Terminal Force Research Articles

Modelling large planar deflections of flexible bundled conductors in substations using a modified chained-beam constraint model

To evaluate the terminal force and configuration of bundled flexible conductors used in high voltage substations, this study developed a parametric method for modelling the large planar deflection of the flexible conductors. The flexible conductors were assumed to be planar beams. Based on the chained-beam constraint model (CBCM), the equations of the constraint effects of spacers and the geometric constraint of the bundled conductors were added to the model. Additionally, the CBCM was modified to capture the loading of a concentrated force on the intermediate part of the conductors. The model was validated by static tests and finite element analyses. Some case studies on the terminal force and configuration of the bundled flexible conductors based on this model were carried out. The terminal force and configuration of the bundled conductors calculated with and without bending stiffness were compared, showing that the constraint effects of the spacers increased the stiffness of the bundled conductors. Ignoring the bending stiffness and the constraint effects of the spacers will lead to analytical errors in the terminal force and configurations of the bundled flexible conductors used in high voltage substations.

Simulation Analysis of Terminal Force of UHV Main Equipment

In this paper, the key stress part of main equipment of the UHV engineering is screened and determined firstly based on principles such as equipment importance, distance away from main equipment, load strength and equipment dimensions; and then, the influence of upper crossing line and down-lead on stress of UHV DC main equipment terminal is taken into consideration, and simulation models of terminal stress of two types of typical key main equipment, i.e. cross line – down-lead and herringbone down-lead are established; next, the comparative analysis between numerical simulation result and test result of herringbone down-lead is conducted to verify correctness of simulation model and test method in this paper.

Common source of miscalculation and misclassification of P-wave negativity and P-wave terminal force in lead V1

BackgroundP-wave terminal force (PTF) > 4000 ms·μV and deep terminal negativity (DTN) are ECG markers of left atrial abnormality associated with both atrial fibrillation and stroke. When the precordial lead V1 is placed higher than the correct position in the fourth intercostal space, it may cause increased PTF and DTN. Several studies have documented that electrode misplacement, especially high placement, is common. The influence of electrode misplacement on these novel ECG markers has not previously been quantified. ObjectiveThe objective was to assess the influence of electrode misplacement on PTF and DTN. Method12-Lead ECGs were recorded in 29 healthy volunteers from the Department of Cardiology at the Copenhagen University Hospital of Bispebjerg. The precordial electrode V1 was placed in the fourth, third and second intercostal space, giving a total of 3 ECGs per subject. Continuous variables were compared using Dunnett's post-hoc test and categorical variables were compared using Fischer's exact test. ResultsHigh placement of V1 electrodes resulted in a more than three-fold increase of PTF (IC4 = 2267 ms·μV, IC2 = 7996 ms·μV, p-value < 0.001). There was a similar increase of DTN (IC4 = 0%, IC2 = 28%, p-value < 0.001). P-wave area and amplitude of the negative deflection increased, and P-wave area and amplitude of the positive deflection decreased. The P-wave shape changed from being predominantly positive or biphasic in IC4 to 90% negative in IC2. The PR-duration and P-wave duration were not altered by electrode placement. ConclusionHigh electrode placement results in significant alteration of PTF and DTN in lead V1.

Succinate links atrial dysfunction and cardioembolic stroke.

