Benefits of Smaller Electrode Surface Area (4 mm2) on Steroid-Eluting Leads

The purpose was to test whether a reduction of pacemaker electrode surface area below 8 mm2 improves leads that elute steroid from the electrode tip to the surrounding myocardium. A standard-sized 8 mm2 lead with 1 mg dexamethasone was implanted in 12 patients and a lead with 4 mm2 electrode surface area and 0.5 mg dexamethasone in ten patients. Pacing threshold, impedance, and sensing threshold were measured at implantation and after 1, 4, and 12 weeks. Pacing thresholds were similar for both groups and were always less than or equal to 0.8 V at 0.5 msec pulse duration in all patients. Impedance was significantly higher (P less than 0.05) for the 4 mm2 lead (implantation: 726 +/- 119 ohms; 1 week: 596 +/- 71 ohms; 4 weeks: 624 +/- 68 ohms; 12 weeks: 643 +/- 56 ohms) than for the 8 mm2 lead (implantation: 422 +/- 43 ohms; 1 week: 402 +/- 48 ohms; 4 weeks: 439 +/- 57 ohms; 12 weeks: 449 +/- 61 ohms). R wave amplitudes did not differ between both groups; no sensing failure occurred at 5 mV sensitivity. Compared to the 8 mm2 lead the reduction of surface area to 4 mm2 did not influence pacing threshold, but resulted in a higher pacing impedance. The amount of pacing energy was lower in the smaller-sized electrode. For clinical impact, low pacing threshold and high impedance leads are the condition to implant pulse generators with smaller battery capacity.     

Determinants of Dual Chamber Pulse Generators Longevity

The aim of tbis 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 (PGl: 409; PG2:168) were retro-spectively reviewed. Battery capacity were 2.3 Ah (PGl) and 3.0 Ah (PG2) while current drain at compara-ble nominal settings was 20 μA (PGl) and 30 μA (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 PGl as compared to PG2 (17.1 ± 0.14 J vs 15.5 ± 0.24 f). Three PGl (0.7%) and 12 PG2 (7.1%) (P < 0.01) had to be exchanged after a mean of 77.3 ± 5.3 months (PGl) and 75 ± 13.5 months (PG2) (P = NS) due to end-of-life being reached. The difference in battery impedances of PGl and PG2 gained statistical significance 5 years after implantation (1.0 kΩ vs 2.4 ± 6.7 kΩ) 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 measurement of battery impedance.     

The glenoid notch and its relation to the shape of the glenoid cavity of the scapula

The prevalence of a notch in the anterior margin of the glenoid cavity of 236 scapulae (118 female, 118 male) was investigated. The notch was found in 129 scapulae (55%) and gave rise to a pear-shaped cavity. In 107 scapulae (45%) the notch was absent, the shape of the cavity being oval. No sex difference was found in the prevalence of the notch. If a distinct notch exists, the glenoid labrum is not attached to bone at the notch and is therefore liable to be sheared off (Bankart lesion).     

Renal Denervation for Treatment of Cardiac Arrhythmias: State of the Art and Future Directions

Renal Denervation for Treatment of Cardiac Arrhythmias . It has now been more than a quarter of a century since modulation of the sympathetic nervous system was proposed for the treatment of cardiac arrhythmias of different origins. But it has also been some time since some of the early surgical attempts have been abandoned. With the development of ablation techniques, however, new approaches and targets have been recently introduced that have revolutionized our way of thinking about sympathetic modulation. Renal nerve ablation technology is now being successfully used for the treatment of resistant hypertension, but the indication spectrum might broaden and new therapeutic options might arise in the near future. This review focuses on the possible impact of renal sympathetic system modulation on cardiac arrhythmias, the current evidence supporting this approach, and the ongoing trials of this method in electrophysiological laboratories. We will discuss the potential roles that sympathetic modulation may play in the future.