Electro-energetics of Biventricular, Septal and Conduction System Pacing

Abnormal electrical activation of the ventricles creates abnormalities in cardiac mechanics. Local contraction patterns, as reflected by strain, are not only out of phase, but also show opposing length changes in early and late activated regions. Consequently, the efficiency of cardiac pump function (the amount of stroke work generated by a unit of oxygen consumed), is approximately 30% lower in dyssynchronous than in synchronous hearts. Maintaining good cardiac efficiency appears important for long-term outcomes. Biventricular, left ventricular septal, His bundle and left bundle branch pacing may minimise the amount of pacing-induced dyssynchrony and efficiency loss when compared to conventional right ventricular pacing. An extensive animal study indicates maintenance of mechanical synchrony and efficiency during left ventricular septal pacing and data from a few clinical studies support the idea that this is also the case for left bundle branch pacing and His bundle pacing. This review discusses electro-mechanics and mechano-energetics under the various paced conditions and provides suggestions for future research

Novel bradycardia pacing strategies

Contains fulltext : 229186.pdf (Publisher’s version ) (Closed access)The adverse effects of ventricular dyssynchrony induced by right ventricular (RV) pacing has led to alternative pacing strategies, such as biventricular, His bundle (HBP), LV septal (LVSP) and left bundle branch pacing (LBBP). Given the overlap, LVSP and LBBP are also collectively referred to as left bundle branch area pacing (LBBAP). Although among these alternative pacing sites HBP is theoretically the ideal strategy as it maintains a physiological ventricular activation, its application requires more skills and is associated with the most complications. LBBAP, where the ventricular pacing lead is advanced through the interventricular septum to its left side, creates ventricular activation that is only slightly more dyssynchronous. Preliminary studies have shown that LBBAP is feasible, safe and encounters less limitations than HBP. Further studies are needed to differentiate between LVSP and LBBP with regard to acute functional and long-term clinical outcome

Evaluation of the Performance of Coordinate Measuring Machines in the Industry, Using Calibrated Artefacts

AbstractThe coordinate measuring machines (CMM's) has given a new impulse in the field of geometrical and dimensional metrology. The CMM's in industrial environments have become an important resource for the quality systems, monitoring manufacturing processes, reduction errors during the manufacturing process, inspection of product specifications and in continuous quality improvement. However, there is a need to evaluate, through practical, fast, effective and low cost methods, the CMM metrological specifications. Using calibrated artefacts, able to reproduce the geometric elements frequently measured, it seeks to ensure stability of the functional and metrological characteristics between calibrations and simultaneously knowing the errors. With better monitoring of the control parameters it is possible evaluate and optimize the calibration set deadlines, timely detection of faults and failures, detect structural changes and changes in environmental conditions of the laboratories, thus seeking to conduct a more detailed assessment of the stability of metrological characteristics of a CMM in industrial environments

Long‐Term Outcomes of Cardiac Resynchronization Therapy Using Apical Versus Nonapical Left Ventricular Pacing

Background Experimental evidence indicates that left ventricular (LV) apical pacing is hemodynamically superior to nonapical LV pacing. Some studies have shown that an LV apical lead position is unfavorable in cardiac resynchronization therapy. We sought to determine whether an apical LV lead position influences cardiac mortality after cardiac resynchronization therapy. Methods and Results In this retrospective observational study, the primary end point of cardiac mortality was assessed in relation to longitudinal (basal, midventricular, or apical) and circumferential (anterior, lateral, or posterior) LV lead positions, as well as right ventricular (apical or septal), assigned using fluoroscopy. Lead positions were assessed in 1189 patients undergoing cardiac resynchronization therapy implantation over 15 years. After a median follow‐up of 6.0 years (interquartile range: 4.4–7.7 years), an apical LV lead position was associated with lower cardiac mortality than a nonapical position (adjusted hazard ratio: 0.74; 95% confidence interval, 0.56–0.99) after covariate adjustment. There were no differences in total mortality or heart failure hospitalization. Death from pump failure was lower with apical than nonapical positions (adjusted hazard ratio: 0.69; 95% confidence interval, 0.51–0.94). Compared with a basal position, an apical LV position was also associated with lower risk of sudden cardiac death (adjusted hazard ratio: 0.34; 95% confidence interval, 0.13–0.93). No differences emerged between circumferential LV lead positions or right ventricular positions with respect to any end point. Conclusions In recipients of cardiac resynchronization therapy, an apical LV lead position was associated with better long‐term cardiac survival than a nonapical position. This effect was due to a lower risk of pump failure and sudden cardiac death

Comparing Ventricular Synchrony in Left Bundle Branch and Left Ventricular Septal Pacing in Pacemaker Patients

Background: Left bundle branch area pacing (LBBAP) has recently been introduced as a novel physiological pacing strategy. Within LBBAP, distinction is made between left bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP, no left bundle capture). Objective: To investigate acute electrophysiological effects of LBBP and LVSP as compared to intrinsic ventricular conduction. Methods: Fifty patients with normal cardiac function and pacemaker indication for bradycardia underwent LBBAP. Electrocardiography (ECG) characteristics were evaluated during pacing at various depths within the septum: starting at the right ventricular (RV) side of the septum: the last position with QS morphology, the first position with r' morphology, LVSP and-in patients where left bundle branch (LBB) capture was achieved-LBBP. From the ECG's QRS duration and QRS morphology in lead V1, the stimulus- left ventricular activation time left ventricular activation time (LVAT) interval were measured. After conversion of the ECG into vectorcardiogram (VCG) (Kors conversion matrix), QRS area and QRS vector in transverse plane (Azimuth) were determined. Results: QRS area significantly decreased from 82 +/- 29 mu Vs during RV septal pacing (RVSP) to 46 +/- 12 mu Vs during LVSP. In the subgroup where LBB capture was achieved (n = 31), QRS area significantly decreased from 46 +/- 17 mu Vs during LVSP to 38 +/- 15 mu Vs during LBBP, while LVAT was not significantly different between LVSP and LBBP. In patients with normal ventricular activation and narrow QRS, QRS area during LBBP was not significantly different from that during intrinsic activation (37 +/- 16 vs. 35 +/- 19 mu Vs, respectively). The Azimuth significantly changed from RVSP (-46 +/- 33 degrees) to LVSP (19 +/- 16 degrees) and LBBP (-22 +/- 14 degrees). The Azimuth during both LVSP and LBBP were not significantly different from normal ventricular activation. QRS area and LVAT correlated moderately (Spearman's R = 0.58). Conclusions: ECG and VCG indices demonstrate that both LVSP and LBBP improve ventricular dyssynchrony considerably as compared to RVSP, to values close to normal ventricular activation. LBBP seems to result in a small, but significant, improvement in ventricular synchrony as compared to LVSP