Long-term symptom improvement and patient satisfaction after AV-node ablation vs. pulmonary vein isolation for symptomatic atrial fibrillation: results from the German Ablation Registry.

BACKGROUND: We aimed to compare patient characteristics and outcome of patients who had either undergone pulmonary vein isolation (PVI) or AV-node ablation (AVN) to control AF-related symptoms. METHODS: From the German Ablation Registry, we analyzed data of 4444 patients (95%) who had undergone PVI and 234 patients (5%) with AVN. RESULTS: AVN patients were on average 10 years older than PVI patients (71 ± 10 vs. 61 ± 10 years, p < 0.001) with 33% aged > 75 years. AVN patients had significantly more cardiovascular comorbidities (diabetes 21% vs. 8%, renal insufficiency 24% vs. 3%, underlying heart disease 80% vs. 36%, severely reduced left ventricular function 28% vs. 1%, all p < 0.001). Significantly more PVI patients had paroxysmal AF (63% vs. 18%, p < 0.001), and more AVN patients had long-standing persistent AF (44% vs. 7%, p < 0.001). At 1-year follow-up, mortality in the AVN group was much higher (Kaplan-Meier estimates 9.8% vs. 0.5%). 20% of PVI patients had undergone another ablation vs. 3% AVN patients (p < 0.001). Symptomatic improvement was equally achieved in about 80%. Re-hospitalization for cardiovascular reasons occurred significantly more often in PVI vs. AVN patients (31% vs. 18%, p < 0.001). CONCLUSION: In the large German Ablation Registry, AVN ablation was performed much less frequently than PVI for symptomatic treatment of AF and typically in older patients with more comorbidity. Symptomatic improvement was similar in both groups. Hospitalizations for cardiovascular reasons were lower in AVN patients despite older age and more cardiovascular comorbidities. 20% of PVI patients had undergone at least one re-ablation.

Verbal aggression in computer-mediated decision making.

37 participants receiving verbally aggressive messages during a mediated interaction viewed their interactants as less socially attractive.

[Anticoagulation in primary prevention of thromboembolism in advanced left ventricular dysfunction]. / Antikoagulation zur Primärprophylaxe thromboembolischer Ereignisse bei fortgeschrittener linksventrikulärer Funktionseinschränkung.

BACKGROUND: Patients with heart failure have an increased risk for thromboembolic events. In clinical practice the physician is often confronted with the decision to establish a prophylactic anticoagulation. DATA: The incidence for clinical embolization is 1.5 to 3.5% per year. It seems that patients with a lower peak oxygen uptake and with a lower ejection fraction are at higher risk for embolic events. There is no evidence for a correlation of such events with the clinical classification (NYHA) or with the genesis of heart failure. Concerning a prophylactic anticoagulation, the results of the published studies and meta-analyses are inhomogenous with a benefit in some, no difference in others and a significant disadvantage for the patients with anticoagulation in a part of them compared to a non-treated control group. None of these data is established by a prospective, randomized, controlled study with the primary endpoint thromboembolic event in patients with or without anticoagulation. The incidence for a hemorrhage under anticoagulation is 0.6-5.3% per year for life-threatening and 0.04-0.64% for fatal bleeding. CONCLUSION: Because of similar incidences for thromboembolic events and for the bleeding complication of anticoagulation, there is no evidence for a general indication for anticoagulation of patients with heart failure, persistent sinus rhythm and lack of risk factors. In patients with high-grade heart failure (e.g. VO2max < 14 ml/min/kg body weight or left ventricular ejection fraction < 20-30%), who belong to a high-risk population, anticoagulation should be considered and may be acceptable in individual cases.

[Morphological changes in correlation with so-called idiopathic ventricular tachycardias from the right ventricular outflow tract]. / Morphologische Veränderungen im Zusammenhang mit sogenannten idiopathischen Kammertachykardien aus dem rechtsventrikulären Ausflusstrakt.

"Idiopathic" ventricular tachycardia is an exclusion diagnosis. The underlying reasons and mechanisms of "idiopathic" ventricular tachycardias are still not completely understood. Recent investigations showed a high prevalence of morphological abnormalities in the right ventricle of patients with "idiopathic" ventricular tachycardia out of the right ventricular outflow tract, which could often be correlated with the origin of the ventricular tachycardia. These described abnormalities were not uniform. Here we report about a patient suffering from drug-refractory "idiopathic" ventricular tachycardia for 10 years. This is the first report in which the origin of an "idiopathic" ventricular tachycardia could be localized by right-ventricular angiography, magnetic resonance tomography and electrophysiological study in the area of an interventricular septal thickening of the right ventricular outflow tract and cured by radiofrequency catheter ablation.

