary flow in anticipation of a complete repair at an older age, or they may undergo complete repair as infants.
At the extreme, there may be complete atresia of the pulmonary valve, and only a thread-like main pulmonary artery. Associated with this more severe obstruction are downstream architectural abnormalities of the pulmonary arteries, with stenosis or absence of branches of the pulmonary arteries and the presence of collateral vessels from the aorta to the pulmonary arteries that may supply multiple segments of the lung. Presence of these aorto-pulmonary collateral vessels and small, stenotic pulmonary arteries makes definitive surgical repair a challenge, and is individualized for each patient’s anatomy, usually requiring a series of staged operations and cardiac catheterizations for dilation of stenotic pulmonary arteries.8
Important pediatric concerns of infants with tetralogy of Fallot, especially when associated with pulmonary atresia, is the association with the 22q deletion/velocardiofacial/DiGeorge syndrome complex. Infants with this heart disease should have genetic testing (fluorescence in situ hybridization (FISH)) done for the 22q deletion, and calcium levels should be monitored in the newborn period. If positive, immunologic workup and genetic and anticipatory guidance should be provided to patients and families. Another important issue for patients with tetralogy of Fallot is the possibility of experiencing “tet-spells,” which are sudden episodes of profound desaturation. The classic explanation of the pathophysiology of this condition is “spasm” of the muscle under the pulmonary valve leading to decreased pulmonary flow and increased cyanosis, though this is certainly an oversimplified mechanism. Tet-spells can be treated by increasing the systemic resistance to force more blood across the pulmonary circuit. This can be done mechanically by putting the patient in a knee-to-chest position, or pharmacologically by administering intravenous phenylephrine. Supplemental oxygen may be of some benefit as is the administration of subcutaneous or intravenous morphine as a sedative. Ketamine is an especially useful drug in managing tet-spells, as it provides both sedation and increased systemic vascular resistance, and it can be administered intravenously or intramuscularly. Patients who have had one or more tet-spells should be considered for surgical palliation or repair, as these spells, if prolonged, can be associated with morbidity and mortality.
d-Transposition of the Great Arteries
In d-transposition of the great arteries (d-TGA), the aorta arises from the right ventricle and the pulmonary artery arises from the left ventricle (Figure 53-6). This leads to systemic blood returning from the body, recirculating to the body, and pulmonary blood recirculating to the lungs (parallel circulations), and profound cyanosis. Survival depends on mixing of the two circulations at the atrial, ventricular, or great vessel levels. Prostaglandin E-1 temporizes this condition by increasing the amount of blood in the pulmonary system, which encourages mixing at the atrial or ventricular level. For prostaglandin to work, there must be an atrial or ventricular septal defect. If no septal defect is present, or if mixing is inadequate as evidenced by oxygen saturation less than 80%, an atrial septal defect may need to be created, or an existing one enlarged, to stabilize the infant in anticipation of corrective surgery. This procedure (balloon atrial septostomy) is accomplished by passing a balloon catheter through the atrial septum, inflating the balloon, and pulling it back across the atrial septum to tear a hole in the atrial septum, thereby creating an atrial septal defect. This procedure can be performed at the bedside under echocardiographic guidance alone, or in the cardiac catheterization laboratory under fluoroscopic guidance.9
d-Transposition of the great arteries. 1. Patent foramen ovale with left-to-right flow. 2. Transposed great arteries. Aorta arises from right ventricle. 3. Ductus arteriosus with flow from aorta to pulmonary artery. 4. Transposed great arteries. Pulmonary artery arises from left ventricle. (Reproduced from Sinclair CM. The Report of the Manitoba Pediatric Cardiac Surgery Inquest: An Inquiry Into Twelve Deaths at the Winnipeg Health Sciences Center in 1994. 2000. Available at http://www.pediatriccardiacinquest.mb.ca/pdf/index.html. Accessed March 21, 2017.)
Definitive therapy for d-TGA is surgical. Since the mid-1980s, the procedure of choice for this lesion is the “arterial switch,” where the aorta and pulmonary arteries are transected above the valves and reattached to their physiologically correct ventricle. The Achilles-heel of this procedure is transfer of the coronary arteries, which must be removed separately and reattached to the aorta. The coronary artery anatomy is variable and makes preoperative definition of this anatomy important and appropriate surgical planning imperative.10 Associated lesions are usually corrected at the same surgery, which may include ventricular septal defect and coarctation of the aorta. The prognosis for children with d-TGA is generally excellent. Postoperative problems related to coronary artery obstruction can occur, as can residual lesions related to the surgical correction.
