Wolfgang M. Hartung

Increased expression of P-selectin in patients with chronic atrial fibrillation.

Previous studies have shown that platelets are activated during atrial fibrillation (AF). However, prophylactic therapy with aspirin is not associated with a reduction of thromboembolic complications in patients with AF. Stimulation of platelet thrombin and ADP receptors causes a release of P‐selectin, which is not affected by aspirin. The purpose of this study was to assess the influence of AF on platelet P‐selectin expression. Blood samples from 30 patients were studied ex vivo. Nineteen patients had chronic AF (> 3 months), 11 patients were in sinus rhythm (SR). P‐selectin expression was determined by flow cytometry (antibody binding capacity [BC]) at baseline and after platelet stimulation with adenosine diphosphate (ADP) and thrombin receptor activating peptide (TRAP). To determine the effect of heart rate and atrial pressure (RAP), measurements were repeated after 10 minutes of ventricular pacing (120 beats/min) in patients with SR. P‐selectin expression was increased in patients with AF at baseline (AF: 1329 ±81 BC vs SR: 968 ± 108 BC; P < 0.05) and after stimulation with ADP (AF: 1445 ± 101 BC vs SR: 1061 ± 109 BC; P < 0.05) and TRAP (AF: 13783 ± 2442 BC vs SR: 5977 ± 800 BC; P < 0.05). RAP (2.0 ± 0.5 vs 6.0 ± 0.8 mmHg; P < 0.01) and atrial rate (75 ± 5 vs 114 ± 5 beats/min; P < 0.001) increased during ventricular pacing. However, P‐selectin levels remained stable. AF was accompanied by increased P‐selectin expression. In contrast, increased ventricular rate and elevated atrial pressure alone had no effect on platelet activity. Further studies are needed to determine if platelet ADP receptor inhibitors offer a therapeutic benefit in patients with AF.

Estimation of Temperature During Radiofrequency Catheter Ablation Using Impedance Measurements

Temperature monitoring during radiofrequency catheter ablation is useful but requires specialized equipment that is not generally available. Previous studies have shown that impedance characteristically decreases as the result of heating at the electrode‐tissue interface. The purpose of the current study was to determine if impedance changes during radiofrequency current application could be used to estimate endocardial temperature in patients undergoing catheter ablation. Data from 43 patients treated with a thermistor ablation catheter were retrospectively analyzed. The slope of the initial 2 seconds of the impedance curve and subsequent changes in impedance were incorporated into an equation for estimation of temperature in real‐time. The accuracy of this equation was assessed by prospectively comparing the calculated and measured temperatures in 19 patients. Of the 88% of energy applications that were suitable for analysis, the average difference between calculated and measured temperatures was 5.2 ± 5.6°C. The average error was ± 10° in 89% of applications. The results of this study suggest that impedance measurements can be used to quantify tissue temperature in real‐time during radiofrequency catheter ablation. This method is sufficiently accurate to allow titration of power output to produce temperatures in the useful range (50–80°C) while avoiding excessive heating (± 90°C).

Pacing of Bachmann's bundle after coronary artery bypass grafting

GOETTE, A., et al.: Pacing of Bachmanns Bundle After Coronary Artery Bypass Grafting. The purpose of this randomized, prospective trial was to determine if Bachmanns bundle pacing reduces the incidence of AF after CABG. The study included 161 patients with no history of AF who were randomized to three groups. Group 1 included 50 patients as controls. Group 2 included 60 patients who had an epicardial wire placed at the lateral wall of the right atrium. In the 51 patients of group 3, the wire was placed at the Bachmanns bundle. In groups 2 and 3, atrial pacing (AAI 96 beats/min) was initiated immediately after CABG and continued for 5 days. The study endpoint was AF lasting ≥ 1 minute. Baseline clinical parameters were similar in all three groups. The incidence of AF was not reduced by pacing (group 1: 42%; group 2: 48%; group 3: 37%; P = NS). The paced P wave duration was increased in group 2 (129 ± 14 ms vs group 3: 96 ± 21 ms; P < 0.05). Paced P wave duration was a risk factor for postoperative AF (odds ratio 1.015; 95% CI 1.0021–1.028; P < 0.05). Analysis comparing the pacing groups revealed a reduction in AF during Bachmanns bundle pacing (50 vs 29%; P < 0.01). Pacing thresholds were significantly better at Bachmanns bundle compared to group 2. In conclusion, an anatomically guided pacing at the Bachmanns bundle does not reduce the overall incidence of postoperative AF compared to controls. However, the Bachmanns bundle offers favorable capabilities for postoperative atrial pacing, and thus it is a preferable site for electrode placement if postoperative atrial pacing is required.