[Drug and electrical therapy of supraventricular tachyarrhythmias]. / Medikamentöse und elektrische Therapie supraventrikulärer Tachyarrhythmien.

This article reviews current pharmacological and electrical approaches to the restoration of sinus rhythm in patients who suffer from atrial fibrillation and atrial flutter. Spontaneous conversion to sinus rhythm occurs in a high proportion of atrial fibrillation of < 24 h duration. Among patients presenting with atrial fibrillation, which was clinically estimated to have lasted < 48 h, the likelihood of cardioversion-related clinical thromboembolism is low, which supports the current practice of early cardioversion without anticoagulation. Antiarrhythmic drugs effective in terminating atrial fibrillation of short duration are those which possess class IA, IC and III properties. Electrical transthoracic cardioversion by using different electrode positions and additional pressure over the electrodes during shock delivery is a highly effective and well-tolerated method in restoration of sinus rhythm even in patients under conscious sedation. Immediate spontaneous reinitiation of atrial fibrillation can occur in a significant proportion of patients undergoing electrical cardioversion and can be reduced after a pretreatment with antiarrhythmic drugs. In patients with failed external cardioversion, internal low energy cardioversion offers an effective option for restoring sinus rhythm. After cardioversion in a high proportion of patients antiarrhythmic drugs are necessary to prevent atrial fibrillation from recurring. A serial cardioversion approach can prevent the evolution of permanent atrial fibrillation in a subgroup of patients. Overdrive atrial pacing is an effective and minimally invasive procedure for termination of atrial flutter. The acute administration of class IA, IC and III antiarrhythmic drugs increases the success rate of this method in restoring sinus rhythm.

[Atrial defibrillators]. / Atriale Defibrillatoren.

The promising results achieved with low-energy, internal atrial cardioversion have stimulated the development of an implantable atrial defibrillator. Initial clinical experience with the Metrix system in a group of highly selected patients with refractory atrial fibrillation (AF) suggests that atrial defibrillation can be performed effectively and safely by using a stand-alone device. The extension of this therapy will depend on the results of further prospective studies comparing this new therapeutic option with other new non-pharmacological methods to treat AF. Internal atrial cardioversion is feasible at low energies with current endocardial transvenous lead configurations primarily designed for ventricular defibrillation. As AF is a frequent arrhythmia in implantable cardioverter defibrillator recipients, the capability for atrial defibrillation has recently been incorporated in a newly designed dual chamber defibrillator (Jewel AF system). Initial clinical experience with this device that combines both detection and treatment in the atrium as well as in the ventricle indicates a significant improvement in the management of patients with both supraventricular and ventricular tachyarrhythmias.

[Is ICD-programming for double intraoperative defibrillation threshold energy safe and effective during long-time follow-up? Results of a prospective randomized multicenter study (Low-Energy Endotak Trial--LEET)]. / Ist eine ICD-Programmierung auf eine Schockenergie der doppelten intraoperativen Defibrillationsschwelle im Langzeitverlauf sicher effektiv? Ergebnisse einer prospektiven randomisierten Multizenterstudie (Low Energy Endotak Trial-LEET).

