Left Ventricular Endocardium Research Articles

Transmural difference in myocardial damage assessed by layer-specific strain analysis in patients with ST elevation myocardial infarction

We performed layer-specific strain analysis with speckle-tracking echocardiography to investigate the transmural difference of myocardial damage as the predicting factor for the viability of damaged myocardium in patients with ST segment elevation myocardial infarction (STEMI). We analysed patients with acute STEMI who had undergone primary percutaneous coronary intervention and echocardiography within 24 h from the intervention and 2 months after the event. Segmental strains of the left ventricular (LV) endocardium, myocardium, epicardium, and strain gradient (SG) between the endocardium and epicardium were evaluated. In 34 patients, 112 akinetic/dyskinetic and 94 hypokinetic segments were observed among 612 segments of the LV at baseline, and 65 akinetic/dyskinetic segments had viability. In our study, layer-specific strains were gradually deteriorated by their wall motion. SG was augmented in the hypokinetic segments where inhomogeneous wall motion impairment was progressed. SG in the akinetic/dyskinetic segments was different between the viable and non-viable myocardium and was maintained in viable segments. We therefore believe that significantly reduced SG is indicative of irreversible transmural damage in the acute stage of STEMI and can be suitably used as a parameter for predicting myocardial viability.

An electrocardiographic sign of idiopathic ventricular tachycardia ablatable from the distal great cardiac vein

Idiopathic ventricular arrhythmias (IVAs) can originate from the distal great cardiac vein (DGCV). However, inadequate distinction sometimes occurs when electrocardiographic (ECG) characteristics are used to distinguish ventricular arrhythmias (VAs) arising from the DGCV from those arising from the adjacent left ventricular endocardium (LV ENDO). The purpose of this study was to identify distinct ECG features in patients with idiopathic IVAs originating from the DGCV. A total of 32 patients with IVAs originating from the DGCV were identified from a consecutive group of 874 patients undergoing IVAs ablation. Patients with IVAs from the DGCV were compared with a consecutively chosen series of 40 patients with IVAs in whom the site of origin was the adjacent LV ENDO. Of the 32 patients with IVAs arising from the DGCV, 13 had distinct ECG characteristics compared with the LV ENDO group. Notches in both the upstroke and downstroke of the R wave in lead III were found in all 13 patients. However, the characteristic ECG pattern in lead III was found in 1 of 40 patients in the LV ENDO group. The ECG characteristic of both early notch and late notches in lead III has sensitivity of 40.6%, specificity of 97.5%, negative predictive value of 67.2%, and positive predictive value of 92.9% to predict VAs arising from the DGCV. The distinct ECG characteristics of VAs originating from the DGCV can help differentiate from adjacent LV ENDO sites of origin.

The association between 24-h blood pressure patterns and left ventricular mechanics.

We sought to investigate left ventricular (LV) mechanics in the recently diagnosed hypertensive patients with different 24-h blood pressure (BP) patterns (dipping, nondipping, extreme dipping and reverse dipping). The current cross-sectional study included 209 hypertensive patients who underwent 24-h ambulatory BP monitoring and comprehensive two-dimensional echocardiographic examination including multilayer strain analysis. There was no difference in 24-h and daytime BP values between four groups. Night-time BP significantly and gradually increased from extreme dippers, across dippers and nondippers, to reverse dippers. LV global longitudinal and circumferential strains were greater in dippers and extreme dippers than in nondippers and reverse dippers. This was also found for endocardial and epicardial LV longitudinal and circumferential strains. Multivariate logistic regression analysis demonstrated that nondipping and reverse dipping patterns were associated with reduced LV longitudinal strain [odds ratio (OR) 1.71 (95% confidence interval (CI): 1.10-5.61) and OR 2.50 (95% CI: 1.31-6.82), respectively] independently of age, sex, 24-h SBP, LV mass index and E/è. Only the reverse dipping BP pattern was independently of clinical and echocardiographic parameters related with reduced LV circumferential strain [OR 1.90 (95% CI: 1.10-4.80)]. Nondipping and reverse dipping BP patterns had stronger impact on LV mechanics compared with patients with dipping and extreme dipping BP patterns in hypertensive population. LV functional and mechanical remodeling deteriorated from extreme dippers and dippers, to nondippers and reverse dippers.

