The Intracardiac Electrogram as an AId in the Localization of Pulmonary Stenosis

The intracardiac electrogram (IEG), as recorded from an electrode at the tip of a cardiac catheter, shows a striking contrast in pattern between that from the lumen of the pulmonary artery and that from the cavity of the right ventricle. The change is well seen in continuous records made during withdrawal of the catheter from the pulmonary artery through the pulmonary valve and is, in general, abrupt. Having regard to the importance of accurate pre-operative diag- nosis of the site of the stenosis, and recognizing the artefacts that may complicate pressure tracings, it appeared to us that recording the IEG along with the pressure pulse during catheterization of patients with pulmonary stenosis might be useful in determining the site of the obstruction in the right ventricular outflow tract.