Electrocardiographic Changes Following Balloon Dilatation of Valvar Pulmonic Stenosis

The purpose of this paper was to study the electrocardiographic changes following balloon pulmonary valvuloplasty for pulmonic stenosis and to see if such changes reflect improvement in pulmonary valve gradient following balloon valvuloplasty. Forty-one patients, ages 7 days to 20 years, underwent balloon valvuloplasty for severe valvar pulmonic stenosis. In 35 of these patients ECGs were available 3 to 34 months (mean 11) following valvuloplasty and were compared with pre-valvu-loplasty electrocardiograms. In 30 children with excellent relief of pulmonic stenosis (group I), frontal plane mean QRS vector moved toward the left from 127 ±25° to 81 ±47°as did the horizontal plane mean QRS vector, 88 ± 36° to 27 ±51°. The amplitude of R wave in V_1, 19 ± 11.6 mm, and V₂, 19.7 ± 12.2 mm, decreased respectively to 9.5 ± 5.9 mm and 11.3 ±6.1 mm. S wave amplitude in V₅ and V₆ also decreased. The improvement in the electrocardiogram is associated with a decrease in pulmonary valve gradient from 95 ± 50 to 29 ± 23 mm Hg. In five children with significant residual pulmonary valve gradient (group II), the electrocardiograms did not show any significant change. Evaluation of the time course of ECG changes in group I revealed that recognizable electrocardiographic improvement was first observed at 6 months following successful balloon pulmonary valvuloplasty. Normal electrocardiogram suggests minimal residual pulmonary valve gradient while right ventricular hypertrophy suggests significant residual obstruction unless the electrocardiogram was recorded at or before six months following balloon valvuloplasty. These data suggest that electrocardiogram is a good indicator of improvement following balloon pulmonary valvuloplasty. (J. Interven Cardiol 1988:1:3)