Session S43.1

Differential Electrograms Computed from Unipolar Endocardial Recordings Improve Purkinje Activation Identification

DJ Dosdall*, J Huang, RE Ideker

University of Alabama
Birmingham, AL, USA

Recent studies have indicated that the Purkinje system plays a critical role in the onset and maintenance of certain arrhythmias. Even with unipolar electrodes on the endocardium in close proximity to Purkinje fibers, electrical mapping of the intact Purkinje system during arrhythmias is difficult because Purkinje potentials may be much smaller in amplitude than local myocardial activation potentials.
A beagle heart was isolated, perfused through the left main artery, and the left ventricular endocardium was exposed through an incision through the right ventricle and septum. A 12x4 electrode plaque was placed on the base of the anterolateral papillary muscle. Unipolar electrograms were recorded at 8 KHz during sinus rhythm, VT, and VF. Using the unipolar recordings, bipolar, quadripolar, and octapolar, and Laplacian electrograms were created. Purkinje potentials were more readily identified with bipolar, quadripolar and Laplacian electrograms than with unipolar recordings. The first temporal derivatives of the electrograms aided in distinguishing Purkinje potentials due to the rapid, narrow morphology of the Purkinje deflections as compared to the activations of the underlying myocardium. Bipolar recording reduce common noise between electrodes and are highly sensitive to directionality of the propagating wavefront. Quadripolar recordings increased sensitivity to local activation, but were also somewhat sensitive to wavefront directionality. Octapolar and Laplacian electrograms had the highest sensitivity to local activation and were not sensitive to the direction of propagation of the wavefront.
Differential electrograms and their temporal derivatives facilitate Purkinje potential identification by reducing common noise in the electrograms and far field effects recorded by the unipolar signal. Combined analysis of the unipolar electrograms, differential computed electrograms, and their derivatives improve identification of Purkinje activation from endocardial electrical recordings.

(Abstract Control Number: 74)