Introduction: Reliable automatic pacing threshold determination functions offer a reduced follow-up examination time and safe remote monitoring. Further, the success rate and accuracy of the automatic pacing threshold determination function have not been sufficiently clarified. Methods: We evaluated 456 patients (male/female: 269/187, age: 70.4±13.3 years, pacemakers/defibrillators: 341/115) with cardiac implantable devices that had an automatic pacing threshold measurement function (the atrium and ventricle/ ventricle only: 298/158). We measured their pacing thresholds with both the automatic and manual methods at periodic device examination visits. Patients who had a high threshold (>4.0V/0.4ms) or out-of-range lead impedance (>2000 or <200Ω) were excluded from the analysis. Results: An automatic pacing threshold was obtained successfully in 206/274 (75.2%) patients in the atrium and in 392/443 (88.5%) in the ventricle. The automatic pacing threshold differed from the manual threshold by more than 1.0mV at the same pulse width in 12 (4.0%) patients in the atrium and in 5 (1.1%) in the ventricle. The success rate of the automatic pacing threshold determination differed depending on which generator manufacturer was used. The success rate for each manufacturer (Medtronic, St. Jude Medical, Biotronik and Sorin) was 167/173 (96.5%), 9/64 (14.1%), 30/37 (81.1%), and 0/0 in the atrium, and 223/224 (99.6%), 79/102 (77.5%), 68/85 (80.0%), and 22/32 (68.8%) in the ventricle, respectively. Regarding the success rate, Medtronic devices were superior to the others in both the atrium and ventricle (P<0.001-P=0.039). St. Jude Medical devices were inferior to the others in the atrium (p<0.001). There were no other significant factors affecting the success rate. The correlation between the pacing threshold measured by the automatic method and that by the manual method was significant in the atrium (r=0.558, P<0.001) and ventricle (r=0.779, P<0.001). Conclusions: The success rate of the automatic pacing threshold determination depended on which generator manufacturer was used. The measurable threshold values using the automatic method were acceptably correlated with those measured by the manual method.
Background: Cryoballoon (CB)-based pulmonary vein isolation (PVI) is an established treatment modality for patients suffering from paroxysmal or persistent atrial fibrillation (AF). Recently, the novel fourth-generation cryoballoon (CB4) was introduced which mainly provides a 40% shorter distal tip as compared to the second-generation cryoballoon (CB2). This two-centre analysis sought to assess the primary efficacy of the 28 mm CB4 for PVI and the feasibility of real-time signal recordings from the PVs considering the time-to-isolation (TTI).Methods and results: Eighty-four patients with paroxysmal or short-standing persistent AF underwent CB4-based PVI at two different hospitals. Individual freeze-cycle duration was set at TTI + 120 seconds. No bonus freeze was applied. A total of 331 pulmonary veins (PVs) including five left common PVs were identified and all PVs were successfully isolated. Mean freeze-cycle duration was 165.7 ± 31.5 seconds. The mean minimal CB temperature was -45.6 ± 7.6 °C with a real-time PVI visualisation rate of 78% (67/84 (79.8%) RSPVs, 55/84 (65.5%) RIPVs, 67/79 (84.8%) LSPVs, 66/79 (83.5%) LIPVs and 2/5 (40%) LCPV). Transient phrenic nerve palsy occurred in 2/84 (2.4%) patients during cryo-application along the RSPV.Conclusions: The novel CB4 provides both, a high acute efficacy and a high rate of real time electrical PV-recordings, thus facilitating individual ablation strategies based on TTI.
Cardiac memory is an electrocardiographic manifestation of transient T wave abnormalities, which is observed after abrupt interruption of abnormal ventricular activation. We report a case with preexisting complete left bundle branch block in whom cardiac memory was induced. This cardiac memory was induced by normalization of QRS morphology after development of complete atrioventricular block due to acute inferior myocardial infarction. .
AimsFor successful ablation of ventricular outflow tract arrhythmia, estimation of its origin prior to the procedure can be useful. Morphology and lead placement in the right thoracic area may be useful for this purpose. Electrocardiography using synthesized right-sided chest leads (Syn-V3R, Syn-V4R, and Syn-V5R) is performed using standard leads without any additional leads. This study evaluated the usefulness of synthesized right-sided chest leads in estimating the origin of ventricular outflow tract arrhythmia.
The cutdown technique for the cephalic vein is a common access route for transvenous cardiac device leads (TVLs), and sometimes one cephalic vein can accomodate two TVLs. We examined a novel ligation technique to balance the hemostasis and lead maneuverability for this two-in-one insertion. A total of 22 patients scheduled for cardiac device implantations with two or more leads were enrolled. The ipsilateral cephalic vein was identified for inserting the TVLs with a cutdown. If two TVLs could be introduced into one cephalic vein, hemostasis was established by ligating the venous wall between the TVLs. We measured the amount of hemorrhaging per minute and the operators assessed the lead maneuverability before and after the ligation. We successfully implanted cardiac devices in 15 patients (68%) with this novel method, whereas only one TVL could be introduced via the cephalic vein in 7 patients. As for the successful patients, hemorrhaging from the gap was significantly reduced (5.6 ± 7.3 to 0.41 ± 0.36g/min, p = 0.016) after the novel ligation. The lead maneuverability was well maintained so there was no difficulty placing the leads into the cardiac chambers in all cases. No major complications were observed. In the present study, the novel ligation method provided significant hemostasis as well as a preserved maneuverability. It could be an optional choice for insertion of multiple TVLs.
