On-treatment comparison between corrective His bundle pacing and biventricular pacing for cardiac resynchronization: A secondary analysis of His-SYNC

Background The His-SYNC pilot trial was the first randomized comparison between His bundle pacing in lieu of a left ventricular lead for cardiac resynchronization therapy (His-CRT) and biventricular pacing (BiV-CRT), but was limited by high rates of crossover. Objective To evaluate the results of the His-SYNC pilot trial utilizing treatment-received (TR) and per-protocol (PP) analyses. Methods The His-SYNC pilot was a multicenter, prospective, single-blinded, randomized, controlled trial comparing His-CRT vs BiV-CRT in patients meeting standard indications for CRT (eg, NYHA II–IV patients with QRS >120 ms). Crossovers were required based on prespecified criteria. The primary endpoints analyzed included improvement in QRS duration, left ventricular ejection fraction (LVEF), and freedom from cardiovascular (CV) hospitalization and mortality. Results Among 41 patients enrolled (aged 64 ± 13 years, 38% female, LVEF 28%, QRS 168 ± 18 ms), 21 were randomized to His-CRT and 20 to BiV-CRT. Crossover occurred in 48% of His-CRT and 26% of BiV-CRT. The most common reason for crossover from His-CRT was inability to correct QRS owing to nonspecific intraventricular conduction delay (n = 5). Patients treated with His-CRT demonstrated greater QRS narrowing compared to BiV (125 ± 22 ms vs 164 ± 25 ms [TR], P < .001;124 ± 19 ms vs 162 ± 24 ms [PP], P < .001). A trend toward higher echocardiographic response was also observed (80 vs 57% [TR], P = .14; 91% vs 54% [PP], P = .078). No significant differences in CV hospitalization or mortality were observed. Conclusions Patients receiving His-CRT on-treatment demonstrated superior electrical resynchronization and a trend toward higher echocardiographic response than BiV-CRT. Larger prospective studies may be justifiable with refinements in patient selection and implantation techniques to minimize crossovers

Early identification of symptomatic aortic stenosis using echocardiographic data

Background: Heart failure (CHF) is the most frequent and prognostically severe symptom of aortic stenosis (AS), and the most common indication for surgery. The mainstay of treatment for AS is aortic valve replacement (AVR), and the main indication for an AVR is development of symptomatic disease. ACC/AHA guidelines define severe AS as an aortic valve area (AVA) ≤1cm², but there is little data correlating echocardiogram AVA with the onset of symptomatic CHF. We evaluated the risk of developing CHF with progressively decreasing echocardiographic AVA. We also compared echocardiographic AVA with Jet velocity (V2) and indexed AVA (AVAI) to assess the best predictor of development of symptomatic CHF. Methods and Results: This retrospective cohort study evaluated 518 patients with asymptomatic moderate or severe AS from a single community based cardiology practice. A total of 925 echocardiograms were performed over an 11-year period. Each echocardiogram was correlated with concurrent clinical assessments while the investigator was blinded to the echocardiogram severity of AS. The Cox Proportional hazards model was used to analyze the relationship between AVA and the development of CHF. The median age of patients at entry was 76.1 years, with 54% males. A total of 116 patients (21.8%) developed new onset CHF during follow-up. Compared to patients with AVA \u3e1.0cm², patients with lower AVA had an exponentially increasing risk of developing CHF for each 0.2cm² decrement in AVA, becoming statistically significant only at an AVA less than 0.8 cm². Also, compared to V2 and AVAI, AVA added more information to assessing risk for development of CHF (p=0.041). Conclusion: In patients with normal or mildly impaired LVEF, the risk of CHF rises exponentially with decreasing valve area and becomes statistically significant after AVA falls below 0.8cm². AVA is a better predictor of CHF when compared to V2 or AVAI

The Miniaturization of Cardiac Implantable Electronic Devices: Advances in Diagnostic and Therapeutic Modalities

The Fourth Industrial Revolution, characterized by an unprecedented fusion of technologies that is blurring the lines between the physical, digital, and biological spheres, continues the trend to manufacture ever smaller mechanical, optical and electronic products and devices. In this manuscript, we outline the way cardiac implantable electronic devices (CIEDs) have evolved into remarkably smaller units with greatly enhanced applicability and capabilities

Root cause analysis of bucket stage III OF GT-2A

In the present study, examination of fractured gas turbine blades (stage III of GT-2A) with identification numbers 23, 39, 40, 49, 453 and 485 was carried out by different characterization methods. Extensive SEM fractography studies on all the fractured surfaces of ruptured blades indicated that surface crack initiation and propagation at the leading edge was by fatigue mechanism as evidenced by striations, rubbing marks and secondary cracks (which are characteristic features of normal fatigue) whereas the crack propagated thereafter through inter-dendritic/inter-granular path as evidenced by large amount of interdendritic/intergranular facets. Since no corrosion products were found on the pressure side/suction side surfaces, it was believed that hot corrosion was not responsible for the present failure. Further, no features like impact with a foreign object were found thus ruling out the possibility of FOD (foreign object damage). Microstructural characterization revealed that there were some significant changes/damages in the microstructure of these blades after service exposure (but these changes alone cannot result in creep failure). Almost all blades, exhibited gamma prime dissolution band at both concave and convex surfaces, in addition to coarsening of gamma/gamma prime, formation of chain of precipitates, coarsening of precipitates. Though the hardness tests indicated considerable hardening effect due to ageing of these blades at high temperatures over a period of time (further ruling out the creep phenomena as the cause of failure), the stress rupture tests did not reveal any significant reduction in the stress rupture life. Based on the results obtained in the present investigation, it can be concluded that the blades were subjected to surface overheating (above the gamma prime dissolution temperature) for a very short period of time. Because of this, the surface edges lost the gamma prime (i.e. dissolved into the gamma matrix). This is a serious problem because all the mechanical properties would be impaired if the precipitates of gamma prime are dissolved into the matrix at surface. Due to this, fatigue cracks were initiated at the leading edge surfaces and further propagated by inter-dendritic/inter-granular (IG) fracture mechanism. No creep/hot corrosion/FOD was noticed. Therefore the primary cause of failure was surface overheating for a very short period of time and the secondary cause of failure is normal fatigue followed by IG cracking