Congenital mitral valve anomalies in transposition of the great arteries

Seventy-nine specimens with transposition of the great arteries were reviewed. Among them were 45 with ventricular septal defect, including 6 with so-called "posterior aorta transposition". The morphology of the mitral valve was carefully studied. Mitral valve anomalies were found in 24 cases (30%). The anomalies involving the mitral valve were classified into 4 groups according to the different components of the valve: A) specimens with anomalies of the leaflets--2 cases with mitral cleft; B) those with anomalies of the commissures--1 case with a mitral gap; C) those with abnormalities of the chordae tendinae--2 cases of malattachment of the chordae tendinae to the ventricular septum and 2 with bridging chordae between the papillary muscles; and D) those with abnormalities of the papillary muscles--5 cases with a parachute valve, 10 with a "form fruste" of the parachute mitral valve (hypoplasia of one papillary muscle and short chordae tendinae) and 2 with abnormally placed papillary muscles, which reached the pulmonary annulus. In 14 cases, abnormalities of the tricuspid valve were also encountered, including 8 cases with a tricuspid gap and 6 with a malattachment of tricuspid chordae on the border of a ventricular septal defect. It can be concluded that mitral valve anomalies are not uncommon in transposition of the great arteries. This pathology must be carefully evaluated at the time of surgery, particularly in those patients for whom an anatomic correction is considered, for in those cases the left ventricle will be supplying the systemic circulation and therefore, a completely normal mitral valve will be required.(ABSTRACT TRUNCATED AT 250 WORDS)