Myocardial Function Assessed by Multi-Layered Two-Dimensional Speckle Tracking Analysis in Asymptomatic Young Subjects with Diabetes Mellitus Type 1

Background: Diabetes mellitus type 1 (DM1) is associated with a high risk for cardiovascular disease, and early detection of myocardial dysfunction is crucial for the prevention of cardiac complications. Objectives: The aim of this study was to evaluate left ventricular (LV) and right ventricular (RV) function by using both conventional echocardiography as well as multi-layered speckle tracking echocardiography (STE) in young adults with DM1. Methods: We included 50 young asymptomatic adults diagnosed with DM1 (mean interval from diagnosis 9 ± 6 years) and 80 healthy controls. STE was acquired using the GE Vivid S60 equipment. The LV longitudinal strain (LS), layer-specific strains of the endocardium, myocardium, and epicardium (global longitudinal strain [GLS]_endo, GLS_myo, GLS_epi) as well as RV strain were obtained using the EchoPAC BT13 workstation. Results: No significant intergroup differences in LV ejection fraction were noted. GLS_endo and GLS_myo were reduced in the DM1 group (–20.6 ± 2.7 vs. –22.0 ± 2.3 and –18.0 ± 2.4 vs. –19.1 ± 1.9, respectively, p < 0.05) compared to controls. Mechanical dispersion was higher in the diabetes group (34 ± 11 vs. 29 ± 7, p < 0.05). RV strain measurements showed no significant difference between the groups. Conclusions: Young adults with DM1 and without known heart disease have subclinical myocardial dysfunction with lower LV endocardium and myocardium LS and higher mechanical dispersion demonstrated by multi-layered STE.

Regional dynamics of fractal dimension of the left ventricular endocardium from cine computed tomography images.

We present a method to leverage the high fidelity of computed tomography (CT) to quantify regional left ventricular function using topography variation of the endocardium as a surrogate measure of strain. 4DCT images of 10 normal and 10 abnormal subjects, acquired with standard clinical protocols, are used. The topography of the endocardium is characterized by its regional values of fractal dimension ( ), computed using a box-counting algorithm developed in-house. The average in each of the 16 American Heart Association segments is calculated for each subject as a function of time over the cardiac cycle. The normal subjects show a peak systolic percentage change in of in all free-wall segments, whereas the abnormal cohort experiences a change of ( ). Septal segments, being smooth, do not undergo large changes in . Additionally, a principal component analysis is performed on the temporal profiles of to highlight the possibility for unsupervised classification of normal and abnormal function. The method developed is free from manual contouring and does not require any feature tracking or registration algorithms. The values in the free-wall segments correlated well with radial strain and with endocardial regional shortening measurements.

Standard peak-to-peak bipolar voltage amplitude criteria underestimate myocardial scar during substrate mapping with a novel microelectrode catheter

Ventricular bipolar voltage values <0.5 and <1.0/1.5 mV (epi- and endocardium) correlating with dense scar and border zone, respectively, were established using a 3.5-mm tip catheter. Novel microelectrode catheters promise improved mapping resolution; however, whether standard voltage criteria apply to catheters with smaller electrode size and interelectrode distance remains unclear. The purpose of this study was to determine whether traditional bipolar voltage criteria for scar apply during substrate mapping with a microelectrode catheter. Paired bipolar and microbipolar voltage values were acquired from control swine (n = 2) using the microelectrode catheter and assessed for systemic differences. In a postinfarction swine model (n = 6), scar characteristics were compared between the bipolar maps and microbipolar maps using both standard and adjusted voltage criteria derived from the control animals. In control swine, although 5th percentile values for bipolar and microbipolar voltage were similar (1.12 vs 1.22 mV [leftventricular (LV) endo]; 0.88 mV vs 0.98 mV [epi]), median values were significantly greater when acquired by microbipolar electrodes (3.60 vs 6.76 mV, P = .002 [LV endo]; 2.61 vs 2.72 mV, P = .02 [epi]). Microbipolar values were systematically larger by 2.0× and 1.4× in the LV endocardium and epicardium, respectively. Application of standard voltage values to microbipolar maps in postinfarct swine underestimated scar area by approximately 41% in the LV endocardium (13.7 vs 33.4 cm2, P = .004). Bipolar voltage values acquired from microelectrodes are systemically larger than those acquired from standard catheters. New reference values should be established for these novel catheters.

