Search PubMed⌕ Search

Biomedical subjects

J Neuzner

Publications and source records attributed to J Neuzner.

At least 37 records · Page 2Linked to original sources
PubMed2000

Detection of ventricular fibrillation in implantable defibrillators with automatic gain control amplifiers: effects of programming sensitivity.

AIMS: In newer implantable cardioverter-defibrillators with automatic gain control amplifiers the maximum possible sensitivity is programmed with the aim of securing optimal detection of ventricular fibrillation. This study was designed to prove that a reduction in maximum sensitivity is safe with respect to appropriate sensing of ventricular fibrillation, while avoiding sensing of extracardiac signals. METHODS AND RESULTS: Forty-two consecutive patients, undergoing defibrillator implantation/replacement with programmable maximum auto-gain sensing sensitivity (Ventak Mini III, Ventak AV , Guidant, St. Paul, MN, U.S.A.), were prospectively investigated. Thirty-four patients were implanted with a dual-coil lead system, providing integrated bipolar sensing (Endotak, Guidant, St. Paul, MN, U.S.A.), eight patients received a single-coil lead system with true bipolar sensing (Sprint, Medtronic, Minneapolis, MN, U.S.A.). During device implantation and pre-discharge testing, arrhythmia detection times of induced ventricular fibrillation were compared at programmed maximum (0.18 mV) and minimum (0.43 mV) sensitivity in a randomized manner. Seventy-six induced episodes of ventricular fibrillation were analysed. The mean arrhythmia detection times did not differ between the programmed sensing levels (maximum sensitivity: 1612 +/- 307 ms, vs minimal sensitivity: 1,602 +/- 330 ms; P = ns). The results were not affected by the type of implanted lead system (integrated bipolar versus true bipolar sensing). CONCLUSION: In the implantable defibrillator devices, reduction in maximum sensitivity did not impair the detection of induced episodes of ventricular fibrillation.

Amplifiers, Electronic↗
PubMed2000

Comparison of pulsed versus continuous radiofrequency energy delivery: diameter of lesions induced with multipolar ablation catheter.

The aim of this study was to compare the efficacy of pulsed versus continuous RF energy delivery via multipolar ablation catheters. In vitro tests were performed in endomyocardial preparations of fresh bovine hearts in a both of physiological saline solution (37 degrees C) at constant flow conditions (1.5 L/min). The catheters were applied to the endocardium at a constant pressure. Energy was delivered pulsed (to 4 electrodes simultaneously, 5-ms duty cycle) or continuously (to each electrode separately). In vivo experiments were performed under fluoroscopy in eight anesthetized pigs, guided by endocardial electrograms to place the catheters in 22 different intraatrial positions. Lesion volume was calculated from measurements of the lesion diameter with a microcaliper. The homogeneity of the lesions was classified from 1 (highest) to 4 (least). More homogeneous linear lesions were produced in significantly less time with pulsed than with continuous energy delivery. There were no differences in electrode temperature or impedance values in vitro and in vivo. The results in the in vitro experiments were reproducible in the intact animal experiments. Significantly larger and more homogeneous linear lesions were created more rapidly with pulsed than with continuous energy delivery.

Animals↗
PubMed1999

Transvenous biventricular pacing for heart failure: can the obstacles be overcome?

Despite increasing evidence of hemodynamic benefit and long-term improvement in clinical status of congestive heart failure (CHF) patients with left ventricular and biventricular pacing, the risks and technical limitations of placing a permanent left ventricular pacing lead have prevented widespread clinical adoption of this therapy. Results of this and other recent investigations suggest it is necessary to target specific sites on the left ventricle to maximize hemodynamic benefit. However, limitations and variations of coronary vein anatomy, as well as patient safety, lead dislodgement, pacing thresholds, lead handling, and ease-of-use issues, present technical challenges for current transvenous permanent pacing lead designs. However, a new transvenous lead system based on an over-the-wire design appears to solve many of these problems and has proved feasible in acute clinical studies.

Animals↗
PubMed1999

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.

Adult↗
PubMed1999

[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)].

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.

