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C Nydegger

Publications and source records attributed to C Nydegger.

8 recordsLinked to original sources
PubMed1992

Clinical experience with a new multiprogrammable dual chamber pacemaker.

We evaluated the clinical performance of a new dual chamber pacemaker, ELA Chorus, in 35 patients. This device incorporates linear rate adaptive AV delay (AVDR), rate smoothing, fallback, impedance telemetry, pacemaker mediated tachycardia (PMT) recognition and reprogramming software, intracardiac electrogram displays, autothreshold testing, diagnostic data, battery depletion curves, and laptop computer programming. Mean patient age was 68 years; 18 patients had AV block, six had sinus node dysfunction (one with AV block), nine had carotid sinus hypersensitivity (three with AV block), and two had vagally mediated syncope. At hospital discharge, programming was DDD with a mean low rate of 60 (50-70) beats/min, mean high rate of 126 (120-154) beats/min; AVDR was ON in 21 patients, rate smoothing ON in six patients, fallback ON in six patients, and PMT reprogramming algorithm ON in 27 patients. Pacemaker follow-up involved 500 clinic visits over 14.3 months (1-36). Three patients developed atrial fibrillation, reprogrammed to DDI mode (two patients) or fallback (one patient). Fallback was used 617 times. PMT occurred 427 times in six patients; the PMT algorithm reprogrammed AV delay and postventricular atrial refractory period (PVARP) automatically, a function unique to the Chorus. Intracardiac electrograms and autothreshold testing improved follow-up efficiency. This new dual chamber pacemaker enhances programming flexibility and improves diagnostic accuracy at follow-up.

Aged↗
PubMed1992

Programmable external automatic antitachycardia pacing as a bridge to definitive therapy in patients with recurrent sustained ventricular tachycardia.

The efficacy and safety of external programmable automatic antitachycardia pacemakers (ATPs) used in the critical care setting for recurrent sustained monomorphic ventricular tachycardia (VT) was evaluated. Ten patients who had failed a mean of 4.0 +/- 1.4 antiarrhythmic medications (range 2-7) and who had previously required electrical cardioversion for VT were enrolled. Prior to ATP use, successful overdrive pacing termination of VT was demonstrated in all patients. Intertach (Intermedics, Inc.; n = 9) and Orthocor II (Cordis, Inc.; n = 1) ATPs were attached to temporary bipolar transvenous or epicardial pacing leads. Mean patient age was 66.4 +/- 11.5 years, and mean left ventricular ejection fraction was 22 +/- 7.5%. At the time of initial ATP use, mean VT cycle length was 347 +/- 88 msec (range 280-550 msec). A burst scanning antitachycardia pacing algorithm was used in each patient; one patient was also treated with a fixed rate burst adapted to VT cycle length. The duration of ATP use ranged from 2-25 days (median 5), successfully terminating greater than 3,369 VT episodes (median 3, range 0 to greater than 3,103 episodes per-patient). Two episodes of ATP induced rate acceleration occurred, each successfully terminated by the ATP. Only two patients required external cardioversion during ATP use, one for primary ventricular fibrillation and one for rapid polymorphic VT associated with antiarrhythmic drug withdrawal. ATPs also provided antibradycardia pacing and allowed for serial programmed ventricular stimulation. No complications were associated with transvenous catheter or ATP use.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Incidence and timing of activity parameter changes in activity responsive pacing systems.

The incidence and timing of rate response parameter reprogramming in activity responsive pacing systems during the year after implantation was evaluated in two groups of patients: 24 patients in whom a VVI,R system was implanted (Activitrax, Medtronic, Inc.), and 21 patients in whom a DDD,R system was implanted (Synchrony, Siemens Pacesetter, Inc.). Activity parameter changes in Activitrax patients were made based on the presence of symptoms, while in Synchrony patients, changes were based on objective data obtained using a sensor indicated rate histogram with a slow and fast walk protocol. No significant difference in the incidence of activity parameter reprogramming was noted at various time intervals during the first year in Activitrax patients; in Synchrony patients a greater incidence of reprogramming changes was noted at the 1-month follow-up visit compared to later follow-up visits (P less than 0.02). Further, the incidence of changes at 1 month was greater for Synchrony compared to Activitrax patients (P less than 0.001), while no difference was detected between groups at subsequent follow-up intervals. Use of the slow and fast walk protocol, by permitting serial evaluation of sensor response, demonstrated alterations in sensor drive rates with similar levels of activity over the initial 4 to 6 postimplant weeks. This may result from postoperative changes at the pacemaker insertion site. Based on this experience, predischarge programming may not predict long-term rate response requirements. We recommend evaluation of sensor function using an exercise protocol performed at 4 to 6 postimplant weeks in all rate responsive pacing systems that utilize a piezoelectric crystal.

Aged↗
PubMed1991

Device interaction--antitachycardia pacemakers and defibrillators for sustained ventricular tachycardia.

We evaluated the combined use of permanent automatic antitachycardia pacemakers and implanted defibrillators in ten patients with recurrent monomorphic sustained ventricular tachycardia (VT). Pacemaker programming was VVI-T automatic burst in eight patients, VVI-T magnet mode in one patient, and VVI in one patient. Device interactions occurred in four patients, requiring changes in pacemaker programming. These included defibrillator multiple counting during pacing, inappropriate pacemaker bursts initiating VT, inappropriate reset of the pacemaker antitachycardia mode by defibrillation, defibrillator discharge after pacemaker VT termination, and defibrillator VT reinitiation. Two patients required pacemaker programming out of the antitachycardia mode, and two required a change in antitachycardia pacing parameters. Seven patients remain in automatic VVI-T and three in VVI modes. Mean follow-up is 13 months and all patients are alive. Thus, although pacemaker/defibrillator combinations function well for patients with more than one VT rate, device interactions occur frequently and may require pacemaker reprogramming or elimination of the overdrive mode. Combined use of these devices should be cautiously considered when single device therapy is unsatisfactory. Devices that combine both pacing and defibrillation features may reduce adverse interaction.

Algorithms↗