title: [Investigation of the preexcitation syndromes].
abstract: Assessment of the localization and function of accessory atrioventricular pathways may be undertaken with noninvasive and invasive examination techniques. Noninvasive methods, however, such as electrocardiography, vectorcardiography, precordial mapping, echocardiography and scintigraphy do not enable exact delineation of the site of the accessory pathway since, in general, their use requires maximal preexcitation; moreover, they are of less value in the presence of septal bundles, multiple accessory pathways or intraventricular conduction disturbances. Accordingly, localization of accessory atrioventricular pathways is based on data obtained from intracardiac electrography such as the interval between stimulus and delta wave during atrial pacing, retrograde atrial sequence, VA conduction time at onset of right or left bundle branch block as well as responses to programmed ventricular stimulation during orthodromic reciprocating tachycardia. The most exact method for determination of the localization of the Kent bundle employs intraoperative endocardial and epicardial mapping with analysis of VA and AV conduction times during reciprocating tachycardia, ventricular stimulation and atrial pacing. The conduction properties of the accessory atrioventricular bundle may be estimated noninvasively based on the persistence of a delta wave as a function of the heart rate, the influence of antiarrhythmic agents on the anterograde conduction via the normal pathway as well as the shortest interval between two consecutive QRS complexes with delta waves during atrial fibrillation. Functional assessment is carried out invasively through recording the anterograde and retrograde refractory periods of the Kent bundle as well as observations during programmed atrial and ventricular stimulation or induced atrial fibrillation.
mesh_terms: D000889:Anti-Arrhythmia Agents; D004452:Echocardiography; D004562:Electrocardiography; D004567:Electrodes, Implanted; D004594:Electrophysiology; D006329:Heart Conduction System / Q000601:surgery; D006801:Humans; D011877:Radionuclide Imaging; D014672:Vectorcardiography; D014927:Wolff-Parkinson-White Syndrome / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000601:surgery
chemical_list: D000889:Anti-Arrhythmia Agents
vernacular_title: Untersuchung des Präexzitationssyndroms.