Defibrillators, Implantable↗
PubMed1999

Bipolar atrial sensing thresholds in sinus rhythm and atrial tachyarrhythmias. A comparative analysis in patients with DDDR pacemakers.

UNLABELLED: Automatic mode switching (AMS) function in dual chamber pacemakers depends on adequate detection of atrial tachyarrhythmias. There are few data on showing how intra-operative atrial signal amplititude during sinus rhythm can predict atrial tachyarrhythmias after pacemaker implantation. In 43 patients undergoing DDDR pacemaker implantation and atrioventricular nodal ablation for the treatment of drug-refractory paroxysmal atrial fibrillation, atrial sensing thresholds during sinus rhythm and during induced atrial tachyarrhythmias (24-48 h after device implantation) were analysed. Five different DDDR pacemaker systems were implanted (Chorus 7034, Ela Medical n = 13; Meta DDDR 1254, Telectronics Pacing Systems n = 12; Vigor DR 1230, Guidant n = 6; Trilogy DR 2364, Pacesetter, n = 2; Kappa DR 401, Medtronic USA n = 10). Every patient received a steroid-eluting, screwing, bipolar atrial lead (Medtronic, Capsure-Fix 4068). The mean P wave amplitude during implantation was 3.91 +/- 1.14 mV. The mean atrial sensing threshold during sinus rhythm and during all modes of induced atrial tachyarrhythmias was 3.35 +/- 1.0 mV, and 1.52 +/- 0.92 mV, respectively (P < 0.001). Atrial fibrillation was induced in 36 patients. The mean sensing threshold during sinus rhythm in this patient group was 3.39 +/- 1.01 mV, the mean sensing threshold during atrial fibrillation was 1.27 +/- 0.56 mV, reflecting a 63% reduction of sensing threshold compared with sinus rhythm (P < 0.001). Atrial flutter was induced in seven patients. The mean sensing threshold during sinus rhythm was 2.92 +/- 1.19 mV, the mean sensing threshold during atrial flutter was 2.79 +/- 1.26 mV, reflecting a reduction of 5% (ns) compared with sinus rhythm. Atrial sensing thresholds during sinus rhythm were significantly correlated with sensing thresholds during atrial tachyarrhythmias (r = 0.44; P < 0.002), but there were significant variations in intra-individual results. The reduction of atrial sensing thresholds between sinus rhythm and induced atrial tachyarrhythmias ranged from 30% to 82%. CONCLUSION: Bipolar atrial sensing thresholds during sinus rhythm are correlated with sensing thresholds during atrial tachyarrhythmias, but there is a large degree of variance in individual patients. A 4:1 to 5:1 atrial sensing safety margin based on sensing threshold during sinus rhythm is a predictor for adequate postoperative detection of atrial tachyarrhythmias and the function of AMS devices.

Arrhythmia, Sinus↗
PubMed1999

Clinical evaluation of a prototype passive fixation dual chamber single pass lead for dual chamber ICD systems.

UNLABELLED: Dual chamber ICD systems use two separate leads for sensing. We developed and tested a new prototype of a single pass dual chamber passive fixation lead for dual chamber ICDs. METHODS AND RESULTS: The prototype was a modification of the Guidant CPI Endotak DSP lead. The additional sensing electrode for the right atrium consisted of a side-mounted porous atrial ring electrode (AR). Atrial signals were recorded from the lead in patients during normal sinus rhythm (NSR), atrial fibrillation (AFib), and/or atrial flutter (AFl) with the AR in stable contact with the atrial wall or floating. During NSR, with the AR in contact with the atrial wall, an average P wave amplitude of 7.2 +/- 1.5 mV (mean +/- SD, n = 12) was measured. After induction of Afib/AFl, the single amplitude decreased to 3.6 +/- 1.5 mV (n = 8) during AFib and 3.4 +/- 1.7 mV (n = 9) during AFl. Amplitudes dropped between 53% and 75% when the AR lost atrial wall contact. The atrial pacing threshold was 1.0 +/- 0.4 V (n = 16) when the AR was in contact with the atrial wall. CONCLUSIONS: In future dual chamber ICDs the signals from a passive fixation single pass lead could be used for atrial sensing and pacing as long as the sensing electrode for the right atrium remains in contact with the atrial wall. This system might lead to a simpler, less invasive implantation of dual chamber ICD systems.

