Overview of Congenital Cardiovascular Anomalies

Profound changes to this system occur after the first few breaths, resulting in

Pulmonary arteriolar resistance drops acutely as a result of vasodilation caused by lung expansion, increased PaO2, and reduced PaCO2. The elastic forces of the ribs and chest wall decrease pulmonary interstitial pressure, further enhancing blood flow through pulmonary capillaries. Increased venous return from the lungs raises left atrial pressure, thus reducing the pressure differential between left and right atria; this effect contributes to the functional closure of the foramen ovale.

As pulmonary blood flow is established, venous return from the lungs increases, raising left atrial pressure. Air breathing increases the PaO2, which constricts the umbilical arteries. Placental blood flow is reduced or stops, reducing blood return to the right atrium. Thus, right atrial pressure decreases while left atrial pressure increases; as a result, the 2 fetal components of the interatrial septum (septum primum and septum secundum) are pushed together, stopping flow through the foramen ovale. In most people, the 2 septa eventually fuse and the foramen ovale ceases to exist.

Soon after birth, systemic resistance becomes higher than pulmonary resistance, a reversal from the fetal state. Therefore, the direction of blood flow through the patent ductus arteriosus reverses, creating left-to-right shunting of blood (called transitional circulation). This state lasts from moments after birth (when the pulmonary blood flow increases and functional closure of the foramen ovale occurs) until about 24 to 72 hours of age, when the ductus arteriosus constricts. Blood entering the ductus and its vasa vasorum from the aorta has a high PO2, which, along with alterations in prostaglandin metabolism, leads to constriction and closure of the ductus arteriosus. Once the ductus arteriosus closes, an adult-type circulation exists. The 2 ventricles now pump in series, and there are no major shunts between the pulmonary and systemic circulations.

During the days immediately after birth, a stressed neonate may revert to a fetal-type circulation. Asphyxia with hypoxia and hypercarbia causes the pulmonary arterioles to constrict and the ductus arteriosus to dilate, reversing the processes described previously and resulting in right-to-left shunting through the now- patent ductus arteriosus Patent Ductus Arteriosus (PDA) Patent ductus arteriosus (PDA) is a persistence of the fetal connection (ductus arteriosus) between the aorta and pulmonary artery after birth. In the absence of other structural heart abnormalities... read more , the reopened foramen ovale, or both. Consequently, the neonate becomes severely hypoxemic, a condition called persistent pulmonary hypertension Persistent Pulmonary Hypertension of the Newborn Persistent pulmonary hypertension of the newborn is the persistence of or reversion to pulmonary arteriolar constriction, causing a severe reduction in pulmonary blood flow and right-to-left... read more or persistent fetal circulation (although there is no umbilical circulation). The goal of treatment is to reverse the conditions that caused pulmonary vasoconstriction.

If there is > 5 g/dL (> 50 g/L) of deoxygenated hemoglobin, cyanosis results. Complications of persistent cyanosis include polycythemia Perinatal Polycythemia and Hyperviscosity Syndrome Polycythemia is an abnormal increase in red blood cell mass, defined in neonates as a venous hematocrit ≥ 65%; this increase can lead to hyperviscosity with sludging of blood within vessels... read more , clubbing, thromboembolism (including stroke), bleeding disorders, brain abscess, and hyperuricemia. Hypercyanotic spells can occur in infants with unrepaired tetralogy of Fallot Tetralogy of Fallot Tetralogy of Fallot consists of 4 features: a large ventricular septal defect, right ventricular outflow tract obstruction and pulmonic valve stenosis, right ventricular hypertrophy, and over-riding... read more .

Depending on the anomaly, pulmonary blood flow may be reduced, normal, or increased (often resulting in heart failure in addition to cyanosis), resulting in cyanosis of variable severity. Heart murmurs are variably audible and are not specific.

Immediately after birth, pulmonary vascular resistance is high and flow through this communication may be minimal or bidirectional. Within the first 24 to 48 hours of life, however, the pulmonary vascular resistance progressively falls, at which point blood will increasingly flow from left to right. The additional blood flow to the right side increases pulmonary blood flow and pulmonary artery pressure to a varying degree. The greater the increase, the more severe the symptoms; a small left-to-right shunt typically does not cause symptoms or signs.

