Use of an advanced mode switching algorithm in Inos 2 CLS and Logus dual chamber pacemakers

Abstract

Background: According to literature, 30–60 % of pacemaker patients suffer from paroxysmal atrial fibrillation (PAF). As rapid tracking of PAF may cause severe symptoms in patients with dual chamber pacemakers, refined algorithms providing AV synchronous pacing during periods of sinus rhythm and preventing high ventricular rates during PAF are highly desirable. Aim and method: This comprehensive paper introduces a new mode switching (MS) algorithm which uses either a fixed (Inos2CLS) or programmable (Logos) number of short intervals out of 8 consecutive atrial intervals to detect PAF. If the MS criterion is fulfilled, a switch from AV synchronous pacing to nontracking mode is automatically performed. The algorithm is described together with a discussion on optimization of the programming of parameters which may indirectly influence the MS sensitivity and specificity. Results: This MS concept maintains the high sensitivity and fast reactivity towards PAF of the “mode conversion” in Actros and Kairos pacemaker systems, preventing a long time delay between onset of PAF, detection of the arrhythmia, and switch to nontracking mode. In addition, adequeate sensing and short blanking periods in the new MS concept enable reliable MS. The occurrence of atrial oversensing should be tested, as it may lead to inappropriate MS. Programmability of the MS algorithm may be advantageous for individual programming with respect to the patients' arrhythmia rate and atrial sensing performance, but the use of very restrictive or very liberal criteria should be avoided as both may lead to mode oscillations. Finally, examples of stored diagnostic data are presented to assess MS reliability, identify possible problems, and optimize MS function during follow-up.