Atrial Fibrillation↗
PubMed1999

Cold pressure test producing coronary spasm, coronary thrombosis and myocardial infarction in a patient with IgM antibodies against Coxsackie B virus.

Several lines of evidence have shown that viral infections are capable of causing coronary spasm and precipitating or mimicking clinical myocardial infarction. Here we report the case of a 41-year-old woman with recurrent angina who was admitted to our hospital because of ventricular tachycardia. Laboratory examination revealed positive IgM titers against Coxsackie B virus. Coronary angiography showed normal coronary arteries, but following a cold pressure test severe spasm of all coronaries with thrombotic occlusion of the second marginal branch of the circumflex artery occurred. We conclude that coronary spasm should be clinically suspected in patients with chest pain and ventricular arrhythmia in combination with IgM antibodies against Coxsackie B virus. In these patients, a cold pressure test should be avoided, and antithrombotic and antispastic therapy is recommended.

Adult↗
PubMed1998

[Therapy with implanted cardioverter-defibrillator: Is a replacement of the impulse generator due to battery depletion also necessary without the occurrence of a tachyarrhythmia episode?].

The aim of this retrospective study was to evaluate the necessity of the replacement of an implantable cardioverter/defibrillator (ICD) in patients with pulse generator battery depletion without an adequate, spontaneous arrhythmia episode during the life-time of the first implanted device. In this study 213 patients with implanted ICDs were enrolled. In 62 patients an elective generator replacement due to battery depletion was performed. Both patient groups (Group A: patients with generator replacement n = 62 and Group B: patients without replacement n = 151) were not different with regard to main clinical characteristics, such as underlying heart disease and left ventricular function. In both groups there was a predominance of male patients (Group A: 89%; Group B: 83%). The mean age was 58 +/- 11 years and 59 +/- 11 years in Group A and Group B, respectively. Coronary artery disease was present in 66% and 68% of the patients. There was a comparable left ventricular ejection fraction: Group A: 30.5 +/- 9% vs Group B: 31.9 +/- 9%. The follow-up time was much longer in Group A patients compared to Group B patients (50.5 +/- 14 vs. 16.5 +/- 11 months). For the total patient group there was a 5 year event-free probability of 23%, no differences were found between both groups. The subanalysis in Group A patients revealed no difference in the probability of ICD-shock occurrence prior to or after the replacement of the pulse generator. In 48/62 (77%) of Group A patients adequate ICD discharges were documented. In 15/62 (24%) patients shock occurred before and after generator replacement. In 6/62 (10%) of Group A patients, the first adequate ICD-therapy was documented after generator replacement. The results of this study indicate the necessity of an ICD-pulse generator replacement even in patients without an adequate device discharge during the life-time of the first implanted device.

Aged↗
PubMed1998

[Dysfunctions of transvenous cardioverter/defibrillator electrode systems: clinical significance of system integrated diagnosis and measurement function--possibilities of partially automated system control].

UNLABELLED: The aim of this study is the analysis of electrical failures in transvenous cardioverter/defibrillator (ICD) lead systems with regard to the importance of device implemented diagnostic and measurement functions and the potential role of an automated device-control in the detection of lead failures. METHODS: All consecutive ICD patients at our institution were enrolled in this retrospective investigation. The routine follow-up controls consisted in a complete evaluation of all diagnostic and measurement ICD features and additional controls in case of spontaneous arrhythmia episodes. RESULTS: Two hundred thirty patients, 193 male and 37 female, were enrolled in this study (mean age: 61.5 +/- 10.2 years; mean LVEF 32 +/- 9%). During a mean follow-up period of 29.5 +/- 18.4 (6-76) months, lead failure occurred in 19 patients (8%), 16 patients were implanted with an ICD, capable of diagnostic and measurement functions. All nonadequate device discharges could be classified as sensing-failure by stored electrograms. Device implemented measurement features revealed clinical important information in 13/16 patients (81%). In 14/16 patients, the lead defect could not be detected during routine follow-up. At the time of documented lead failure the safety of the implanted devices was already lost in 6/16 patients (38%). CONCLUSIONS: Device implemented diagnostic and measurement options are of great importance in the early detection of ICD lead failures. The implementation of automated measurements of lead related parameters in connection with a patient alert function may contribute to a further increase in the safety of ICD therapy.