To determine whether altered metabolic profiles represent a link between atrial dysfunction and cardioembolic (CE) stroke, and thus whether underlying dysfunctional atrial substrate may contribute to thromboembolism risk in CE stroke. A total of 144 metabolites were measured using liquid chromatography-tandem mass spectrometry in plasma samples collected within 9 hours of stroke onset in 367 acute stroke patients. Stroke subtype was assigned using the Causative Classification of Stroke System, and CE stroke (n = 181) was compared to non-CE stroke (n = 186). Markers of left atrial dysfunction included abnormal atrial function (P-wave terminal force in lead V1, PTFV1 >4,000 μV·ms), left atrial enlargement on echocardiography, and frank atrial fibrillation on ECG. Stroke recurrence risk was assessed using CHADS2 and CHA2DS2-VASc scores. Associations between metabolites and CE stroke, atrial dysfunction, and stroke recurrence risk were evaluated using logistic regression models. Three tricarboxylic acid metabolites-succinate (odds ratio [OR] 1.71, 95% confidence interval [CI] 1.36-2.15, p = 1.37 × 10-6), α-ketoglutarate (OR 1.62, 95% CI 1.29-2.04, p = 1.62 × 10-5), and malate (OR 1.58, 95% CI 1.26-1.97, p = 2.57 × 10-5)-were associated with CE stroke. Succinate (OR 1.36, 95% CI 1.31-1.98, p = 1.22 × 10-6), α-ketoglutarate (OR 2.14, 95% CI 1.60-2.87, p = 2.08 × 10-8), and malate (OR 2.02, 95% CI 1.53-2.66, p = 1.60 × 10-7) were among metabolites also associated with subclinical atrial dysfunction. Of these, succinate was also associated with left atrial enlargement (OR 1.54, 95% CI 1.23-1.94, p = 1.06 × 10-4) and stroke recurrence based on dichotomized CHADS2 (OR 2.63, 95% CI 1.68-4.13, p = 3.00 × 10-6) and CHA2DS2-VASc (OR 2.43, 95% CI 1.60-3.68, p = 4.25 × 10-6) scores. Metabolite profiling identified changes in succinate associated with CE stroke, atrial dysfunction, and stroke recurrence, revealing a putative underlying link between CE stroke and energy metabolism.

Refining Prediction of Atrial Fibrillation-Related Stroke Using the P2-CHA2DS2-VASc Score.

In people with atrial fibrillation (AF), periods of sinus rhythm present an opportunity to detect prothrombotic atrial remodeling through measurement of P-wave indices (PWIs)-prolonged P-wave duration, abnormal P-wave axis, advanced interatrial block, and abnormal P-wave terminal force in lead V1. We hypothesized that the addition of PWIs to the CHA2DS2-VASc score would improve its ability to predict AF-related ischemic stroke. We included 2229 participants from the ARIC study (Atherosclerosis Risk in Communities) and 700 participants from MESA (Multi-Ethnic Study of Atherosclerosis) with incident AF who were not on anticoagulants within 1 year of AF diagnosis. PWIs were obtained from study visit ECGs before development of AF. AF was ascertained using study visit ECGs and hospital records. Ischemic stroke cases were based on physician adjudication of hospital records. We used Cox proportional hazards models to estimate hazard ratios and 95% CIs of PWIs for ischemic stroke. Improvement in 1-year stroke prediction was assessed by C-statistic, categorical net reclassification improvement, and relative integrated discrimination improvement. Abnormal P-wave axis was the only PWI associated with increased ischemic stroke risk (hazard ratio, 1.84; 95% CI, 1.33-2.55) independent of CHA2DS2-VASc variables, and that resulted in meaningful improvement in stroke prediction. The β estimate was approximately twice that of the CHA2DS2-VASc variables, and thus abnormal P-wave axis was assigned 2 points to create the P2-CHA2DS2-VASc score. This improved the C-statistic (95% CI) from 0.60 (0.51-0.69) to 0.67 (0.60-0.75) in ARIC and 0.68 (0.52-0.84) to 0.75 (0.60-0.91) in MESA (validation cohort). In ARIC and MESA, the categorical net reclassification improvements (95% CI) were 0.25 (0.13-0.39) and 0.51 (0.18-0.86), respectively, and the relative integrated discrimination improvement (95% CI) were 1.19 (0.96-1.44) and 0.82 (0.36-1.39), respectively. Abnormal P-wave axis-an ECG correlate of left atrial abnormality- improves ischemic stroke prediction in AF. Compared with CHA2DS2-VASc, the P2-CHA2DS2-VASc is a better prediction tool for AF-related ischemic stroke.