CRITICAL NEWBORN HEART DISEASE: PATENT DUCTUS ARTERIOSUS AUGMENTS
In this set of lesions, a portion of the normal anatomy supporting systemic blood flow (mitral valve, left ventricle, aortic valve, and aorta) is narrowed, small, or absent. The ductus arteriosus provides systemic blood flow by shunting some of the pulmonary blood through the ductus arteriosus to the aorta. Infants with these lesions often present with shock or decreased femoral pulses as the ductus arteriosus closes. Critical aortic stenosis, interrupted aortic arch, and critical coarctation of the aorta are all examples of critical left heart disease that require prostaglandin to stabilize and temporize, but can all have repairs that result in a complete repair. Hypoplastic left heart syndrome is an extreme form of left heart obstructive disease that requires a single ventricle surgical approach.
In this lesion, the aortic valve opening is narrowed by partial fusion of the leaflets and there is severe obstruction to outflow from the left ventricle. Before repair, most of the blood returning from the left atrium passes across the foramen ovale to the right atrium and subsequently to the right ventricle and main pulmonary artery, where a portion of the blood passes across the ductus arteriosus to the body and a portion passes to the lungs. For this lesion to be defined as critical aortic stenosis rather than hypoplastic left heart syndrome, the left ventricle, and mitral valve need to be of normal size, though the left ventricular function is often severely depressed before intervention.
Treatment of this condition is usually transcatheter balloon dilation of the aortic valve. This procedure relieves the narrowing at the valve sufficiently to permit recovery of left ventricular function, allowing the left ventricle to pump all the systemic blood. Prostaglandin can be discontinued after the dilation once the left ventricle has recovered adequately, but this may take several days. There is usually residual aortic stenosis of a mild to moderate degree after neonatal dilation, and these patients usually require further interventions for the aortic valve later in infancy or childhood.11
COARCTATION OF THE AORTA AND INTERRUPTED AORTIC ARCH
In coarctation of the aorta, the aorta is severely narrowed at or just beyond the origin of the left subclavian artery. In interrupted aortic arch, there is a discontinuity of the aorta at a point between one of the head and neck vessels (usually between the left carotid and left subclavian arteries). Both lesions typically present with shock and/or decreased femoral pulses as the ductus arteriosus closes and are temporized by prostaglandin E-1, which opens the ductus arteriosus, supplementing systemic blood flow.
The treatment of either lesion is surgical repair in the neonatal period. The surgical repair for critical coarctation usually involves removing the narrowed segment and rejoining the descending aorta to the aortic arch in an unobstructed fashion.12 The repair is usually done without the need for cardiopulmonary bypass. The repair of interrupted aortic arch is a much more complex arch reconstruction requiring the use of cardiopulmonary bypass. A ventricular septal defect—associated with the most common type of interrupted aortic arch—is repaired at the same surgery. Interrupted aortic arch (type B) is also associated with the 22q deletion/DiGeorge complex and as with tetralogy of Fallot, these patients should have appropriate calcium monitoring, and genetic and immunologic workup.
HYPOPLASTIC LEFT HEART SYNDROME
When the left-sided heart structures (mitral valve, left ventricle, aortic valve, and aortic arch) are too small to support the cardiac output needed for the body, the condition is referred to as hypoplastic left heart syndrome (Figure 53-7). The mitral or aortic valves may be so small as to be atretic. In the unrepaired state, the right ventricle pumps the combined venous return from the body and from the lungs to the pulmonary artery, where a portion of the blood passes to the lungs and a portion passes through the ductus arteriosus to supply the body. The degree of cyanosis depends on the proportion of pulmonary to systemic blood flow. As the ductus arteriosus closes, more blood is directed to the lungs and less to the body, leading to higher systemic saturations but signs and symptoms of low cardiac output and ultimately shock. Prostaglandin E-1 opens the ductus arteriosus and temporizes the situation.
Hypoplastic left heart syndrome. 1. Atrial septal defect with left-to-right flow. 2. Coarctation of the aorta. 3. Patent ductus arteriosus with flow from pulmonary artery to aorta. 4. Hypoplastic ascending aorta. 5. Small mitral valve—sometimes atretic. 6. Small Aortic valve—sometimes atretic. (Reproduced from Sinclair CM. The Report of the Manitoba Pediatric Cardiac Surgery Inquest: An Inquiry Into Twelve Deaths at the Winnipeg Health Sciences Center in 1994. 2000. Available at http://www.pediatriccardiacinquest.mb.ca/pdf/index.html. Accessed March 21, 2017.)
