Advances in Left Bundle Branch Pacing: Definition, Evaluation, and Applications

Left bundle branch pacing (LBBP) emerged as a new physiological pacing strategy during the past several years. Recent observational studies have demonstrated the advantages of LBBP, including a high success rate, stable pacing parameters, and excellent clinical benefits. Widespread adoption of LBBP will depend on improvements in device/lead technology and further verification of its efficacy in large randomized clinical trials. In this review, we summarize recent advancements in LBBP, including the definition and evaluation of left bundle branch capture, LBBP applications, and future directions in this growing field

Learning based image transformation using convolutional neural networks

We have developed a learning-based image transformation framework and successfully applied it to three common image transformation operations: downscaling, decolorization, and high dynamic range image tone mapping. We use a convolutional neural network (CNN) as a non-linear mapping function to transform an input image to a desired output. A separate CNN network trained for a very large image classification task is used as a feature extractor to construct the training loss function of the image transformation CNN. Unlike similar applications in the related literature such as image super-resolution, none of the problems addressed in this paper have a known ground truth or target. For each problem, we reason abouta suitable learning objective function and develop an effective solution. This is the first work that uses deep learning to solve and unify these three common image processing tasks. We present experimental results to demonstrate the effectiveness of the new technique and its state-of-the-art performances

Efficacy of upgrading to left bundle branch pacing in patients with heart failure after right ventricular pacing

Background: Chronic right ventricular (RV) pacing is associated with an increased incidence of heart failure and mortality. Left bundle branch (LBB) pacing could produce near-physiological electrical activation and mechanical synchrony. We aimed to report the effects of upgrading to LBB pacing in heart failure patients after chronic RV pacing. Methods: The indications included pacing-induced cardiomyopathy (PICM) in Group 1 and heart failure after RV pacing with left ventricular ejection fraction (LVEF) ≥ 50% in Group 2. LBB pacing was achieved by penetrating the pacing lead to the subendocardium of left-sided interventricular septum through the venous access. Left ventricular activation time (LVAT) was measured from the pacing stimulus to the ascending peak of lead V5 or V6. All patients underwent clinical and echocardiographic evaluations before and after upgrading. Results: Totally 27 patients (13 in Group 1 and 14 in Group 2) were consecutively enrolled. The mean follow-up time after upgrade was 10.4 ± 6.1 months. Paced QRS duration was significantly shortened from 174.1 ± 15.8 milliseconds to 116.6 ± 11.7 milliseconds (p \u3c .0001). The mean LVAT was 83.2 ± 11.7 milliseconds. LVEF increased from 40.3 ± 5.2% before upgrading to 48.1 ± 9.5% at follow-up in patients with PICM. Serum N-terminal probrain natriuretic peptide levels decreased and New York Heart Association classification improved in both groups. No upgrade-related complications were observed. Conclusions: Upgrading to LBB pacing was feasible and effective with improved cardiac function in heart failure patients with both reduced and preserved LVEF after RV pacing

HLO: Half-kernel Laplacian Operator for surface smoothing

This paper presents a simple yet effective method for feature-preserving surface smoothing. Through analyzing the differential property of surfaces, we show that the conventional discrete Laplacian operator with uniform weights is not applicable to feature points at which the surface is non-differentiable and the second order derivatives do not exist. To overcome this difficulty, we propose a Half-kernel Laplacian Operator (HLO) as an alternative to the conventional Laplacian. Given a vertex v, HLO first finds all pairs of its neighboring vertices and divides each pair into two subsets (called half windows); then computes the uniform Laplacians of all such subsets and subsequently projects the computed Laplacians to the full-window uniform Laplacian to alleviate flipping and degeneration. The half window with least regularization energy is then chosen for v. We develop an iterative approach to apply HLO for surface denoising. Our method is conceptually simple and easy to use because it has a single parameter, i.e., the number of iterations for updating vertices. We show that our method can preserve features better than the popular uniform Laplacian-based denoising and it significantly alleviates the shrinkage artifact. Extensive experimental results demonstrate that HLO is better than or comparable to state-of-the-art techniques both qualitatively and quantitatively and that it is particularly good at handling meshes with high noise. We will make our source code publicly available.Comment: Accepted to Computer Aided Design; Binary (exe) program avaliable: https://github.com/WillPanSUTD/hl