Retrograde aortic access during ventricular tachycardia ablation: Indications, techniques, and challenges.

The retrograde aortic (RA) route is a widely used access route for mapping and ablation of ventricular tachycardias (VT) arising from the left ventricular endocardium. With the expanding role of VT ablation in patients with significant comorbidity, the choice between the RA and transseptal access routes is an increasingly important consideration. An individualized decision based on the location of the arrhythmogenic substrate, vascular anatomy, aortic valve morphology, and operator experience is necessary when deciding on the optimal access route. Among patients with challenging vascular anatomy, growing experience from structural interventions such as transcatheter aortic valve replacements and peripheral vascular interventions has provided valuable insights into techniques for safe retrograde access. The present review focuses on patient selection for RA access, potential complications associated with the technique, and optimal approaches for access in patients with challenging vascular or aortic valve anatomy.

The relationship between functional capacity and left ventricular strain in patients with uncomplicated type 2 diabetes.

We aimed to evaluate the association between functional capacity and left ventricular (LV) mechanics in the patients with uncomplicated type 2 diabetes. The present cross-sectional study included 80 controls and 70 uncomplicated diabetic patients. These participants underwent laboratory analysis, comprehensive echocardiographic examination and cardiopulmonary exercise testing. Global longitudinal (-21.6 ± 2.8 vs. -18.4 ± 2.3%, P < 0.001) and circumferential (-22.0 ± 2.9 vs. -19.5 ± 2.6%, P < 0.001) strains were significantly reduced in diabetic participants. The same was found for longitudinal and circumferential endocardial, mid-myocardial and epicardial strains. Peak oxygen uptake (27.0 ± 4.3 vs. 20.7 ± 4.0 ml/kg/min, P < 0.001) and oxygen pulse (14.1 ± 3.0 vs. 11.6 ± 3.2 ml/beat, P < 0.001) were significantly lower in the diabetic group, while ventilation/carbon dioxide slope was significantly higher in these patients. In the whole study population glycosylated hemoglobin, as well as LV endocardial longitudinal and circumferential strains were independently of other clinical and echocardiographic parameters of LV structure, systolic and diastolic function associated with peak oxygen consumption and oxygen pulse. Our investigation showed that diabetes equally affected all LV myocardial layers. Endocardial LV longitudinal and circumferential strains, as well as glycosylated hemoglobin - main parameter of glucose regulation, were independently associated with functional capacity in the whole study population. These findings indicate that determination of LV strain and functional capacity could detect subclinical target organ damage and prevent development of further complications in uncomplicated diabetes mellitus patients.

Impact of chronic total coronary occlusion revascularisation on infarct-related myocardial scars responsible for recurrent ventricular tachycardia.

The aim of this study was to determine whether revascularisation of an infarct-related artery chronic total occlusion (IRA-CTO) has a modulatory effect on myocardial scar composition. This is a unique, first-time report of three consecutive patients presenting with myocardial scar-related recurrent ventricular tachycardia (rVT) on a background of ischaemic cardiomyopathy. Electro-anatomic mapping of the left ventricular endocardium was performed before and immediately after IRA-CTO percutaneous coronary intervention (PCI) to assess for changes in scar composition and size. There were substantial percentage reductions in the low voltage area of scar compared to baseline after IRA-CTO PCI (Patient 1: -12.8%, Patient 2: -27.0%, and Patient 3: -15.3%). Interval remapping ≥6 months after the index procedure demonstrated extensive net reductions in all areas of myocardial scar (Patient 1: dense scar =-7.5%, border zone scar =-54.9%, low voltage area =-32.7%, and Patient 2: dense scar =-38.6%, border zone scar =-59.6%, low voltage area =-51.7%). Patient 3 declined interval remapping but has remained free of rVT at one-year follow-up. IRA-CTO PCI may positively modify the size and composition of myocardial scar associated with rVT in the context of ischaemic cardiomyopathy.

