A 7-year-old boy presented with dusky lips and face and a history of decreasing exercise tolerance. His mother had occasionally observed these signs since age 4 years, but had noted a marked worsening over the last 2 months. During the same period, a progressive decrease in energy and attention had been noted by the child's first-grade teacher. A review of systems yielded otherwise normal results. A detailed family history revealed that the mother had several small ruby telangiectasia on her lips and that the maternal grandfather had undergone a thoracotomy at age 39 years for "a blood vessel coming off his heart."
The physical examination revealed an alert, cooperative child with circumoral and mucous membrane cyanosis. Pulse was 84 beats per min, respirations were 20/min, and blood pressure was 104/60 mm Hg. The S1 and S2 were normal. A soft systolic murmur was audible over the entire precordium.