Data from: Enhanced in vitro biocompatibility and osteogenesis of titanium immobilized with dopamine-assisted superparamagnetic Fe3O4 nanoparticles for hBMSCs

Titanium(Ti) is an ideal bone substitute due to its superior bio-compatibilities and remarkable corrosion resistance properties. However, in order to improve the osteoconduction and osteoinduction capacity in clinic applications, different kinds of surface modifications were usually applied for the Ti alloys. In this study, we fabricated a tightly attached PDA-assisted Fe3O4 nanoparticles coating on Ti with magnetic properties, aiming to improve the osteogenesis of the Ti substrates. The PDA-assisted Fe3O4 nanoparticles coatings were characterized by utilizing scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), atom force microscope(AFM), water contact angle measurement. Cell attachment and proliferation rate of the hBMSCs on the Ti surface were significantly improved with the Fe3O4/PDA coating when compared to the pure Ti without coatings. Furthermore, the results of in vitro ALP activity at 7, 14 days and ARS staining at 14 days both showed that Fe3O4/PDA coating on Ti promoted the osteogenic differentiation of hBMSCs. Moreover, hBMSCs co-cultured with the Fe3O4/PDA-coated Ti for about 14 days also exhibited significantly higher mRNA expression level of alkaline phosphatase(ALP), osteocalcin(OCN) and runt-related transcription factor-2(RUNX-2). Our in vitro results revealed that the present PDA-assisted Fe3O4 nanoparticles surface coating would be an innovative method for Ti surface modification and showed great potential for clinical application

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A pilot study to determine if left ventricular activation time is a useful parameter for left bundle branch capture: Validated by ventricular mechanical synchrony with SPECT imaging

Background Left bundle branch (LBB) pacing has emerged as a novel pacing modality. Left ventricular activation time (LVAT) was reported to be associated with the activation via LBB, but the value of LVAT for determining LBB pacing was unknown. We conducted a pilot study to determine if LVAT could define LBB capture by validating left ventricular (LV) mechanical synchrony. Methods We analyzed LVAT in 68 bradycardia-indicated patients who received LBB pacing. LVAT was measured from the stimulus to R-wave peak in lead V5 and V6. LV mechanical synchrony assessed by SPECT MPI was compared according to the value of LVAT and the presence of LBB potential. Results The mean LVAT was 75.4 ± 12.7 ms. LBB potential was recorded in 47 patients (69.1%). Patients with LVAT \u3c 76 ms had better LV mechanical synchrony than those with LVAT ≥ 76 ms. Patients with LVAT \u3c 76 ms or LBB potential had better mechanical synchrony than those with LVAT ≥ 76 ms and no potential. LVAT \u3c 76 ms could predict the normal synchrony with a sensitivity of 88.9% and a specificity of 87.5%. Conclusion A short LVAT indicated favorable mechanical synchrony in SPECT imaging. LVAT \u3c 76 ms might be a practical parameter for defining LBB capture

Assessment of Left Ventricular Contraction Patterns Using Gated SPECT MPI to Predict Cardiac Resynchronization Therapy Response

Background: The U-shaped left ventricular (LV) contraction pattern, identified by MRI or echocardiography, is associated with improved CRT response. Gated SPECT MPI can measure both myocardial viability and mechanical dyssynchrony in a single scan. The aim of this study is to examine the relationship of the LV contraction pattern and the response of CRT in patients with left bundle branch block (LBBB). Methods: Fifty-eight patients who met CRT guidelines and who had pre-CRT MPI were enrolled. Myocardial segments with tracer uptake \u3c 50% of maximum were considered as scar. The LV contraction pattern was considered as U-shaped or non-U-shaped (U-shaped has a block line in the direction of contraction propagation). CRT response was defined as an increase in left ventricular ejection fraction ≥ 5% after 6-month follow-up. Results: Twenty-eight patients (48%) had a U-shaped contraction pattern and thirty patients (52%) had a non-U-shaped contraction pattern. The U-shaped group showed a significantly higher response rate than the non-U-shaped group (90% vs. 57%; P = 0.005). By univariate and multivariate logistic regression analysis, the U-shaped pattern was an independent predictor of CRT response. Conclusion: Non-invasive gated SPECT MPI can characterize LV mechanical contraction patterns. A U-shaped contraction pattern identified is associated with improved CRT response. This may prove useful for improved patient selection for CRT