Obstruction of right ventricular inflow and outflow in corrected transposition of the great arteries (S,L,L): two-dimensional echocardiographic diagnosis.

Obstruction of systemic ventricular inflow and outflow is considered uncommon in corrected transposition of the great arteries (S,L,L). Between 1979 and 1985, 42 patients with corrected transposition and two ventricles and atrioventricular valves underwent two-dimensional echocardiography. Obstruction of right ventricular inflow and outflow was present and diagnosed by two-dimensional echocardiography in 5 of the 42 patients. A supratricuspid stenosing ring, recognized in the apical or subxiphoid four chamber view as a bright, linear structure on the left atrial side of the tricuspid valve, occurred in two patients. Subaortic obstruction due to infundibular hypertrophy with or without displaced muscle bundles was seen in three patients. Subxiphoid long- and short-axis views and parasternal long-axis views best displayed these features. Aortic coarctation was present in four cases and could be diagnosed using modified suprasternal notch views. Thus, systemic ventricular inflow and outflow obstruction may be more common in corrected transposition than previously believed (occurring in up to 10 to 15% of patients). The mechanisms producing the obstruction appear to be characteristic of the left atrium and right ventricle irrespective of location or connections. Echocardiography appears to be an excellent technique for diagnosing these associated lesions in corrected transposition.