Hans Schüller

Lund University, Lund, Skåne, Sweden

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Publications (25)86.55 Total impact

  • Carl J Höijer · Peter Höglund · Hans Schüller · Johan Brandt
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    ABSTRACT: Despite several decades of experience with atrial pacing, many centers do not apply this mode to any greater extent, mainly because of concerns for the development of future atrioventricular (AV) block or atrial fibrillation. Recent studies have emphasized possible negative effects of right ventricular stimulation, even when AV-synchrony is preserved, and have thus given rise to renewed interest in single chamber atrial pacing for sinus node disease. This study presents the results of up to 19 years' follow-up of 213 patients with sinus node disease treated with atrial pacing with respect to survival and causes of death, development of atrial fibrillation and AV block, and total mode survival. Patients were divided into two groups: with or without associated atrial tachyarrhythmias at the time of implant. Results are given for all patients and for the two groups separately. The mean follow-up time was 10.1 years. The survival of the entire group was lower after 10 years than that of an age and gender-matched general Swedish population. This was caused by patients with the brady-tachy syndrome (BT) having a significantly higher mortality rate than controls, whereas those with bradycardia only (B) had survival comparable to the general population. Permanent atrial fibrillation (AF) developed in 20% of patients and was significantly more common in patients with BT. The majority of patients with AF (78%) no longer needed any pacing, i.e., did not require ventricular stimulation due to slow ventricular rate. The annual incidence of high grade AV block was 1.8%. If patients with preexisting bundle branch block were excluded, the incidence was 1.6%. No fatal episode of AV block was seen. The overall mode survival at the end of follow-up was 75%, with 155 patients still with atrial pacemakers. Atrial pacing is a safe and reliable mode of pacing in patients with sinus node disease, even in the very long-term.
    No preview · Article · Jul 2007 · Pacing and Clinical Electrophysiology
  • Berit Larsson · Håkan Elmqvist · Lars Rydén · Hans Schüller

    No preview · Article · Feb 2003 · Pacing and Clinical Electrophysiology
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    ABSTRACT: The Autocapture algorithm enables automatic capture verification on a beat-by-beat basis by recognizing the evoked response signal following each pacemaker stimulus. The algorithm intends to increase patient safety while decreasing energy consumption. However, the occurrence of fusion beats, particularly during dual chamber pacing, may limit the energy saving effect of Autocapture. The aim of this multicenter, prospective, randomized study was to evaluate the impact of the Fusion Avoidance (FA) algorithm on the incidence of fusion beats. Thirty-eight patients (mean age 69 +/- 13 years) with intrinsic AV conduction who were implanted with an Affinity DR were studied. After programming a PV/AV delay of 120/190 ms, patients were randomized to FA On or Off. Each group was further randomized with respect to activation of the AutoIntrinsic Conduction Search (AICS) algorithm. The total number of beats, ventricular paced beats, fusion beats, backup pulses, and threshold searches were analyzed from 24-hour Holter recordings. The number of total beats was comparable in both FA groups. The number of total ventricular paced beats, fusion beats, backup pulses, and threshold searches were significantly reduced in the FA On group (% reduction: 68% P < 0.001, 75% P < 0.01, 95% P < 0.01, and 94% P < 0.05, respectively). The number of ventricular paced beats with full capture was significantly reduced when AICS was activated (P < 0.05). In conclusion, the FA algorithm substantially reduces the amount of ventricular paced beats, fusion beats, unnecessary backup pulses and threshold searches, and therefore, provides added benefits in energy saving obtained by Autocapture.
    No preview · Article · Dec 2002 · Pacing and Clinical Electrophysiology
  • Lars Rydén · Hans Schüller · Berit Larsson
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    ABSTRACT: No abstract is available for this article.