The aim of this prospective and randomized study was to evaluate the safety and efficacy of a reduced shock strength in transvenous implantable defibrillator therapy. So far clinical data concerning the safety margin of the shock energy in ICD therapy do not exist. The shock energy tested during long-term follow-up in this study was twice the intraoperatively measured defibrillation threshold (DFT). A total number of 176 consecutive patients representing a typical cohort of ICD patients were evaluated. All patients received a non-thoracotomy lead system (CPI, Endotak 0070, 0090) and a biphasic cardioverter-defibrillator with the ability to store episodes (Cardiac Pacemakers Inc., Ventac TM PRx II, PRx III). The intraoperative defibrillation threshold (DFT) was evaluated in a step-down protocol (15, 10, 8, 5 J) and had to be < or = 15 J for inclusion into the study. The lowest effective energy terminating induced ventricular fibrillation had to be confirmed and was defined as DFT+ augmented defibrillation threshold. The DFT+ value was tested immediately after successful implantation, at discharge, and after a follow-up period of one year. Prior to implantation the patients were randomized into two groups. The energy of the first shock in the study group was programmed at twice DFT+ and in the control group at the maximum energy output (34 J). The efficacy of the first shock and its reproducibility in DFT testings and in spontaneous episodes during long-term follow-up of the study group were compared to those in the control group. A DFT+ value was found to be < or = 15 J in 166 of 176 patients (94%). The DFT+ in the study group was 9.6 +/- 3.2; in control group 10.1 +/- 3.5 J. The prohability of successful defibrillation at DFT+ level after one year was 84%. The success rate of the first shock meant to terminate induced ventricular fibrillation (VF) was 99.5% in the study group (217 of 218 episodes) and 99% in the control group (201 of 203 episodes). During follow-up of 24 +/- 9 months spontaneous episodes in the study group, 83/86 (96.5%) monomorphic ventricular tachycardias (MVT) and 38/40 (95%) VF-episodes were converted successfully by the 2x DFT+ shock. In the control group the first shock was successful in 151/156 (96.8%) spontaneous MVTs and in 30/33 (91%) VF episodes. The efficacy of the first shock was not influenced by clinical data such as the underlying cardiac disease, left ventricular function, ongoing antiarrhythmic therapy with amiodarone, or the number of spontaneous episodes per day or by the DFT itself. At a mean follow-up of two years there was no significant difference between the two groups concerning the incidence of sudden cardiac death (2.4% in the study group vs. 3.8% in the control group). In conclusion programming the first shock with the ICD lead system used in this study at 2x DFT+ is as efficient as a shock energy of 34 J in order to terminate induced and spontaneous episodes of VT/VF. Thus, the safety of ICD-therapy is not impaired when programming the shock energy at the 2x DFT+ value.

Safety and efficacy of implantable defibrillator therapy with programmed shock energy at twice the augmented step-down defibrillation threshold: results of the prospective, randomized, multicenter Low-Energy Endotak Trial.

Whether the safety and efficacy of implantable cardioverter defibrillator (ICD) therapy can be assured with lower output devices is an important question. The purpose of this study was to evaluate whether programming the device output at twice the augmented defibrillation threshold was as safe and effective as using the maximum energy. Patients indicated for ICD therapy, but without slow monomorphic ventricular tachycardia (MVT), who achieved an augmented defibrillation threshold (DFT plus) < or = 15 joules (J) with a single endocardial lead system and a biphasic defibrillator were included in the study. Prior to ICD implantation, patients were randomized into 2 groups. The shock energies in test group patient were set as follows: first shock at twice DFT plus, the second to fifth shocks at maximum output (34 J). In control group patients, all shocks were programmed at 34 J. The study population consisted of 166 consecutive patients (mean age 57.4 +/- 12.1 years, mean left ventricular ejection fraction 36.8 +/- 13.8%). Mean DFT plus was 9.6 +/- 3.2 J in test group patients and 10.1 +/- 3.5 J in control group patients (p = 0.36). During a mean follow-up of 24.2 +/- 9.6 months, 736 arrhythmia episodes were analyzed. The first shock efficacy was 98.3% in the test group patients versus 97.4% in the control group (p = 0.45). Total mortality was 6%, equally distributed in both study groups. The results of this study prove that the method of doubling the defibrillation energy at the DFT plus level provides an adequate safety margin in defibrillator therapy.

The atrial defibrillator: a stand-alone device or part of a combined dual-chamber system?

Atrial fibrillation (AF) is an extremely common arrhythmia seen in clinical practice. Because of the limited efficacy of traditional therapeutic strategies to restore and maintain normal sinus rhythm, several nonpharmacologic options have evolved. The promising results achieved with internal atrial defibrillation have facilitated the development of an implantable atrial defibrilator. Preliminary results obtained from an initial study on a small number of highly selected patients with refractory AF suggest that atrial defibrillation can be performed effectively and safely with adequate patient tolerance by using a stand-alone device. The extension of this therapy will depend on the results of well-designed prospective studies comparing this new therapeutic option with traditional methods. Several acute studies have shown that internal conversion of AF is feasible at low energies with current endocardial transvenous lead configurations primarily designed for ventricular defibrillation, but long-term efficacy has, to date, only been demonstrated with atrial implantable defibrillator lead systems. As AF is a frequent arrhythmia in implantable cardioverter defibrillator (ICD) recipients, it would seem desirable to incorporate the capability for atrial defibrillation into an ICD. Clinical studies have shown that an atrial defibrillator, as part of a combined dual-chamber ICD system, may not require a potentially complicated switching network for establishing different electrode configurations for atrial and ventricular tachyarrhythmia. The efficacy in atrial cardioversion of such a combined, less complex device seems to be as high as reported for a pure atrial defibrillator, but generally at somewhat higher energy requirements. The results of further investigations will show whether a dual-chamber cardioverter defibrillator would be of clinical relevance in patients with ventricular and supraventricular tachyarrhythmia.

