title: Surface electrocardiographic clues suggesting presence of a nodofascicular Mahaim fiber.
abstract: Standard electrocardiograms from 87 consecutive patients with tachycardia of left bundle branch block configuration were analyzed retrospectively for features that might be characteristic of tachycardia utilizing a nodofascicular Mahaim fiber. The study group consisted of 13 patients with nodofascicular tachycardia, 34 with supraventricular tachycardia and aberrant conduction over the His-Purkinje system, 22 with ventricular tachycardia and 18 with antidromic tachycardia utilizing a right-sided accessory atrioventricular pathway. Six variables present during tachycardia of left bundle branch block configuration were predictive of a nodofascicular fiber: cycle length between 220 and 450 ms, QRS axis of 0 to -75 degrees, QRS duration 0.15 second or less, R wave in lead I, rS wave in precordial lead V1 and a precordial transition from a negative to a positive QRS complex after lead V4. All six criteria were present in 16 of the 87 patients. No patient with ventricular tachycardia satisfied these criteria, whereas 3 of 34 with supraventricular tachycardia, 1 of 18 with antidromic tachycardia and 12 of 13 with tachycardia using a nodofascicular fiber did. It is concluded that analysis of the surface electrocardiogram during tachycardia may suggest the presence of a nodofascicular fiber.
mesh_terms: D000293:Adolescent; D000328:Adult; D001283:Atrioventricular Node / Q000002:abnormalities* / Q000503:physiopathology; D002037:Bundle-Branch Block / Q000175:diagnosis / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000002:abnormalities*; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D013610:Tachycardia / Q000151:congenital / Q000175:diagnosis* / Q000503:physiopathology