High-pressure shunts (those at the ventricular or great artery level) become apparent several days to a few weeks after birth; low-pressure shunts (atrial septal defects Atrial Septal Defect (ASD) An atrial septal defect (ASD) is an opening in the interatrial septum, causing a left-to-right shunt and volume overload of the right atrium and right ventricle. Children are rarely symptomatic... read more ) become apparent considerably later. If untreated, elevated pulmonary blood flow and pulmonary artery pressure may lead to pulmonary vascular disease and eventually Eisenmenger syndrome Eisenmenger Syndrome Eisenmenger syndrome is a complication of uncorrected large intracardiac or aortic to pulmonary artery left-to-right shunts. Increased pulmonary resistance may develop over time, eventually... read more . Large left-to-right shunts (eg, large ventricular septal defect Ventricular Septal Defect (VSD) A ventricular septal defect (VSD) is an opening in the interventricular septum, causing a shunt between ventricles. Large defects result in a significant left-to-right shunt and cause dyspnea... read more [VSD], patent ductus arteriosus Patent Ductus Arteriosus (PDA) Patent ductus arteriosus (PDA) is a persistence of the fetal connection (ductus arteriosus) between the aorta and pulmonary artery after birth. In the absence of other structural heart abnormalities... read more [PDA]) cause excess pulmonary blood flow and left ventricular volume overload, which may lead to signs of heart failure and during infancy often result in failure to thrive. A large left-to-right shunt also leads to lower lung compliance and higher airway resistance. These factors increase the likelihood of hospitalization in infants with respiratory syncytial virus Respiratory Syncytial Virus (RSV) and Human Metapneumovirus Infections Respiratory syncytial virus and human metapneumovirus infections cause seasonal lower respiratory tract disease, particularly in infants and young children. Disease may be asymptomatic, mild... read more or other upper or lower respiratory tract infections.

The resulting pressure overload proximal to the obstruction may cause ventricular hypertrophy and heart failure. The most obvious manifestation is a heart murmur, which results from turbulent flow through the obstructed (stenotic) point. Examples are congenital aortic stenosis Aortic Stenosis Aortic stenosis (AS) is narrowing of the aortic valve, obstructing blood flow from the left ventricle to the ascending aorta during systole. Causes include a congenital bicuspid valve, idiopathic... read more , which accounts for 3 to 6% of congenital heart anomalies, and congenital pulmonic stenosis Pulmonic Stenosis Pulmonic stenosis (PS) is narrowing of the pulmonary outflow tract causing obstruction of blood flow from the right ventricle to the pulmonary artery during systole. Most cases are congenital... read more , which accounts for 8 to 12%.

Some congenital heart anomalies (eg, bicuspid aortic valve Bicuspid Aortic Valve Bicuspid aortic valve is the presence of only two (rather than the normal three) valve cusps. Bicuspid aortic valve is the most common congenital cardiovascular abnormality. It is present in... read more , mild aortic stenosis) do not significantly alter hemodynamics. Other anomalies cause pressure or volume overload, sometimes causing heart failure Heart Failure (HF) Heart failure (HF) is a syndrome of ventricular dysfunction. Left ventricular (LV) failure causes shortness of breath and fatigue, and right ventricular (RV) failure causes peripheral and abdominal... read more . Heart failure occurs when cardiac output is insufficient to meet the body’s metabolic needs or when the heart cannot adequately handle venous return, causing pulmonary congestion (in left ventricular failure), edema primarily in dependent tissues and abdominal viscera (in right ventricular failure), or both. Heart failure in infants and children has many causes other than congenital heart anomalies (see table Common Causes of Heart Failure in Children Common Causes of Heart Failure in Children ).

The ductus arteriosus is a normal connection between the pulmonary artery and aorta; it is necessary for proper fetal circulation. At birth, the rise in PaO2 and decline in prostaglandin concentration cause closure of the ductus arteriosus, typically beginning within the first 10 to 15 hours of life.

