The intracardiac electrogram as an aid in cardiac catheterization.

Electrocardiograms have been recorded by unipolar leads from the great veins and cavities of the right heart during cardiac catheterization in 30 of 130 cases of congenital and rheumatic heart disease. These intracardiac electrograms have given information that has proved useful in diagnosis. Further, continuous monitoring on an oscilloscope of these tracings, rather than of records from surface leads, adds to the safety of the procedure. In this paper an attempt is made to assess the help thus afforded by intracardiac electrography.