A Multi-channel Deep Learning Approach for Segmentation of the Left Ventricular Endocardium from Cardiac Images.

Cardiac segmentation is the first most important step in assessing cardiac diseases. However, it still remains challenging owing to the complicated information of myocardium's boundary. In this work, we investigate approaches based on deep learning for fully automatic segmentation of the left ventricular (LV) endocardium using cardiac magnetic resonance (CMR) images. The deep convolutional neural network architectures, specifically, GoogleNet and U-Net, are modified and deployed to extract the features and then classify each pixel into either endocardium or background. Since adjacent frames for a given slice are imaged over a short time period across a cardiac cycle, the LV endocardium exhibit strong temporal correlation. To utilize the temporal information of heart motion to assist segmentation, we propose to construct multi-channel cardiac images by combining adjacent frames together with the current frame, which are used as the inputs for deep learning models. This allows the deep learning models to automatically learn spatial and temporal information. The performance of our constructed networks is evaluated by using the Dice metric to compare the segmented areas with the manually segmented ground truth. The experiments show that the multi-channel approaches converge more rapidly and achieve higher segmentation accuracy compared to the single channel approach.

Electrocardiographic and Electrophysiologic Characteristics of Idiopathic Ventricular Arrhythmias Originating From the Basal InferoseptalLeft Ventricle.

This study sought to characterize ventricular arrhythmia (VA) ablated from the basal inferoseptal left ventricular endocardium (BIS-LVe) and identify electrocardiographic characteristics to differentiate from inferobasal crux (IBC) VA. The inferior basal septum is an uncommon source of idiopathic VAs, which can arise from its endocardial or epicardial (crux) aspect. Because the latter are often targeted from the coronary venous system or epicardium, distinguishing between the 2 is important for successful ablation. Consecutive patients undergoing ablation of idiopathic VA from the BIS-LVe or IBC from 2009 to 2018 were identified and clinical characteristics and electrocardiographs of VA were compared. Of 931 patients undergoing idiopathic VA ablation, Virginia was eliminated from the BIS-LVe in 19 patients (2%) (17 male, age 63.7 ± 9.2 years, LV ejection fraction: 45.0 ± 9.3%). QRS complexes typically manifested right bundle branch block morphology with "reverse V2 pattern break" and left superior axis (more negative in lead III than II). VA elimination was achieved after median of 2 lesions (interquartile range [IQR]: 1-6; range 1 to 20) (radiofrequency ablation time: 123s [IQR: 75-311]). Compared with 7 patients with IBC VA (3 male, age 51.9 ± 20.1 years, LV ejection fraction: 51.4 ± 17.7%), BIS-LVe VA less frequently had initial negative forces (QS pattern) in leads II, III, and/or aVF (p<0.001), R-S ratio<1 in lead V1 (p= 0.005), and notching in lead II (p= 0.006) were narrower (QRS duration: 178.2 ± 22.4 vs. 221.1 ± 41.9ms; p= 0.04) and more frequently had maximum deflection index of<0.55 (p<0.001). The BIS-LVe region is an uncommon source of idiopathic VA. Distinguishing these from IBC VA is important for procedural planning and ablation success.

Impact of recanalization of chronic total occlusion on left ventricular electrical remodeling