An Increase in Sinus Rate Following Radiofrequency Energy Application in the Posteroseptal Space

An increase in sinus rate has been previously described in patients with AV node reentry (AVNRT) following successful A V node modification. This increase could either be a specific sign of elimination of slow pathway conduction or it could be a consequence of energy application in the posteroseptal area. Thus, we compared the changes in sinus cycle length following successful slow pathway ablation (defined as complete elimination of dual AV node physiology) in patients having AVNRT with those in patients undergoing successful ablation of a posteroseptal atriovetriricular accessory connection. Twenty five patients (16 women and 9 men, mean age 41 ± 4 years) with typical AVNRT (cycle length 378 ± 12 ms and 29 patients (16 women and 13 men, age 34 ± 5 years) with an accessory connection (17 manifest and 12 concealed) were studied. The electrophysiology study was performed during sedation with Fentanyl and Midazolam. The mean number of energy applications was 3 ± 1 for successful slow pathway ablation and 4 ± 1 for successful ablation of the accessory connection (p:NS). Following the successful energy application, the sinus cycle length decreased significantly 776 ms at baseline to 691 ms in patients with AVNRT. Following successful ablation of the posteroseptal AC, sinus cycle length decreased from 755 ms at baseline to 664 ms (p < 0.05 in both groups [difference between groups not significant]). The decrease in sinus cycle length did not correlate with the number ofRF energy applications required for successful ablation or the total energy delivered. In conclusion, ablation of the AV node slow pathway and a posteroseptal accessory connection results in similar increases in the sinus rate. Thus, the increase in sinus rate is probably due to energy application in the posteroseptal space, possibly due to concomitant destruction of vagal inputs, and it is not specific for elimination of slow pathway conduction.

Transcatheter Subendocardial Infusion: A Novel Technique for Mapping and Ablation of Ventricular Myocardium

BACKGROUND Catheter ablation with radiofrequency energy is feasible in a limited subset of patients with ventricular tachycardia. The purpose of this study was to evaluate a technique for mapping and ablation of ventricular myocardium with the use of transcatheter subendocardial infusion. METHODS AND RESULTS A needle-tipped deflectable electrode catheter was used to deliver reagents to endocardial target sites. This was equipped with two central lumens to allow sequential administration of mapping and ablation injectants with minimal admixture. The mapping injectant consisted of a mixture of lidocaine, iohexal, and glycerin; the ablation injectant contained ethanol, iohexal, and glycerin. Infusion of the mapping injectant (1 cm3 over 3 or 5 seconds, n = 14) produced a stain on fluoroscopy and increased local capture threshold by 61%. No lesions resulted from mapping infusions. Infusion of the ethanol-containing injectant (n = 48) produced discrete lesions, with a mean volume ranging from 0.6 to 1.5 cm3. There was a direct relationship between infusion volume, infusion duration, and resultant lesion volume. Fibrosis in a region of healed myocardial infarction did not impair diffusion of the injectant or affect lesion dimensions. Microscopic analysis of chronic lesions showed a sharply demarcated border zone between fibrotic and normal myocardium. CONCLUSIONS Transcatheter subendocardial infusion can be used to reversibly impair local excitability and mark an injection site fluoroscopically. Subendocardial injection of ethanol can predictably ablate a large volume of ventricular myocardium. Additional study of this system in an arrhythmia model will help to define its potential for mapping and ablation of hypotensive ventricular tachycardia.