Surgical repair of this condition follows the principles of the single ventricle pathway outlined in a subsequent section and involves three stages. The first stage is more involved than most other types of first-stage single ventricle palliations because the main pulmonary artery must be used along with the native (small) aorta and prosthetic patch material to refashion the aortic arch. Pulmonary blood flow is provided by placing a tube graft from either a subclavian artery to pulmonary artery (modified Blalock Taussig shunt) or from the right ventricular outflow tract to the pulmonary artery (Sano modification13).
The initial palliation strategy for hypoplastic left heart syndrome is technically difficult and even in the best centers has one of the higher mortalities for congenital heart disease surgery. As a result, the past decade has seen the development and refinement of an alternative strategy called a “hybrid stage I” (Figure 53-8). This technique is a hybrid surgical and transcatheter technique where a surgical noose (band) is placed on each pulmonary artery to limit pulmonary blood flow, and a stent is placed in the ductus arteriosus to maintain systemic perfusion. The atrial septum is also enlarged if needed using catheter balloon and/or stent techniques. This hybrid stage I approach results in a much more stable infant post-procedure. The infant is then adequately palliated until he/she is about 4 to 6 months of age and then undergoes a “comprehensive stage II” procedure where the ductal stent and pulmonary artery bands are removed, and then the previously described first-stage operation is performed, with the exception that a Glenn shunt (superior vena cava to pulmonary artery) is used rather than a systemic-pulmonary artery shunt. This makes for a more complex stage II procedure, but at a time when the infant is much bigger, making the procedure easier. In addition, the Glenn shunt is a more stable source of pulmonary blood flow than is a systemic-pulmonary artery shunt. The infant then continues down the single ventricle pathway to arrive at a Fontan procedure typically between 3 to 5 years of age. These two techniques in multicenter series appear to have similar outcomes, but some centers prefer one technique over the other depending on their center-specific outcomes for both approaches.
Hypoplastic left heart syndrome after hybrid stage I palliation. 1. Stent in atrial septum (sometimes required). 2. Pulmonary artery bands on right and left pulmonary arteries. 3. Stent across ductus arteriosus. Note that stent often covers the origin of the aortic arch. Blood traverses through the struts of the stent to reach the head and perfuse the coronary arteries. (Reproduced from Sinclair CM. The Report of the Manitoba Pediatric Cardiac Surgery Inquest: An Inquiry Into Twelve Deaths at the Winnipeg Health Sciences Center in 1994. 2000. Available at http://www.pediatriccardiacinquest.mb.ca/pdf/index.html. Accessed March 21, 2017.)
Another strategy for managing patients with hypoplastic left heart syndrome is infant heart transplantation. Despite significant advances in immunosuppressive regimens, success of the heart transplantation strategy for hypoplastic left heart syndrome has been limited by a lack of donor organs and late graft failure, which occurs over decades in virtually all transplanted hearts.14
CRITICAL NEWBORN HEART DISEASE: PATENT DUCTUS ARTERIOSUS NOT REQUIRED
Total anomalous pulmonary venous return (TAPVR) with obstruction is the classic example of newborn heart disease that is not temporized by prostaglandin E-1. In this lesion, the pulmonary veins do not return to the left atrium, but communicate with the systemic veins by means of a supplemental venous channel. This channel may be obstructed, leading to progressive pulmonary edema, “whiteout” on chest x-ray, and an inability to ventilate or oxygenate. This lesion is the one most often mistaken for pulmonary disease in the newborn. If a newborn has progressive pulmonary disease and is failing conventional treatment, the diagnosis of congenital heart disease—especially obstructed TAPVR—should be entertained and an echocardiogram obtained. Repair consists of reattaching the pulmonary venous chamber to the left atrium.
LESIONS PRESENTING WITH CONGESTIVE HEART FAILURE OR MURMUR IN INFANCY
As the pulmonary vascular resistance falls in the first weeks of life, lesions that permit the transmission of high flow or pressure to the lungs become manifest. These lesions include ventricular septal defect (VSD), atrioventricular septal defect (AVSD), and patent ductus arteriosus (PDA).
VENTRICULAR SEPTAL DEFECT
The ventricular septum is a complex anatomical structure dividing the left and right ventricles (Figure 53-9). Near the aortic valve, the septum is a thin membrane (membranous septum) whereas it is a thick muscle in other parts. A defect in the wall is called a ventricular septal defect (VSD). The most common defects occur in the membranous septum, but they can occur anywhere in the wall, and may be multiple. The presentation of VSD is dependent on two factors—the size of the ventricular septal defect and the pulmonary vascular resistance.
