Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ Key Features +++ Essentials of Diagnosis ++ Hypoxemic spells during infancy Right-sided aortic arch in 25% of patients Systolic ejection murmur at the upper left sternal border +++ General Considerations ++ Most common cyanotic cardiac lesion Accounts for 10% of all congenital heart disease Atrial septal defect occurs in 15% Obstruction to right ventricle (RV) outflow with a large ventricular septal defect (VSD) causes a right-to-left shunt at the ventricular level with arterial desaturation The greater the obstruction and the lower the systemic vascular resistance, the greater the right-to-left shunt Associated with deletions in the long arm of chromosome 22 (22q11, DiGeorge syndrome) in as many as 15% of affected children; this is especially common in children with an associated right aortic arch +++ Clinical Findings +++ Symptoms and Signs ++ Few children are asymptomatic Cyanosis Easy fatigability Dyspnea on exertion Clubbing of fingers and toes Growth and development are not typically delayed Hypoxemic spells are one of the hallmarks of severe disease Also called cyanotic or "Tet spells" Can occur spontaneously and at any time Episodes most commonly start at age 4–6 months Characterized by Sudden onset of cyanosis or deepening of cyanosis Dyspnea Alterations in consciousness, from irritability to syncope Decrease or disappearance of the systolic murmur (as RV the outflow tract becomes completely obstructed) On examination, an RV lift is palpable S2 is predominantly aortic and single A grade II–IV/VI, rough, systolic ejection murmur is present at the left sternal border in the third intercostal space and radiates well to the back +++ Diagnosis +++ Laboratory Findings ++ Elevated hemoglobin, hematocrit, and red blood cell count due to chronic arterial desaturation +++ Imaging ++ Chest radiographs Show a normal-size heart RV is hypertrophied, often shown by an upturning of the apex (boot-shaped heart) Main pulmonary artery segment is usually concave If there is a right aortic arch, the aortic knob is to the right of the trachea Pulmonary vascular markings are usually decreased +++ Diagnostic Studies ++ Electrocardiography QRS axis is rightward, ranging from +90 to +180 degrees P waves are usually normal RV hypertrophy is always present RV strain patterns are rare Echocardiography Reveals thickening of the RV wall, overriding of the aorta, and a large subaortic VSD Obstruction at the level of the infundibulum and pulmonary valve can be identified Size of the proximal pulmonary arteries can be measured Anatomy of the coronary arteries should be visualized, since abnormal branches crossing the RV outflow tract are at risk for transection during surgical enlargement of the area Cardiac catheterization Establishes coronary artery and distal pulmonary artery anatomy when not clearly defined by echocardiography Perform in patients with hypoplastic pulmonary arteries Reveals a right-to-left shunt at the ventricular ... Your Access profile is currently affiliated with [InstitutionA] and is in the process of switching affiliations to [InstitutionB]. Please select how you would like to proceed. Keep the current affiliation with [InstitutionA] and continue with the Access profile sign in process Switch affiliation to [InstitutionB] and continue with the Access profile sign in process Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Error: Incorrect UserName or Password Username Error: Please enter User Name Password Error: Please enter Password Sign in Forgot Password? Forgot Username? Sign in via OpenAthens Sign in via Shibboleth You already have access! Please proceed to your institution's subscription. Create a free profile for additional features.