Pacemaker dependency after pacemaker implantation

Background: Pacemaker dependency (PD) can be defined as the risk of serious injury or death from sudden pacemaker failure, an event more dangerous than progressive rate decrease. The aim of this study was to evaluate the incidence of PD during long-term follow-up after pacing system implantation. Methods and Results: The study included 3638 patients (mean age 65.3 &plusmn; 10.2 years). Indications for pacing were sick sinus syndrome (SSS) in 1315 patients, atrioventricular block (AVB) in 1482, AVB and SSS in 478 and atrial fibrillation (AF) with bradycardia in 363 patients. The mean follow-up was 4.8 &plusmn; 1.8 years. Pacemaker dependency was defined as the absence of an intrinsic rhythm of 30 beats/min during back-up pacing and after switching off the pacemaker. If any significant symptoms of bradycardia developed or if the underlying rhythm did not appear (asystole > 5 s) the pacing was restarted. Pacemaker dependency was observed in 76 (2.1%) of the 3638 patients. In this subgroup pacing indications were SSS in 8 (0.6%) of 1315 patients, AVB in 52 (3.5%) of 1482, SSS and AVB in 15 (3.1%) of 478 and AF with bradycardia in 1 (0.3%) of 363. Patients with AVB had a significantly higher incidence of PD than patients with SSS or AF (p < 0.001, p < 0.005, respectively). A total of 139 patients suffered from myocardial infarction and 106 patients had a temporary pacing prior to pacemaker implantation. The majority of these patients were pacemaker dependent (p < 0.001). Conclusions: In our study PD occurred very rarely, being found in 2.1% of all patients. Patients with AVB have a significantly higher incidence of PD than patients with SSS or AF. Temporary pacing prior to pacemaker implantation and previous myocardial infarction indicate patients at risk of PD development. (Cardiol J 2007; 14: 83&#8211;86

Transient atrioventricular block following catheter radiofrequency sinus node modification

Complete atrioventricular block, second-degree Mobitz type II and first-degree atrioventricular block with right bundle branch block were observed consecutively following successful radiofrequency ablation in close proximity to the sinus node. This resulted in the modification and disappearance of the inappropriate sinus tachycardia that had previously been present. Neither tachycardia nor conduction disturbances have been recorded in the 9-year follow-up, implying that ventricular pacing standby should also be considered in high atrial ablation cases

Transient atrioventricular block following catheter radiofrequency sinus node modification

Complete atrioventricular block, second-degree Mobitz type II and first-degree atrioventricular block with right bundle branch block were observed consecutively following successful radiofrequency ablation in close proximity to the sinus node. This resulted in the modification and disappearance of the inappropriate sinus tachycardia that had previously been present. Neither tachycardia nor conduction disturbances have been recorded in the 9-year follow-up, implying that ventricular pacing standby should also be considered in high atrial ablation cases. (Cardiol J 2007; 14: 504-507

Retrospective analysis of reasons for failure of DDD pacemaker implantation in patients operated on between 1993 and 2005

Background: During implantation of a DDD pacemaker the following difficulties may be encountered: venous anomalies (the absence of vessels of adequate calibre or difficulty in subclavian vein puncture), arrhythmias during implantation (episodes of atrial flutter/fibrillation while the atrial leads are being positioned), lack of mechanical stability of the electrode in the heart chamber and inability to achieve an acceptable pacing and sensing threshold during implantation. The purpose of the study was to analyse retrospectively the reasons for DDD pacemaker failure in patients operated on between 1993 and 2005. Methods: We reviewed retrospectively all implantation data from 1988 to 2005 to identify patients with primary failure of DDD pacemaker implantation. Further analysis included patients who had received a DDD pacemaker between 1993 and 2005, when this type of pacemaker made up between 9 and 40% of all pacemaker implantations. We implanted 7469 pacemakers, including 1958 (26.2%) dual-chamber pacemakers, in 783 patients with atrioventricular block (AVB), 392 with sick sinus syndrome (SSS), 450 with AVB &#177; SSS and 333 with tachy-brady syndrome (TBS). The mean age of the patients was 65.5 &#177; 17.3 years. DDD pacing was unsuccessful in 108 (1.4%) patients, including 32 with AVB, 22 with SSS, 16 with SSS &#177; AVB and 38 with TBS. The mean age of these patients was 78.5 &#177; 19.4 years. Results: The reasons for failed implantation were venous anomalies in 12%, an arrhythmia episode in 27.8%, a high pacing threshold in the atrium in 17.6%, low atrial potential amplitude in 25.9% and lack of mechanical stability of the electrode in 16.7% of patients. The difficulties were encountered in elderly patients (p < 0.01), most frequently in patients with SSS and TBS (71). Between 2004 and 2005 venous anomalies and a high pacing threshold were the main causes of failure. Conclusions: Currently the main difficulties encountered during pacemaker implantation are venous anomalies and a high pacing threshold. Arrhythmia episodes, low atrial potential amplitude and lack of mechanical stability are of minor importance. Elderly patients with sick sinus syndrome and tachy-brady syndrome have the highest failure rate. (Cardiol J 2007; 14: 155-159

Forms of the symmetry energy relevant to neutron stars

The symmetry energy is an invaluable tool for studying dense nuclearmatter. Unfortunately, its definition is somewhat implicit, and therefore, phenomenologicalmethods are necessary to describe experimental facts. This paper discusses the differences arising from the use of Taylor series expansion and Padé approximation to determine theoretically the symmetry energy and the possible consequences for neutron stars. For this purpose, a form of the nuclear matter equation of state that explicitly depends on the symmetry energy is used. The obtained results point out that the applied approximations lead to modifications of the equilibrium proton fractions and equation of state, especially in their high-density limit. However, this effect is small near the saturation density n0

Percutaneous extraction of a coiled, 20-year-old lead in a patient with cardiac resynchronization therapy

A 61-year-old patient with a 20-year history of permanent pacemaker implantation and half- -a-year cardiac resynchronization therapy using a left ventricular lead placed via surgical approach was admitted for extraction of an old coiled right ventricular lead, which triggered ventricular arrhythmia and created a risk of pulmonary embolism. The lead was extracted via the left femoral vein in two stages: untying a loop on the lead using a pig-tail catheter and Dotter basket followed by traction and dissection of adhesions using a Byrd dilator sheath. Dissection of the old lead from the active right ventricular one posed special technical problems