The Importance of Right Atrial Pacing Electrode Position and Pacing Configuration for Intra-atrial and Inter-atrial Conduction Times

Pace prevention of atrial tachyarrhythmias is based in part on the reduction of intra-atrial (IAA) and/or inter-atrial (IEA) conduction. We previously introduced a novel pacing mode using floating atrial ring electrodes on a VDD-lead (BIdirectional MO nophasic impulSe: BIMOS). The effects of BIMOS pacing on IAA and IEA conduction times has not been studied. In nine Merino sheep electrode catheters were placed at the His-Bundle (HBE), high right atrium (HRA), coronary sinus ostium (Cs-Os), and left lateral atrium (LLA). A VDD-lead was introduced with floating electrodes in the high and mid right atrium (Floating). IAA (S/P-HRA, S/P-Cs-Os, S/P-HBE, S/P-Floating), IEA conduction times (S/P-LLA), and P-wave duration (PD) were measured during sinus rhythm (S), during bipolar cathodal pacing (P) in the HRA, in the Cs-Os position, as well as during BIMOS floating pacing. The mean PD during S was significantly shorter than during HRA- (66.6±12.8ms; vs. 116.2±11.1ms; p<0.05) and Cs-Os-P (66.6±12.8ms vs. 94.4±9.0ms; p<0.05). In comparison to HRA-P, BIMOS configuration lead to a significant reduction of the P-wave duration (116.2±11.1ms vs. 85.4±8.8ms; p<0.05). During BIMOS pacing, the global atrial conduction time was significantly shorter than during pacing in the HRA and Cs-Os position. The results of this study demonstrate a clear reduction of IAA and IEA conduction times using BIMOS configurations compared to conventional HRA-P. Furthermore, BIMOS pacing produced a more homogeneous atrial activation when compared with conventional HRA- and Cs-Os-P.

Intra- und interatriale Leitung – Konsequenzen für die atriale Elektrodenplatzierung?

