[Association between parachute mitral valve and Down's syndrome. Report of a case].

The trisomy 21 form of Down's syndrome is the most common human chromosomal aberration. Congenital heart disease is found in as many as 50 per cent of patients with this disorder. The two most common cardiac lesions in Down's syndrome are septal ventricular defect and endocardial cushion defect. Secundum atrial septal defect, tetralogy of Fallot and isolated patent ductus arteriosus are also observed in these Down's patients. Transposition of great arteries and coarctation of the aorta are rarely seen. Most patients having Down's syndrome with congenital heart disease have a single lesion. However, as many as 30 per cent may have multiple cardiac defects. Parachute mitral valve is a rare congenital mitral defect: a single papillary muscle in the left ventricle is the hallmark of this lesion. A parachute mitral valve is frequently associated with other left heart disorders such as supravalvular mitral ring, abnormal and stenosed mitral valve, subaortic stenosis and coarctation of the aorta, thus constituting either a complete form of Shone's complex (when all 4 components are present) or an incomplete form when there are fewer. The aim of the present report is to describe the connection between Down's syndrome and isolated, non-stenosed parachute mitral valve, which has never been reported before.