No abstract

The aim of this study was to investigate the effect of battery capacity, internal current drain, and stimulation energy on pulse generators longevity, and if battery impedance measurements can reliably predict pulse generators end-of-life. For this purpose, the records of 577 patients with a mean age of 65 +/- 14 years who had undergone implantation of two different dual chamber pulse generators (PG1: 409; PG2: 168) were retrospectively reviewed. Battery capacity were 2.3 Ah (PG1) and 3.0 Ah (PG2) while current drain at comparable nominal settings was 20 microA (PG1) and 30 microA (PG2) indicating a higher internal current drain of PG2. After a mean follow-up of 46 +/- 23 months, stimulation energy at reprogrammed output settings was significantly higher in PG1 as compared to PG2 (17.1 +/- 0.14) vs 15.5 +/- 0.24 J). Three PG1 (0.7%) and 12 PG2 (7.1%) (P < 0.01) had to be exchanged after a mean of 77.3 +/- 5.3 months (PG1) and 75 +/- 13.5 months (PG2) (P = NS) due to end-of-life being reached. The difference in battery impedances of PG1 and PG2 gained statistical significance 5 years after implantation (1.0 k omega vs 2.4 +/- 6.7 k omega) preceding the significant difference in PG survival after 6 years (98.7 +/- 1.3% vs 90.7 +/- 4.8%). These results indicate that internal current drain is the most important determinant of the pulse generators longevity and that battery impedance can reliably predict end-of-life. Therefore, the essential information about internal current drain should be available for each pacemaker, since it is required for adequate pulse generator selection. Diagnostic functions of dual chamber pulse generators should include measurements of battery impedance.

In the beginning of transvenous pacemaker therapy, the external or alternatively internal jugular vein was commonly used for lead implantation. Due to frequent long-term complications both approaches are nowadays obsolete. In most pacemaker centers implantation via the cephalic vein has become standard. As an alternative, in 1975 Sterz et al. introduced puncture of the subclavian vein in the Seldinger technique as an approach for lead implantation. At this time, the commonly used introducers of pacemaker leads had to be cut for removal. No earlier than 1980 "peel away" introducers were commercially available. Since then, we consequently use this technique for implantation of single or dual chamber pacemaker devices. In the course of the last seven years merely 1.5-2% of implantations were performed via the cephalic vein; no jugular vein approach was performed. Due to a routinely performed subclavian vein puncture, we were able to optimize the procedure, proven by an enormous reduction in implantation time (local anesthesia - skin closure), x-ray time and complication rate. In the year 2000 we performed 52 implantations of a single chamber device with an average fluoroscopy time of 1.5 (0.3-9.3) minutes, radiation dose of 4.5 (0.1-47) Gycm(2) and implantation time of 17.6 (8-40) minutes and 144 implantations of a dual chamber device with an average fluoroscopy time of 2.86 (0.7-6.6) minutes, radiation dose of 8.31 (0.7-28) Gycm(2) and implantation time of 21.25 (10-45) minutes. Complications were rare, clinically irrelevant arterial punctures. Neither nerval damage nor pneumothoraces with the necessity for chest tube placement were seen in the above mentioned time frame. No early or late thrombosis of the subclavian vein was encountered.    The primary subclavian vein approach led to an enormous reduction in overall procedure time without significant morbidity.

The individual adjustment of the AV intervals is a prerequisite for the hemodynamic advantages of dual-chamber pacing. The methods for the optimization of the AV-Delay (AVD) applied so far are time intensive. A simple and fast method is the approximate adjustment of the AVD with the surface-ECG. The aim of this work is the conception and validation of this new method. The optimal AVD is given if at the end of the atrial contraction the mitral valve is closed by the ventricular increase of pressure. In order to achieve this with pacemaker patients, the individually different atrial and ventricular conduction times must be considered. The different conduction times can be determined from the surface-ECG. Intra- and interatrial conduction times can be defined by the beginning of the atrial spike up to the end of the p-wave. The beginning of ventricular pressure increase corresponds to the peak of the stimulated QRS complex (beginning of the Iso-Volumetric Contraction time, ISVC) and depends on the interventricular conduction time.¶   In the case of 100 patients, who did not receive a cardiac pacemaker, the interval at the end of the p-wave (left atrial excitation, EP) up to the peak of the r-wave (ISVC) during rest and exercise was measured and an age referred average value of 100ms determined; this serves as standard value if no AV-conduction is available. The approximated optimized AVD is given if the interval of the end at the p-wave to the peak of the QRS-Complex amounts to 100ms. By means of a simple algorithm, the optimized AVD can, thus, be calculated:¶   After programming a long AVD, the interval at the end of the native or paced p-wave up to the peak of the stimulated QRS-Complex (EP/ISVC) is determined. This value EP/ISVC is then taken from the long AVD, the 100ms standard value is added and one receives the approximately optimized AVD.¶   In order to validate the described method, 13 consecutive patients (2 female, 11 male, average age 67±7.8 years) were included, and received for different indication (7 sick sinus syndrome, 4 AV block III, 2 binode disease) a DDD pacemaker (Affinity, St. Jude Medical).¶   About 8 weeks after implantation all patients underwent a PA catheter investigation, in order to optimize the AV-/PV-Delay of the pacemaker regarding the maximum cardiac output (CO). For CO measurement the thermo dilution method was applied. Altogether 17 complete hemodynamic measurements (9 times with different PVDs, 8 times with different AVDs) were executed. The patients 10-13 could be examined both in the VDD and in the DDD mode.¶   The minimum determined CO amounted to 3.5 l/min, the maximal CO 7.1 l/min and the average value was 5.62±0.98 l/min. In all patients not only one optimal AVD was found but, moreover, a varied interval of AVDs with which optimal CO results could be obtained. The comparison of surface ECG optimized AVD with the PA catheter optimized AVD showed a statistically significant correlation (0.825PV, 0.982 AV, P<0.01). Sixteen out of seventeen measurements were at an interval whic...