Clinical significance of sleep-related breathing disorders in patients with implantable cardioverter defibrillators.

The prevalence and clinical significance of sleep-related breathing disorders (SRBDs) in patients with cardiac disease and a history of life-threatening ventricular tachyarrhythmias is unclear. Forty consecutive recipients of implantable cardioverter defibrillators (ICDs) with cardiac disease and a documented history of spontaneous, life-threatening, ventricular tachyarrhythmias underwent full night polysomnography. SRBDs were diagnosed if the apnea/hypopnea index was > 10. SRBD were diagnosed in 16 of 40 patients (40%): central sleep apnea (CSA) was present in 9 of these 16 patients (56%), 8 of whom had associated Cheyne-Stoke respiration. Seven of the 16 patients with SRBD (44%) had obstructive sleep apnea (OSA). Patients with and without SRBDs were comparable with respect to left ventricular ejection fraction, NYHA classification, underlying heart disease, ICD indications, and concomitant antiarrhythmic drug and beta-blocker therapy. Patients were followed prospectively for 2 years. ICD-treated ventricular tachyarrhythmias occurred in 10 of 24 patients (42%) without SRBD, in 4 of 9 patients (44%) with CSA, and in 3 of 7 patients (44%) with OSA (NS). The numbers and circadian distributions of episodes recorded during follow-up in patients without SRBD versus with CSA or OSA were not significantly different (14 +/- 25, median = 4 vs 4 +/- 5, median = 2.5 vs 15 +/- 15, median = 7, respectively). The 2-year mortality, which was entirely attributable to nonsudden cardiac events, was highest in patients with CSA (4/9 [44%], vs 0/7 [0%] with OSA, vs 3/24 patients (12.5%) without SRBD; P < 0.05).

Transvenous atrial cardioversion threshold in patients with implantable cardioverter defibrillator: influence of active pectoral can.

Recent studies have shown that transvenous atrial cardioversion is feasible with lead configurations primarily designed for implantable cardioverter defibrillators (ICD). The purpose of this study was to examine the influence of an active pectoral ICD can on the atrial cardioversion threshold (ADFT). Forty consecutive patients received a transvenous single lead system (Endotak DSP 0125, CPI, St. Paul, MN, USA) in combination with a left subpectoral ICD (Ventak Mini, CPI) for treatment of malignant ventricular tachyarrhythmias. Patients were randomized into two groups: 21 received a Hot Can 1743 and 19 patients a Cold Can 1741. Step-down testing of the ventricular defibrillation threshold (VDFT) was performed intraoperatively and evaluation of the ADFT for induced atrial fibrillation (AF) at predischarge. After testing, each patient received a 2-J shock and was asked to quantify discomfort on a numerical scale ranging from 0 to 10. Both groups were comparable with regard to all clinical parameters studied. The mean VDFT in patients with a Hot Can device was significantly lower than in patients with a Cold Can (7.5 +/- 2.3 J vs 9.8 +/- 3.8 J; P < 0.03). The mean ADFT in the Hot Can group tended to be lower than in the group with Cold Cans (3.4 +/- 1.4 J vs 4.5 +/- 2.4 J; P = 0.07), and the proportion of patients in whom atrial cardioversion was accomplished at low energies (< or = 3 J) was higher in patients with active compared with patients with inactive pulse generators (57% vs 26%; P < 0.04). The mean discomfort reported after delivery of a 2-J shock was comparable in both groups (Hot Can 5.2 +/- 1.9; Cold Can: 5.3 +/- 2.1; P = NS). We conclude that the inclusion of an active left subpectoral can in the defibrillation vector of a ventricular ICD seems to reduce the energy requirements for atrial cardioversion without increasing the discomfort caused by low energy shocks.

