Low atrial septum pacing in pacemaker patients

Abstract

In patients with an indication for anti bradycardia pacing, atrial fibrillation (AF) is a common arrhythmia (30-50%) even in the absence of atrial tachy arrhythmias before pacemaker implantation. Pace prevention and pace intervention for atrial tachy arrhythmias could be an interesting adjuvant treatment in the prevention of the arrhythmia related complications. These treatment modalities when available in pacemaker systems could come at a relative low cost as the indication for pacemaker implant already exists. This thesis is aimed to explore the possibilities of an alternative atrial site pacing modality in the prevention of AF in pacemaker patients. Though the "perfect candidate" for this kind if preventive pacing is not clearly evident, the method of pacing and its feasibility is explored. Chapter 2-3-4 The technique of low atrial septum pacing is more complicated as compared to RAA pacing. The technique of implantation with the aid of a locator tool, its pitfalls and the verification of a proper right low atrial septal lead positioning is described and the results are evaluated. The typical ECG is described, electrical measurements as pacing threshold, sensing, impedance and far field R-wave detection are compared to the more traditional right atrial appendage pacing. Chapter 5 When the result of a therapy is to be appreciated, the yardstick for measurement should be reliable. For this reason the duration of the automated mode switch (AMS) was compared with 7 days Holter derived atrial arrhythmia data. Cumulative duration of AF and atrial tachycardia (AT) from Holter was correctly interpreted by the pacemaker in 99.9 %. In patients with AT without AF on Holter the cumulative AT duration did not compare well (63%) with the Holter recordings. The number of mode switches does not reflect the number of episodes of AF/AT. Chapter 6 A good sensing characteristic of atrial arrhythmias (AA) is imperative for AA prevention and intervention pacemakers. A newly designed bipolar screw-in lead was evaluated. As a result of the positive outcome with the animal study, an acute human experiment was performed. In the acute human tests in 15 patients, the mean P-wave voltage was comparable with the commercially available lead. The far field signal reduction was importantly improved (p < 0.0001). Pacing thresholds and pacing impedances were comparable. Chapter 7 A prospective patient blinded study was performed to evaluate right atrial appendage (RAA) and low atrial septum (LAS) overdrive pacing to non overdrive pacing on the AF burden in 280 pacemaker patients. The algorithm was switched on or off in a 3 month, single blind crossover design and antiarrhythmic drugs were kept stable. A control group of 96 patients without PAF served to assess any proarrhythmic effect of overdrive pacing. AF burden was not reduced during automatic atrial overdrive neither from the RAA nor from the LAS. There was no proarrhythmia induced by the overdrive algorithm in the control group. At this moment in time, it is unlikely that pacemaker mediated therapy for AF will be effective in pacemaker patients as single strategy.