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Key Features

Essentials of Diagnosis

  • Early heart failure (HF) with or without cyanosis

  • Systolic ejection click

General Considerations

  • Accounts for < 1% of congenital heart malformations

  • A single great artery arises from the heart, giving rise to the systemic, pulmonary, and coronary circulations

  • The number of truncal valve leaflets varies from two to six, and the valve may be insufficient or stenotic

  • Divided into subtypes by the anatomy of the pulmonary circulation

    • A single main pulmonary artery may arise from the base of the trunk and gives rise to branch pulmonary arteries (type 1)

    • Alternatively, the pulmonary arteries may arise separately from the common trunk, either in close association with one another (type 2) or widely separated (type 3)

  • The degree of systemic arterial oxygen saturation depends on the ratio of pulmonary to systemic blood flow

    • If pulmonary vascular resistance is normal, the pulmonary blood flow is greater than the systemic blood flow and the saturation is relatively high

    • If pulmonary vascular resistance is elevated because of pulmonary vascular obstructive disease or small pulmonary arteries, pulmonary blood flow is reduced and oxygen saturation is low

Clinical Findings

  • Growth retardation, easy fatigability, and HF are most common manifestations

  • High pulmonary blood flow is characteristic

  • Cyanosis

    • Usually minimal

    • More profound in patients with decreased pulmonary blood flow

  • Examination of the heart reveals a hyperactive precordium

  • At the lower left sternal border

    • A systolic murmur is heard

    • A systolic thrill is common

    • A loud holosystolic murmur is audible

  • A loud early systolic ejection click is commonly heard

  • A diastolic flow murmur can often be heard at the apex due to increased pulmonary venous return crossing the mitral valve

  • An additional diastolic murmur of truncal insufficiency may be present

  • S1 and S2 are single and loud

  • A VSD is always present



  • Radiography

    • Shows cardiomegaly; absence of the main pulmonary artery segment; and a large aorta, which has a right arch 30% of the time

    • Pulmonary vascular markings vary with the degree of pulmonary blood flow

  • Echocardiography

    • Shows override of a single great artery (similar to tetralogy of Fallot, but no second great artery arises directly from the heart)

    • Defines origin of the pulmonary arteries and the degree of truncal valve abnormality

    • Color-flow Doppler can aid in the description of pulmonary flow and the function of the truncal valve, both of which are critical to management

    • Identifies associated lesions that will impact surgical planning, such as the presence of an interrupted aortic arch

Diagnostic Procedures

  • Electrocardiography

    • The axis is usually normal

    • Right ventricular hypertrophy or combined ventricular hypertrophy is commonly present

  • Cardiac catheterization

    • Not routinely performed

    • May be of value in older infants in whom pulmonary vascular disease must be ruled ...

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