    No preview · Article · Apr 2002 · Pacing and Clinical Electrophysiology
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    ABSTRACT: Bipolar leads have been shown to provide superior sensing conditions compared to unipolar leads as bipolar sensing is less susceptible to interference. However, the mechanical long-term integrity and longevity of bipolar leads is inferior to that of unipolar leads. A prospective randomized, multicenter study was performed to investigate a new atrial detection configuration called combipolar sensing. This new sensing concept is designed for the use of conventional unipolar leads in the atrium and the ventricle. While the atrial stimulation is unipolar, atrial sensing is accomplished in a bipolar way using the ventricular lead tip as the indifferent electrode. A modified dual chamber pacemaker provided with this sensing concept was implanted in 26 patients. At predischarge and at the 1- and 3-month follow-ups no significant differences in atrial sensing thresholds and P wave amplitudes were found between the unipolar and the combipolar sensing configuration at rest or during provocation. Myopotential inhibition could be demonstrated in 22 patients during unipolar sensing at sensitivity settings as "low" as 2 mV. In contrast, during combipolar sensing it could only be demonstrated in one patient once and only at the highest atrial sensitivity of 0.5 mV. Combipolar atrial sensing is feasible under normal conditions and during provocation. Myopotential interference is negligible. Thus, combipolar sensing offers comparable atrial sensing to bipolar without the disadvantages of a bipolar lead.
    No preview · Article · Dec 2001 · Pacing and Clinical Electrophysiology
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    ABSTRACT: Background: Cardiovascular anatomy and limited venous access may preclude the implantation of endocardial pacing systems in children as well as adults with congenital heart disease. Thus, the implantation of myo/epicardial pacing leads is required in these patients. The less favorable long-term results experienced in the past with myocardial screw-in leads are often used to justify the transvenous approach whenever possible, even in infants. However, encouraging preliminary results were reported from modern bipolar steroid eluting epicardial pacing leads. Further follow-up data are now warranted to obtain arguments for the dispute regarding the preferable or optimal pacing approach in infants and small children. Methods From January 1994 to November 2000 a total of 64 bipolar steroid-eluting epicardial pacing leads (Medtronic CapSure Epi 10366 and 4968, Medtronic, Inc, Minneapolis, MN, USA) were implanted in 52 children at our institutions (52 electrodes in ventricular and 12 in atrial position). The median age of the children was 25.5 months (range 0.03 to 193 months). As part of a prospective multicenter study these leads were continuously followed in combination with AutoCapture devices since December 1996. Results Telemetry data demonstrated at discharge low pacing thresholds both for the ventricular (0.8±0.37Volt @ 0.5ms) and the atrial leads (0.8±0.4Volt @ 0.5ms) as well as excellent sensing signals (P wave 2.9±1.4mV and R wave 10.6±5.5mV) without significant changes during follow-up up to 24 months. AutoCapture controlled pacing could be applied in 46/52 (88%) children rendering a calculated battery service life of 14.8±2.9 years with a VVIR device (Regency SR 5130, St. Jude Medical, Sylmar, CA, USA) and 10.8±1.1 years with a dual chamber device (Affinity DR 5330, St. Jude Medical, Sylmar, CA, USA). Apart from the necessity to reposition three leads in the immediate postoperative period no late lead related complications have been experienced during follow-up. Conclusions The new steroid-eluting bipolar epicardial pacing lead demonstrates a high reliability and consistent extraordinary pacing as well as sensing thresholds. AutoCapture controlled pacing is feasible in most patients and may result in marked battery service life extension. Hence epicardial pacing can now be highly recommended as the first choice for permanent pacing in infants and children. Hintergrund Bei Säuglingen und Kleinkindern erschwert