[Acute pericardial tamponade in cardiac echinococcosis]. / Akute Perikardtamponade bei kardialer Echinokokkose.

An echinococcal cyst of the heart is a rare cause of acute cardiac tamponade. We report on a 24 year old male from the Kosovo who was brought in an emergency state from a provincial hospital complaining of severe dyspnea, thoracic pain, dizziness, and a short period of unconsciousness. Surgical decompression had to be performed urgently, because the pericardium could not be punctuated due to the position of the hydatid cyst. The differential diagnosis was cardiac tumor or echinococcal cyst. Because of a negative result of a test for anti-echinococcal antibodies (indirect haemagglutination) and no eosinophilia (5%), the diagnosis of hydatid cyst was at first discarded. Later on, the test for anti-echinococcal antibodies became positive and a marked eosinophilia (59%) was manifest. In combination with a typical appearance in the echocardiograph and NMR, the diagnosis of a cardiac hydatid cyst was made. After preoperative treatment with albendazole, the cyst was sterilized with a 20% NaCl solution and the contents evacuated. The therapy with albendazole was continued. When last seen eight months after the first incidence, the patient was well except some degree of dyspnea on exertion. As a differential diagnosis of a cardiac tumor, a hydatid cyst should be taken into account in patients from an area where Echinococcus granulosus is endemic. A negative test on antiechinococcal antibodies and the absence of eosinophilia do not rule out echinococcosis.

Early time course of heart rate variability after thrombolytic and delayed interventional therapy for acute myocardial infarction.

In 89 of 97 consecutive patients with myocardial infarction (MI) undergoing thrombolysis and delayed early coronary angiography with PTCA, if indicated, heart rate variability (HRV) in time domain was evaluable 40 +/- 11 h after the onset of chest pain using 24-hour ECG recordings. Patients with anterior MI (n = 40) had lower values for HRV and left ventricular ejection fraction (p < 0.05). The mean of all 5-min standard deviations of RR intervals (SDNNi) and the root-mean-square difference of successive RR intervals (rMSSD) decreased significantly (p < 0.001 each), whereas the standard deviation of all normal RR intervals and the percentage of absolute differences between successive RR intervals only showed a tendency to lower values 4 weeks after MI (p = 0.20 and 0.08, respectively). The decreases in SDNNi and rMSSD were more evident in inferior than in anterior MI. The time course of HRV following MI was similar in patients with and without PTCA. These results indicate an initial vagal hyperactivity in inferior MI, which is quickly predominated by sympathetic activation and a prolonged recovery of the cardiac autonomic imbalance after MI despite a successful combined reperfusion therapy.

[Clinical significance of sleep apnea disorders after implantation of a cardioverter-defibrillator in patients with cardiac disease and sustained ventricular tachyarrhythmia]. / Klinische Bedeutung schlafbezogener Atmungsstörungen nach Implantation eines Kardioverter-Defibrillators bei Patienten mit kardialer Grundkrankheit und anhaltenden ventrikulären Tachyarrhythmien.

The purpose of our study was to determine the prevalence of sleep related breathing disorders (SRBD) in patients with an implantable cardioverter-defibrillator (ICD) and to evaluate prospectively the possible influence of SRBD on arrhythmia recurrence and circadian arrhythmia variation as well as on cardiac mortality during long-term follow-up. Forty consecutive ICD recipients with cardiac disease and a documented history of spontaneous, life-threatening, ventricular tachyarrhythmias underwent full-night polysomnography and were followed for 2 years. In 16 of 40 patients (40%), SRBD were diagnosed (Apnea/Hypopnea Index (AHI) > 10); in 9 of these 16 patients (56%) central sleep apneas (CSA) occurred (in 8 of these 9 patients in combination with Cheyne-Stokes respiration). Seven of the 16 patients with SRBD (44%) revealed obstructive sleep apneas (OSA). AHI was 32 +/- 15 (12-60) in patients with CSA and 32 +/- 27 (11-86) in patients with OSA. Patients with and without SRBD were comparable concerning left ventricular ejection fraction, NYHA classification, cardiac disease, ICD indication, and concomitant medication. ICD registered ventricular tachyarrhythmias occurred in 10 of 24 patients (42%) without SRBD, in 4 of 9 patients (44%) with CSA, and in 3 of 7 patients (44%) with OSA. The numbers and circadian variation of episodes registered during follow-up in patients without SRBD, with OSA or CSA were comparable (14 +/- 25, median 4 vs 15 +/- 15, median 7 vs 4 +/- 5, median 2.5). The 2-year cardiac mortality was highest in patients with CSA (4/9 (44%) vs. 0/7 patients (0%) with OSA vs 3/24 patients (12.5%) without SRBD. Thus, the prevalence of SRBD in patients with chronic heart failure and a history of malignant ventricular tachyarrhythmias is high (40%) and the occurrence of CSA seems to be predictive for cardiac mortality in these patients. An influence of moderate SRBD on arrhythmia recurrence and circadian variation of spontaneous sustained tachyarrhythmic events could not be demonstrated.