SummaryBackground Intra-atrial (IAA) and inter-atrial (IEA) conduction times during atrial pacing (P) are determined by conduction characteristics of IAA and IEA activation and by the atrial origin of stimulation. It seems that atrial P at identical locations can induce different conduction times dependent on the quality of the IAA and IEA conduction structures. Purpose of the study The aim of this study was to analyze the influence of pacing on normal IAA and IEA activation and the p-wave duration (PWD) in a sheep model. Different atrial wall contact pacing positions as well as a novel floating pacing configuration (BIdirectional MOnophasic ImpulSe: BIMOS; induced partial overlapping of electrical fields by splitting a conventional pacing impulse between three electrodes) were tested. The influence of pacing on a primary prolonged PWD is summarized, using published data. Methods Normal IAA, IEA conduction times and PWD: Twenty Merino sheep (4.6±0.7 years; 60.1±3.6 kg) were studied. EP catheters were placed under fluoroscopy close to the His Bundle (HBE), in the high right atrium (HRA), in the coronary sinus ostium (Cs-Os), and in the left lateral atrium (LLA). A modified single-VDD lead was introduced with the atrial ring electrodes floating in the high and mid right atrium. IAA (S/P-HRA, S/P-Cs-Os, S/P-HBE, S/P-floating), IEA conduction times (S/P-LLA), and P-wave duration (PWD) were assessed during intrinsic sinus rhythm (S), during bipolar cathodal P during wall contact in the HRA and in the Cs-Os, as well as during floating P with BIMOS configuration. Primary prolonged PWD: the influence of different novel pacing concepts (“biatrial” P, “dual site” P, “septal” P, “Bachmann bundle” P) on primary prolonged PWD were analyzed using data from the literature. Results Normal IAA and IEA conduction times and PWD: The mean PWD during S was significantly shorter than during HRA- (66.6±12.8 ms; vs. 116.2±11.1 ms; p<0.05) and Cs-Os-pacing (66.6±12.8 ms vs. 94.4±9.0 ms; p<0.05). Floating pacing with BIMOS showed no significant difference to S: 66.6±12.8 ms vs. 85.4±8.8 ms (p>0.05). PWD decreased significantly when the pacing protocol was changed from HRA pacing to floating pacing with BIMOS. The IEA conduction time (S/P-LLA) was also significantly shorter during S than during HRA pacing (34.7±14.7 ms vs. 89.7±13.5 ms; p<0.05), Cs-Os pacing (34.7±14.7 ms vs. 66.3±7.0 ms; p<0.05), and BIMOS pacing (34.7±14.7 ms vs. 61.3±12.7 ms; p<0.05). Compared to HRA pacing, floating pacing with BIMOS leads to a significant reduction of the PWD. Primary prolonged PWD: All new pacing concepts were developed primary for pace prevention of atrial arrhythmias. These pacing concepts reduce significantly primary prolonged PWD compared to S as known from the literature (“biatrial”: S: 181±28 ms vs. P: 108±13 ms; p<0.05; “dual site”: S: 120±12 ms vs. P: 103±17 ms; p<0.05, “septal”: S: 132±23 ms vs. P: 84±14 ms; p<0.05; and “Bachmann bundle” S: 163±14.7 ms vs. P: 134±13.5 ms; p<0.05). Conclusion This study demonstrates the prolongation of primary normal IAA and IEA conduction times by pacing at different locations compared to S. Thereby floating pacing using BIMOS results in the smallest prolongation of conduction times. Pacing at the Cs-Os does not reduce the IAA conduction time but reduces the IEA conduction time in comparison to HRA pacing. On the other hand, the new pacing concepts for pace prevention of atrial fibrillation always showed a significant reduction of a primary prolonged PWD. This different behavior of IAA and IEA conduction times and PWD during pacing has to be taken into account before implantation of an atrial pacing lead.ZusammenfassungHintergrund Die intraatrialen (IAA) und interatrialen (IEA) Leitungszeiten (LZ) werden während