die begrenzte venöse Zugängigkeit häufig die Implantation transvenöser Schrittmachersysteme. Ausserdem verhindern verschiedene kardiale Missbildungen die Einführung transvenöser Elektroden völlig. Die hohe Komplikationsrate konventioneller Myokardelektroden in früheren Jahren wird häufig als Argument angeführt um die Implantation transvenöser Elektroden auch bei sehr kleinen Kindern zu rechtfertigen. Erste Berichte über eine neue, bipolare, steroid beschichtete epikardiale Elektrode sind sehr ermutigend. Es bedarf nun weiterer Daten über deren Zuverlässigkeit im Langzeitverlauf zur Beurteilung ob der transvenöse Zugang bei sehr kleinen Kindern auch zukünftig noch bevorzugt werden sollte. Methoden Von Januar 1994 bis November 2000 wurden insgesamt 64 bipolare, steroid beschichtete epikardiale Schrittmacherelektroden (Medtronic CapSure Epi 10366 and 4968, Medtronic, Inc, Minneapolis, MN, USA) bei 52 Kindern mit einem medianen Alter von 25,5 Monaten (0,03–193 Monate) implantiert (in 12 Fällen handelte es sich um Zweikammersysteme). Diese Elektroden wurden als Teil einer prospektiven Multizenterstudie von AutoCapture Schrittmachern seit Dezember 1996 laufend nachkontrolliert. Resultate Die postoperativen Reizschwellenwerte waren niedrig sowohl bei Ventrikelelektroden (0,8±0,37 Volt @ 0,5ms) als auch bei den Vorhofelektroden (0,8±0,4Volt @ 0,5ms) und zeigten wie die sehr guten intrinsischen Signale (P Wellen 2,9±1,4mV und R Wellen 10,6±5,5mV) keine signifikanten Veränderungen während 24 Monaten Beobachtungszeit. AutoCapture kontrollierte Stimulation war möglich bei 46/52 (88%) Kindern und ergab eine berechnete Batterielebensdauer von 14,8±2,9 Jahren bei VVIR Stimulation (Regency SR 5130, St.Jude Medical, Sylmar, CA, USA) und 10,8±1,1 Jahren bei Zweikammersystemen (Affinity DR 5330, St.Jude Medical, Sylmar, CA, USA). Abgesehen von 3 Repositionierungen im unmittelbaren postoperativen Verlauf traten keine Elektroden abhängige Komplikationen auf. Schlussfolgerung Bipolare epikardiale Elektroden zeigen eine hohe Zuverlässigkeit mit ausgezeichneten Stimulations- und Wahrnehmungsschwellen auch im Langzeitverlauf. Eine AutoCapture kontrollierte Stimulation ist bei den meisten Patienten möglich und führt zu einer deutlichen Verlängerung der Batterielebensdauer. Epikardiale Schrittmachersysteme können deshalb als erste Wahl bei der Schrittmacherbehandlung von Säuglingen und Kleinkindern empfohlen werden.
    No preview · Article · Aug 2001 · Herzschrittmachertherapie & Elektrophysiologie
  • Fırat Duru · Urs Bauersfeld · Hans Schüller · Reto Candinas
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    ABSTRACT: Continuous monitoring of pacemaker stimulation thresholds and automatic adjustment of pacemaker outputs were among the longstanding goals of the pacing community. The first clinically successful implementation of threshold tracking pacing was the Autocapture feature which has accomplished automatic ventricular capture verification for every single stimulus by monitoring the Evoked Response (ER) signal resulting from myocardial depolarization. The Autocapture feature not only decreases energy consumption by keeping the stimulation output slightly above the actual threshold, but also increases patient safety by access to high-output back-up pulses if there is loss of capture. Furthermore, it provides valuable documentation of stimulation thresholds over time and serves as a valuable research tool. Current limitations for its widespread use include the requirements for implantation of bipolar low polarization leads and unipolar pacing in the ventricle. Fusion/pseudofusion beats with resultant insufficient or even non-existent ER signal amplitudes followed by unnecessary delivery of back-up pulses and a possible increase in pacemaker output is not an uncommon observation unique to the Autocapture feature. The recent incorporation of the Autocapture algorithm in dual chamber pacemakers has been challenging because of more frequent occurrence of fusion/pseudofusion beats in the presence of normal AV conduction. Along with a review of the previously published studies and our clinical experience, this article discusses the clinical advantages and potential problems of Autocapture.