Assessment of intersignal variability for discrimination of atrial fibrillation from atrial flutter.

The analysis of endocardial signals obtained from an electrode located in the right atrium enabled by new dual chamber implantable cardioverter defibrillators may be helpful to provide additional therapies such as overdrive pacing or low energy atrial cardioversion for the treatment of concomitant atrial flutter (AFL) or atrial fibrillation (AF). Algorithms for discrimination of atrial tachyarrhythmias based on rate counting are of limited efficacy. The aim of this study was to assess the intersignal variability by using fast discrete wavelet transforms (FDWT) as a new method of discrimination of AF from AFL. Patients with spontaneous episodes of AF/AFL or patients who developed AF/AFL during an electrophysiological study were studied. The endocardial signals were recorded from the high right atrium using a transvenous 5 Fr bipolar electrode catheter (interelectrode spacing: 1 cm). The signals were digitized (2 kHz, 12-bit resolution) after amplification and filtering (40-500 Hz). Within data segments of 10-second duration, 25 consecutive signals were selected and normalized and FDWT was applied. Standard deviations of the wavelet coefficients (SD) from coarse scales (scale 4-8) were calculated. A total of 94 data segments (AF: 52, AFL: 42) from 28 patients were analyzed. SD at each considered scale was higher for AF than for AFL (P < 0.001). SD at scale 8 discriminated between AF from AFL with 100% sensitivity and specificity. We conclude that assessment of intersignal variability of bipolar endocardial recordings using FDWT is an effective method for the discrimination of AF from AFL. The implementation of this tool in a discrimination algorithm of an implantable device may help provide the appropriate differential therapy for atrial tachyarrhythmias.

Telemetry guided pacemaker programming: impact of output amplitude and the use of low threshold leads on projected pacemaker longevity.

In a prospective study, a low threshold screw-in electrode (Medtronic 5078, group I, n = 9) was compared to a conventional active fixation lead (Biotronik Y60BP, group II, n = 9) to investigate whether lower pacing thresholds really translate into longer projected service life of the pacemaker. The leads were implanted in the atrium and were connected to a dual chamber pacing system which included the same ventricular lead (Medtronic 5024) and the same pulse generator model (Intermedics 294-03) in both groups. Eighteen months after implantation, atrial and ventricular pacing thresholds were measured as the charge delivered per pulse [microC] at 0.5, 1.0, 1.5, 2.0, and 3.5 V, respectively. For chronic output programming in both channels, patients capturing at 0.5 V were set to 1.0 V, those capturing at 1.5 V were permanently programmed to 2.0 V with the double of the charge threshold as the safety margin for pacing ("safety charge"). A combination of atrial and ventricular output settings was optimal, if it resulted in minimum battery current drain (microA] as measured by pacemaker telemetry. In both groups, current consumption [microA] decreased significantly as output amplitude was decreased, exhibiting its lowest value at 1.0 V in either channel. All ventricular leads could be programmed to the optimum output amplitude of 1.0 V in groups 1 and 2. As the 2:1 "safety charge" values were almost identical, the ventricular channel essential contributes the same amount to the battery drain of the pacing system in both groups. In the atrium, all patients of group 1 could be programmed to the optimum output amplitude of 1.0 V with an average pulse duration of 0.42 +/- 0.15 ms. In group 2, however, all patients had to be programmed to 2.0 V with a mean pulse width of 0.52 +/- 0.15 ms. With the atrial and ventricular output being optimized, the average battery drain of the whole pacing system was 12.19 +/- 0.63 microA in group 1 versus 14.42 +/- 0.32 microA in group 2 (P < 0.001). As patients were chronically programmed to these output settings, this difference translates into a clinically relevant gain in projected pacemaker longevity of 17 months or 18.3% (121 +/- 4 vs. 104 +/- 2 months; P < 0.001). Thus, programming a 2:1 safety margin in terms of charge and optimizing the output parameters by real-time telemetry of the battery current is a useful approach to reduce battery current drain. Making the most of modern lead technology with a different performance in only one channel of an otherwise identical DDD pacing system translates into a significant prolongation of projected pacemaker service life which is of great importance with the increasing awareness of health care expenditures. The gain in projected longevity is mainly due to the option of reducing the output amplitude which is still significantly beneficial well below the nominal voltage of the power source.

