title: A technical approach to optimized atrial recognition in the ICD: the intrathoracic six-channel farfield ECG.
abstract: Present-day ICD systems offer the possibility to reconstruct an intrathoracic 6-lead ECG (IT-ECG), using the defibrillator coils in the right ventricle and superior vena cava and the left-laterally positioned ICD as electrodes according to Einthoven and Goldberger. The aim of this study was to assess the feasibility of (1). automated P wave recognition in the IT-ECG without an additional atrial electrode as the basis of AV synchronous ventricular pacing (VDD) and for improved differentiation between supraventricular tachyarrhythmias and, (2). the automated detection of pacing evoked atrial potentials (EAP) in dual chamber ICDs as the basis for atrial "autocapture"pacing systems. In 27 patients during ICD implanation intraoperatively, the IT-ECG was digitally recorded. A recently established algorithm for automatic P wave and EAP detection correctly identified 1663/1672 (99.5%) P waves (oversensing rate 0.6%) and 543/554 (98.0%) EAP (no oversensing). During subthreshold atrial stimulation, 405/412 (98.3%) P waves were correctly identified (oversensing due to pacemaker spikes, n = 421, without subsequent EAP, 1.9%,n = 8). During stimulated ventricular tachycardia in 26/27 patients retrograde P wave or AV dissociation were identified. The 6-lead IT-ECG, easily implementable in ICD systems, is a diagnostic tool providing reliable information about atrial activation, serving as a basis for VDD pacing in single chamber ICD systems, allowing reliable EAP recognition that enables atrial "autocapture"pacing in dual chamber ICDs, and improves the differentiation between supraventricular and ventricular tachycardia.
authors.affiliation: Universiätsklinikum Freiburg, Innere Medizin III, Kardiologie und Angiologie, Freiburg, Germany. grom@med 1.ukl.uni-freiburg.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Grom
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Baron
authors.forename: Michael
authors.initials: M
authors.lastname: Brunner
authors.forename: Ulrich
authors.initials: U
authors.lastname: Giesler
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Faber
authors.forename: Christoph
authors.initials: C
authors.lastname: Bode
authors.forename: Manfred
authors.initials: M
authors.lastname: Zehender
mesh_terms: D016275:Atrial Function / Q000502:physiology*; D017147:Defibrillators, Implantable; D004562:Electrocardiography / Q000295:instrumentation*; D022062:Electrophysiologic Techniques, Cardiac; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019736:Prostheses and Implants; D017180:Tachycardia, Ventricular / Q000503:physiopathology* / Q000628:therapy*