Abstract
It would be extreme importance for the phonocardiographic analysis of murmur in cases of patent ductus arteriosus, to have precise consideration on the size of the ductus. The author has observed the fact that variation of the size of the ductus results in the variation of the pressure gradient between systemic and pulmonary pressure causing significant change in phonocardiographic findings, The role of the size of the ductus arteriosus playing the pathogenic mechanism of pulmonary hypertension in this disease has been also discussed.