Ventricular septal defect. 1. Ventricular septal defect (VSD) with flow from left ventricle to right ventricle. Position of VSD in ventricular septum determines type. More common type located just underneath the aortic valve (membranous). (Reproduced from Sinclair CM. The Report of the Manitoba Pediatric Cardiac Surgery Inquest: An Inquiry Into Twelve Deaths at the Winnipeg Health Sciences Center in 1994. 2000. Available at http://www.pediatriccardiacinquest.mb.ca/pdf/index.html. Accessed March 21, 2017.)
A small muscular ventricular septal defect presents in the first days to weeks of life with a high-pitched, asymptomatic murmur. When the resistance in the pulmonary circulation falls, so too does the right ventricular pressure, creating a large pressure difference between the left and right ventricles. A small hole between the ventricles creates a turbulent left-to-right flow jet, and a loud murmur is heard. In this scenario, the total amount of blood recirculated through the lungs and back to the left ventricle is minimal.
If the VSD is somewhat larger, as the pulmonary resistance falls, the VSD may still be small enough to limit the pressure transmitted to the right ventricle but large enough to admit more blood flow. In this circumstance, the amount of extra blood flow to the lungs recirculating back to the left heart may be significant, and the infant may have respiratory symptoms and perhaps some degree of congestive heart failure. A loud murmur will be present as the pressure gradient and flow are high.
At a certain point, the VSD is so large as to be unable to limit the pressure transmitted by the left ventricle. As the pulmonary resistance falls, there is more and more blood recirculating to the lungs, but the pressure in the right ventricle and pulmonary artery remains at systemic levels (so-called “unrestrictive” defects). The intensity of the systolic murmur is proportional to the degree of left-to-right shunting; however, there is often only a relatively soft murmur because there is little turbulence across the large VSD. With excessive pulmonary blood flow, infants typically display failure to thrive. If left uncorrected for a prolonged period of time, these infants run the risk of developing irreversible changes to the pulmonary vasculature that progresses even after the defect is corrected. Pulmonary blood vessels when exposed to high pressure for too long develop irreversible changes called pulmonary vascular obstructive disease (PVOD). PVOD is averted by limiting the pressure to which the lung vasculature is exposed by either closing the VSD or applying downstream resistance to flow by placing a pulmonary artery “band.” Irreversible PVOD does not usually develop until after age 1 year, although the time course after this point is remarkably variable. Patients with Down syndrome seem to be at higher risk at an earlier age and intervention is recommended before age 9 months in this subgroup.15
Although most infants with large VSDs with left-to-right shunt present with congestive heart failure as the pulmonary resistance falls, there is a small group of patients with unrestrictive VSDs in whom the pulmonary resistance falls very little or not at all. These infants will not develop congestive heart failure, and if the pulmonary resistance is very high, may not have much additional pulmonary flow. There is little if any heart murmur as there is no restriction to flow at the ventricular level and not enough increase in pulmonary flow to produce an appreciable flow murmur. The only cardiac sign may be relatively subtle—a single, loud second heart sound. These children often have frequent respiratory illness, which may further limit the ability of the pediatrician to clearly auscultate the heart. With no loud murmur demanding attention, and the more subtle signs often masked by respiratory noise, these children may go undiagnosed for a prolonged period and are therefore at high risk of developing PVOD. The pediatric hospitalist should keep this infrequent presentation of congenital heart disease in mind when assessing and treating infants and young children with frequent respiratory problems.
Surgical closure of a VSD is indicated in infancy (less than 1 year of age) if there is persistent congestive heart failure, or if the pulmonary pressures remain high. As some VSDs get smaller with time and even close, medical management with anticongestive medications (lasix, digoxin, angiotensin-converting enzyme inhibitors) may be indicated for a period in some infants with moderate and large VSDs. More complex decision-making is required for VSDs that are multiple—especially those located at the apex of the heart. This location is typically difficult to approach surgically. In this instance, a pulmonary artery band may be placed to limit pulmonary flow and pressure until the child is larger. Transcatheter closure devices may be another option in selected children–, sometimes combined with a surgical approach.16
Moderate ventricular septal defects are usually followed through infancy and early childhood as many become small and not require intervention. Closure is recommended for VSDs that remain moderate with a pulmonary to systemic flow ratio of more than about 2:1.
