Prolongation of Q-I interval in atrial septal defect.

The present paper is concerned with Q-I interval and factors affecting this interval in 55 patients with atrial septal defect of ostium secundum type (ASD) in comparison with the interval in 60 healthy individuals and 37 patients with mitral stenosis. The results obtained are as follows: 1) Q-I interval was significantly greater in patients with ASD than in healthy individuals, and less than in patients with mitral stenosis. 2) The Q-I interval in ASD showed significant correlations with size of septal defect and age, but no correlation with other variables such as heart rate, blood pressure, and right heart catheterization data. 3) The interval was significantly shortened following the surgical closure of ASD. These findings suggest that left-to-right shunt at atrial level leads to prolongation of Q-I interval. Mechanisms for these results were discussed.