希尔伯特变换法分析心室颤动电压与电除颤结果的相关性研究

探讨数字化的心电图（ECG）绝对心室颤动电压（AVFV）与心室电除颤结果之间的相关性。在11只成龄犬中按矢状方向（Y轴）、横向（X轴）和纵向（Z轴）连接电极建立正交ECG并安置经静脉双导管心脏电除颤系统；诱发室颤持续10s，按选定的除颤成功率为50％的电量进行电除颤；使用希尔伯特（Hilbert）变换测定ECG包络电压。结果显示：在236个心室电除颤成功的试验（DF1）和249个电除颤失败的试验（DF2）两组中的AVFV包络电压无明显一致性的差别；DF1组的移动平均电压并不大于DF2组，其Z轴方向上电压反而小于DF2组。研究表明：心室颤动期间ECG的AVFV与心室电除颤结果之间无很强的相关性。     

心室颤动时心电图双频谱能量与电除颤结果的相关研究

目的 为探讨心室颤动时正交心电图（ECG）相位耦联程度与心室电除颤结果之间的相关性。方法 在10只成龄犬中按矢状方向（Y轴）、横向（X轴）和纵向（Z轴）连接电极建立正交ECG并按置经静脉双导管心脏电除颤系统；诱发室颤持续10s，按选定的除颤成功率为50％的电量进行电除颤（DF）；使用数字化ECG双频谱能量估价相位耦联程度。结果 在206个心室电除颤成功的试验（DF1）和221个电除颤失败的试验（DF2）两组中，DF2双频谱能量明显大于DF1。结论 研究结果提示正交ECG中相位耦联程度与DF结果之间有相关性。     

超声多普勒检测糖尿病患者心功能的研究

目的检测糖尿病患者心功能。方法采用脉冲多普勒彩色超声心动图检测糖尿病、糖尿病合并冠心病患者各33例的心室结构和功能，并与健康组对照。结果糖尿病组的左心室舒张功能较健康组减退，而合并症组较糖尿病组减退更显著。结论糖尿病组的收缩功能与健康组间无统计学意义（P〉0．05），而三组问舒张功能有统计学意义（P〈0．01）。提示心室舒张功能较收缩功能变化更早、更显著。糖尿病组及合并症组左右心室均存在舒张功能障碍，表现为舒张早期心室充盈减低及房缩充盈代偿增强等（E峰流速减慢，A峰流速增快）。糖尿病的心室舒张功能减退与糖尿病的心脏病变和代谢紊乱均有关系，纠正代谢紊乱可避免心功能进一步恶化。     

加用β受体阻滞剂对高血压病左室舒张功能改善的评价

目的 评价美托洛尔+尼群地平联合治疗高血压病患者左室舒张功能改善.方法 选择60例心电图为窭性心律.有ST-T改变的高血压病患者,分为两组,每组30例,一组使用尼群地平(简称组Ⅰ),另一组使用美托洛尔联合尼群地平(简称组Ⅱ)抗高血压治疗.8周后复查心电图与心脏彩超比较两组治疗前后的左室舒张功能变化.结果 两组治疗后,血压均降至正常范围,心率变化:组Ⅰ t=2.96 P>0.05无差异,组Ⅱt=10.83 P<0.01有显著差异;两组心电图ST～T无变化,心脏彩超复查:心脏大小形态及左室射血分数(EF%)无变化,但两组多普勒频谱超声心动图左室舒张功能指标E/A比值有显著性差异,组1 t=10.83 p<0.01,组Ⅱt=17.74 P<0.001.且组Ⅰ E/A<1,组ⅡE/A>1.结论 联合应用β受体阻滞剂抗高血压治疗,能更有效的改善左室舒张功能,心脏彩超二尖瓣多普勒频谱E/A比值是简单有效的评价方法.心电图P/PR段指数短期内评价治疗后的左室舒张功能不敏感.     

不同部位绝对不应期电刺激对慢性心力衰竭兔心功能的影响

 目的：观察心脏不同部位绝对不应期电刺激对慢性心力衰竭兔心脏功能及心脏收缩同步性的影响,探讨绝对不应期电刺激治疗慢性心力衰竭的最佳模式。方法：40只新西兰大白兔通过升主动脉根部套扎法建立兔慢性心力衰竭模型,将其分为心衰组、左室前壁（LVAW）刺激组、左室后侧壁（LVPLW）刺激组和右室心尖（RVA）刺激组。刺激组发放心脏收缩力调节信号（CCM）,每天刺激6 h,连续刺激7 d。观察心脏功能及心脏收缩同步性的变化。结果：与心衰组相比,LVAW刺激组、LVPLW刺激组及RVA刺激组的左室收缩末内径、左室舒张末内径和血浆脑钠肽(BNP)水平下降（P<0.05）,左室射血分数和左室短轴缩短率升高（P<0.05）,其中以LVAW刺激组变化最为明显,其次为LVPLW刺激组与RVA刺激组。室间隔厚度和左室后壁厚度各组之间刺激前后未见明显变化（P>0.05）。采用脉冲多普勒频谱测量主、肺动脉射血前间期之差评价心脏收缩同步性,各组之间刺激前后未见明显变化。结论：心脏不同部位绝对不应期电刺激改善心功能的程度不同,左室前壁刺激组最为明显,其次为左室后侧壁与右室心尖刺激组。绝对不应期电刺激并不影响左右心室之间的收缩同步性。     