Transcatheter closure devices for membranous VSDs are in clinical trials. These devices need special design and delivery systems to avoid interfering with the aortic valve, which forms the superior border of the membranous septum.17
Atrioventricular Septal Defect
The atrioventricular septal defect (AVSD) is a more complex form of heart disease than simply a combination of an atrial and ventricular septal defect (Figure 53-10). It involves an incomplete separation of the embryonic common atrioventricular valve into separate tricuspid and mitral components. In addition, there is both a ventricular and atrial septal defect in the portion of the septa that are immediately adjacent to the atrioventricular valve. This lesion is often associated with Down syndrome. Presentation is similar to those patients with moderate or large ventricular septal defects. The septal defects do not close spontaneously and so all patients with AVSD will require surgical repair to partition the atrioventricular valve and close the atrial and ventricular septal defects. Partitioning the atrioventricular valve is surgically challenging so as not to produce mitral stenosis or regurgitation. Most centers perform complete repairs on these children between 3 and 6 months when the infants are somewhat larger, but soon enough to prevent the development of pulmonary vascular disease.18
Atrioventricular septal defect. 1. Atrial septal defect (ostium primum type). 2. Right side of common atrioventricular valve (incompletely formed tricuspid valve). 3. Left side of common atrioventricular valve (incompletely formed mitral valve). 4. Ventricular septal defect (of “inlet” ventricular septal type). (Reproduced from Sinclair CM. The Report of the Manitoba Pediatric Cardiac Surgery Inquest: An Inquiry Into Twelve Deaths at the Winnipeg Health Sciences Center in 1994. 2000. Available at http://www.pediatriccardiacinquest.mb.ca/pdf/index.html. Accessed March 21, 2017.)
The ductus arteriosus is the conduit for fetal blood to bypass the lungs in utero (Figure 53-11). After birth, the ductus usually closes in the first days of life. If it does not close, as pulmonary vascular resistance falls, blood shunts from the aorta into the pulmonary artery. Depending on the size of the ductus arteriosus and the pulmonary vascular resistance, the ductus will shunt a variable amount of blood similar to the physiology of a ventricular septal defect, and this lesion may present with congestive heart failure if large, or a murmur if the ductus is smaller.
Patent ductus arteriosus. 1. Ductus arteriosus with flow from aorta into pulmonary artery. (Reproduced from Sinclair CM. The Report of the Manitoba Pediatric Cardiac Surgery Inquest: An Inquiry Into Twelve Deaths at the Winnipeg Health Sciences Center in 1994. 2000. Available at http://www.pediatriccardiacinquest.mb.ca/pdf/index.html. Accessed March 21, 2017.)
The treatment of a patent ductus arteriosus is surgical or transcatheter closure. Transcatheter closure is now routine in children and infants older than 6 months.19 Surgical closure is indicated for refractory heart failure in smaller infants, premature infants, or in those where there is other accompanying heart disease that requires surgical intervention. A small patent ductus arteriosus associated with a murmur—even in the absence of significant shunting—is closed in the catheterization laboratory to prevent the lifelong risk of endarteritis of the ductus, which is estimated at ~0.45%/year.20
The general consensus is that a small ductus arteriosus found by echocardiography without an associated murmur should not be closed, as the risk of endarteritis does not appear to be higher than that of the general population.
When severe, this lesion presents in the newborn period as a critical newborn heart lesion with shock or cyanosis. If milder, this lesion may present with a murmur, or more commonly, with the astute pediatrician noting decreased intensity of the femoral pulses. Repair of this lesion is usually done surgically. Diagnosis of coarctation later in childhood is sometimes made by the finding of upper extremity hypertension. Therapeutic options later in childhood and through adulthood include surgery or transcatheter balloon dilation with stent placement. Later diagnosis and repair of this lesion may lead to persistent hypertension even after repair.
LESIONS PRESENTING WITH A MURMUR IN CHILDHOOD
Less severe obstructions and shunts typically present with a murmur in childhood. Stenosis of the semilunar valves (aortic stenosis or pulmonary stenosis) as well as atrial septal defects may present in this time frame.
PULMONARY STENOSIS AND AORTIC STENOSIS
These lesions, when severe, present as critical heart disease in the newborn, as previously discussed. When milder, they present as a murmur. Treatment is undertaken for pulmonary stenosis when the narrowing is moderate or severe, and consists of transcatheter balloon dilation of the valve. Such intervention is highly effective and typically does not need to be repeated.21 Treatment is undertaken for aortic stenosis when the gradient is moderate to severe. The first approach is usually balloon dilation of the valve. The success of aortic balloon dilation may be good, but relief of stenosis in many patients is often accompanied by creation of aortic regurgitation. Surgical valve repair, replacing the aortic valve with the patient’s own pulmonary valve (Ross procedure), or prosthetic valve replacement are all options. Prosthetic valve replacement is undesirable in small children because of the limited lifespan of these valves, and growth considerations.
