动态心电图对起搏器间歇性感知功能异常的诊断价值

目的 :探讨动态心电图检测对起搏器间歇性感知功能异常的诊断价值。方法 :采用MarquetteMars30 0 0动态心电图仪 ,对 36例 (4 9例次 )安装起搏器的患者进行随访 ,分析起搏、感知及与起搏器相关的心律失常。结果 :共检出起搏器间歇性感知功能异常 17例 (2 4例次 ) ,检出率为 4 7.2 % ,有 5例 (7例次 )合并两项感知异常。所有感知异常除 1例在常规心电图中检出外 ,其余 16例只在动态心电图中发现。检出与起搏器相关的心律失常 12例。根据动态心电图结果进行相应临床处理后 ,部分起搏器的感知功能异常消失。结论 :起搏器的感知功能异常多为间歇性的 ,动态心电图对间歇性感知异常的检出率较高 ,应是起搏器随访不可或缺的手段。     

小儿先心病心电图P波,QRS波时限,振幅与左房和肺动脉压力的相关分析

小儿先心病术后左房夺和肺动脉压力的监测在ＩＣＵ中十分重要。心电图是论断和评价心脏疾患的常用方法。本文分析了３２例小儿先心病手术前后（伴肺动脉高压１６例）６个肢体导联心电图中Ｐ波和ＱＲＳ波时限总和及振幅总和与左房、肺动脉压力的关系。结果表明两者均有良好的相关性（ｒ＝０．８５￣０．８８，ｒ＝０ｍ７４￣０．８０，Ｐ〈０．０１），该法简单、方便，可广泛开展，尤其在术后未放置ＰＡ和ＬＡ管或在ＩＯＵ中已拨除Ｌ     

急性心肌梗死患者J波的临床研究

目的　研究心电图有 J波的急性心肌梗死 ( AMI)患者的临床情况。方法　选择住院的急性心肌梗死患者 10 2例 ,心电图有 J波者 5 0例为研究组 ,心电图无 J波者 5 2例为对照组 ,比较两组临床情况。结果　心电图有 J波组比心电图无 J波组发生胸闷 ( 3 0 /5 0∶ 2 0 /5 2 ,P<0 .0 5 )、前壁心肌梗死 ( 2 8/5 0∶ 18/5 2 ,P<0 .0 5 )、合并糖尿病 ( 14/5 0∶ 4/5 2 ,P<0 .0 5 )、超声心动图检查发生舒张功能减低 ( 2 4/5 0∶ 14/5 2 ,P<0 .0 5 )、心电图检查发现室性心动过速 ( 11/5 0∶ 1/5 1,P<0 .0 5 )者多。结论　心电图有 J波者比心电图无 J波者临床情况差 ,易于发生严重心律失常     

Detection of electrocardiographic ‘left ventricular strain’ using neural nets

The use of artificial neural networks for classification of ST-T abnormalities of the electrocardiogram (ECG) was investigated. A training set of 356 lateral leads selected from 105 ECGs was visually classified as exhibiting one particular ST-T morphology (left ventricular (LV) strain) or not. Selected measurements, together with the classification, were fed as input to a three-layer software-based network during the learning process. The performance of the network was evaluated by comparing the results obtained from the network with conventional criteria, using two test sets. Set 1 comprised 63 lateral leads from 32 ECGs with ST-T changes showing atypical forms of LV strain. Set 2 consisted of 80 lateral leads from 20 ECGs containing normal and abnormal T-waves. For set 1, the network outperformed conventional criteria, having a higher sensitivity (96 per cent against 85 per cent) and specificity (67 per cent against 50 per cent). With test set 2, both network and conventional criteria were 100 per cent sensitive and 100 per cent specific. For sets 1 and 2 combined, the network had a higher overall sensitivity (97 per cent agaisst 89 per cent) and specificity (88 per cent against 82 per cent). The results suggest that neural networks may be useful in selected areas of electrocardiography, but care is required when selecting patterns for use in the training process.     