BackgroundSuccessful percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) is associated with reduction of cardiac mortality, as well as reducing fatal ventricular arrhythmias. The aim of this study was to evaluate the effect of recanalization of CTO on endocardial left ventricular voltages by paired electrophysiological studies.MethodsSixteen consecutive patients who underwent PCI for de novo CTO lesions were included. High‐density mapping was performed during sinus rhythm before and 8 months after PCI. According to the amplitude of bipolar electrograms, the left ventricular endocardium was classified into a preserved normal voltage (>1.5 mV), border zone (0.5–1.5 mV), and dense scar areas (<0.5 mV).ResultsThe border zone area had a significant positive correlation with CTO length, as well as a significant negative correlation observed in the preserved voltage region. In the successful PCI patient, the median dense scar area did not change significantly (reported as [median difference: 95% confidence interval]) between baseline and after PCI (0.1 cm2: –2.8 to 2.9). However, the area of the border zone decreased (–10.5 cm2: –16.8 to –4.1) and the preserved voltage area increased significantly (19.2 cm2: 7.7–30.6). In addition, successful PCI was related to slight, but significant, increase in the amplitude of unipolar and bipolar voltage (1.55 mV: 0.88–3.33, 0.23 mV: 0.08–0.36).ConclusionsRecanalization of CTO may promote reverse electrical remodeling in the border zone of the left ventricle, without affecting the dense scar tissue.

Design and rationale for the Stimulation Of the Left Ventricular Endocardium for Cardiac Resynchronization Therapy in non-responders and previously untreatable patients (SOLVE-CRT) trial

Cardiac resynchronization therapy (CRT) improves outcomes, functional capacity and quality of life in patients with heart failure. Despite two decades of experience with CRT, the rate of non-response remains approximately 30%. CRT efficacy is impacted by pacing location, which is anatomically limited in conventional systems. A new wireless endocardial left ventricular (LV) pacing system allows CRT without such limitations and has shown promise in open-label studies. The purpose of this study is to evaluate its use in a patient population with poor therapeutic alternatives. The SOLVE CRT study is an international, multi-center, randomized, double-blind, sham-controlled trial of patients with Class I and IIa indications for CRT who have either failed to respond to or have been unable to receive conventional CRT. Enrollment will comprise 350 patients implanted with the wireless CRT system randomized 1:1 to therapy on (Treatment) or therapy off (Control) for the six-month period over which trial primary endpoints will be evaluated. The primary safety endpoint will measure the proportion of patients free from system- and procedure-related complications. Primary efficacy endpoints will assess absolute change in LV end-systolic volume LVESV, proportion of patients reducing LVESV by ≥15% and clinical composite score for Treatment versus Control patients. Primary endpoints will be evaluated on an intention-to-treat basis, though per-protocol and as-treated analysis will also be performed. SOLVE-CRT will quantify the safety and effectiveness of wireless CRT in non-responders to conventional CRT and indicated patients who have been unable to receive CRT via the usual transvenous approach.

Radiofrequency ablation lesion assessment using optical coherence tomography - a proof-of-concept study.

Radiofrequency catheter ablation (RFA) is an effective treatment for atrial fibrillation. However, ablation lesions are usually only assessed functionally. The immediate effect of RFA on the tissue is not directly visualized. Optical coherence tomography (OCT) is an imaging technique that uses light to capture high-resolution images with histology-like quality. Therefore, it might be used for high-precision imaging of ablation lesions. Radiofrequency ablation lesions (n = 25) were produced on the freshly excised left and right ventricular porcine endocardium. A Thermocool ST SF NAV ablation catheter (Biosense Webster Inc) and an EP-Shuttle ablation generator (Stockert GmbH) were used to produce ablation lesions with powers from 10 to 40 W (energies ranging from 100 Ws to 900 Ws). After ablation, the tissue was imaged with a swept source OCT system (at a wavelength of 1300 nm). Subsequently, the ablation lesions underwent the histological analysis. The ablation lesions could be visualized by OCT in all 17 samples with ablation powers ≥20 W, meanwhile, no lesion could be observed in the other eight samples with lower power (10 W). Lesion depths and lesion radiuses, as assessed by OCT, correlated well with those observed on the subsequent histological analysis (Spearman's r = 0.94, P < 0.001 and r = 0.84, P < 0.001). In addition, successful three-dimensional reconstructions of ablation lesions were performed. OCT can provide a visual high-resolution assessment of ablation lesions.