    No preview · Article · Nov 2000 · Journal of Interventional Cardiac Electrophysiology
  • K Hanséus · S Sandström · H Schüller
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    ABSTRACT: We report successful emergency pacing followed by permanent pacemaker implantation due to complete block in an otherwise healthy premature infant of 1,770 g. Via the umbilical vein a temporary bipolar pacing lead was placed in the right ventricle. The lack of spontaneous improvement warranted implantation of a permanent pacemaker system at the age of 2 weeks. Via a transatrial approach an endocardial unipolar screw-in lead was placed in the right ventricle and connected to a pulse generator implanted subcutaneously. During the follow-up period of 6 years the child has been doing well with his VVI-R pacemaker operating at rates between 80 and 160 pulses/minute at a chronic stimulation threshold below 0.9 V at 0.37 msec.
    No preview · Article · Sep 2000 · Pediatric Cardiology
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    ABSTRACT: Permanent cardiac pacing in children results commonly in augmented energy consumption because of the high pacing rates and the ample stimulation safety margin applied in children. Cardiovascular anatomy and limited venous access sometimes preclude the otherwise preferred endocardial approach. In this multicenter patient series, we studied the feasibility, safety, and energy saving obtained by a combination of steroid-eluting epicardial leads with autocapture devices capable of ongoing adjustment of the stimulation output to the prevailing threshold. Autocapture devices (Pacesetter Microny SR+/- and Regency SR+/-; Pacesetter, Solna, Sweden) and steroid-eluting epicardial pacing leads (Medtronic CapSure Epi 10366; Medtronic, Inc, Minneapolis, MN) were implanted in 14 children. Thresholds, telemetry data, evoked response, and polarization signals were obtained at discharge and follow-up, and battery service life was calculated. During a median follow-up of 6.5 months, autocapture pacing was applied in 12 of 14 children. The automatically adjusted pulse amplitude of autocapture devices demonstrated low-energy pacing with no significant changes between discharge and 6 months follow-up (1.1 +/- 0.3 versus 0.9 +/- 0.3 V). Autocapture-programmed pacemakers had calculated life spans of 7.8 +/- 1.4 years (Microny) and 21.0 +/- 1.6 years (Regency). No adverse effects were noted. Autocapture-controlled pacing with bipolar epicardial pacing leads is feasible and safe in children. Autocapture programming results in substantial energy savings and extends battery life markedly.
    No preview · Article · Nov 1999 · The Annals of Thoracic Surgery
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    Johan Brandt · Hans Schüller
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    ABSTRACT: Symptomatic sinus node disease is a common indication for permanent pacemaker implantation. Single-chamber ventricular (VVI) pacing, single-chamber atrial (AAI) stimulation, and dual-chamber (DDD or DDI) systems are used to a varying extent at different implanting centers. Hemodynamic and clinical studies relevant to the choice of pacing mode in these patients are reviewed. The data currently available strongly support the use of pacing systems providing atrial stimulation. The choice between single-chamber atrial or dual-chamber pacing can be based on the relative importance assigned to a number of factors: Hemodynamic aspects, the risk of ventricular lead problems, cost, and complexity aspects favor AAI pacing, whereas patients with a substantial risk of developing atrioventricular block should receive a DDD or DDI unit.
    Preview · Article · Oct 1994 · Clinical Cardiology
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    ABSTRACT: This study was designed to analyze the incidence and determinants of complications and long-term survival in sinus node disease treated with atrial pacing. Knowledge of the natural history of sinus node disease treated with different pacing modes is imperfect, and controversy exists regarding the optimal pacemaker therapy. A consecutive series of 213 patients with sinus node disease initially treated with atrial pacing was studied for a median follow-up period of 60 months. The end points studied were permanent atrial fibrillation, high grade atrioventricular (AV) block, P wave undersensing, pacing mode change, reoperation and death. Several prognostic factors were evaluated statistically and the survival rate was compared with that of a matched general population. The incidence rate of permanent atrial fibrillation during follow-up was 7% (1.4%/year). The risk of this arrhythmia increased substantially with age greater than or equal to 70 years at pacemaker implantation. Only 2 of the 15 patients who developed permanent atrial fibrillation required ventricular pacing. High grade AV block occurred in 8.5% (1.8%/year) and its incidence was much greater in patients with complete bundle branch block or bifascicular block (35%) than in patients without such conduction disturbances (6%). A change to ventricular or dual-chamber stimulation was necessary in 14% of all patients, primarily because of early lead dislodgment or high grade AV block. Surgical intervention with maintenance of atrial pacing was required in 7% of patients. The survival rates of 97% at 1 year, 89% at 5 years and 72% at 10 years did not differ significantly from those of a matched general population. In sinus node disease, atrial pacing can be successfully applied during long-term follow-up. Patients with complete bundle branch or bifascicular block in addition to sinus node disease should initially receive a dual-chamber pacemaker, but routine application of dual-chamber stimulation does not appear to be warranted.
