The inside-out electrocardiographic stress test: a view from the left ventricular cavity

A new method is described for measuring the unipolar left ventricular cavitary electrogram by means of a standard pigtail ventriculography catheter. Experiences with this technique in 30 patients are described with particular reference to changes in the S-T segment of the cavitary electrogram during cardiac stress by atrial pacing. This method allows convenient recording of His bundle potentials from the left ventricular outflow tract in most patients.