十名志愿者口服维拉帕米缓释片药代动力学和心电图研究

对10名男性受试者单剂量po240mgVer缓释片药代动力学及心电图变化进行研究。血药浓度—时间数据用零级吸收过程的一室模型拟合,其药代动力学参数:T_max5.9±1.6h;C_max118.9±37.2μg·L^-1;T₁ 5.4±1.5h;k₀30.5±17.5μg·L^-1·h^-1;T_1/210.8±4.9h。PR间期延长有显著意义,血药浓度与PR间期变化满足S 型模型,其药效学参数:EC₅₀ 64.6±16.9μg·L^-1; E_max54±11ms;s 1.68±0.66。     

Sinoatrial Node Electrogram Studies in Patients with Sick Sinus Syndrome

Sinoatrial node electrogram (SNE) was recorded successfully in recent years, using transvenous electrode catheter. Via SNE and intratrialelectrogram (IEG), one could measure sinoatrial conduction time(SACT) directly, observe sinoatrial node (SN) potential changes in cadiac cycles, diagnose some sinus arrhythmias which couldn't be confirmed by surface ECG. All these could offer accurate evidence for differential diagnosis of sick sinus syndrome (SSS). The authors recommend a modified method for the location of the electrode catheter, by which one can increase success rate of obtaining stable SNE. Using this method, the authors recorded SNE in 10 cases with SSS successfully.     

Vortex Shaped Current Sources in a Physical Torso Phantom

Recent studies reported differential information in human magnetocardiogram and in electrocardiogram. Vortex currents have been discussed as a possible source of this divergence. With the help of physical phantom experiments, we quantified the influence of active vortex currents on the strength of electric and magnetic signals, and we tested the ability of standard source localization algorithms to reconstruct vortex currents. The active vortex currents were modeled by a set of twelve single current dipoles arranged in a circle and mounted inside a phantom that resembles a human torso. Magnetic and electric data were recorded simultaneously while the dipoles were switched on stepwise one after the other. The magnetic signal strength increased continuously for an increasing number of dipoles switched on. The electric signal strength increased up to a semicircle and decreased thereafter. Source reconstruction with unconstrained focal source models performed well for a single dipole only (less than 3-mm localization error). Minimum norm source reconstruction yielded reasonable results only for a few of the dipole configurations. In conclusion active vortex currents might explain, at least in part, the difference between magnetically and electrically acquired data, but improved source models are required for their reconstruction.     

Accuracy of Quadratic Versus Linear Interpolation in Noninvasive Electrocardiographic Imaging (ECGI)

Electrocardiographic Imaging (ECGI) is a cardiac functional imaging modality, noninvasively reconstructing epicardial potentials, electrograms and isochrones (activation maps) from multi-channel body surface potential recordings. The procedure involves solving Laplace’s equation in the source-free volume conductor between torso and epicardial surfaces, using Boundary Element Method (BEM). Previously, linear interpolation (LI) on three-noded triangular surface elements was used in the BEM formulation. Here, we use quadratic interpolation (QI) for potentials over six-noded linear triangles. The performance of LI and QI in ECGI is evaluated through direct comparison with measured data from an isolated canine heart suspended in a human-torso-shaped electrolyte tank. QI enhances the accuracy and resolution of ECGI reconstructions for two different inverse methods, Tikhonov regularization and Generalized Minimal Residual (GMRes) method, with the QI-GMRes combination providing the highest accuracy and resolution. QI reduces the average relative error (RE) between reconstructed and measured epicardial potentials by 25%. It preserves the amplitude (average RE reduced by 48%) and morphology of electrograms better (average correlation coefficient for QI ∼ 0.97, LI ∼ 0.92). We also applied QI to ECGI reconstructions in human subjects during cardiac pacing, where QI locates ventricular pacing sites with higher accuracy (≤ 10 mm) than LI (≤ 18 mm).     

急性有机磷中毒患者心肌酶和心电图的变化及临床意义

目的　探讨急性有机磷中毒 (AOPP)患者血清肌酸激酶 (CK)、肌酸激酶同工酶 (CK -MB)、乳酸脱氢酶 (LDH)和心电图的变化规律及其临床意义。方法　 6 1例AOPP患者 (中毒组 )在中毒后第 1～ 10天分别检测血清心肌酶和心电图 ,同时选择 41例正常人作对照。结果　 (1)与对照组比较中毒组的CK、CK -MB、LDH水平在第 1～ 10天均明显增高 ,差异有显著性 (P <0 0 5～ 0 0 1) ,在第 2～ 4天有较高的峰值平台 ;(2 )轻、中、重度中毒组和对照组间血清中CK、CK -MB、LDH水平的两两比较差异均有显著性 (P <0 0 1) ;(3)心电图异常改变构成比随中毒程度加重而增大 ,重度中毒组心电图异常改变占严重心律失常的主要比例。结论　在中毒的第 2～ 4天组织损害越严重 ,血清中各酶水平增加越明显 ,则组织损害更加严重 ;中毒程度越深 ,心电图异常改变越多 ,严重的心律失常也更多 ,对重度中毒患者应进行心电监护 ,以避免心源性猝死