title: His bundle recordings in diagnosis of impulse formation in Kent and Mahaim tracts.
abstract: His bundle electrograms were recorded in 2 patients with ectopic beats arising in accessory atrioventricular tracts. Case 1 had Wolff-Parkinson-White (WPW) type A and a left-sided Kent tract with a short effective refractory period. Though ectopic impulse formation most probably occurred within the Kent tract itself, a vulnerability-related origin in the ventricular muscle close to the distal end of the Kent tract could not be excluded. In Case 2, with a Mahaim tract extending from His bundle to ventricles, there were three types of QRS morphologies resulting from : (a) atrioventricular conduction exclusively through the normal pathways; (b) atrioventricular conduction through both, normal pathway, and Mahaim tract; and (c) ectopic impulse formation in the Mahim tract. Specialized electrophysiological studies were essential to diagnose these unusual arrhythmias.
mesh_terms: D000328:Adult; D001145:Arrhythmias, Cardiac / Q000175:diagnosis*; D001283:Atrioventricular Node / Q000503:physiopathology; D002036:Bundle of His / Q000503:physiopathology*; D005117:Cardiac Complexes, Premature / Q000175:diagnosis; D004562:Electrocardiography; D006329:Heart Conduction System / Q000503:physiopathology*; D006352:Heart Ventricles / Q000294:innervation; D006801:Humans; D008297:Male; D014927:Wolff-Parkinson-White Syndrome / Q000175:diagnosis / Q000503:physiopathology