    Full-text · Article · Oct 1992 · Journal of the American College of Cardiology
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    ABSTRACT: Forty-four patients with sinus node disease and chronotropic incompetence but no evidence of AV conduction disturbances were treated with rate adaptive atrial (AAI,R) pacemakers. Medtronic Activitrax and Siemens Sensolog activity sensing single chamber pulse generators were used. Twenty-four patients (55%) had the bradycardia-tachycardia syndrome. The mean follow-up time is 20 +/- 14 months (range 1-48, median 17 months). All patients remain alive. Two patients were reoperated upon for lead problems without change of pacing mode. One patient developed symptomatic second-degree Wenckebach block during follow-up, and received a DDD,R system. Although 22 of the patients were treated with antiarrhythmic drugs postoperatively, no further cases of significant AV conduction disturbances were seen. During rapid atrial pacing, exercise-induced enhancement of AV conduction was a consistent finding, although less pronounced in patients treated with beta-blocking drugs. One patient developed permanent atrial fibrillation with an adequate ventricular rate. By systematic reprogramming procedures, QRS complex sensing through the atrial electrode could be demonstrated in 25 patients (23/28 with unipolar and 2/16 with bipolar leads). It could be counteracted effectively by pulse generator program selection in all cases. Forty-two of 44 patients (95%) remain in AAI,R pacing with normal function. Rate adaptive atrial pacing can be successfully applied in this patient group.
    No preview · Article · Sep 1991 · Pacing and Clinical Electrophysiology
  • H Schüller · J Brandt
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    ABSTRACT: The pacemaker syndrome refers to symptoms and signs in the pacemaker patient caused by inadequate timing of atrial and ventricular contractions. The lack of normal atrioventricular synchrony may result in decreased cardiac output and venous "cannon A waves." A sudden increase in atrial pressure at the onset of asynchrony may elicit a systemic hypotensive reflex response. A wide range of symptoms can be observed. The pacemaker syndrome is encountered in a significant number of patients with ventricular (VVI) pacemakers, mostly when 1:1 retrograde ventriculoatrial conduction is present. The risk of occurrence of the pacemaker syndrome is minimized if pacemaker systems are used which restore or maintain the normal atrioventricular contraction sequence. Hence, in sinus node disease, atrial stimulation with or without ventricular stimulation should be employed, while in high-grade atrioventricular block dual-chamber pacing is recommended. The pacemaker syndrome is not restricted to the VVI stimulation mode. It can be seen, though rarely, in atrial and dual-chamber pacing, and an awareness of these new causes is necessary. An established pacemaker syndrome can often be counteracted by adjusting the pulse generator function.
