Transposition of the Great Arteries Clinical Presentation

Infants with transposition of the great arteries (TGA) are usually born at term, with cyanosis apparent within hours of birth.

The clinical course and manifestations depend on the extent of intercirculatory mixing and the presence of associated anatomic lesions.

• Transposition of the great arteries with intact ventricular septum: Prominent and progressive cyanosis within the first 24 hours of life is the usual finding in infants.
• Transposition of the great arteries with large ventricular septal defect: Infants may not initially manifest symptoms of heart disease, although mild cyanosis (particularly when crying) is often noted. Signs of congestive heart failure (tachypnea, tachycardia, diaphoresis, and failure to gain weight) may become evident over the first 3-6 weeks as pulmonary blood flow increases.
• Transposition of the great arteries with ventricular septal defect and left ventricular outflow tract obstruction: Infants often present with extreme cyanosis at birth, proportional to the degree of left ventricular (pulmonary) outflow tract obstruction. The clinical history may be similar to that of an infant with tetralogy of Fallot.
• Transposition of the great arteries with ventricular septal defect and pulmonary vascular obstructive disease: Progressively advancing pulmonary vascular obstructive disease can prevent this rare subgroup of patients from developing symptoms of congestive heart failure, despite a large ventricular septal defect. Most often, patients present with progressive cyanosis, despite an early successful palliative procedure.

Newborns with transposition of the great arteries are usually well developed, without dysmorphic features. Physical findings at presentation depend on the presence of associated lesions.

• Transposition of the great arteries with intact ventricular septum: Infants typically present with progressive central (perioral and periorbital) cyanosis. Other than cyanosis, the physical examination is often unremarkable.
• Transposition of the great arteries with large ventricular septal defect: Cyanosis may be mild initially, although it is usually more apparent with stress or crying. Upon presentation, infants often have an increased right ventricular impulse, a prominent grade 3-4/6 holosystolic murmur, third heart sound, mid-diastolic rumble, and a gallop rhythm. Hepatomegaly may be present.
• Transposition of the great arteries with ventricular septal defect and left ventricular outflow tract obstruction: Cyanosis is prominent at birth, and the findings are similar to those of infants with tetralogy of Fallot. A single, or narrowly split, diminished second heart sound and a grade 2-3/6 systolic ejection murmur may be present. Hepatomegaly is rare.
• Transposition of the great arteries with ventricular septal defect and pulmonary vascular obstructive disease: Progressive pulmonary vascular obstructive disease is not always evident from physical examination findings. Cyanosis is usually present and can progress despite palliative therapy in the newborn period.
• No murmur (despite the ventricular septal defect) or early short systolic ejection sounds are heard.
• The second heart sound is often single, with increased intensity.
• In later childhood or adolescence, a high-pitched, blowing, early decrescendo diastolic murmur of pulmonary insufficiency and a blowing apical murmur of mitral insufficiency are evident.

• Etiology for transposition of the great arteries is unknown and is presumed to be multifactorial.
• Embryology likely involves abnormal persistence of the subaortic conus with resorption or underdevelopment of the subpulmonary conus (infundibulum). This abnormality aligns the aorta anterior and superior with the right ventricle during development.