Regional differences in the expression of tetrodotoxin-sensitive inward Ca2+ and outward Cs+/K+ currents in mouse and human ventricles

ABSTRACTTetrodotoxin (TTX) sensitive inward Ca2+ currents, ICa(TTX), have been identified in cardiac myocytes from several species, although it is unclear if ICa(TTX) is expressed in all cardiac cell types, and if ICa(TTX) reflects Ca2+ entry through the main, Nav1.5-encoded, cardiac Na+ (Nav) channels. To address these questions, recordings were obtained with 2 mm Ca2+ and 0 mm Na+ in the bath and 120 mm Cs+ in the pipettes from myocytes isolated from adult mouse interventricular septum (IVS), left ventricular (LV) endocardium, apex, and epicardium and from human LV endocardium and epicardium. On membrane depolarizations from a holding potential of −100 mV, ICa(TTX) was identified in mouse IVS and LV endocardial myocytes and in human LV endocardial myocytes, whereas only TTX-sensitive outward Cs+/K+ currents were observed in mouse LV apex and epicardial myocytes and human LV epicardial myocytes. The inward Ca2+, but not the outward Cs+/K+, currents were blocked by mm concentrations of MTSEA, a selective blocker of cardiac Nav1.5-encoded Na+ channels. In addition, in Nav1.5-expressing tsA-201 cells, ICa(TTX) was observed in 3 (of 20) cells, and TTX-sensitive outward Cs+/K+ currents were observed in the other (17) cells. The time- and voltage-dependent properties of the TTX-sensitive inward Ca2+ and outward Cs+/K+ currents recorded in Nav1.5-expressing tsA-201 were indistinguishable from native currents in mouse and human cardiac myocytes. Overall, the results presented here suggest marked regional, cell type-specific, differences in the relative ion selectivity, and likely the molecular architecture, of native SCN5A-/Scn5a- (Nav1.5-) encoded cardiac Na+ channels in mouse and human ventricles.

Layer-specific strain analysis of left ventricular myocardium after alcohol septal ablation for hypertrophic obstructive cardiomyopathy.

Introduction:We aimed to explore the layer-specific systolic strain of left ventricular (LV) myocardium in patients with hypertrophic obstructive cardiomyopathy (HOCM) before and after alcohol septal ablation (ASA).The routine 2D (frame rate: >50 Hz) data sets were acquired using GE Vivi7 system for 44 consecutive HOCM patients and 21 matched normal subjects. Fifteen of HOCM patients had serial echocardiograms available for speckle tracking analyses before and 1 year after ASA. 2D strain was analyzed by EchoPAC software.The layer strain from inner to mid-myocardial and outer layers in basal and middle segments in HOCM patients continuously declined. The absolute values of peak systolic strains from the endocardium to mid-myocardium and epicardium in the basal septum of the HOCM group were significantly lower than those of the normal group (P <.01). Meanwhile, the layer systolic strain of LV endocardium in the basal septum increased significantly during a 1-year follow-up (P <.05).Conclusions:The layer-specific strains of HOCM patients measured by tissue Doppler echocardiography decreased significantly compared to those of normal individuals. The increased specific layer strain of LV endocardium in the basal septum may be a valid marker of echocardiographic improvement in HOCM patients receiving ASA.

Arrhythmogenic Remodeling of the Left Ventricle in a Porcine Model of Repaired Tetralogy of Fallot.

Ventricular arrhythmias are frequent in patients with repaired tetralogy of Fallot (rTOF), but their origin and underlying mechanisms remain unclear. In this study, the involvement of left ventricular (LV) electrical and structural remodeling was assessed in an animal model mimicking rTOF sequelae. Piglets underwent a tetralogy of Fallot repair-like surgery (n=6) or were sham operated (Sham, n=5). Twenty-three weeks post-surgery, cardiac function was assessed in vivo by magnetic resonance imaging. Electrophysiological properties were characterized by optical mapping. LV fibrosis and connexin-43 localization were assessed on histological sections and protein expression assessed by Western Blot. Right ventricular dysfunction was evident, whereas LV function remained unaltered in rTOF pigs. Optical mapping showed longer action potential duration on the rTOF LV epicardium and endocardium. Epicardial conduction velocity was significantly reduced in the longitudinal direction in rTOF LVs but not in the transverse direction compared with Sham. An elevated collagen content was found in LV basal and apical sections from rTOF pigs. Moreover, a trend for connexin-43 lateralization with no change in protein expression was found in the LV of rTOFs. Finally, rTOF LVs had a lower threshold for arrhythmia induction using incremental pacing protocols. We found an arrhythmogenic substrate with prolonged heterogeneous action potential duration and reduced conduction velocity in the LV of rTOF pigs. This remodeling precedes LV dysfunction and is likely to contribute to ventricular arrhythmias and sudden cardiac death in patients with rTOF.

