New ICD‐Technologies: First Clinical Experience with Dual‐Chamber Sensing for Differentiation of Supraventricular Tachyarrhythmias

Abstract

Inappropriate ICD therapy for supraventricular arrhythmias remains an unsolved problem and may lead to serious clinical situations. Current algorithms for differentiation of supraventricular and ventricular arrhythmias are based on ventricular sensing solely and, therefore, lack sensitivity and specificity. This preliminary analysis from a multicenter trial comprises data from the first 26 patients who received a Res-Q Micron active-can ICD (Sulzer Intermedics) with a ventricular defibrillation lead and an additional bipolar lead for atrial sensing. Digitized atrial and ventricular waveform storage as well as interval charts from 102 induced and 30 spontaneous arrhythmia episodes were prospectively collected and analyzed with regard to appropriateness of ICD therapy. From all 132 arrhythmia episodes, high-quality stored dual-chamber intracardiac electrograms (IEGM) could be retrieved for further analysis: in 40 (30%) episodes, atrial fibrillation (AF with rapid ventricular response 22, AF with VT 9, AF with VF 9) was identified as the underlying intrinsic rhythm, and inappropriate ICD therapy was delivered in 4/22 (18%) episodes of AF with rapid ventricular response. In the remaining 92 (70%) episodes, sinus rhythm was the underlying atrial rhythm (SR with VT 13, SR with VF 79), and no inappropriate therapy was observed. Three of 22 (15%) high-energy shocks delivered for ventricular arrhythmias (VT 9, VF 9, rapid AF 4) terminated AF at the same time. In total, there were 3 complications (2 atrial lead dislodgments, 1 revision for bleeding). Both atrial lead dislodgments occurred in the 2 patients with passive-fixation leads compared to none in the 24 patients with active-fixation leads (p = 0.003). In conclusion, dual-chamber sensing and waveform storage of the new Res-Q Micron offer very helpful diagnostic tools for the detection of inappropriate ICD-therapy. Placement of an additional atrial lead is safe and does not interfere with proper ICD function. However, for avoidance of atrial lead dislodgment, active fixation leads are recommended. With the tested active-can lead configuration, the efficacy of successful atrial cardioversion by high-energy shocks delivered for ventricular arrhythmias seems to be low.

Methods of minimizing inappropriate implantable cardioverter-defibrillator shocks

“…In our own study, which evaluated another dual-chamber algorithm (Res-Q Micron, Sulzer-Intermedics; Winterthur, Switzerland) in comparison with the performance of a single-chamber algorithm (sudden onset + rate stability) in the same device, we had similar findings with nominal default settings: the sensitivity for proper discrimination of supraventricular arrhythmias was 79% with the singlechamber algorithm and 61% with the dual-chamber algorithm [21,22]. The main reasons for misclassifications were atrial farfield sensing leading to "abnormal" AV-intervals, which were interpreted as VA conduction, and atrial undersensing after high-energy shocks.…”

Komplikationen mit Sonden bei 340 Patienten mit einem implantierbaren Kardioverter/Defibrillator

“…Zwischen Patienten mit und ohne sondenbedingte Komplikationen bestanden keine signifikanten klinischen Unterschiede, lediglich die Nachbeobachtungsdauer betrug bei den Patienten ohne sondenbedingte Komplikation 25 ± 21 Monate vs 45 ± 24 Monate mit Komplikation bedingt durch frŸher implantierte komplikationstrŠchtigere Systeme. Die von anderen Untersuchern ermittelte Komplikationsrate mit Sonden betrug 2Ð16 %, je nach Grš §e des Patientenkollektivs, der Nachbeobachtungsdauer, der verwendeten Elektroden, des Anteils der Patienten mit abdominellem Aggregat und mit Patch-oder Array-Elektroden (1,2,7,9,10,11,13,14,16,19,20,21).…”

Implantable dual-chamber cardioverter-defibrillator-pacemaker

“…Newer mechanisms of inappropriate ICD discharges by atrial undersensing [58], T-wave oversensing [36•,54] or dependent on the software are described [59,60]. In contrast to the recommendation of an additional atrial fixed lead [61], preliminary data documented that a new VDD lead provides stable detection of atrial signals during sinus rhythm or SVT in a German multicenter study in 30 patients [62]. Inappropriate interventions have not been as fully suppressible up to now in dual-chamber ICDs as in singlechamber ICDs.…”