Transposition (Complete) of the Great Arteries

KEY FEATURES

ESSENTIALS OF DIAGNOSIS

• Cyanosis that worsens shortly after birth at the time of ductal closure

• Prominent right ventricular impulse, palpable and delayed A₂

• Murmurs from associated defects (eg, ventricular septal defect, pulmonic stenosis)

• Chest x-ray shows narrowing at base of heart in region of great vessels; prominent pulmonary vascularity unless pulmonary vascular resistance is increased

• Discordant ventriculoarterial connections such that the aorta arises from the right ventricle and the pulmonary artery arises from the left ventricle

• Right atrial enlargement, right ventricular hypertrophy; occasionally biventricular hypertrophy (with an associated ventricular septal defect) visualized with echocardiography

GENERAL CONSIDERATIONS

• Most common cyanotic congenital heart lesion

• Survival of patients with transposition of the great arteries (D-TGA) after birth depends on mixing saturated and desaturated blood via a patent ductus arteriosus or atrial septal defect or ventricular septal defect

• When a ventricular septal defect is present, there is a risk of developing pulmonary vascular disease in the absence of pulmonary stenosis because of increased pulmonic blood flow

• Virtually all surviving adults with transposition of the great arteries have had corrective surgeries, such as the Mustard or Senning (atrial switch) or the Jatene (arterial switch)

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

• Male predominance (3:1)

• History of cyanosis at birth that worsens after the ductus closes

• Adults who have had corrective surgeries may develop signs and symptoms of heart failure due to systemic right ventricular dysfunction or atrial baffle obstruction or leaks

PHYSICAL EXAM FINDINGS

• Prominent right ventricular impulse

• Accentuated S₂ (A₂) with soft or inaudible pulmonic component

• Murmurs caused by associated defects (ventricular septal defect, pulmonic stenosis)

• Adults who develop systemic right ventricular failure may have a gallop and/or pulmonary rales

DIFFERENTIAL DIAGNOSIS

• Truncus arteriosus

• Tetralogy of Fallot

• Eisenmenger’s syndrome

DIAGNOSTIC EVALUATION

ELECTROCARDIOGRAPHY

• Right atrial enlargement

• P-R prolongation

• Bradycardia (in patients with the atrial switch)

• Right ventricular hypertrophy

• Right-axis deviation

• Q waves in the right precordial leads

IMAGING STUDIES

• Chest x-ray:

  • – Absence of left-sided aortic knob, prominent right atrium and right ventricle

• Echocardiography:

  • – Atria and ventricles in the normal position with severe right ventricular hypertrophy and some degree of right ventricular enlargement with or without right ventricular systolic dysfunction

  • – In patients with atrial switch procedures, baffle leaks or obstruction can be detected with color-flow Doppler and contrast injection

  • – Arterial switch procedures may show neo-aortic valve regurgitation, neo-pulmonary valve stenosis, or branch pulmonary artery stenosis

• MRI:

  • – May be helpful in determining the anatomy of the vena cavae and pulmonary veins

DIAGNOSTIC PROCEDURES

• Useful in adults for assessment of ...