The atrial septum divides the right and left atria (Figure 53-12). A defect in the wall is called an atrial septal defect (ASD). Blood returning to the left atrium passes from left to right across the ASD and recirculates to the lungs, placing a volume load on the right ventricle, pulmonary vascular bed, and atria. The amount of excess blood flow (or “shunt”) is determined by both the size of the defect as well as the balance between the diastolic compliance of the left and right heart. In infancy, the right ventricle is relatively noncompliant, and there may be minimal flow across even a large ASD. During childhood the right ventricle becomes more compliant while the left ventricular compliance decreases, thereby increasing the amount of shunting. The consequences of an unrepaired ASD include right ventricular dysfunction and atrial arrhythmias from chronic volume load, the potentially devastating complication of pulmonary hypertension and pulmonary vascular disease—which may develop in up to 5% to 10% of these patients during adult life—and risk of paradoxical embolus.
Atrial septal defect. 1. Atrial septal defect with flow from left atrium into right atrium. (Reproduced from Sinclair CM. The Report of the Manitoba Pediatric Cardiac Surgery Inquest: An Inquiry Into Twelve Deaths at the Winnipeg Health Sciences Center in 1994. 2000. Available at http://www.pediatriccardiacinquest.mb.ca/pdf/index.html. Accessed March 21, 2017.)
If there is evidence of right ventricular volume overload by echocardiography, then the lesion should be closed. Usually this decision is made after age 2 years, as some ASDs will get smaller over the first years of life. If the defect is of the secundum type it may be closed in the cardiac catheterization laboratory with specially designed closure devices.22 If the defect is large or is located in other anatomic regions of the atrium, then surgery is required for closure.
ADMISSION AND DISCHARGE CRITERIA
Patients who present critically ill obviously require admission. Infants with congestive heart failure may require admission for initiation or optimization of medical management that may include diuretics, digoxin, and supplemental caloric addition and/or nasogastic feeding to assist with growth.
Patients with congenital heart disease may require admission for intercurrent illness such as respiratory syncytial virus and other viral or bacterial infections. Infants with congenital heart disease may have a more severe course with a higher risk of complications than other children.
Discharge of patients after congenital heart disease surgery has been evolving. There has been a greater move to “fast-track” patients with congenital heart disease after surgery with a view toward early extubation, early removal of central lines and chest tubes, and ultimately early discharge. The average length of stay in some centers for simple congenital heart disease surgery is now 1 day for atrial septal defect and 3 days for VSD repair.23 When properly implemented, this has been shown to not increase mortality or readmission rates. Infants and children are discharged postoperatively once all the acute surgical issues are resolved, they are able to be fed, pain is well controlled, and they are on an oral medical regimen. Early discharge, however, also mandates close early follow-up.
For infants with shunt-dependent pulmonary blood flow or those with hypoplastic left heart syndrome after conventional stage I or hybrid stage I, a significant “interstage” mortality has been recognized. Some of these children will die at home or present in extremis to the emergency department for anatomic problems that can arise insidiously. For this reason, many centers have taken the approach that a very close monitoring program will lead to decrease in interstage mortality if these children can be monitored very closely at home and appropriate intervention undertaken preemptively. These conditions include development of residual arch obstruction, shunt narrowing, atrial septal narrowing, and other issues. Preliminary research seems to support this hypothesis.24 Many centers have established intensive home monitoring programs where parents are provided with an oxygen saturation monitor and a scale to monitor daily oxygen saturations and at least biweekly weights. Some programs use visiting nurse checks one a week or more to ensure medication compliance, verify oxygen saturation and weight checks, and communicate with the cardiology and pediatric team.
Close collaboration between the pediatric cardiologist and the pediatrician is essential for successful outcomes in patients with complex congenital heart disease. Other teams that are frequently consulted include:
Genetics: In many children, there may be an underlying genetic syndrome or genetic etiology that is important for prognosis, anticipatory guidance and reproductive counseling.
Neurology: Congenital heart disease may be associated with neurologic deficits or these may develop as a result of neurologic injury during interventions, primarily cardiac surgical.
Developmental and behavioral pediatrics: Many children with complex congenital heart disease will require assessment for developmental and behavioral needs so they can be provided with the needed services.
Social work: The social work team is invaluable in assessing the needs of the patient and family with regard to access to care, insurance, social supports, ability of parents and caregivers to care for a child with additional needs, etc.
Other subspecialty consultations may be needed as indicated.
SPECIAL CONSIDERATIONS FOR THE PEDIATRIC HOSPITALIST CARING FOR PATIENTS WITH CONGENITAL HEART DISEASE
Most congenital heart lesions put patients at risk for the development of endocarditis. Children with congenital heart disease should have regular dental care and maintain good oral hygiene. It used to be recommended that antibiotics be given prior to dental and other gastrointestinal procedures for most patients with congenital heart disease. These recommendations were recently revised and have generally been lifted except for patients with unrepaired cyanotic congenital heart disease and others with turbulence adjacent to prosthetic material (see Chapter 54, Infective endocarditis).