Some congenital cardiac disorders are dependent on the ductus arteriosus remaining open to maintain systemic blood flow (eg, hypoplastic left heart syndrome Hypoplastic Left Heart Syndrome Hypoplastic left heart syndrome consists of hypoplasia of the left ventricle and ascending aorta, maldevelopment and hypoplasia of the aortic and mitral valves (frequently aortic atresia is... read more , critical aortic stenosis Aortic Stenosis Aortic stenosis (AS) is narrowing of the aortic valve, obstructing blood flow from the left ventricle to the ascending aorta during systole. Causes include a congenital bicuspid valve, idiopathic... read more , coarctation of the aorta Coarctation of the Aorta Coarctation of the aorta is a localized narrowing of the aortic lumen that results in upper-extremity hypertension, left ventricular hypertrophy, and malperfusion of the abdominal organs and... read more ) or pulmonary blood flow (cyanotic lesions such as pulmonary atresia Pulmonary atresia with intact ventricular septum Other structural congenital cardiac anomalies include the following: Aortopulmonary window Congenitally corrected transposition Double outlet right ventricle Ebstein anomaly read more or severe tetralogy of Fallot Tetralogy of Fallot Tetralogy of Fallot consists of 4 features: a large ventricular septal defect, right ventricular outflow tract obstruction and pulmonic valve stenosis, right ventricular hypertrophy, and over-riding... read more ). Keeping the ductus arteriosus open with exogenous prostaglandin infusion is therefore vital in these disorders prior to definitive repair (usually surgery).

Most left-to-right shunts and obstructive lesions cause systolic murmurs. Systolic murmurs and thrills are most prominent at the surface closest to their point of origin, making location diagnostically helpful. Increased flow across the pulmonary or aortic valve causes a midsystolic crescendo-decrescendo (ejection systolic) murmur. Regurgitant flow through an atrioventricular valve or flow across a ventricular septal defect causes a holosystolic (pansystolic) murmur that obscures the first heart sound (S1) as its intensity increases.

Patent ductus arteriosus Patent Ductus Arteriosus (PDA) Patent ductus arteriosus (PDA) is a persistence of the fetal connection (ductus arteriosus) between the aorta and pulmonary artery after birth. In the absence of other structural heart abnormalities... read more typically causes a continuous murmur that is uninterrupted by the S2 because blood flows through the ductus during systole and diastole. This murmur is 2-toned, having a more pronounced sound during systole (when driven by higher pressure) than during diastole.

Central cyanosis is characterized by bluish discoloration of the lips and tongue and/or nail beds; it occurs when there is an increase in deoxygenated hemoglobin (at least 5 g/dL [50 g/L]) and implies a low blood oxygen level (usually oxygen saturation < 85%). Perioral cyanosis and acrocyanosis (cyanosis of the hands and feet) without lip or nail bed cyanosis is caused by peripheral vasoconstriction rather than hypoxemia and is a common, normal finding in neonates. Older children with longstanding cyanosis often develop clubbing of the nail beds.

In infants, symptoms or signs of heart failure include

Dyspnea during feeding causes inadequate intake and poor growth, which may be worsened by increased metabolic demands in heart failure and frequent respiratory tract infections. In contrast to adults and older children, most infants do not have distended neck veins and dependent edema; however, they occasionally have edema in the periorbital area. Hepatomegaly is a particularly prominent feature of heart failure in infants. Findings in older children with heart failure Symptoms and Signs Heart failure (HF) is a syndrome of ventricular dysfunction. Left ventricular (LV) failure causes shortness of breath and fatigue, and right ventricular (RV) failure causes peripheral and abdominal... read more are similar to those in adults.

In neonates, circulatory shock may be the first manifestation of certain anomalies (eg, hypoplastic left heart syndrome Hypoplastic Left Heart Syndrome Hypoplastic left heart syndrome consists of hypoplasia of the left ventricle and ascending aorta, maldevelopment and hypoplasia of the aortic and mitral valves (frequently aortic atresia is... read more , critical aortic stenosis, interrupted aortic arch, coarctation of the aorta Coarctation of the Aorta Coarctation of the aorta is a localized narrowing of the aortic lumen that results in upper-extremity hypertension, left ventricular hypertrophy, and malperfusion of the abdominal organs and... read more ). Neonates appear extremely ill with pale or cyanotic mucous membranes, cold extremities, diminished pulses, low blood pressure, and reduced response to stimuli.

