Left bundle branch pacing: the new kid on the block

Right ventricular pacing is has deletorius effects due to left ventricular dysynchrony and remodelling and may result in heart failure. Over the last decade, His bundle pacing has emerged as the most physiologic form pacing. However, it has limitations, such as higher capture thresholds, lower R wave amplitudes, atrial oversensing, and increased risk for lead revisions from late threshold increase with subsequent premature battery depletion, which has prevented a wider adoption of this technique in routine clinical practice. Left bundle branch pacing has been developed as an alternative physiologic pacing strategy that overcomes most of His bundle pacing limitations. This article summarizes the current status of left bundle branch pacing. Keywords: His bundle pacing, left bundle branch pacing, cardiac resynchronization, therapy heart failure.

His bundle pacing capture threshold stability during long-term follow-up and correlation with lead slack

Aims His bundle pacing (HBP) is the most physiologic form of pacing. Long-term HBP capture threshold stability and its relation to lead characteristics at the time of implantation have not been adequately described. The aim of this study was to characterize HB capture threshold in follow-up and to identify potential lead characteristics predictive of lead capture instability. Methods and results Consecutive patients with successful HBP for bradycardia indications were identified from the Geisinger HBP registry. His bundle capture thresholds, baseline comorbidities, and radiographic lead slack characteristics were analysed. An increase in HB capture threshold ≥1 V above implant values at any time during follow-up was tracked. Forty-four of the 294 studied (15%) experienced HB capture threshold increase by ≥ 1 V. Threshold increase was seen early (41% by 8 weeks, 66% by 1 year). Eighteen (6%) patients required lead revision in follow-up. Abnormal slack shape was associated with a trend toward capture threshold increase [hazard ratio (HR) 2.07; 95% confidence interval (CI) 0.9–4.6; P = 0.08]. Non-perpendicular angle of lead insertion on radiography was associated with the capture threshold increase (HR 2.81, 95% CI 1.4–5.8; P < 0.01). Conclusion His bundle capture threshold remains stable in the majority (85%) of patients. Implant characteristics may predict the threshold rise. Further evaluation of the aetiology of threshold increase and design changes in lead and delivery systems may lead to chronically stable capture thresholds.

Analysis of Resective Osseous Surgical Procedures - A Retrospective Hospital Based Study

Resective osseous surgery is a procedure to modify osseous support either by reshaping the alveolar bone to achieve physiologic form without removal of supporting bone (osteoplasty) and by the removal of some alveolar bone (ostectomy). The aim of this study is to analyse the prevalence of resective osseous surgical procedures performed in the outpatient department of Saveetha dental college and hospitals. Overall, 100 case sheets were reviewed which were dated between June 2019 to March 2020. The data was collected by the patient records of a dental college hospital. From this study, we observed that resective osseous surgical techniques were done in 60% of male patients and in 40% of female patients and the most frequent technique performed was osteoplasty which was 68% Within the limits of this study, the most common techniques used were osteoplasty and frequent anatomical site was upper first molar and male patients underwent more resective osseous surgery than that of females.

Association between Field Liming and the Epidemic of Type 1 Diabetes

Zinc is an essential nutrient for mammals. Zinc has only one oxidation state Zn2+ but it has many coordination states, which can alter without demanding energy. Coordination states depend on prevailing pH. In soils the coordination state changes from octahedral (nonphysiologic) form to tetrahedral (physiologic) form when pH rises to about 6.5. Weathering processes of common soil mineral mica are also pH dependent. Large scale argricultural field liming began from 1950's onward in the Western Countries and since that time the incidence of T1D began to increase in the Western Countries. Liming elevates soil pH often near 6.5 and favours mosaic mica-vermiculite nanoparticle formation in which vermiculite corner binds zinc in tetrahedral (physiological) coordination state. In this pH mica corner remains in native form and offers the plane for soluble pMHC molecule (binded with antigenic beta-cell specific self peptide) to adhere on mica and as a consequence to trigger the activation of autoreactive CD4 and/or CD8 T cells. Beta-cell specific autoantigens are released because abundant zinc derived from endocytosed zinc-mica-vermiculite particles in lysosomes leads to incresed beta-cell apoptosis, also the physiological neonatal beta-cell mass remodeling enhance beta-cell specific auto-antigen release. Furthermore enterovirusinfections during first years of life are common and can release beta-cell specific auto-antigens. The probable disease mechanism is dealt with this review article.

Neural Tube and Craniofacial Defects With Special Emphasis On Folate Pathway Genes

Neural tube and orofacial defects are common congenital malformations in humans. While etiologically heterogeneous, they are for the most part multifactorial in their pathogenesis, having both genetic and environmental components in their development. In recent years, there has been a great deal of epidemiologic evidence demonstrating that women who received multivitamins containing folic acid periconceptionally had significantly reduced occurrence and recurrence risks for producing infants with such malformations. This risk reduction is not observed in all populations, further suggestive of a genetic regulation of this phenomenon. Unfortunately, the mechanisms underlying the beneficial effects of folic acid are not well-understood. In this article, we review the relevant epidemiologic data on both neural tube defects and orofacial malformations, the fundamental embryological processes involved in closing the neural tube, and the development of the craniofacies, and propose a working hypothesis for susceptibility to these malformations. This hypothesis is based on the interworkings of cellular folate transport, focusing on the key elements involved in potocytosis. We propose that infants with mutations in the folate receptor alpha gene might be at increased risk for congenital anomalies due to a reduced binding affinity for 5-methyltetrahydrofolate, the physiologic form of folic acid. Various experimental approaches to test the working hypothesis are considered.

VARIETAL TRIALS, PHYSIOLOGIC SPECIALIZATION, AND BREEDING SPRING WHEATS FOR RESISTANCE TO TILLETIA TRITICI AND T.LEVIS

There has been a considerable increase in the amount of bunted wheat in western Canada recently. One hundred and forty-nine varieties and selections of spring wheat showed all gradations in reaction to this disease when inoculated artificially, varying from apparent immunity to high susceptibility. The increase in bunt can be accounted for in part by the use of certain varieties that are more susceptible than some of those grown formerly. There has also been an increase in the number and virulence of physiologic forms. One physiologic form of T. tritici and five of T. levis were obtained from six collections of bunt in this study. The isolation and study of relatively pure forms of the organism will be necessary for a study of the genetic factors in the host governing the reaction to bunt. Inheritance studies at present indicate that multiple factors, the exact nature of which has not yet been determined, govern the reaction to this disease. Production of resistant varieties suitable for the prairie provinces of Canada offers a very promising means for reducing the losses due to bunt of wheat.