RESPIRATORY SYNCYTIAL VIRUS
Respiratory syncytial virus (RSV) may produce severe disease in children less than 2 years of age with cyanotic heart disease, single ventricle anatomy pre or post surgery, dilated or hypertrophic cardiomyopathy, pulmonary hypertension, or significant left-to-right shunts requiring medication to control pulmonary vascular congestion. In such patients the American Academy of Pediatrics recommends monthly passive immunization during the RSV season with palivizumab.25 Steps should be taken to minimize the risk from this potentially life-threatening illness. If a congenital heart lesion needs repair, consideration should be given to timing the repair before the RSV season which typically extends from November through March. Appropriate reverse isolation of hospitalized children with heart disease at high risk should be undertaken to prevent nosocomial transmission.
PACEMAKERS AND IMPLANTABLE DEFIBRILLATORS
Children with congenital heart disease may have congenital or iatrogenic surgical conduction defects that necessitate pacemaker placement. Pacemakers work by emitting an electric current that stimulates cardiac depolarization. Though pacemakers are very reliable, the interface between the pacemaker and the heart (the leads) are prone to a variety of problems. Extreme physiologic changes (e.g. acidosis) in the patient may also increase the amount of energy needed to depolarize the heart above that set by the pacemaker. In-hospital monitoring of children with pacemakers using a cardiac monitor is insufficient, as these monitors will usually detect the pacemaker impulse even when not followed by a cardiac depolarization. A physiologic monitor such as a pulse oximeter or arterial waveform should be used to confirm heat rate in paced patients. Similarly, during resuscitation, one should not mistake the pacemaker impulse as a cardiac depolarization, and physiologic parameters (e.g. palpation of a pulse) should be used to determine the cardiac rate.
Patients with pacemakers or implantable defibrillators requiring non–cardiac surgery may need the device reprogrammed prior to surgery to avoid oversensing, and electrocautery should be avoided. Patients with these devices may not undergo MRI examinations with the exception of the Medtronic Revo dual chamber pacemaker system with both atrial and ventricular leads in place and the pacemaker verified and programmed for MRI use.
CENTRAL ACCESS AND PARADOXICAL EMBOLIZATION
Central access may be difficult in patients with congenital heart disease because of vein occlusion owing to previous long-term access lines or cardiac catheterization access. Central access in the internal jugular or subclavian veins is usually discouraged in patients who are progressing down the single ventricle pathway because of the risk of possible superior vena cava obstruction making the Fontan palliation problematic.
In children with any right-to-left shunting, bubbles or clots introduced in the venous system risk traveling to the cerebral circulation, causing strokes. Intravenous lines should be meticulously cleared of air prior to infusion to prevent this potential problem, and indwelling lines should be heparinized.
Infants with congenital heart disease and pulmonary overcirculation have significantly increased caloric needs. Infants may require more than 160 Kcal/kg/day to grow with these increased metabolic demands. In addition, infants may be less able to tolerate normal feeding volumes due to tachypnea. Increased caloric density of feeds is usually required and tube feeding is sometimes required to assist these infants.
There have been studies showing a decrease in the incidence of congenital heart defects in infants of mothers taking multivitamins with folic acid during the periconceptual period compared to a similar group of mothers who did not take supplements. A case-control study in Atlanta showed a 24% decrease in the incidence of congenital heart disease,26 and a study in California had similar results. These studies are not definitive, but folate appears to be a reasonable preconceptual regimen, and the additional risk-reduction of neural tube defects appears to make this recommendation compelling. Other than folate, there have been no other preventative measures identified that may decrease the risk of congenital heart disease. Fetal diagnosis may provide the option of termination for those defects with poor prognosis if the parents so choose.
The incidence of congenital heart disease is 0.8%, while the incidence of congenital heart disease requiring intervention is lower—about 3 to 4/1000. Nonetheless, congenital heart disease remains in the top 10 causes of death for children <1 year of age, at ~ 2/100,000 live births.
Children with congenital heart disease may be hospitalized at the time of diagnosis if they present with critical heart disease, after cardiac interventions (surgery or transcatheter), or for acute illness related or unrelated to their heart condition.
The four main alterations of physiology with congenital heart disease are desaturation, pulmonary overcirculation, pulmonary vascular disease, and compromised systemic perfusion.
Newborn pre-discharge screening with right hand and foot pulse oximetry has a high sensitivity and low false positive rate for the detection of critical congenital heart disease.