    No preview · Article · May 1991 · Clinical Cardiology
  • Johan Brandt · Robyn Attewell · Thomas Fahraeus · HANS SCHÜLLER
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    ABSTRACT: The atrial and ventricular pacing threshold development during the first postoperative year was studied in a group of patients receiving DDD pacemakers. Identical carbon-tip endocardial leads were implanted in atrium and ventricle. Atrial and ventricular voltage stimulation thresholds were measured at implantation, and noninvasively at 1 and 12 months thereafter. The atrial amplifier sensitivity required for adequate P wave sensing during follow-up was also determined. The possible influence of a number of factors upon atrial and ventricular threshold evolution was statistically assessed. The threshold data were complete in 57 patients (mean age +/- SD, 65.2 +/- 12.4 years). Thirteen patients had a diagnosis of sinus node disease, whereas 44 had not. Patient age and diagnosis did not significantly influence atrial or ventricular stimulation threshold development. Atrial sensing thresholds were not related to atrial stimulation thresholds during follow-up. Atrial pacing thresholds were higher than ventricular thresholds at pacemaker implantation (P less than 0.00005), but the postoperative threshold rise and thresholds at 1 and 12 months postoperatively did not differ significantly between the atrium and ventricle. The ratio of chronic to acute stimulation thresholds was higher on the ventricular than on the atrial level (0.001 greater than P greater than 0.0005). The chronic atrial threshold showed a logarithmic relation to the threshold at implantation (P = 0.0006); postoperative threshold rise was not a significant determinant of the chronic atrial threshold (P = NS). On the ventricular level, the reverse was seen: The chronic threshold was related to the postoperative threshold rise (P = 0.0015, logarithmic relation), but not to the implantation threshold (P = NS).(ABSTRACT TRUNCATED AT 250 WORDS)
    No preview · Article · Aug 1990 · Pacing and Clinical Electrophysiology
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    ABSTRACT: Patients with sinus node disease (SND) who are unable to achieve an adequate increase in heart rate during exercise are candidates for atrial rate-responsive pacing (AAI-R). We have implanted 40 AAI-R systems in SND patients with an average follow-up of 12.5 +/- 8 (range 3-30) months. All the patients received an activity-sensing pulse generator (Activitrax, Medtronic or Sensolog, Siemens-Pacesetter) with a single atrial lead. Only patients with an intraoperative AV nodal block cycle-length above 100 beats min-1 were included. During follow-up, one patient was observed to have transient asymptomatic 2:1 AV-block during sleep. No patient developed persistent AV-block or chronic atrial fibrillation. Twelve patients with persistent chronotropic incompetence were assigned for a randomized double-blind crossover study, comparing exercise treadmill capacity in AAI-R with conventional atrial inhibited pacing (AAI). During AAI-R pacing the maximum heart rate during exercise was 120 +/- 1 beats min-1 compared with 97 +/- 21 beats min-1 during AAI pacing (P less than 0.01). The average exercise time increased from 11.2 +/- 2 min during AAI-pacing to 13.4 +/- 3 min during AAI-R pacing (P less than 0.01). AAI pacing should be considered for patients with SND and chronotropic incompetence.
    No preview · Article · Jul 1990 · European Heart Journal
  • Johan Brandt · Robyn Attewell · Thomas Fahraeus · HANS SCHÜLLER
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    ABSTRACT: Data are reviewed from 88 patients who received double, passive-fixation unipolar endocardial leads for DDD pacemaker treatment. Identical electrodes were used in the right atrium and the right ventricle. Intra-atrial P wave amplitudes, intraventricular QRS complex amplitudes, and atrial and ventricular pacing thresholds were determined at implantation. The intra-atrial P wave amplitudes were not significantly correlated to the intraventricular QRS complex amplitudes. No significant correlation was found between the atrial stimulation thresholds and the ventricular pacing thresholds. The intra-atrial P wave amplitude showed a significant inverse and logarithmic correlation with patient age (P = 0.007). Furthermore, patients with sinus node disease had significantly lower intra-atrial P wave amplitudes (P = 0.04) than patients without this abnormality. The acute atrial and ventricular pacing thresholds and the intraventricular QRS complex amplitude were not correlated to patient age or presence of sinus node disease. Patients requiring higher atrial amplifier sensitivity settings during follow-up were significantly older (P less than 0.05) than those in whom lower atrial sensitivities were sufficient. A postoperative attenuation of the atrial electrogram was detectable by sensitivity programming procedures in 29 of the patients (35%). This phenomenon did not significantly relate to patient age or presence of sinus node disease. No case of permanent atrial undersensing occurred. It is suggested that the lower intra-atrial P wave amplitudes in older patients and patients with sinus node disease reflect degenerative changes in the atrial myocardium. The statistical relations found appear to motivate special attention to atrial sensing in these patient groups.
