Current permanent right ventricular and right atrial endocardial pacing leads are implanted utilizing a central lumen stylet. Right ventricular apex pacing initiates an abnormal asynchronous electrical activation pattern, which results in asynchronous ventricular contraction and relaxation. When pacing from right atrial appendage, the conduction time between two atria will be prolonged, which results in heterogeneity for both depolarization and repolarization. Six patients with Class I indication for permanent pacing were implanted with either single chamber or dual chamber pacemaker. The SelectSecure 3830 4-French (Fr) lumenless lead and the SelectSite C304 8.5-Fr steerable catheter-sheath (Medtronic Inc., USA) were used. Pre-selected pacing sites included inter-atrial septum and right ventricular outflow tract, which were defined by ECG and fluoroscopic criteria. All the implanting procedures were successful without complication. Testing results (mean atrial pacing threshold: 0.87 V; mean P wave amplitude: 2.28 mV; mean ventricular pacing threshold: 0.53V; mean R wave amplitude: 8.75 mV) were satisfactory. It is concluded that implantation of a 4-Fr lumenless pacing lead by using a streerable catheter-sheath to achieve inter-atrial septum or right ventricular outflow tract pacing is safe and feasible.
Cardiac Pacing, Artificial/*methods ; Electrodes, Implanted ; Equipment Safety ; Pacemaker, Artificial ; Prosthesis Implantation/methods ; Sick Sinus Syndrome/*therapy

OBJECTIVEThe present study retrospectively evaluated the reliability of detecting atrial tachyarrhythmias (ATA), the efficacy of automatic atrial antitachycardia pacing (ATP) and the performance of atrial preventive pacing (APP) algorithms in an implanted antitachycardia DDDRP pacemaker for patients with sick sinus syndrome and paroxysmal ATA.

METHODSIn all 24 patients, a DDDRP pacemaker (Medtronic AT500/AT501) was implanted. APP algorithms were switched on at the implanting physician's discretion. During each pacemaker follow-up, information was saved to disk and the ATA burden between those patients with APP algorithms switched "ON" and "OFF" were compared. Reliability of ATA detection was determined by reviewing the stored electrograms and ATP efficacy was also reviewed. Both the pacemaker memory data and manual EGM retrieval were used for the analysis.

RESULTSComplication-free survival at (17.63 +/- 8.79) months was 100%. In 12 patients APP was not turned "ON" until the latest follow-up, in 6 patients APP was switched "ON" at their first visit after implantation, and in another 6 patients APP was switched "ON" after a median follow-up of 9.29 months. There were 97 367 episodes of ATA detected by the devices, of those with stored atrial electrograms the correct classification of ATA was (76.77 +/- 20.52)%. The percentage of atrial pacing with APP algorithms turned on was (87.95 +/- 20.93)%, which was significantly higher than that in patients with APP "OFF" (50.73 +/- 34.46)% (P < 0.01). ATP efficacy was (50.27 +/- 19.29)%. However, the ATA burden (14.73% vs 16.52%, or 7.52 hours vs 6.58 hours per week, P > 0.05) and the longest duration of single ATA episode (27.27 hours vs 20.75 hours, P > 0.05) were not significantly different between those patients with APP "ON" and "OFF". No proarrhythmic effect or major cardiovascular event was observed.

CONCLUSIONSThe antitachycardia DDDRP pacemaker correctly detects and diagnoses about 75% of the ATA episodes, while the ATP therapy successfully terminates atrial tachycardia or flutter in about 50% of attacks. However, there is no difference in ATA burden with the APP algorithms and high incidence of atrial pacing. As a non-curative therapy strategy, this high-cost device may only be used in strictly selected indication patients in addition to other treatments of ATA.

Aged ; Aged, 80 and over ; Algorithms ; Atrial Fibrillation ; diagnosis ; prevention & control ; therapy ; Cardiac Pacing, Artificial ; methods ; Electrophysiologic Techniques, Cardiac ; Female ; Follow-Up Studies ; Humans ; Male ; Middle Aged ; Pacemaker, Artificial ; Retrospective Studies ; Treatment Outcome

Current permanent fight ventricular and fight atrial endocardial pacing leads are implanted utilizing a central lumen stylet. Right ventricular apex pacing initiates an abnormal asyno chronous electrical activation pattern, which results in asynchronous ventricular contraction and re-laxation. When pacing from right atrial appendage, the conduction time between two atria will be prolonged, which results in heterogeneity for both depolarization and repolarization. Six patients with Class Ⅰ indication for permanent pacing were implanted with either single chamber or dual chamber pacemaker. The SelectSecure 3830 4-French (Fr) lumenless lead and the SelectSite C304 8.5-Fr steerable catheter-sheath (Medtronic Inc., USA) were used. Pre-selected pacing sites included inter-atrial septum and right ventricular outflow tract, which were defined by ECG and fluoroscopic criteria. All the implanting procedures were successful without complication. Testing results (mean atrial pacing threshold: 0.87 V; mean P wave amplitude: 2.28 mV; mean ventricular pacing threshold:0.53V; mean R wave amplitude: 8.75 mV) were satisfactory. It is concluded that implantation of a 4-Fr lumenless pacing lead by using a streerable catheter-sheath to achieve inter-atrial septum or right ventricular outflow tract pacing is safe and feasible.