Adult↗
PubMed1998

[Reproducibility of the effectiveness of defibrillation for terminating induced ventricular fibrillation using intraoperatively measured defibrillation threshold energy in patients with implanted cardioverter-defibrillator].

The aim of the present study was to assess the long-term reproducibility of the defibrillation efficacy of energies set at the intraoperatively measured defibrillation threshold using a modified testing protocol. Between December 1993 and January 1996, 83 patients receiving an implantable cardioverter-defibrillator (ICD) in combination with a non-thoracotomy lead system and having an intraoperatively measured defibrillation threshold (DFT) < or = 15 J were enrolled in a substudy of a prospective, randomized multicenter trial ("Low Energy Endotak Trial" (LEET)). Step-down DFT testing was performed intraoperatively (15, 10, 8, 5 J). It was mandatory to reproduce a successful conversion of ventricular fibrillation at the DFT energy during implantation (DFT+). At the end of implantation, at predischarge, and after one year, assessment of the defibrillation efficacy of DFT+ energy was repeated (first shock: DFT+, second shock: 2 x DFT+). Mean DFT+ at implant was 9.6 + 3.3 J. Immediately after implantation, successful conversion of induced ventricular fibrillation was achieved in 70/79 (89%) patients using DFT+ energies. In 7/8 (89%) patients only the second shock set at 2 x DFT+ and in one patient only the third shock set at maximum energy (34 J) was successful. At predischarge, defibrillation efficacy of DFT+ was reproducible in 61/77 (79%) patients. The remaining 16 patients were successfully converted using a second shock set at 2 x DFT+. One year after implantation, conversion of ventricular fibrillation was achieved at energies set at DFT+ in 52/62 (84%) patients and in the remaining 10 patients at energies set at 2 x DFT+. A total of 183/218 (84%) episodes of induced ventricular fibrillation were terminated successfully using DFT+ energies. There was no correlation between the intraoperatively determined DFT+ or the underlying cardiac disease and the defibrillation efficacy. These results demonstrate that the defibrillation efficacy for termination of induced ventricular fibrillation using DFT+ energies is reproducible at implantation, at predischarge, and one year after ICD insertion. Energies set at twice DFT+ seems to allow for reliable defibrillation within the first year after ICD implantation.

Adult↗
PubMed1998

Interrelation of tissue temperature versus flow velocity in two different kinds of temperature controlled catheter radiofrequency energy applications.