Dynamic Response Analysis for a Terminal Guided Projectile With a Trajectory Correction Fuze

Successful terminal correction without an attitude feedback loop is a challenging task. Much innovative effort is required to achieve a balance between performance and affordability. This paper presents a unique trajectory correction fuze with a reduced number of sensors and actuators. A rapidly calculable analytical dynamic response model for the terminal control force is derived, in which the oscillation part is emphasized because of the limited time-to-go. The accuracy and effectiveness of the analytical model are verified by comparison with 6DOF nonlinear simulations. The influences of the velocity, rotation rate, and pitch on the dynamic response during terminal correction are subsequently investigated using the analytical model. To enable a deep investigation of stability under terminal control with a trajectory correction fuze, the Routh stability criterion is considered to define the necessary prerequisites for stable flight. The validity of the derived instability boundaries is demonstrated through numerical simulations.

An Elevated P Wave Terminal Force V1 is not Associated with Worsening Atrial Electroanatomic Substrate

An Elevated P Wave Terminal Force V1 is not Associated with Worsening Atrial Electroanatomic Substrate

Atrial cardiopathy in patients with embolic strokes of unknown source and other stroke etiologies

To investigate the prevalence and clinical determinants of atrial cardiopathy in patients with embolic stroke of unknown source (ESUS) and compare with other established stroke etiologies. In a cross-sectional study of 846 consecutive patients with ischemic stroke, we compared the prevalence of atrial cardiopathy (defined by p-wave terminal force in V1 >5,000 µV·ms or severe left atrial enlargement) between ESUS patients and patients with large artery atherosclerosis (LAA) and small vessel disease (SVD) strokes. Baseline characteristics were also compared between ESUS and cardioembolic (CE) patients. Of all, 158 (19%) patients met ESUS diagnostic criteria, while others were classified into LAA (n = 224, 26%), SVD (n = 154, 18%), and CE (n = 310, 37%). The prevalence of atrial cardiopathy was higher in ESUS patients compared to noncardioembolic stroke patients (26.6% vs 12.1% in LAA vs 16.9% in SVD; p = 0.001). ESUS patients were younger, were less hypertensive, and had higher cholesterol and low-density lipoprotein levels, but also had less left ventricular or atrial abnormalities when compared to CE patients. The prevalence of atrial cardiopathy was high in ESUS patients compared with patients with nonembolic strokes. Interestingly, ESUS patients were also clinically different from CE patients. While the presence of atrial cardiopathy may reflect a unique mechanism of thromboembolism in ESUS patients, it is still unclear if they may benefit from anticoagulation, or if the presence of atrial cardiopathy in this population could serve as a risk-stratifying marker for stroke recurrence. Further efforts are necessary to provide better characterization of the ESUS population in order to develop better stroke preventive strategies.

An Unusual LnIII‐Based Metal‐Organic Framework with Dinuclear Nodes Exhibiting Single‐Molecular Magnet Behavior

Three LnIII‐based metal‐organic frameworks (MOFs), namely [(Me2NH2)[Ln(OBA)2](Hatz)(H2O)1.5]n [Ln = Dy (1), Er (2), Ho (3); H2OBA = 4, 4'‐oxybis(benzoate) acid, Hatz = 3‐amino‐1,2,4‐triazole], were synthesized with Hatz as the template. In the structure of the three MOFs, the dinuclear LnIII nodes are bridged by four oxygen atoms from syn, syn‐carboxylate groups and this model result in a long distance between Dy–Dy, about 4.143(7) Å. In addition, the terminal carboxylate groups force a sandwich‐like coordination environment. Slow relaxation of the magnetization can be observed for 1, indicative of a single‐molecule magnet (SMM) behavior.

