Evaluation of P wave axis in distinguishing anatomical site of atrial septal defect.

It has been previously proposed that a method of distinguishing sinus venosus atrial septal defects from ostium secundum atrial septal defects is a leftward axis deviation (less than +300) of the P waves on the electrocardiograms of patients with sinus venosus defects. The electrocardiograms of i5o patients with surgically corrected atrial septal defects were reviewed to test this proposition. The preoperative P wave