UNLABELLED: The influence of blood flow cooling down the energy delivering electrode during temperature controlled radiofrequency energy application is an important factor for ablation success. In this experimental in-vitro study, using tempered saline as blood equivalent, we observed a highly significant increase in tissue temperature, lesion depth and required energy amount with increasing flow velocity. Second, we found significant deeper lesions with use of pulsed radiofrequency energy application compared to continuous application. We conclude that, even with lower electrode temperatures, success can be achieved dependent on the local blood flow velocity, and deeper lesions can be created with the use of pulsed radiofrequency energy application. BACKGROUND: Success in temperature-controlled radiofrequency (RF) catheter ablation of arrhythmogenic areas in human hearts depend largely (among others) on the size of the electrode, developed pressure of electrode against tissue, as well as on the localization of the thermistor sensor within the electrode. In addition, the blood flow velocity at various sites of ablation is an important factor for the calculation of heat transport from the electrode, which obviously has not been given much consideration of in the past. The aim of the present in-vitro study, therefore, was to evaluate this important factor's influence on the temperature developed at the electrode and within the myocardial tissue. METHODS AND RESULTS: All experiments were carried out in a bath containing NaCl solution at 37 degrees C. Four different flow velocities were applied (0, 110, 180, 320 ml/cm2 *min). During and after temperature-controlled unipolar radiofrequency energy delivery (60 degrees C, 40 sec) the electrode temperature, the tissue temperature 5 mm in depth, and the total energy delivered were measured, as well as the actual depth of the lesion. The amount of energy applied to the electrode was regulated by the thermosensor in the electrode to obtain a maximum temperature of 60 degrees C. Two different kinds of radiofrequency energy delivery have been used: (1) continuous radiofrequency energy delivery as usual regarding clinical use, (2) pulsed radiofrequency energy delivery with a duty cycle length of 10 ms and a pause of at least the same duration during two consecutive duty cycles. At pulsed radiofrequency energy application, the energy for each duty cycle was held constant during delivery. The amount of pulses delivered to the electrode was regulated by the electrode's thermosensor. With both modes of radiofrequency energy delivery a uniform observation could be made. The more the flow velocity applied accelerated, the more the tissue temperature rose (R = 0.85; p < 0.00000001), and the lesion depth increased in spite of electrode temperature being held constant. The amount of the total energy delivered rose in proportion to the cooling down of the electrode dependent on the flow velocity (R = 0.69, p < 0.0000004). Steady-state temperatures had not been accomplished after 40 sec time. When energy was delivered at the pulsed mode, intramyocardial temperatures proved higher compared to the continuous mode with significant differences (p < 0.05) at comparable flow velocities applied between 180 and 320 ml/cm2*min and at same electrode temperatures. This resulted in significantly (p < 0.05) larger lesion depths in pulsed radiofrequency energy delivery. We suppose that this significant difference can be explained by a higher amount of total energy delivered at comparable electrode temperature in the pulsed mode as compared to the continuous mode.

Acceleration↗
PubMed1998

Short- and long-term performance of a tripolar down-sized single lead for implantable cardioverter defibrillator treatment: a randomized prospective European multicenter study. European Endotak DSP Investigator Group.

A new, thinner (10 Fr) and more flexible, single-pass transvenous endocardial ICD lead, Endotak DSP, was compared with a conventional lead, Endotak C, as a control in a prospective randomized multicenter study in combination with a nonactive can ICD. A total of 123 patients were enrolled, 55 of whom received a down-sized DSP lead. Lead-alone configuration was successfully implanted in 95% of the DSP patients vs 88% in the control group. The mean defibrillation threshold (DFT) was determined by means of a step-down protocol, and was identical in the two groups, 10.5 +/- 4.8 J in the DSP group versus 10.5 +/- 4.8 J in the control group. At implantation, the DSP mean pacing threshold was lower, 0.51 +/- 0.18 V versus 0.62 +/- 0.35 V (p < 0.05) in the control group, and the mean pacing impedance higher, 594 +/- 110 omega vs 523 +/- 135 omega (p < 0.05). During the follow-up period, the statistically significant difference in thresholds disappeared, while the difference in impedance remained. Tachyarrhythmia treatment by shock or antitachycardia pacing (ATP) was delivered in 53% and 41%, respectively, of the patients with a 100% success rate. In the DSP group, all 28 episodes of polymorphic ventricular tachycardia or ventricular fibrillation were converted by the first shock as compared to 57 of 69 episodes (83%) in the control group (p < 0.05). Monomorphic ventricular tachycardias were terminated by ATP alone in 96% versus 94%. Lead related problems were minor and observed in 5% and 7%, respectively. In summary, both leads were safe and efficacious in the detection and treatment of ventricular tachyarrhythmias. There were no differences between the DSP and control groups regarding short- or long-term lead related complications.

Adult↗
PubMed1998

Multielectrode basket catheter mapping for human atrial fibrillation.