atrialer Stimulation (ST) sowohl von den Leitungseigenschaften der IAA- und IEA-Leitungsstrukturen als auch vom atrialen Stimulationsort bestimmt. Dabei scheint eine identische atriale ST in Abhängigkeit von den IAA- und IEA-Leitungsqualitäten eine unterschiedliche Auswirkung auf die LZ zu haben. Studienziel Das Ziel der vorliegenden Arbeit ist es, die Beeinflussung normaler IAA- und IEA-Leitungseigenschaften bzw. der P-Wellendauer (PWD) durch unterschiedliche wandständige Stimulationsorte sowie durch eine neuartige Floatingstimulation (F-ST) (BIdirektionaler MOnophasischer ImpulS: BIMOS; überlappende elektrische Feldverläufe, erzeugt durch einen konventionellen Schrittmacherimpuls zwischen drei Elektroden), in einer tierexperimentellen Studie zu untersuchen. An Hand der Literatur wird der Einfluss des atrialen Stimulationsortes auf eine primär verlängerte PWD analysiert. Methode Normale IAA-, IEA-LZ und PWD: Bei 20 Merinoschafen (4,6±0,7 Jahre; 60,1±3,6 kg), wurden EP-Katheter am His-Bündel (HBE), im hohen lateralen rechten Vorhof (HRA), im Koronarsinus-Ostium (Cs-Os) und am lateralen linken Vorhof (LLA) platziert. Weiterhin wurde eine modifizierte VDD-Elektrode (3 Ringelektroden) so platziert, dass die distale Ringelektrode im mittleren rechten Vorhof frei flottierte (F). Es wurden während Sinusrhythmus (SR) und während ST neben der PWD sowohl die IAA- (SR/ST-HRA; SR/ST-Cs-Os; SR/ST-HBE, SR/ST-F) als auch die IEA-LZ (SR/ST-LA) für konventionelle ST im HRA und am Cs-Os sowie für F-ST mit BIMOS ermittelt und miteinander verglichen. Primär verlängerte PWD: Der Einfluss verschiedener neuartiger Stimulationskonzepte („biatriale” ST, „dual site” ST, „atriale septale” ST, „Bachmann-Bündel” ST) auf primär verlängerte PWD wurde an Hand der Erstdaten zu diesen Konzepten aus der Literatur analysiert. Ergebnisse Normale IAA-, IEA-LZ und PWD: Die mittlere PWD war während SR signifikant kürzer als während HRA- (66.6±12.8 ms; vs. 116,2±11,1 ms; p<0,05) bzw. Cs-Os-ST (66,6±12,8 ms vs. 94,4±9,0 ms; p<0,05). Während F-ST mit der BIMOS Konfiguration bestand kein signifikanter Unterschied (66,6±12,8 ms vs. 85,4±8,8 ms; p>0,05). Weiterhin bestand eine signifikante Verkürzung der PWD beim Wechsel von HRA-ST zur BIMOS F-ST. Die IEA-LZ war während SR im Vergleich zur Stimulation im HRA (34,7±14,7 ms vs. 89,7±13,5 ms; p<0,05), vom Cs-Os (34,7±14,7 ms vs. 66,3±7,0 ms; p<0,05) und mit BIMOS (34,7±14,7 ms vs. 61,3±12,7 ms; p<0,05) am kürzesten. Die IEA-LZ waren jedoch während F-ST mit BIMOS signifikant kürzer als während ST im HRA. Primär verlängerte PWD: Für alle neuartigen Stimulationskonzepte, die primär für die Prävention von Vorhofflimmern entwickelt wurden, sind in der Literatur signifikante Reduktionen der primär verlängerten PWD („biatrial”: SR: 181±28 ms vs. ST: 108±13 ms; p<0,05; „dual site”: SR: 120±12 ms vs. ST: 103±17 ms; p<0,05, „septal”: SR: 132±23 ms vs. ST: 84±14 ms; p<0,05; und „Bachmann Bündel”: SR: 163±14,7 ms vs. ST: 134±13,5 ms; p<0,05) nachweisbar. Schlussfolgerungen Die Ergebnisse dieser Arbeit zeigen, dass bei normaler IAA- und IEA-LZ eine atriale ST, unabhängig vom Stimulationsort, immer eine Verlängerung dieser LZ bewirkt. Dabei zeigt die atriale F-ST mit der BIMOS-Konfiguration die geringste Verlängerung der IAA- und IEA-LZ gegenüber SR. Die ST am Cs-Os hat keinen positiven Einfluss auf die IAA-LZ gegenüber der ST im HRA. Die ST am Cs-Os bewirkt aber eine signifikante Reduktion der IEA-LZ gegenüber der ST im HRA. Im Gegensatz dazu zeigen die Analysen der verschiedenen neuartigen Stimulationskonfigurationen bei primär verlängerter PWD eine generelle Reduktion der PWD. Dieses unterschiedliche Verhalten der IAA- und IEA-LZ sowie der PWD während ST sollte vor der Implantation einer atrialen Elektrode bedacht werden.