Chest pain in children is usually noncardiac. In infants, chest pain may be manifested by unexplained marked irritability, particularly during or after feeding, and can be caused by anomalous origin of the left coronary artery from the pulmonary artery. In older children and adolescents, chest pain due to a cardiac etiology is usually associated with exertion and may be caused by a coronary anomaly, pericarditis Pericarditis Pericarditis is inflammation of the pericardium, often with fluid accumulation in the pericardial space. Pericarditis may be caused by many disorders (eg, infection, myocardial infarction, trauma... read more , myocarditis Myocarditis Myocarditis is inflammation of the myocardium with necrosis of cardiac myocytes. Myocarditis may be caused by many disorders (eg, infection, cardiotoxins, drugs, and systemic disorders such... read more , or severe aortic stenosis Aortic Stenosis Aortic stenosis (AS) is narrowing of the aortic valve, obstructing blood flow from the left ventricle to the ascending aorta during systole. Causes include a congenital bicuspid valve, idiopathic... read more .

Syncope, typically without warning symptoms and often in association with exertion, may occur with certain anomalies including cardiomyopathy Overview of Cardiomyopathies A cardiomyopathy is a primary disorder of the heart muscle. It is distinct from structural cardiac disorders such as coronary artery disease, valvular disorders, and congenital heart disorders... read more (hypertrophic or dilated), anomalous origin of a coronary artery, or inherited arrhythmia syndromes (eg, long QT syndrome Torsades de Pointes Ventricular Tachycardia Torsades de pointes ventricular tachycardia is a specific form of polymorphic ventricular tachycardia in patients with a long QT interval. It is characterized by rapid, irregular QRS complexes... read more , catecholaminergic polymorphic ventricular tachycardia [CPVT], Brugada syndrome Brugada Syndrome Brugada syndrome is an inherited channelopathy causing an increased risk of ventricular tachycardia (VT) and ventricular fibrillation (VF) leading to syncope and sudden death. (See also Overview... read more ). High school–age athletes are most commonly affected.

Manifestations of congenital heart disease may be subtle or absent in neonates, and failure or delay in detecting critical congenital heart disease, particularly in the 10 to 15% of neonates who require surgical or inpatient medical treatment in the first hours or days of life, may lead to neonatal mortality or significant morbidity. Thus, universal screening for critical congenital heart disease using pulse oximetry is recommended for all neonates before hospital discharge. The screening is done when infants are ≥ 24 hours old and is considered positive if ≥ 1 of the following is present:

All neonates with a positive screening result should undergo a comprehensive evaluation for congenital heart disease and other causes of hypoxemia (eg, various respiratory disorders, central nervous system depression, sepsis) typically including a chest x-ray, ECG, echocardiography, and often blood testing. Sensitivity of pulse oximetry screening is slightly > 75%; the congenital heart disease lesions most often missed are left heart obstructive lesions (eg, coarctation of the aorta).

Acute, severe heart failure or cyanosis during the first week of life is a medical emergency. Secure vascular access should be established, preferably via an umbilical venous catheter.

When critical congenital heart disease is suspected or confirmed, an IV infusion of prostaglandin E1 should be started at 0.05 to 0.1 mcg/kg/min. Keeping the ductus open is important because most cardiac lesions manifesting at this age are ductal-dependent for either systemic blood flow (eg, hypoplastic left heart syndrome Hypoplastic Left Heart Syndrome Hypoplastic left heart syndrome consists of hypoplasia of the left ventricle and ascending aorta, maldevelopment and hypoplasia of the aortic and mitral valves (frequently aortic atresia is... read more , critical aortic stenosis Aortic Stenosis Aortic stenosis (AS) is narrowing of the aortic valve, obstructing blood flow from the left ventricle to the ascending aorta during systole. Causes include a congenital bicuspid valve, idiopathic... read more , coarctation of the aorta Coarctation of the Aorta Coarctation of the aorta is a localized narrowing of the aortic lumen that results in upper-extremity hypertension, left ventricular hypertrophy, and malperfusion of the abdominal organs and... read more ) or pulmonary blood flow (cyanotic lesions such as critical pulmonary stenosis, pulmonary atresia Pulmonary atresia with intact ventricular septum Other structural congenital cardiac anomalies include the following: Aortopulmonary window Congenitally corrected transposition Double outlet right ventricle Ebstein anomaly read more or severe tetralogy of Fallot Tetralogy of Fallot Tetralogy of Fallot consists of 4 features: a large ventricular septal defect, right ventricular outflow tract obstruction and pulmonic valve stenosis, right ventricular hypertrophy, and over-riding... read more ).