In complex congenital heart disease, the ideal goal is a repair that creates a four-chambered septated heart with the anatomic left ventricle pumping to the body. When this is not possible, the best palliation is usually a Fontan circulation, where the systemic venous return is routed passively to the lungs and the heart is used to pump the blood to the body.
VSDs are one of the most common congenital heart lesions. Small VSDs rarely require closure. Moderate and large VSDs may become small but have three time horizons during which surgical closure is contemplated: in the first 6 months of life for failure to thrive, by 1 year of age if the VSD is not sufficiently restrictive to eliminate pressure damage to the pulmonary vascular bed, and by 3 to 5 years of age if there continues to be a large volume load on the left ventricle.
Mortality and emergent readmission for infants with shunts and hypoplastic left heart syndrome may be reduced by adopting a discharge strategy of intensive home monitoring.
JI. Incidence of congenital heart disease: 1. Postnatal incidence. Pediatr Cardiol
DC. Report of New England Regional Cardiac Program. Pediatrics
MA. Deaths: final data for 2010. Natl Vital Stat Rep
LK. Comparison of outcome when hypoplastic left heart syndrome and transposition of the great arteries are diagnosed prenatally versus when diagnosis of these two conditions is made only postnatally. Am J Cardiol
AK. Pulse oximetry screening for critical congenital heart defects in asymptomatic newborn babies: a systematic review and meta-analysis. Lancet
et al. Targeted neonatal echocardiography in the neonatal intensive care unit: practice guidelines and recommendations for training: writing group of the American Society of Echocardiography (ASE) in collaboration with the European Association of Echocardiography (EAE) and the Association for European Pediatric Cardiologists (AEPC). J Am Soc Echocardiog. 2011;24(10):1057–1078.
HJ. Surgical treatments for the tetralogy of Fallot by open intracardiac repair. J Thorac Surg
et al. Tetralogy of Fallot with diminutive pulmonary arteries: preoperative pulmonary valve dilation and transcatheter rehabilitation of pulmonary arteries. J Am Coll Cardiol
et al. Role of balloon atrial septostomy before early arterial switch repair of transposition of the great arteries. J Am Coll Cardiol
JE Jr, Sanders
G. Coronary artery pattern and outcome of arterial switch operation for transposition of the great arteries. Circulation. 1990;82(5 Suppl):IV 139–145.
JF. Repeat balloon dilation of congenital valvar aortic stenosis: immediate results and midterm outcome. Catheter Cardiovasc Interv
TJ. Repair of coarctation with resection and extended end-to-end anastomosis. Ann Thorac Surg
et al. Right ventricle-pulmonary artery shunt in first-stage palliation of hypoplastic left heart syndrome. J Thorac Cardiovasc Surg
et al. The Registry of the International Society of Heart and Lung Transplantation: Sixth Official Pediatric Report—2003. J Heart Lung Transplant
et al. Comparison of hemodynamic data before and after corrective surgery for Down’s syndrome and ventricular septal defect. Heart Vessels
ZM; Amplatzer Muscular Ventricular Septal Defect Investigators. Device closure of muscular ventricular septal defects using the Amplatzer muscular ventricular septal defect occluder: immediate and mid-term results of a U.S. registry. J Am Coll Cardiol
C. Transcatheter closure of perimembranous ventricualr septal defects with the Amplatzer asymmetric ventricular septal defect occluder: preliminary experience in children. Heart
DJ. Atrioventricular canal defects. Curr Treat Opin Cardiovasc Med. 1999;1(4):323–334.
WE. Multicenter USA Amplatzer patent ductus arteriosus occlusion device trial: initial and one-year results. J Am Coll Cardiol
M. Natural history of persistent ductus arteriosus. Br Heart J
et al. Comparative long-term results of surgery versus balloon valvuloplasty for pulmonary valve stenosis in infants and children. Ann Thorac Surg
T. Long-term outcome of transcatheter secundum-type atrial septal defects closure using Amplatzer septal occluders. J Am Coll Cardiol
et al. Economic and safety implications of introducing fast tracking in congenital heart surgery. Circ Cardiovasc Qual Outcomes
et al. New Approach to interstage care for palliates high-risk patients with congenital heart disease. J Thorac Cardiovasc Surg
Revised Indications for the Use of Palivizumab
and Respiratory Syncytial Virus Immune Globulin Intravenous for the Prevention of Respiratory Syncytial Virus Infections. American Academy of Pediatrics Policy Statement. Pediatrics
JD. Occurrence of congenital heart defects in relation to maternal mulitivitamin use. Am J Epidemiol