557 His bundle pacing: how to troubleshoot the implantation of a ventricular back-up lead

Aims Interest in permanent His bundle pacing (HBP) as a means of both preventing pacing-induced cardiomyopathy and providing physiological resynchronization by normalization of His-Purkinje activation is constantly growing. Current devices are not specifically designed for HBP, which gives rise to programming challenges. To evaluate the critical troubleshooting HBP options in patients with permanent atrial fibrillation (AF) and variable degree of atrio-ventricular block (AVB) who receive HBP through a lead connected to the atrial port, and an additional ventricular ‘backup’. Methods and results Between December 2018 and July 2021, 156 consecutive patients with indication for pacing underwent HBP. Among these, 37 had permanent AF with documented symptomatic pauses. Fourteen of them received a dual-chamber device which was used to place a backup right ventricle (RV) lead; in this scenario, the His lead is implanted in the right atrial (RA) port, the RV lead in the RV port. Depending on the presence of an additional left ventricle (LV) lead, either a dual-chamber and a CRT device can be used. In this context, the events marked as atrial sensed (As) or paced (Ap) are indeed ventricular, so that sensing is more complex. A clinical scenario is atrial activity oversensed on the His channel (As) leading to RV dyssynchronous pacing in the ventricular safety pacing (VSP) window. A second one is intrinsic QRS undersensing causing inappropriate His pacing. The interplay of intrinsic ventricular activity (rate, signal amplitude, and slew rate on both the His and the ventricular channel) and of the HV interval may be of key importance to troubleshoot As–Vp (atrial sensed–ventricular paced) (Figure 1A) as well as Vs–Ab (ventricular sensed–atrial blanking period) sequences (Figure 1B). Changing sensitivity and sensing configuration may help to fix these issues. DVI(R) mode programming may indeed prove safer than DDD(R) in the setting of preserved intrinsic activity or in the event of intermittent His capture loss. Paced AV delay should be programmed slightly longer than H-V+QRS duration to avoid unnecessary RV pacing with pseudo-fusion (too short) (Figure 2A) and possibly R/T events (too long). Stability of H-V interval and of QRS duration must be verified at each device follow-up by decremental His pacing to ensure consistent sensitivity of the ventricular signal beyond stable His capture, that may be challenged by infra-Hisian block (Figure 2B). Conclusions Owing to the absence of HBP-specific devices, HBP shall be made safe and effective by careful troubleshooting, consisting of sensitivity setting, paced AV interval and mode programming. 557 Figure

STUDI KOORDINASI KERJA RELE DIFERENSIAL DAN RELE RESTRICTED EARTH FAULT SETELAH UPRATING PADA TRANSFORMATOR II DI GI KAPAL

The differential relay on the power transformer II in the Kapal Substation has a sensitivity setting of 30% to the nominal current of winding. Fault current that occurs below setting is not detected because the fault current has not reached the set limit. To overcome the fault current it is equipped with REF relay that has sensitivity below 30%. The analysis was performed by calculation method according to the relay setting manual. The results of sensitivity setting of REF relay is 382.75 A or fault point at 22.09% of the transformer winding, while the differential relay is 519.6 A or fault point at 30% of the transformer winding. The calculation result shows that the first to work is the REF relay than the differential relay. So the fault on the transformer winding is overcome by the REF relay.

Equivalent Sensitivity Setting During Ultrasonic Inspection of Steel Butt Welded Joints

Introduction. The echo-pulse technique is commonly used for welded joints ultrasonic testing. The first step of the technique is setting the ultrasonic flaw detector sensitivity. For this purpose NDT-operators usually use calibration blocks with a flat cylindrical or hemispherical reflectors, which are to be manufactured and metrologically certified for every weld joint size and transducer angle. The objective of this work was to develop a sensitivity setting technique using the CO-2 reference block, which could take into account the equivivalent area of the flat cilindrical reflector (as a model of a point-planar flaw) and the equivivalent area of the hemispherical reflector (as a model of a point-bulk flaw). Method. The paper analyzes methods of ultrasonic flaw detector sensitivity setting while testing of butt welded joints with the use of samples and reference reflectors of different types. The theoretical studies using beam acoustics and the Kirchhoff method, were carried out. Results. The analytical dependences for calculation of the sensitivity correction factors have been presented for the equivalent sensitivity setting on a side cylindrical reflector of 6 mm in diameter with the center line location at a depth of 15 mm within the CO-2 reference block. For automation of calculations the NDTRT-20.01 software has been developed and implemented. The sensitivity setting procedures with the use of the NDTRT-20.01 software and without it are given. Discussion. The offered technique has the following advantages: for different thicknesses of welded sheets with different requirements to the minimum acceptable defect the only CO-2 reference block is needed; the sensitivity can be adjusted on both the flat cilindrical reflector and the hemispherical reflector; the NDTRT-20.01 software allows automating the calculations of sensitivity correction factors and flaw detector sweep parameters.

Rapid and Sensitive Detection of BRCA1/2 Mutations in a Diagnostic Setting: Comparison of Two High-Resolution Melting Platforms

Background: High-resolution melting is an emerging technique for detection of nucleic acid sequence variations. Developments in instrumentation and saturating intercalating dyes have made accurate high-resolution melting analysis possible and created opportunities to use this technology in diagnostic settings. We evaluated 2 high-resolution melting instruments for screening BRCA1 and BRCA2 mutations. Methods: To cover the complete coding region and splice sites, we designed 112 PCR amplicons (136–435 bp), amplifiable with a single PCR program. LCGreen® Plus was used as the intercalating dye. High-resolution melting analysis was performed on the 96-well Lightscanner™ (Idaho Technology Inc.) and the 96-well LightCycler® 480 (Roche) instruments. We evaluated sensitivity by analyzing 212 positive controls scattered over almost all amplicons and specificity by blind screening of 22 patients for BRCA1 and BRCA2. In total, we scanned 3521 fragments. Results: All 212 known heterozygous sequence variants were detected on the Lightscanner by analysis on normal sensitivity setting. On the LightCycler 480, the standard instrument sensitivity setting of 0.3 had to be increased to 0.7 to detect all variants, decreasing the specificity to 95.9% (vs 98.7% for the Lightscanner). Conclusions: Previously, we screened BRCA1/2 by direct sequencing of the large exon 11 and denaturing gel gradient electrophoresis (DGGE) for all other coding exons. Since the introduction of high-resolution melting, our turnaround time has been one third of that with direct sequencing and DGGE, as post-PCR handling is no longer required and the software allows fast analyses. High-resolution melting is a rapid, cost-efficient, sensitive method simple enough to be readily implemented in a diagnostic laboratory.