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KEY FEATURES

ESSENTIALS OF DIAGNOSIS

  • Neonate, infant, or child with cyanosis (typically a neonate) or heart failure (infant or child)

  • Central cyanosis, mildly prominent right ventricular (RV) impulse, murmur of pulmonic stenosis (with sufficient pulmonary blood flow), and absent pulmonic component of S2

  • Membranous ventricular septal defect (VSD) and obstruction of the RV outflow tract (subvalvular, valvular, supravalvular, or branch pulmonary artery stenosis)

GENERAL CONSIDERATIONS

  • RV outflow tract obstruction is often at multiple levels

  • Associated cardiac anomalies occur in approximately 40% of patients, including: right-sided aortic arch, coronary artery anomalies, systemic to pulmonary collateral vessels, patent ductus arteriosus, multiple ventricular defects, atrioventricular septal defects, and aortic cusp prolapse and regurgitation

  • Fifteen percent of patients have extracardiac anomalies, including Down’s syndrome, Alagille’s syndrome, DiGeorge’s syndrome, and velocardiofacial syndrome

  • Physiologic manifestations depend on the degree of RV outflow tract obstruction

    • – More severely obstructed RV outflow tract leads to greater shunting right to left across the VSD and into the aorta, resulting in cyanosis and polycythemia

  • Women who have had corrective surgery without severe hemodynamic abnormalities before pregnancy generally have good maternal and infant outcomes

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

  • Symptoms depend on the degree of RV outflow tract obstruction

  • Children may present with profound cyanosis at birth, dyspnea related to heart failure due to increased pulmonary blood flow, or no symptoms

  • Infants may have spells with profound cyanosis

PHYSICAL EXAM FINDINGS

  • Central cyanosis

  • Digital clubbing

  • Single S2

  • Early systolic click along the left sternal border due to flow into a dilated ascending aorta

  • Harsh systolic ejection murmur along the left mid to upper sternal border that radiates posteriorly owing to the RV outflow tract obstruction

  • A murmur from the VSD is not usually appreciated

DIFFERENTIAL DIAGNOSIS

  • Truncus arteriosus

  • Double outlet right ventricle

  • VSD and pulmonic stenosis

  • Transposition of the great vessels

  • Other causes of cyanosis with exercise intolerance

DIAGNOSTIC EVALUATION

LABORATORY TESTS

  • No specific laboratory tests

  • Arterial blood gases consistent with hypoxia

  • Erythrocytosis in cyanotic patients

ELECTROCARDIOGRAPHY

  • Right atrial enlargement and RV hypertrophy with right-axis deviation, prominent anterior R waves and posterior S waves, upright T wave in V1, and qR in the right chest leads

IMAGING STUDIES

  • Chest x-ray findings: classic boot-shaped heart with an upturned apex and concave main pulmonary artery segment; normal heart size; normal or decreased pulmonary flow pattern; 25% of patients have a right aortic arch

  • Echocardiography: demonstrates all essential features of tetralogy of Fallot for the diagnosis and preoperative evaluation

DIAGNOSTIC PROCEDURES

  • Transesophageal echocardiography: usually not necessary

  • Cardiac catheterization: helpful for assessing degree and levels of RV outflow ...

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