Effects of High Energy Shocks on Pacing Impedance During Transvenous ICD Implantation

The purpose of the current study was to characterize the effects of transvenous ICD shocks on myocardial impedance. Rather than recording impedance during shocks, it was measured during continuous pacing in order to minimize confounding effects such as electrode polarization. Pacing impedance (reflecting the combined impedances of the electrode‐tissue interface, myocardium, and blood pool) was measured every 5 seconds before and after 58 single shocks in 22 patients undergoing ICD implantation with a Transvene (n = 14) or Endotak (n = 8) lead. There was a progressive and long‐lasting decrease in impedance after shocks. The magnitude of this change was similar for 0.6‐J test shocks and shocks ≥ 5 J (28 ± 32 Ω vs 23 ± 16 Ω P = 0.8). However, the drop in impedance was more abrupt after high energy shocks. Because impedance continued to decline throughout the 5‐minute interval between shocks, successive shocks had a cumulative effect, with a decrease of 46 ± 42 Ω after four discharges. In conclusion, a progressive decline in pacing impedance is a characteristic response to transvenous ICD discharges.

Intra- und interatriale Leitung – Konsequenzen für die atriale Elektrodenplatzierung?@@@Intra- and interatrial conduction – consequences for electrode placement

SummaryBackground Intra-atrial (IAA) and inter-atrial (IEA) conduction times during atrial pacing (P) are determined by conduction characteristics of IAA and IEA activation and by the atrial origin of stimulation. It seems that atrial P at identical locations can induce different conduction times dependent on the quality of the IAA and IEA conduction structures. Purpose of the study The aim of this study was to analyze the influence of pacing on normal IAA and IEA activation and the p-wave duration (PWD) in a sheep model. Different atrial wall contact pacing positions as well as a novel floating pacing configuration (BIdirectional MOnophasic ImpulSe: BIMOS; induced partial overlapping of electrical fields by splitting a conventional pacing impulse between three electrodes) were tested. The influence of pacing on a primary prolonged PWD is summarized, using published data. Methods Normal IAA, IEA conduction times and PWD: Twenty Merino sheep (4.6±0.7 years; 60.1±3.6 kg) were studied. EP catheters were placed under fluoroscopy close to the His Bundle (HBE), in the high right atrium (HRA), in the coronary sinus ostium (Cs-Os), and in the left lateral atrium (LLA). A modified single-VDD lead was introduced with the atrial ring electrodes floating in the high and mid right atrium. IAA (S/P-HRA, S/P-Cs-Os, S/P-HBE, S/P-floating), IEA conduction times (S/P-LLA), and P-wave duration (PWD) were assessed during intrinsic sinus rhythm (S), during bipolar cathodal P during wall contact in the HRA and in the Cs-Os, as well as during floating P with BIMOS configuration. Primary prolonged PWD: the influence of different novel pacing concepts (“biatrial” P, “dual site” P, “septal” P, “Bachmann bundle” P) on primary prolonged PWD were analyzed using data from the literature. Results Normal IAA and IEA conduction times and PWD: The mean PWD during S was significantly shorter than during HRA- (66.6±12.8 ms; vs. 116.2±11.1 ms; p<0.05) and Cs-Os-pacing (66.6±12.8 ms vs. 94.4±9.0 ms; p<0.05). Floating pacing with BIMOS showed no significant difference to S: 66.6±12.8 ms vs. 85.4±8.8 ms (p>0.05). PWD decreased significantly when the pacing protocol was changed from HRA pacing to floating pacing with BIMOS. The IEA conduction time (S/P-LLA) was also significantly shorter during S than during HRA pacing (34.7±14.7 ms vs. 89.7±13.5 ms; p<0.05), Cs-Os pacing (34.7±14.7 ms vs. 66.3±7.0 ms; p<0.05), and BIMOS pacing (34.7±14.7 ms vs. 61.3±12.7 ms; p<0.05). Compared to HRA pacing, floating pacing with BIMOS leads to a significant reduction of the PWD. Primary prolonged PWD: All new pacing concepts were developed primary for pace prevention of atrial arrhythmias. These pacing concepts reduce significantly primary prolonged PWD compared to S as known from the literature (“biatrial”: S: 181±28 ms vs. P: 108±13 ms; p<0.05; “dual site”: S: 120±12 ms vs. P: 103±17 ms; p<0.05, “septal”: S: 132±23 ms vs. P: 84±14 ms; p<0.05; and “Bachmann bundle” S: 163±14.7 ms vs. P: 134±13.5 ms; p<0.05). Conclusion This study demonstrates the prolongation of primary normal IAA and IEA conduction