Poor reliability of P-wave terminal force V1 in ischemic stroke

IntroductionSeveral ECG markers are postulated to represent underlying atrial remodelling and have been associated with ischemic stroke. P-wave terminal force in lead V1 (PTFV1) is one such marker. We examined the factors that contribute to the reliability of PTFV1 and its association with ischemic stroke. Material and methodsFour hundred and thirty-five patients that presented with an ischemic stroke or transient ischemic attack (TIA) were identified through a prospectively maintained multi-site institutional stroke database. Control group consisted of age matched patients without prior history of an ischemic stroke or TIA. All patients underwent a 12-lead ECG and 24-hour Holter monitoring during the study period to exclude atrial fibrillation. ResultsMorphology consistent with PTFV1 occurred commonly in both the stroke/TIA and control groups. There was no significant difference in the median PTFV1 value between the stroke 3.96 mV ms [Interquartile range (IQR) 2.78–5.58] and control 4.23 mV ms [IQR 2.91–5.57] groups. Measurements of PTFV1 demonstrated excellent intra-observer reliability on assessment of the same P-wave (Intra class correlation (ICC) 0.91, p < 0.001) with narrow limits of agreement 2.21 to −2.95 mV ms. A change in the P wave assessed led to a significant reduction in reliability (ICC 0.79, p < 0.001). Inter-observer, inter P-wave assessment demonstrated further reduction in reliability (ICC 0.68, p < 0.002) with wide limits of agreement 6.17 to −5.78 mV ms, indicating significant under and overestimation of PTFV1. ConclusionThe utility of PTFV1 as a clinical marker for ischemic stroke is limited by the reduction in reliability associated with inter-observer and inter P-wave measurements.

Abstract 17255: Standard 12-Lead Electrocardiogram Can Predict Diffuse Myocardial Fibrosis in Patients With Atrial Fibrillation

Background: The pathophysiology of atrial fibrillation (AF) involves a continuum of myocardial remodeling with increased diffuse fibrosis. Purpose: To examine whether the extent of diffuse fibrosis in the left atrium (LA) and left ventricle (LV), evaluated using the surrogate marker, post-contrast T1 myocardial relaxation time on cardiac magnetic resonance imaging (CMR), in patients with paroxysmal and persistent AF is associated with ECG markers obtained during sinus rhythm. Methods: This is a prespecified secondary analysis from the randomized controlled trial INSPIRE-AF (n=95) (ClinicalTrials.gov NCT02764619). Patients with paroxysmal and persistent AF underwent CMR. Post-contrast T1 times were quantified in 47 paroxysmal AF (mean age, 63 ±8 years), and 43 persistent AF (mean age, 54 ±7 years) patients using a previously validated modified look-locker inversion-recovery sequence. Standard resting 12-lead ECGs were analyzed using commercially available software. Results: Baseline characteristics were generally similarly distributed between AF groups. Mean LA T1 time was 492 +/- 72 ms and mean LV T1 time was 494 +/- 49 ms. P-wave area, P-wave terminal force, PR-interval, P-wave peak amplitude, and P-wave duration were unassociated with LA T1 time, and no significant interactions with AF type were detected. Similarly, neither R-wave duration, corrected QT interval (Bazett’s formula), nor QRS duration were associated with LV T1 time. P-wave terminal force in lead V1 did not differ between groups of investigation, but the joint mean value of -0.04 mm/s in the two groups is prominently different from normal controls. AF type significantly interacted with the association between R-wave duration and T1 time (P=0.03 for interaction), and between QRS duration and T1 time (P=0.009 for interaction). Specifically, R-wave duration and QRS duration were only significantly associated with T1 time among patients with persistent AF. Conclusions: Diffuse fibrosis in the LV, defined as post-contrast T1 time, was associated with R-wave duration and QRS duration in patients with persistent AF. Our findings suggest that surface 12-lead ECG obtained in sinus rhythm could provide predictive information regarding diffuse myocardial fibrosis.

Influence of left atrial size on P-wave morphology: differential effects of dilation and hypertrophy.

Chronic left atrial enlargement (LAE) increases the risk of atrial fibrillation. Electrocardiogram (ECG) criteria might provide a means to diagnose LAE and identify patients at risk; however, current criteria perform poorly. We seek to characterize the potentially differential effects of atrial dilation vs. hypertrophy on the ECG P-wave. We predict effects on the P-wave of (i) left atrial dilation (LAD), i.e. an increase of LA cavity volume without an increase in myocardial volume, (ii) left atrial concentric hypertrophy (LACH), i.e. a thickened myocardial wall, and (iii) a combination of the two. We performed a computational study in a cohort of 72 anatomical variants, derived from four human atrial anatomies. To model LAD, pressure was applied to the LA endocardium increasing cavity volume by up to 100%. For LACH, the LA wall was thickened by up to 3.3 mm. P-waves were derived by simulating atrial excitation propagation and computing the body surface ECG. The sensitivity regarding changes beyond purely anatomical effects was analysed by altering conduction velocity by 25% in 96 additional model variants. Left atrial dilation prolonged P-wave duration (PWd) in two of four subjects; in one subject a shortening, and in the other a variable change were seen. Left atrial concentric hypertrophy, in contrast, consistently increased P-wave terminal force in lead V1 (PTF-V1) in all subjects through an enlarged amplitude while PWd was unaffected. Combined hypertrophy and dilation generally enhanced the effect of hypertrophy on PTF-V1. Isolated LAD has moderate effects on the currently used P-wave criteria, explaining the limited utility of PWd and PTF-V1 in detecting LAE in clinical practice. In contrast, PTF-V1 may be a more sensitive indicator of LA myocardial hypertrophy.

P-wave terminal force in lead V1 is a predictive indicator for the diagnosis of tuberculous constrictive pericarditis

ObjectivesThe purpose of this study is to explore the value of P-wave terminal force in lead V1 (PTFV1) in the clinical diagnosis of tuberculous constrictive pericarditis (TCP). MethodsA total of 53 patients with TCP and 64 patients with tuberculous exudative pericarditis were enrolled in this retrospective study. The demographic and clinical characteristics were collected, including gender, age, the course of disease and New York Heart Association (NYHA) classification. Besides, echocardiography data also were obtained, including left atrial diameter, left ventricular end-diastolic diameter and left ventricular ejection fraction. In addition, the parameters of electrocardiogram (ECG) were obtained, such as heart rate, the time from the corrected ORS wave origin to T-wave terminal, atrial fibrillation, right bundle branch block, atrial premature beat, and PTFV1 value. ResultsNo significant differences were found in age, gender, the course of disease, echocardiography results, ECG parameters (in addition to PTFV1) between patients with TCP and patients with tuberculous exudative pericarditis. The percentage of patients located in NYHA class IV in the patients with TCP was significantly higher than those of patients with tuberculous exudative pericarditis (p = 0.041). Moreover, the incidence rate of abnormal PTFV1 (≤ -0.04 mm·s) was obviously higher in patients with TCP than those of patients with tuberculous exudative pericarditis (64.2% vs 9.4%, p < 0.001). ConclusionsAbnormal PTFV1 (≤ -0.04 mm·s) is associated with TCP, and PTFV1 may be a potential novel diagnostic indicator for TCP diagnosis.

Electrocardiographic left atrial abnormality and silent vascular brain injury: The Northern Manhattan Study.

HypothesisWe hypothesized that P wave terminal Force in the V1 lead (PTFV1) would be associated with leukoaraiosis and subclinical infarcts, especially cortical infarcts, in a population-based, multi-ethnic cohort.MethodsPTFV1 was collected manually from baseline electrocardiograms of clinically stroke-free Northern Manhattan Study participants. Investigators read brain MRIs for superficial infarcts, deep infarcts, and white matter hyperintensity volume (WMHV). WMHV was adjusted for head size and log transformed, achieving a normal distribution. Logistic regression models investigated the association of PTFV1 with cortical and with all subclinical infarcts. Linear regression models examined logWMHV. Models were adjusted for demographics and risk factors.ResultsAmong 1174 participants with PTFV1 measurements, the mean age at MRI was 70 ± 9 years. Participants were 14.4% white, 17.6% black, and 65.8% Hispanic. Mean PTFV1 was 3587.35 ± 2315.62 μV-ms. Of the 170 subclinical infarcts, 40 were cortical. PTFV1 ≥ 5000 μV-ms was associated with WMHV in a fully adjusted model (mean difference in logWMHV 0.15, 95% confidence interval 0.01–0.28). PTFV1 exhibited a trend toward an association with cortical infarcts (unadjusted OR per SD change logPTFV1 1.30, 95% CI 0.94–1.81), but not with all subclinical infarcts.ConclusionElectrocardiographic evidence of left atrial abnormality was associated with leukoaraiosis.

An analytical investigation on large post-buckling behavior of a drilling shaft modeled as a rotating beam with various boundary conditions

Post-buckling behavior of a drilling shaft modeled as a rotating beam subjected to terminal force is investigated in this paper. Three boundary conditions: clamped-clamped, clamped-free, and clamped-hinged are considered. Classical Bernoulli-Euler beam model including shear force is applied to depict the problem. In particular, for clamped-hinged ends boundary condition, the analytical approximate solutions are more difficult to construct, due to asymmetric boundary and configuration. Unlike numerical results in the existing literatures, analytical approximate solutions of the problem above are established via combining the Maclaurin series expansion, orthogonal Chebyshev polynomials, Galerkin and Harmonic balance method in this paper. Compared with numerical solutions obtained by using the shooting method on the exact governing equation, the approximate analytical solutions here show excellent accuracy and rapid convergence. The effect of the system parameters on the dynamic response and stability of system can conveniently be investigated via the present analytical approximate solutions. In conclusion, the analytical approximate solutions presented here are sufficiently precise for a wide range of the maximum angle of the rotating beam.

A refined quasi-3D zigzag beam theory for free vibration and stability analysis of multilayered composite beams subjected to thermomechanical loading

A refined four-unknown quasi-3D zigzag beam theory is developed to model the free vibration and buckling behaviors of multilayered composite beams subjected to axial mechanical loading (e.g., distributed load and terminal force) and uniform temperature variation. Types of the composite beams considered include laminated composite beams, sandwich beams with composite face sheets, and fiber metal laminates. The proposed theory accounts for not only thickness stretching but also interlaminar continuity of transverse shear stresses and displacements. Associated eigenvalue problems for various boundary conditions are derived using the Ritz method. Accuracy and effectiveness of the theoretical predictions are verified by comparison with existing results and present finite element simulations. The theory is employed to quantify the effects of axial distributed load/terminal force and temperature variation on free vibration and buckling for different boundary conditions, geometric parameters and material properties. The present theory could produce sufficiently accurate predictions of natural frequencies and buckling capacities of multilayered beams at a very low computational cost.

A reduced-order approach to the adaptive fuzzy sliding mode control of the constrained manipulator

A reduced-order approach to the adaptive fuzzy sliding mode control of the constrained manipulator is proposed. Based on the Udwadia–Kalaba motion constraint equation, the dynamic equation of the constrained manipulator with both ideal and non-ideal constraints is obtained. Considering the uncertainty of the terminal non-ideal constrained force and the chattering phenomenon of sliding mode control, the adaptive fuzzy and the sliding mode control method are combined to control the constrained manipulator. Because the system is constrained, the model order reduction method is innovatively used in the control algorithm. The stability of the system is proved by Lyapunov theorem. For demonstrating the effectiveness of the control algorithm, the 2-degree-of-freedom manipulator is taken as the research object. Finally, the high-precision control of the manipulator is achieved and the chattering phenomenon caused by the sliding mode control is weakened.

Nonlinear mechanics of flexible cables in space robotic arms subject to complex physical environment

A nonlinear model of a special cable in space robotic arms is developed in space environment. The mechanic effects of control cables in powerful robots can often be neglected. However, in complex space multi-physics environments, involving ultra-low temperature, radiation, and other extreme conditions of outer space, the externally mounted cables (protected by shielding layers) can induce strong nonlinear interference to robot arms; and this can induce further small-range slow rotations or oscillations of the flexible joint of robots at a specific posture, which consequently affect the precision and operation performance of end effectors. Effective mathematical models on nonlinear mechanics of strong cables under multi-physics environments and their effects on weak robots have not been well developed yet. Complex key factors, such as low gravity, nonlinear friction, and unexpected curved surface constraints, have not been extensively investigated either. In this study, considering all these key factors, a Kirchhoff nonlinear mechanical model of cables in complex space environments is developed, and a relatively improved algorithm based on a trust-region strategy is proposed for solving this nonlinear model, based on which the geometry and terminal force of the modeled robot cable can be obtained. The validity and accuracy of the proposed algorithm and theoretical calculation results are verified via experiments. The theoretical findings revealed in this study are significant to future research on the slow rotations and oscillations of weak robot joints in space exploration with robotic arms.

Evaluation of atrial electromechanical functions in dipper and nondipper hypertension patients using left atrial strain P-wave dispersion and P terminal force.

Nondippers are known to carry a high risk of cardiovascular morbidity and mortality. The aim of this study was to investigate the effects of dipper and nondipper status of hypertension on left atrial (LA) systolic and diastolic functions using two-dimensional speckle tracking echocardiography (2D-STE), P-wave dispersion (PWD), and P terminal force (PTF) in hypertensive patients. A total of 72 patients and 39 healthy individuals were included in the study. The patients were classified as nondippers if their daytime ambulatory systolic and diastolic blood pressure did not decrease by at least 10% during the night. Atrial electromechanical delay times, LA strain values were obtained by 2D-STE with automated software and compared between the groups. PWD and PTF data were calculated on the electrocardiography. Inter-atrial (dippers: 25.5±3.9, nondippers: 32.2±7.4, P<.001), left-atrial (dippers: 14.9±3.7, nondippers: 18.2±6.0, P=.016), and right atrial (dippers: 10.5±2.1, nondippers: 14.2±5.2, P<.001) electromechanical delay times were significantly longer in nondippers. LA strain S (dippers: 34.2 [29.7-38.7], nondippers: 27.7 [22.7-32.2], P<.001), LA strain E (dippers: 18.2 [16.6-20.1], nondippers: 14.4 [11.6-16.8], P<.001), and LA strain A (dippers: 15.8 [13.5-17.9], nondippers: 12.7 [9.9-14.5], P<.001) were significantly lower in nondippers. Nondippers also had an increased values of maximum P-wave duration (dippers: 0.117 [0.10-0.12], nondippers: 0.126 [0.12-0.14], P<.001), PWD (dippers: 0.062 [0.06-0.07], nondippers: 0.069 [0.06-0.08], P=.004), and PTF (dippers: 0.055±0.02, nondippers: 0.066±0.02, P=.02). Nondipping pattern in hypertensive patients had a worse cardiac remodeling, and impaired mechanical LA function compared with dipping pattern. The PWD and PTF findings support these changes.

Relation of Electrocardiographic Left Atrial Abnormalities to Risk of Stroke in Patients with Atrial Fibrillation

The P-wave terminal force in lead V1 (PTFV1) on the 12-lead electrocardiogram (ECG) quantifies left atrial (LA) structural and electrophysiologic abnormalities. We aimed to evaluate the association between PTFV1 and cerebrovascular accident (CVA) as well as LA structure and function in patients with atrial fibrillation (AF). We conducted a cross-sectional study of 229 patients with AF (60 ± 10years, 72% men) with (n = 21) and without (n = 208) a history of CVA, who underwent preablation ECG and cardiac magnetic resonance in sinus rhythm. PTFV1 was defined as the duration (in milliseconds) of the downward deflection of the P wave in lead V1 multiplied by the absolute value of its amplitude (in microvolts) on ECG. PTFV1 is associated with LA minimum volume (Vmin) and left ventricular ejection fraction but not associated with the extent of LA fibrosis quantified by cardiac magnetic resonance late gadolinium enhancement. In addition, PTFV1 is associated with CVA independent of the CHA2DS2-VASc score and LA Vmin (odds ratio 1.23; 95% confidence interval 1.08 to 1.40; p = 0.002). Furthermore, PTFV1 has an incremental value over the CHA2DS2-VASc score as a marker of CVA (p <0.001). In conclusion, ECG-defined PTFV1 is independent marker of stroke in patients with AF and reflects the underlying LA remodeling. Our findings suggest that evaluation of PTFV1 can improve the current risk stratification of stroke.