His-Bundle Pacing and LV Endocardial Pacing as Alternatives to Traditional Cardiac Resynchronization Therapy.

Cardiac resynchronization therapy (CRT) using biventricular pacing (BVP) is the cornerstone of treatment for patients with heart failure and left bundle branch block. Up to a third of patients do not respond to BVP. This article reviews the utility of His-bundle pacing (HBP) and Left ventricular (LV) endocardial pacing as alternatives to BVP to provide ventricular synchrony. HBP has shown promising results in observational studies. By significantly narrowing or normalizing QRS, HBP has improved clinical outcomes including ejection fractions both as a rescue option in patients who failed BVP or as a primary alternative. LV endocardial pacing has also shown promise with improved clinical outcomes. Using traditional pacing leads or novel technology, direct stimulation of the LV endocardium allows for better site selection as well as a more physiological activation of the LV compared to traditional epicardial LV stimulation. HBP and LV endocardial pacing are valuable alternatives to traditional BVP to achieve CRT. Randomized clinical trials in progress will allow for a deeper understanding of how they can benefit our patients.

心外膜起源の非持続性心室頻拍に対し,心内膜アプローチからの焼灼で,根治しえた1例

心外膜起源の非持続性心室頻拍に対し,心内膜アプローチからの焼灼で,根治しえた1例

Rapid 12-lead automated localization method: Comparison to electrocardiographic imaging (ECGI) in patient-specific geometry

BackgroundRapid accurate localization of the site of ventricular activation origin during catheter ablation for ventricular arrhythmias could facilitate the procedure. Electrocardiographic imaging (ECGI) using large lead sets can localize the origin of ventricular activation. We have developed an automated method to identify sites of early ventricular activation in real time using the 12-lead ECG. We aim to compare the localization accuracy of ECGI and the automated method, identifying pacing sites/VT exit based on a patient-specific model. MethodsA patient undergoing ablation of VT on the left-ventricular endocardium and epicardium had 120-lead body-surface potential mapping (BSPM) recorded during the procedure. (1) ECGI methodology: The L1-norm regularization was employed to reconstruct epicardial potentials based on patient-specific geometry for localizing endocardial ventricular activation origin. We used the BSPM data corresponding to known endocardial pacing sites and a VT exit site identified by 3D contact mapping to analyze them offline. (2) The automatedmethod: location coordinates of pacing sites together with the time integral of the first 120 ms of the QRS complex of 3 ECG predictors (leads III, V2 and V6) were used to calculate patient-specific regression coefficients to predict the location of unknown sites of ventricular activation origin (“target” sites). Localization error was quantified over all pacing sites in millimeters by comparing the calculated location and the known reference location. ResultsLocalization was tested for 14 endocardial pacing sites and 1 epicardial VT exit site. For 14 endocardial pacing sites the mean localization error of the automated method was significantly lower than that of the ECGI (8.9 vs. 24.9 mm, p < 0.01), when 10 training pacing sites are used. Emulation of a clinical procedure demonstrated that the automated method achieved localization error of <5 mm for the VT-exit site; while the ECGI approach approximately correlates with the site of VT exit from the scar within a distance of 18.4 mm. ConclusionsThe automated method using only 3 ECGs shows promise to localize the origin of ventricular activation as tested by pacing, and the VT-exit site and compares favourably to inverse solution calculation, avoiding cumbersome lead sets. As 12-lead ECG data is acquired by current 3D mapping systems, it is conceivable that the algorithm could be directly incorporated into a mapping system. Further validation in a prospective cohort study is needed to confirm and extend observations reported in this study.