Mechanical ventilation is often necessary in critically ill neonates. Supplemental oxygen should be given judiciously or even withheld because supplemental oxygen can decrease pulmonary vascular resistance, which is harmful to infants with certain defects (eg, hypoplastic left heart syndrome).

Other therapies for neonatal heart failure include diuretics, inotropic drugs, and drugs to reduce afterload. The diuretic furosemide is given as an initial bolus of 1 mg/kg IV and titrated based on urine output. Infusions of the inotropes dopamine or dobutamine can support blood pressure but have the disadvantage of increasing heart rate and afterload, thus increasing myocardial oxygen consumption. They are infrequently used in infants with congenital heart disease. Milrinone, frequently used in postoperative patients with congenital heart disease, is both a positive inotrope and a vasodilator. Dopamine, dobutamine, and milrinone all have the potential to increase the risk of arrhythmias. Nitroprusside, a pure vasodilator, may be used for postoperative hypertension. It is started at 0.3 to 0.5 mcg/kg/minute and titrated to desired effect (usual maintenance dose is about 3 mcg/kg/minute).

Therapies often include a diuretic (eg, furosemide 0.5 to 1 mg/kg IV or 1 to 3 mg/kg orally every 8 to 24 hours, titrated upward as needed) and an ACE inhibitor (eg, captopril 0.1 to 0.3 mg/kg orally 3 times a day). A potassium-sparing diuretic (eg, spironolactone 1 mg/kg orally once or twice a day, titrated up to 2 mg/kg/dose if needed) may be useful, particularly if high-dose furosemide is required. Beta-blockers (eg, carvedilol, metoprolol) are often added for children with chronic congestive heart failure.

Digoxin is used less often than in the past but may still have a role in children with heart failure who have large left-to-right shunts and in certain postoperative patients with congenital heart disease (dose varies by age; see table Oral Digoxin Dosage in Children Oral Digoxin Dosage in Children* ). Notably, digoxin has been shown to reduce mortality in single-ventricle patients after the Norwood procedure and before the second stage surgery (1 Treatment references Congenital heart disease is the most common congenital anomaly, occurring in almost 1% of live births ( 1). Among birth defects, congenital heart disease is the leading cause of infant mortality... read more ). Use of digoxin as a front-line drug in the treatment of neonatal supraventricular tachycardia has declined because it results in higher mortality than treatment with propranolol (2 Treatment references Congenital heart disease is the most common congenital anomaly, occurring in almost 1% of live births ( 1). Among birth defects, congenital heart disease is the leading cause of infant mortality... read more ). However, if Wolff-Parkinson-White syndrome Reentrant Supraventricular Tachycardias (SVT) Including Wolff-Parkinson-White Syndrome Reentrant supraventricular tachycardias (SVT) involve reentrant pathways with a component above the bifurcation of the His bundle. Patients have sudden episodes of palpitations that begin and... read more is not present, it may be a useful as a primary agent if propranolol is ineffective or as a second agent combined with propranolol or other antiarrhythmic drugs.

Supplemental oxygen may lessen hypoxemia and alleviate respiratory distress in heart failure; when possible, fractional inspired oxygen (FIO2) should be kept < 40% to minimize the risk of pulmonary epithelial damage. Supplemental oxygen must be used with caution, if at all, in patients with left-to-right shunt lesions or left heart obstructive disease because it may exacerbate pulmonary overcirculation.

In general, a healthy diet, including salt restriction, is recommended, although dietary modifications may be needed depending on the specific disorder and manifestations. Heart failure increases metabolic demands and the associated dyspnea makes feeding more difficult. In infants with critical congenital heart disease, particularly those with left heart obstructive lesions, feedings may be withheld to minimize the risk of necrotizing enterocolitis. In infants with heart failure due to left-to-right-shunt lesions, enhanced caloric content feedings are recommended; these feedings increase calories supplied and do so with less risk of volume overload. Some children require tube feedings to maintain growth. If these measures do not result in weight gain, surgical repair of the anomaly is indicated.

Current guidelines of the American Heart Association for prevention of endocarditis Prevention Infective endocarditis is infection of the endocardium, usually with bacteria (commonly, streptococci or staphylococci) or fungi. It may cause fever, heart murmurs, petechiae, anemia, embolic... read more state that antibiotic prophylaxis is required for children with congenital heart disease who have the following: