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Rather than memorizing a multitude of individual lesions, the emergency physician should concentrate on a few scenarios: the undifferentiated sick infant, ductal-dependent lesions, CHF, hypoxemic “tet” spells, and presentations seen in older children. These scenarios require rapid emergency management to prevent further decompensation and cardiac arrest. Knowledge of the exact lesion is often not necessary to provide the critical management needed in these cases.
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Undifferentiated Sick Infant
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Patients present in two main categories: the “H&P patient” and the “ABC patient.” The “H&P patient” is typically stable, with a chronic or subacute presentation; the emergency physician has some time to examine, run tests, observe, and come to a diagnosis. The “ABC patient” presents in acute distress or in extremis and the emergency physician must be ready to diagnose and treat simultaneously.
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The sick infant is the prototype of the “ABC” patient, often presenting with little available information and a palpable need to intervene. As there is significant similarity in presentation between CHD and other life-threatening disorders, a systematic approach is needed for the wide differential diagnosis (Fig. 39-17). The mnemonic “THE MISFITS” outlines the broad and varied causes of acute illness in very young children.9
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T—Trauma (accidental and nonaccidental)
H—Heart disease and hypovolemia
E—Endocrine (congenital adrenal hyperplasia and thyrotoxicosis)
M—Metabolic (electrolyte abnormalities)
I—Inborn errors of metabolism
S—Sepsis (meningitis, pneumonia, and pyelonephritis)
F—Formula problems (over- or underdilution)
I—Intestinal disasters (intussusception, necrotizing enterocolitis, and volvulus)
T—Toxins
S—Seizures
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As with any sick infant, assessment and intervention in airway, breathing, and circulation is critical, with close attention to vital signs, such as tachycardia and tachypnea. Always check bedside blood glucose and keep the infant warm during the course of evaluation and treatment. Even with a detailed differential diagnosis, final diagnosis may not be possible until much later in the child's management because conditions such as sepsis and CHD have significant overlap. Concomitant treatment with fluids, antibiotics, and possibly prostaglandin E1 (PGE1) to cover the most common causes is often appropriate in these circumstances.
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The most important mantra in the care for the sick newborn is that neonates who present in shock with cyanosis in the first few weeks of life are presumed to have ductal-dependent systemic flow until proven otherwise. Resuscitation depends on opening the ductus arteriosus with PGE1. Start PGE1 before a definitive anatomic diagnosis is made.3
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This dictum should be balanced with an even more basic tenet of emergency medicine: perform an intervention and carefully evaluate its effect. This is true for any patient, but essential in treating critically ill newborns. An algorithmic approach reminds the emergency physician of possible pathways, not to usurp clinical judgment. For example, some children with CHD may worsen with supplemental oxygen; at baseline, an infant with CHD may have preexisting pulmonary hypertension that shunts blood to the systemic circulation, maintaining adequate blood pressure. Overoxygenation can dilate the pulmonary vasculature to the point where it shunts blood away from the systemic circulation, causing sustained hypotension and either no improvement or worsening of the patient's condition with oxygen therapy.10 Oxygen is a cornerstone of therapy in sick infants and the physician should not hesitate to begin treatment with oxygen. However, this rare adverse effect serves to illustrate the importance of assessment, intervention, and reassessment.
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Ductal-Dependent Lesions and Cardiogenic Shock
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Lesions, which are completely dependent on a PDA for systemic or PBF, present with acute onset cyanotic circulatory failure and shock when the ductus closes, typically within the first week of life. Such lesions include HLHS, severe aortic coarctation, interrupted aortic arch, and lesions such as pulmonary atresia or TGA without a mixing lesion (e.g., a VSD). No symptoms or signs of CHD may have been noted in the newborn nursery or at home prior to presentation. Ductal-dependent cardiac failure should be suspected in any infant in the first week of life with sudden-onset circulatory collapse and cyanosis leading to hypoperfusion, hypotension, and severe acidosis. Infants may present in the second week of life, but rarely present beyond 4 weeks of age.
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The mainstay of therapy for suspected ductal-dependent cardiogenic shock is PGE1 infusion to maintain the patency of the ductus arteriosus. It is infused initially at 0.05 to 0.1 μg/kg/min and advanced to 0.2 to 0.4 μg/kg/min if necessary.11 When an increase in PaO2 is noted, titrate down to the lowest effective dose; the usual dose needed is 0.01 to 0.4 μg/kg/min. Potential adverse effects include hyperthermia, apnea, hypotension, rash, tremors, focal seizures, and bradycardia. Nevertheless, PGE1 is critical for infants in ductal-dependent cardiac shock and should be initiated in the ED. Be prepared to provide definitive airway management in the case of apnea, and to add inotropic medications as needed for circulatory support. Other etiologies for shock must be entertained and treated as well, such as sepsis. A pediatric cardiologist must be consulted immediately and the patient admitted to the pediatric or neonatal intensive care unit.
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Congestive Heart Failure
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Children differ from adults both in the causes and in the presentation of CHF. A common scenario is that of an infant 2 to 6 months old with a left-to-right shunting lesion (VSD, PDA, AV canal defect, or less commonly, an ASD alone) resulting in volume overload and CHF (Fig. 39-18). Excessive pressure load from left-sided obstruction (e.g., aortic coarctation, AS) may also result in CHF. Causes other than congenital heart lesions include myocardial dysfunction (e.g., cardiomyopathies) and dysrhythmias.
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Symptoms are gradual in onset and may be subtle. They include poor feeding (increased time to feed) or sweating while feeding; poor growth; irritability, lethargy, or a weak cry; increased respiratory effort, dyspnea, tachypnea, chronic cough, or wheezing; and increased frequency of respiratory infections.
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Physical examination may reveal tachypnea, retractions, nasal flaring, grunting, wheezing, or rales (although less commonly than in adults). One may also find tachycardia, a gallop rhythm, hyperactive precordium, murmur, poor peripheral pulses with delayed capillary refill, and hepatomegaly (a cardinal sign of CHF in infants). Jugular venous distension and peripheral edema, often seen in adults with CHF, are rarely seen in young children. If present, edema is best appreciated in the eyelids, sacrum, and legs. More commonly, children will present with hepatic congestion or hepatomegaly, as the relatively pliable liver becomes congested with venous blood. It is important to start palpation for hepatomegaly low in the abdomen, just above the pelvic bones. CXR shows cardiomegaly (cardiothoracic ratio >0.55 in infants, >0.50 for children older than 1 year) and increased pulmonary vascularity. When evaluating for cardiomegaly, remember that infants often have a prominent thymus shadow overlying the heart; the thymus gives an appearance of an enlarged mediastinum and will be apparent as anterior to the heart on the lateral film. ECG findings depend on the specific lesion.
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Treatment includes oxygen to keep saturations near 95%. Overoxygenating the patient may lead to pulmonary vascular dilation and worsened failure. Keep the infant in a semi-reclining position (such as when in an infant car seat) if possible. Fluid and sodium restriction is necessary, and furosemide should be given at 1 mg/kg intravenously. Nitrates are not first-line emergent therapy in children. In consultation with a pediatric cardiologist, the patient should be started on digoxin. Consult a pediatric drug handbook for digitalization doses. Patients may require sedation, but closely monitor the airway and ventilatory efforts. Make preparations for endotracheal intubation and ventilatory support in the event that they are needed. If a patient's respiratory status allows, a trial of continuous positive airway pressure (CPAP) may be applied nasally in an attempt to avoid intubation. If the child is in shock, fluids must be used cautiously (boluses of only 5–10 mL/kg, if at all); inotropic support with norepinephrine, dopamine, or dobutamine may be more appropriate. Milrinone may be added to the traditional vasopressors for its inotropic and chronotropic effects, typically in consultation with a cardiologist or pediatric intensivist; expect peripheral vasodilation and afterload reduction. The loading dose of milrinone is 50 μg/kg, followed by a 0.25 to 1 μg/kg/min infusion.12 Complete blood count, chemistry panel, calcium level, rapid bedside glucose test, and arterial blood gas should be assessed. Monitor vital signs, including blood pressure, cardiac rhythm, and oxygen saturation continuously.
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B-type Natriuretic Peptide Assay
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The role of B-type natriuretic peptide (BNP) is well described in specific congenital heart lesions in children. Traditionally used in adults as an indirect marker of atrial chamber stretch from volume overload, it may be used judiciously in the ED as an ancillary screening tool in the evaluation of the dyspneic young child. BNP levels spike at birth with the physiologic transition from fetal to neonatal circulation, reaching a plateau at day 3 to 4; BNP levels subsequently fall to a constant level during infancy.13 As natriuretic peptides do not cross the placenta, BNP measurements will reflect the neonate's own production and clearance.
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The interpretation of normal BNP ranges is under continued investigation, with variability by age of patient, kits used, units reported, and specific cardiac lesions. Nonetheless, multiple studies have attempted to provide normal mean BNP values in children (Table 39-5).14 There are as of yet no established BNP “cutoff” values in children to support definitively or to rule out acute CHF. Currently, BNP values can be interpreted as either consistent with the normal mean value or not. The standard deviations are reported as a reference, and not as a diagnostic tool. As always, the physician should note the normal laboratory values used at each institution.
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In the case of CHF in children, just as in adults, the patient's clinical presentation will often provide an adequate basis to make the diagnosis. No single laboratory test should replace or supersede a clinician's judgment. However, in the undifferentiated dyspneic child, a screening BNP level may help to exclude the diagnosis if very low and support the diagnosis if markedly high.
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In children with known cardiomyopathy or CHD, there is recent evidence to suggest higher mortality with increasing BNP values. In a sub-group analysis of a large, multi-center study, stable, outpatient, euvolemic children with cardiomyopathy or CHD and a BNP value of ≥140 pg/mL on routine draw were almost four times more likely to die within a 9-month period (hazard ratio of 3.69; 95% CI: 1.61–8.44).15 Although exact numbers have not been established in the acute setting, knowledge of the patient's overall status and trajectory may aid in management, disposition, counseling, and follow-up.
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Hypoxemic “Tet” Spells
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Sudden-onset spells of increased cyanosis may occur in young children with tetralogy of Fallot and less commonly in other complex lesions with decreased PBF, such as tricuspid atresia. Various theories exist regarding the initiation of a spell. The classic teaching is a precipitous “clamping down” of the pulmonary infundibular RV outflow tract, leading to increased right-to-left shunting; although not a complete explanation, this provides a useful model to understand spell physiology. The increased right-to-left shunting leads to hypoxemia, cyanosis, and acidosis. Attempts at compensation occur via hyperventilation and decreased systemic vascular resistance (SVR) to increase cardiac output. Decreased SVR and increased venous return result in further right-to-left shunting, perpetuating a cycle of ongoing shunting and hypoxemia.
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Spells are most common in children younger than 2 years and often occur when SVR is naturally decreased: in the morning after awakening, after a feed, after defecation, and after a bout of crying. Symptoms include restlessness, irritability, or lethargy. Signs include a sudden increase in cyanosis and occasional syncope. Hyperpnea is a cardinal sign of hypoxemic spells. Previously appreciated murmurs of left-to-right shunting may disappear during a spell. The “tet spell” may occur in a previously acyanotic patient and may be the first presentation of a child with previously unrecognized CHD. Spells must be differentiated from seizures, CHF, and respiratory disease. Differentiating factors include history of CHD, profound cyanosis unresponsive to oxygen, and presence of features consistent with tetralogy of Fallot (Fig. 39-19).
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Keep the child as calm as possible, in a position of comfort with a parent present. Avoid unnecessary painful or stressful procedures. Provide oxygen, although it will have little effect in shunt-induced hypoxemia. Place the child in a knee-chest position (to simulate squatting) to increase SVR (older children may even have a history of squatting on their own to abort spells). Morphine, 0.05 to 0.2 mg/kg intravenously or intramuscularly is the traditional first-line medical therapy, although the exact mechanism by which it “breaks” the spell is unknown. Administer a fluid bolus of 10 mL/kg normal saline intravenously to counteract the vasodilatory effects of morphine and to ensure adequate preload, on which pulmonary flow is dependent. Ketamine may be used to decrease agitation and to increase SVR.16 If metabolic acidosis is suspected or confirmed, sodium bicarbonate may be administered to help to break the cycle of hypoxemia, acidosis, and worsening hypotension and perfusion.
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Successful therapy will be evidenced by improved pulse oximetry, decreased cyanosis, decreased hyperpnea, and a calmer child. If the above therapies are unsuccessful, propranolol 0.1 to 0.25 mg/kg (mechanism of action unclear) by a slow intravenous route may be given and repeated once after 15 minutes. Phenylephrine 5 to 20 μg/kg/dose (alpha-agonist resulting in increased SVR) intravenously may be used and repeated every 10 to 15 minutes as necessary. Propranolol and phenylephrine are customarily given in consultation with a cardiologist. If these interventions fail, general anesthesia may be necessary.
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Presentations in Older Children and Adults
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Clinically unapparent lesions are frequently discovered by recognition of a murmur during routine physical examination. Common lesions include ASD, small VSD, PDA, PS, AS, and aortic coarctation. Patients with an ASD will also be noted to have a fixed, split S2. Adult patients with unrepaired ASD may present with atrial arrhythmias, often in the fourth decade of life. Patients with PDA and AS may present with dyspnea on exertion and fatigue. Patients with critical AS may present with syncope. Patients with critical PS may present with cyanosis on exertion, right-sided heart failure, or syncope. Patients with aortic coarctation (Fig. 39-20) are often diagnosed during evaluation for hypertension. They may present with symptoms resulting from hypertension such as headache, intracranial hemorrhage, dizziness, palpitations, or epistaxis. Occasionally, they may complain of claudication due to decreased perfusion of the lower extremities.
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Hypertrophic Cardiomyopathy
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Hypertrophic cardiomyopathy (HCM) is a genetic disorder of sarcomeric proteins that results in varying degrees of LVH, found in 1:500 of the general population.17 It is a primary myopathy, not secondary to hypertension or AS. The term hypertrophic cardiomyopathy (HCM) includes both hypertrophic obstructive cardiomyopathy (HOCM) and idiopathic hypertrophic subaortic stenosis (IHSS). The distinction is made depending on the degree of outflow obstruction and/or asymmetric hypertrophy found in each case. The shared feature is diastolic dysfunction, with resultant impaired cardiac output on exertion.
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Approximately half of patients with HCM have a family history of the same. Young children may be asymptomatic, and the first clinical manifestation may be cardiac arrest. Children and young adults may complain of dyspnea, angina, fatigue, or syncope, especially after strenuous exercise. Patients often have a harsh systolic murmur increasing after the first heart sound (diamond-shaped) best heard at the lower left sternal border or apex; this may be accompanied by an S4. The murmur may be more prominent with tachycardia or Valsalva maneuver, which both reduce ventricular volume, mimicking the conditions of exercise in these patients. Conversely, the murmur may decrease with squatting, hand grip, or leg raise, which augment venous return and increase ventricular volume. Patients may also demonstrate a prominent apical impulse and rapidly rising carotid impulse on physical examination.
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ECG may show LVH and/or wide Q waves. Although an athlete may have LVH on ECG due to normal physiologic changes in left ventricular wall thickness (LVWT) from training, this cannot be assumed in the ED; an echocardiogram is needed in the symptomatic patient to measure LVWT (typically, less than 12 mm in an athlete) to rule out HCM (greater than 16 mm in HCM).18 CXR may be normal or reflect a mild-to-moderate increase in the size of the cardiac silhouette. Echocardiography is the mainstay of diagnosis.
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Treatment options span from medication such as β-blockers or calcium-channel blockers to septal myomectomy to placement of an automated implantable cardioverter-defibrillator. Any child with a history consistent with arrhythmia and syncope warrants inpatient investigation, including urgent echocardiography and possibly electrophysiology studies. If the clinician has high suspicion of HCM in a currently asymptomatic child without high-risk historical features such as arrhythmia or syncope, nonemergent referral to a cardiologist is recommended.19 The child should avoid dehydration and refrain from strenuous activity until a definitive diagnosis is made.
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Arrhythmogenic Right Ventricular Dysplasia
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Arrhythmogenic right ventricular dysplasia (ARVD) is a disorder in which normal heart muscle is progressively replaced by fibrous fatty tissue in a triangular configuration in the right ventricle. The true prevalence is unknown but estimated at 6 in 10,000 in the general population and up to 44 in 10,000 in certain Mediterranean and southern U.S. populations; it is an inherited condition in up to 50% of cases.20 ARVD is the second most common cause of sudden cardiac death in young people, after HCM.21
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The clinical presentation of ARVD may vary from palpitations and syncope to sudden cardiac arrest. There may be a history of sudden cardiac or unexplained death in a young relative. Physical examination is usually unremarkable.22 The ECG is an important screening tool: more than 90% of cases of ARVD will have some ECG abnormality, such as right bundle branch block or prolonged right precordial QRS duration (>110 ms).23 The distinguishing ECG finding in ARVD is the epsilon wave, which is a terminal upward deflection at the end of the QRS complex in any of the precordial leads, typically V1–V3 (Fig. 39-21). Echocardiography often readily reveals the diagnosis, but cardiac MRI may also be used to confirm.
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ARVD is a progressive disease and a prime goal in management is to prevent a lethal dysrhythmia. Treatment options include lifestyle modifications (no strenuous activity), antiarrhythmic medications, radiofrequency ablation, and/or placement of an automated implantable cardioverter-defibrillator.24
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Left Ventricular Noncompaction Syndrome
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During normal embryonic development, trabeculations allow the myocardium to expand quickly and grow without an epicardial arterial supply; later, epicardial vessels penetrate and vascularize the myocardium, and replace the spongy trabecular network with thicker, stronger myocytes. If this process is halted early in the first trimester, this loosely interwoven spongiform mesh of muscle fibers results in weakened myocardium and left ventricular noncompaction syndrome (LVNC).25
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LVNC may occur in isolation, or in conjunction with other CHD. Patients may present with palpitations or nonspecific chest pain from resultant dysrhythmias or CHF. Although the ECG is often nonspecific, the majority (87%) will have some abnormality: intraventricular conduction delay, evidence of left bundle branch block, or LVH.25 In more advanced disease, the classic triad is heart failure, ventricular dysrhythmias, and a systemic embolic event, such as a stroke or renal infarction. Echocardiography may be nondiagnostic; cardiac MRI is increasingly used to make the diagnosis.26
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Although an uncommon cause of palpitations or dysrhythmias, LVNC should be included in the differential diagnosis of a young person with unexplained syncope, especially with previous symptoms consistent with heart failure. As ventricular dysrhythmias are reported in up to 20% of patients, most are treated with an automated implantable cardioverter-defibrillator and possibly anticoagulation.
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Isolated Coronary Artery Anomalies
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Congenital lesions of the coronary arteries are uncommon, occurring in less than 1% of the population.27 During fetal development, abnormalities may form affecting the number (duplication of artery), site of origin (e.g., from pulmonary trunk), anatomic course (e.g., between the aorta and pulmonary trunk), anomalous termination (e.g., fistula formation), or structure (stenosis and atresia) of the coronary arteries. Virtually any coronary artery may be affected. These lesions may be isolated to a single coronary artery or associated with other congenital heart defects.
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Depending on the lesion, patients may present from infancy to young adulthood. Neonates with an isolated coronary artery anomaly may demonstrate anginal symptoms such as irritability, episodic diaphoresis, and/or color change when symptomatic. Older infants may have poor feeding, dyspnea, failure to thrive, or unexplained episodes of pallor. Diaphoresis during feeding is an ominous sign, reflecting both a decreased “exercise tolerance” and a splanchnic steal syndrome. Older children and young adults typically present with more familiar ischemic symptoms such as angina and dyspnea. Unfortunately, a child's first presentation may be sudden death.
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A rare but serious lesion primarily affects neonates—anomalous origin of the left coronary artery arising from the pulmonary artery (ALCAPA), also called Bland–White–Garland syndrome.28,29 Most children present within the first few months of life, often with nonspecific complaints such as irritability; they are often misdiagnosed with colic. Signs and symptoms of CHF, such as tachypnea, tachycardia, poor feeding, and weight gain, may ensue. On physical examination, the baby may be completely normal or show signs of CHF. ECG may show an anterolateral infarct pattern with deep and wide Q waves laterally and absent Q waves inferiorly. CXR may be consistent with CHF. Echocardiography with Doppler flow is often diagnostic, especially if retrograde flow from the left coronary artery to the pulmonary trunk is shown.
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Surgical correction is necessary to restore blood flow. ED care is supportive, with great attention paid to volume status and very careful use of diuretics and nitrates if needed. Titrate oxygen to effect; 100% oxygen may dilate pulmonary vasculature and create a steal syndrome from the right coronary artery to the pulmonary arteries in this lesion. Although isolated coronary artery anomalies are rare, they should be considered in the child with unexplained age-specific anginal symptoms.
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Patients with a large left-to-right shunt that is left unrepaired, either by choice or because the lesion was never recognized, gradually develop pulmonary vascular disease due to the increased volume overload. When pulmonary hypertension becomes severe enough, the direction of shunting will reverse to right to left, and cyanosis ensues. Typically, this occurs in adolescence to early adulthood. Patients may complain of decreased exercise tolerance, dyspnea on exertion, hemoptysis, palpitations due to atrial arrhythmias, and symptoms of hyperviscosity due to chronic polycythemia (vision disturbances, fatigue, headache, dizziness, paresthesias, and even cerebrovascular accident). Brain abscesses can occur with right-to-left passage of an infected embolus. On examination, the murmur may no longer be present when the left-to-right shunting ends and S2 is loud due to the pulmonary hypertension. CXR shows decreased vasculature (pruned pattern), and ECG shows RVH. Although no definitive therapy exists, other than heart–lung transplant, patients should avoid dehydration, heavy exertion, altitude, vasodilators, and pregnancy (which are associated with a high-mortality rate). Symptoms of hyperviscosity may be treated with phlebotomy and isovolemic replacement. Patients should be medically managed by a cardiologist to optimize cardiac function as long as possible.