Congenitally corrected transposition of the great arteries (L transposition)
A 48 year old woman under went diagnostic coronary angiography for atypical chest pains. During catheterisation the aorta was seen to be in an abnormal anterior position and subsequent cannulation of the coronary circulation proved extremely difficult requiring multiple catheters. Eventually a single coronary artery was cannulated, which was normal.
Subsequent transthoracic and transoesophageal echocardiography was arranged which revealed that the morphological left ventricle with the mitral valve lay on the right side in continuation with the venous right atrium and was connected to the pulmonary artery. The morphological right ventricle with the tricuspid valve lay on the left in continuation with the arterial left atrium and was connected to the aorta. The patient therefore had congenitally corrected transposition of the great arteries.
Echo clues to its diagnosis are: (1) the triscupid valve (TV) always lies closer to the apex when compared to the mitral valve (MV) and this will be apparent on the left side of the heart (upper and lower panels, middle column); (2) a moderator band and thicker trabeculation may be seen in the morphological right ventricle again on the left side of the heart; (3) a five chamber view will not be possible on the left side, the aorta can be imaged from the right side on occasions; (4) left ventricle/mitral papillary muscles always insert into the free walls, and right ventricle/tricuspid valves insert into one free wall and the septum.
Our patient did not have any complications or evidence of coronary artery disease. Coronary angiography showed a single coronary artery origin, giving rise to a left anterior descending system and an equally dominant circumflex, with no right coronary artery (upper and lower panels, right column).
This is only the second known case of a congenitally corrected transposition of the great arteries (L transposition) associated with a single coronary artery.