Influence of beta-blockers on the frequency of arrhythmia recurrences in patients with implantable cardioverter-defibrillator: an intraindividual comparison.

We studied retrospectively 60 consecutive recipients of an implantable cardioverter-defibrillator and identified 16 patients who were temporarily on and off beta-blockers (further medication unchanged). An intraindividual analysis revealed that 56% of the patients experienced more arrhythmic episodes during follow-up off beta-blockers compared to 44% while being on beta-blockers. Also, the mean episode frequency during follow-up time on and off beta-blockers was comparable (0.4+/-0.6 vs. 0.5+/-0.5, ns).

Influence of thermal stress on the incidence of acute myocardial infarction in a temperate climate.

Using a Poisson regression model the relative incidence of acute myocardial infarctions (AMI) prospectively registered in 8 hospitals within a radius of 50 km during a 2-year period was correlated with the outside conditions characterized by a complete thermophysiological model (Klima-Michel Model) defining thermal stress. An increase in the incidence of AMI related to thermal stress could be demonstrated neither by splitting the study period into 12 equally sized 'felt-temperature' classes by months of the year nor by single days. This was confirmed by correlation of the AMI rate with the mean felt-temperature level during the preceding 14 days. Thermal stress caused by the atmospheric conditions in a temperate climate may be too weak to influence significantly the incidence of AMI.

Permanent junctional re-entry tachycardia. A multicentre long-term follow-up study in infants, children and young adults.

AIMS: Permanent junctional re-entry tachycardia is a relatively uncommon form of re-entry tachycardia with antegrade conduction occurring through the atrioventricular node and retrograde conduction over an accessory pathway usually located in the postero-septal region. It was the aim of the study to investigate the course of permanent junctional re-entry tachycardia with particular regard to the effectiveness of pharmacological treatment and ablation procedures; evaluation was performed with respect to the patient's symptoms, tachycardia rate, frequency of the tachycardia and left ventricular function. METHODS AND RESULTS: The long-term follow-up of 32 patients with permanent junctional re-entry tachycardia was evaluated. The first presentation with supraventricular tachycardia occurred between the 27th week of gestation and 27 years. The tachycardia rate ranged from 100 to 250 beats.min-1. During Holter-ECG, permanent junctional re-entry tachycardia was documented as present for over 50% of the time in 24 h in 22 patients (69%). Left ventricular performance was impaired in nine patients (28%) due to a tachycardia-related cardiomyopathy. Symptoms or signs of heart failure were mild to moderate in eight and severe in four patients; 20 patients showed no clinical impairment. Follow-up time was 1 to 31 (mean 10) years; current age of the patients ranged from 1.5 months to 35 (mean = 15 x 3) years. Four patients needed no therapy because of the infrequency of permanent junctional re-entry tachycardia episodes. Twenty-five patients initially received antiarrhythmic drugs, which were effective or partially effective in 14 (56%). Eight of them are still on medical therapy; in five treatment was discontinued because of absence of symptoms. Eleven patients had ablation of the accessory pathway during follow-up, three underwent ablation as a primary procedure. CONCLUSION: Permanent junctional re-entry tachycardia in our experience is an arrhythmia with a large variety of clinical symptoms. Patients with a slow tachycardia rate and infrequent episodes of tachycardia may never develop symptoms and therefore do not need any therapy. Patients with frequent permanent junctional re-entry tachycardia, a fast tachycardia rate and impaired left ventricular function need effective therapy. In infancy and early childhood medical therapy is recommended as a first option, whereas in older and symptomatic patients catheter ablation is an effective and safe procedure.