In 9 patients with a history of paroxysmal atrial fibrillation (AF), basket catheters with 64 electrodes were used to determine electrophysiologic aspects of onset and early minutes of AF in the right atrium. Mapping was performed using 32 bipolar recordings after induction of AF by programmed atrial stimulation. In 7 patients, registrations were obtained that allowed the onset of AF to be analyzed after the induction. The most common mode of induction was a conduction block and local fragmentation of electrical activation in the area anterior to the tricuspid valve; this was observed in 5 patients. Local cycle lengths (5 min) and correlation dimension of repolarization Dpw_De (2 min) was calculated in 7 patients. The recording sites of the basket catheter were fluoroscopically projected to the anatomic sites of the right atrium. The highest Dpw_Re dimensions as an expression of pronounced chaotic activity were found in the area anterior to the tricuspid valve.

Algorithms↗
PubMed1997

Clinical predictors of defibrillation energy requirements.

In implantable cardioverter-defibrillator therapy with endocardial lead systems, certain clinical variables are associated with defibrillation energy requirements. Because of the weak correlation coefficients, these variables cannot predict defibrillation thresholds in individual patients.

Age Factors↗
PubMed1997

[Biatrial stimulation in therapy of paroxysmal atrial tachycardia: a case report].

A biatrial pacemaker was inserted in a 68-year-old female with paroxysmal atrial fibrillation and atrial flutter refractory to antiarrhythmic drugs based on a sick-sinus-syndrome and concomitant interatrial conduction delay. One electrode positioned in the right atrium and another electrode located in the coronary sinus were connected to a dual-chamber pacemaker. The electrode in the right atrium was connected to the atrial channel, the electrode in the coronary sinus to the ventricular channel. The pacemaker was programmed in DDD-mode with an AV-delay of 30 ms. Under a chronic antiarrhythmic medication with 160 mg sotalol per day there was no evidence for recurrent episodes of atrial tachyarrhythmias in the patient's history, 24-h-Holter-ECG, nor in the memory of the pacemaker during a follow-up of 8 months.

Aged↗
PubMed1997

Implantable cardioverter-defibrillator therapy: influence of left ventricular function on long-term results.

The degree of left ventricular impairment in an acknowledged important prognostic marker of long-term outcome for patients being evaluated for implantation of cardioverter-defibrillators. Just how left ventricular function impacts freedom from all-cause mortality, as well as from sudden death and cardiac death, is a subject of current major debate, and is analyzed hereunder from a large, recent multicenter ICD patient cohort. The multicenter database consists of data from 361 patients receiving implantable cardioverter-defibrillators for standard indications, that is, documented episodes of ventricular fibrillation or sustained ventricular tachycardias with poor hemodynamic toleration. Data were collected from 1988 to 1995 at three centers in Germany. Two-hundred and three patients (56%) had a left ventricular ejection fraction (LVEF) > 0.30 (group I), and 158 patients (44%) had a LVEF < or = 0.30 respectively (group II). The mean follow-up was 23.9 months (range 3-98 months). Overall survival at 5 years for group II patients was lower, as expected, at 74.1% versus 94.2%, respectively (P < 0.0001). Mortality was higher for each different cause of death in group II patients than in Group I: sudden arrhythmic deaths, 5 versus 1 (P < 0.048); nonsudden cardiac deaths, 16 versus 5 (P < 0.002); noncardiac deaths, 7 versus 2 (P < 0.03). Group II patients received a higher rate of at least one presumably appropriate shock at 86 (54.4%) versus 89 (43.8%) in group I (P < 0.05). However (and somewhat surprisingly), neither the time from ICD implantation to death, comparing only the patients who died, nor the event-free probability of appropriate shocks due to very rapid, sustained ventricular arrhythmias (> 230 beats/min), including a presumed risk of sudden arrhythmogenic death, differed between groups I and II. Sudden cardiac death was only marginally affected by LVEF (group I, 1.5% actuarial, 5-year survival 99.5%; group II, 3.1% and 95.8%, respectively). Therefore, the lower overall survival in ICD patients with LVEF < or = 0.30 resulted mainly from causes of death that cannot be directly influenced by cardioverter-defibrillator therapy. However, because group II patients had a far higher incidence of at least one ventricular tachyarrhythmia terminated by ICD shocks than group I patients, they also probably derived benefit from ICD therapy.

Cohort Studies↗