times by pacing at different locations compared to S. Thereby floating pacing using BIMOS results in the smallest prolongation of conduction times. Pacing at the Cs-Os does not reduce the IAA conduction time but reduces the IEA conduction time in comparison to HRA pacing. On the other hand, the new pacing concepts for pace prevention of atrial fibrillation always showed a significant reduction of a primary prolonged PWD. This different behavior of IAA and IEA conduction times and PWD during pacing has to be taken into account before implantation of an atrial pacing lead.ZusammenfassungHintergrund Die intraatrialen (IAA) und interatrialen (IEA) Leitungszeiten (LZ) werden während atrialer Stimulation (ST) sowohl von den Leitungseigenschaften der IAA- und IEA-Leitungsstrukturen als auch vom atrialen Stimulationsort bestimmt. Dabei scheint eine identische atriale ST in Abhängigkeit von den IAA- und IEA-Leitungsqualitäten eine unterschiedliche Auswirkung auf die LZ zu haben. Studienziel Das Ziel der vorliegenden Arbeit ist es, die Beeinflussung normaler IAA- und IEA-Leitungseigenschaften bzw. der P-Wellendauer (PWD) durch unterschiedliche wandständige Stimulationsorte sowie durch eine neuartige Floatingstimulation (F-ST) (BIdirektionaler MOnophasischer ImpulS: BIMOS; überlappende elektrische Feldverläufe, erzeugt durch einen konventionellen Schrittmacherimpuls zwischen drei Elektroden), in einer tierexperimentellen Studie zu untersuchen. An Hand der Literatur wird der Einfluss des atrialen Stimulationsortes auf eine primär verlängerte PWD analysiert. Methode Normale IAA-, IEA-LZ und PWD: Bei 20 Merinoschafen (4,6±0,7 Jahre; 60,1±3,6 kg), wurden EP-Katheter am His-Bündel (HBE), im hohen lateralen rechten Vorhof (HRA), im Koronarsinus-Ostium (Cs-Os) und am lateralen linken Vorhof (LLA) platziert. Weiterhin wurde eine modifizierte VDD-Elektrode (3 Ringelektroden) so platziert, dass die distale Ringelektrode im mittleren rechten Vorhof frei flottierte (F). Es wurden während Sinusrhythmus (SR) und während ST neben der PWD sowohl die IAA- (SR/ST-HRA; SR/ST-Cs-Os; SR/ST-HBE, SR/ST-F) als auch die IEA-LZ (SR/ST-LA) für konventionelle ST im HRA und am Cs-Os sowie für F-ST mit BIMOS ermittelt und miteinander verglichen. Primär verlängerte PWD: Der Einfluss verschiedener neuartiger Stimulationskonzepte („biatriale” ST, „dual site” ST, „atriale septale” ST, „Bachmann-Bündel” ST) auf primär verlängerte PWD wurde an Hand der Erstdaten zu diesen Konzepten aus der Literatur analysiert. Ergebnisse Normale IAA-, IEA-LZ und PWD: Die mittlere PWD war während SR signifikant kürzer als während HRA- (66.6±12.8 ms; vs. 116,2±11,1 ms; p<0,05) bzw. Cs-Os-ST (66,6±12,8 ms vs. 94,4±9,0 ms; p<0,05). Während F-ST mit der BIMOS Konfiguration bestand kein signifikanter Unterschied (66,6±12,8 ms vs. 85,4±8,8 ms; p>0,05). Weiterhin bestand eine signifikante Verkürzung der PWD beim Wechsel von HRA-ST zur BIMOS F-ST. Die IEA-LZ war während SR im Vergleich zur Stimulation im HRA (34,7±14,7 ms vs. 89,7±13,5 ms; p<0,05), vom Cs-Os (34,7±14,7 ms vs. 66,3±7,0 ms; p<0,05) und mit BIMOS (34,7±14,7 ms vs. 61,3±12,7 ms; p<0,05) am kürzesten. Die IEA-LZ waren jedoch während F-ST mit BIMOS signifikant kürzer als während ST im HRA. Primär verlängerte PWD: Für alle neuartigen Stimulationskonzepte, die primär für die Prävention von Vorhofflimmern entwickelt wurden, sind in der Literatur signifikante Reduktionen der primär verlängerten PWD („biatrial”: SR: 181±28 ms vs. ST: 108±13 ms; p<0,05; „dual site”: SR: 120±12 ms vs. ST: 103±17 ms; p<0,05, „septal”: SR: 132±23 ms vs. ST: 84±14 ms; p<0,05; und „Bachmann Bündel”: SR: 163±14,7 ms vs. ST: 134±13,5 ms; p<0,05) nachweisbar. Schlussfolgerungen Die Ergebnisse dieser Arbeit zeigen, dass bei normaler IAA- und IEA-LZ eine atriale ST, unabhängig vom Stimulationsort, immer eine Verlängerung dieser LZ bewirkt. Dabei zeigt die atriale F-ST mit der BIMOS-Konfiguration die geringste Verlängerung der IAA- und IEA-LZ gegenüber SR. Die ST am Cs-Os hat keinen positiven Einfluss auf die IAA-LZ gegenüber der ST im HRA. Die ST am Cs-Os bewirkt aber eine signifikante Reduktion der IEA-LZ gegenüber der ST im HRA. Im Gegensatz dazu zeigen die Analysen der verschiedenen neuartigen Stimulationskonfigurationen bei primär verlängerter PWD eine generelle Reduktion der PWD. Dieses unterschiedliche Verhalten der IAA- und IEA-LZ sowie der PWD während ST sollte vor der Implantation einer atrialen Elektrode bedacht werden.