The incidence and significance of superior QRS axis in children with cyanotic congenital heart disease.

The Incidence of superior ORS axis in 200 consecutive infants and children with cyanotic congenital heart disease who underwent cardiac catheterization is 26%. Patients with asplenia syndrome, transposition of great arteries, double outlet right ventricle and dextrocardia complex are most likely to have superior ORS axis. The frequency of superior QRS axis in patients with tetralogy of Fallot is 13%, a finding that has not been previously high -lighted. Transposition of great arteries accounts for more than a quarter, and tetralogy of Fallot about one -fifth, of all the cases of cyanotic congenital heart disease with superior ORS axis. Tricuspid atresia is extremely rare, accounting for only 2% in our series. Further classification of these cases according to the mean frontal QRS axis and the roentgenologic patterns provides further diagnostic informations. Definitive diagnosis of cyanotic congenital heart disease requires, however, cardiac catheterization and angiography.