    No preview · Article · May 1990 · Pacing and Clinical Electrophysiology
  • Johan Brandt · Thomas Fahraeus · H Schüller
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    ABSTRACT: To study the prevalence and significance of far-field QRS complex sensing via unipolar atrial electrodes, we attempted to provoke this phenomenon postoperatively in 119 patients with DDD pacemakers. It occurred in 42 patients (35%), with different types of atrial electrodes. In 27 cases with documented far-field QRS complex sensing, selection of an adequate atrial amplifier sensitivity eliminated the problem; in the remaining 15 cases, other program adjustments were necessary. In all patients DDD pacing could be maintained, and no reoperations were required. In a retrospective analysis of a subgroup of 26 patients, all having received endocardial unipolar carbon tip electrodes in the right atrial appendage, the possibility of predicting subsequent far-field QRS complex sensing was studied. The occurrence thereof was not significantly related to patient age or sex, indication for pacing, or routinely obtained electrophysiological measurements. Potential far-field QRS complex sensing via the atrial electrode is significantly common in patients with DDD pacemakers. Patient characteristics and intraoperatively measured intraatrial signal amplitudes are not useful in predicting the postoperative occurrence of the phenomenon. As a rule, it can be handled effectively by pulse generator reprogramming.
    No preview · Article · Dec 1988 · Pacing and Clinical Electrophysiology
  • J Brandt · T Fåhraeus · H Schüller
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    ABSTRACT: Unintended sensing of QRS complexes via atrial pacemaker leads may cause disorders of pacemaker function in AAI, VDD and DDD pacing. The consequences of this phenomenon depend upon the pacing mode and the timing of the inappropriate sensing as related to the technical characteristics of the pulse generator. With AAI pacemakers, "inappropriate pacemaker bradycardia" may be seen or P-wave undersensing may be simulated. With VDD and DDD systems a special kind of pacemaker mediated tachycardia or apparent P-wave undersensing may result. With knowledge of the underlying mechanisms, differential diagnosis is possible. The countermeasures available are discussed.
    No preview · Article · Nov 1988 · Pacing and Clinical Electrophysiology
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    ABSTRACT: Unintended sensing of QRS complexes via atrial pacemaker leads may cause disorders of pacemaker function in AAI, VDD and DDD pacing. The consequences of this phenomenon depend upon the pacing mode and the timing of the inappropriate sensing as related to the technical characteristics of the pulse generator. With AAI pacemakers, “inappropriate pacemaker bradycardia” may be seen or P-wave undersensing may be simulated. With VDD and DDD systems a special kind of pacemaker mediated tachycardia or apparent P-wave undersensing may result. With knowledge of the underlying mechanisms, differential diagnosis is possible. The countermeasures available are discussed.
    No preview · Article · Sep 1988 · Pacing and Clinical Electrophysiology
  • Mȧrten Rosenqvist · Johan Brandt · Hans Schüller
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    ABSTRACT: In a previous retrospective treatment-comparison study of 168 patients with sinus node disease, we found a significantly higher incidence of permanent atrial fibrillation and congestive heart failure in patients treated with ventricular (VVI) pacing compared to atrial (AAI) pacing, after an average follow-up period of 2 years. To determine whether these differences persisted and whether AAI pacing resulted in a lower mortality rate than VVI pacing during long-term follow-up, the treatment groups were restudied after an average of 4 years of pacemaker treatment. The incidence of permanent atrial fibrillation was still significantly higher (p less than 0.0005) in the VVI group than in the AAI group after the additional 2 years (VVI = 47%, an increase from 29%; AAI = 6.7%, an increase from 3.4%). Congestive heart failure occurred significantly more often in the VVI group than in the AAI group (37% vs 15%, p less than 0.005). Analysis of survival data showed a higher overall mortality rate in the VVI group (23% vs 8%, p less than 0.05). The development of high-degree atrioventricular block in the AAI group remained low (total 4.5%). Thus, in sinus node disease, the advantages of AAI over VVI pacing persist during long-term follow-up. The differences in cardiovascular morbidity between the groups tend to increase with time and appear to result in a lower mortality rate among patients treated with AAI pacing.
    No preview · Article · Aug 1988 · American Heart Journal