杭白菊提取液对抗缺血再灌注引起的离体大鼠心肌收缩功能下降

目的:观察杭白菊水提取液在缺血再灌注和缺氧/复氧过程中对离体心脏和心室肌细胞的影响,并探讨其作用机制。方法:采用Langendorff离体灌流心脏模型,观察心室收缩功能;用视频跟踪系统和细胞内双波长荧光系统分别记录单个心肌细胞收缩和i;测定心肌丙二醛(MDA)和超氧化物歧化酶(SOD)水平。结果:杭白菊(0.5g/L)可明显减轻缺血再灌注引起的离体灌流心脏左室发展压、最大收缩/舒张速率、冠脉流量和左室发展压与心率乘积的抑制作用;并明显减弱缺氧/复氧抑制心室肌细胞收缩幅度、最大收缩/舒张速度和细胞钙瞬态的作用。杭白菊处理的缺血再灌注组心肌SOD水平明显升高,MDA含量显著降低。结论:杭白菊可能通过对抗自由基的作用,从而减轻缺血再灌注和缺氧/复氧对心肌收缩功能的抑制。     

胎儿心脏畸形孕早期筛查中脐静脉导管血流频谱参数与染色体异常的关系分析

目的探讨胎儿心脏畸形孕早期筛查中脐静脉导管血流频谱参数与染色体异常的关系。方法本研究回顾性分析了2013年1月至2018年5月期间1326例孕11~14w胎儿的临床资料。采用GE E8型彩色多普勒超声诊断仪检查胎儿脐静脉导管血流频谱参数,其中包括心室收缩期波峰(S波)、心室舒张早期波峰(D波)、心房收缩期波峰(a波)、阻力指数(RI)、搏动指数(PI)和S/a比值。结果1326例孕11~14w胎儿中共有1267例为正常胎儿,59例为异常胎儿。随着孕周的升高,胎儿的RI、PI和S/a比值均逐渐降低。43例脐静脉导管异常胎儿中38例为a波反向,5例为a波消失。脐静脉导管异常组的胎儿异常率(18.60%)显著高于正常组(3.98%),差异有统计学意义(P<0.001)。脐静脉导管正常组和异常组的染色体异常具有显著差异(P<0.05)。脐静脉导管血流频谱参数诊断染色体异常的特异度为0.74%,阴性预测值为96.08%。结论在孕11~14w胎儿的早期筛查中,脐静脉导管血流频谱参数异常主要表现为a波反向和消失。脐静脉导管血流频谱参数诊断胎儿染色体异常的特异度和阴性预测值较高,可作为胎儿染色体异常早期筛查的诊断指标。     

外源性促红细胞生成素对压力超负荷引起的小鼠左心功能障碍的保护作用

目的探讨外源性促红细胞生成素对压力超负荷引起小鼠左心功能障碍的保护作用。方法选取45只C57BL/6J雄性小鼠,主动脉弓缩窄术(TAC)后,将小鼠随机分为假手术组(Sham)、模型组(TAC-PBS)和治疗组(TAC-EPO),每组15只。采用M型超声心动图分别测量小鼠术前和术后2、4、6、8周左室舒张末期直径、左室收缩末期直径、左室短轴缩短率、舒张末期室间隔厚度、左室游离壁厚度和心室率;术后8周进行心导管测定,测量左心室收缩峰压、左室舒张末压和心室率。结果超声心动图示,与假手术组比较,模型组和治疗组小鼠左心室舒张和收缩末期直径均增加(P0.05),左心室短轴缩短率均减少(P0.05);但经EPO治疗后,与模型组相比,治疗组小鼠左心室舒张和收缩末期直径显著降低(P0.05),左心室短轴缩短率显著增加(P0.05)。结论外源性促红细胞生成素对压力超负荷引起的小鼠左心功能障碍的保护作用可能通过降低左心室扩张而实现。     

组织工程化心肌片层移植心肌梗死大鼠的心功能及电生理变化

背景：组织工程化心肌组织在组成结构上类似于心脏组织的三维电偶联网络和肌肉横纹,而且具有心肌组织样收缩功能,为病损心肌提供了修复的可能性。 目的：观察心肌细胞/胶原复合体移植后心肌梗死大鼠心室肌的心功能及电生理变化。 方法：将成年SD大鼠分为假手术组、模型组、移植组,后2组制作心肌梗死动物模型,假手术组仅开胸,不结扎冠状动脉。移植组移植心肌细胞与胶原材料复合组织,其他2组不进行移植。 结果与结论：①左室心功能：与假手术组相比,模型组左室舒张末期内径、左室收缩末期内径均显著增大(P < 0.01),左室射血分数和左室短轴缩短率显著降低(P < 0.01);移植组左室舒张末期内径、左室收缩末期内径、左室射血分数和左室短轴缩短率均未见明显增大或降低(P > 0.01)。②左室有效不应期变化：与假手术组相比,模型组梗死周边区有效不应期显著缩短(P < 0.01);移植组梗死周边区有效不应期较模型组延长,差异有显著性意义(P < 0.01)。③Cx43免疫荧光结果：假手术组、模型组和移植组大鼠缝隙连接蛋白43阳性表达依次呈现阳性,弱阳性,弱阳性。但移植组缝隙连接蛋白43阳性表达高于模型组。结果可见移植的心肌细胞/胶原复合体在组织和结构上形成电偶联网络和收缩偶联,能改善心肌梗死大鼠心室肌的收缩功能及电生理特性。     

参麦注射液改善急性心肌梗死大鼠心功能与左室重构的机制初探

目的：观察了参脉注射液对心肌梗死后心功能和心室重构的影响，及其对心肌细胞凋亡的影响。方法：（1）结扎大鼠左冠状动脉前降支建立大鼠心肌梗死心室重构模型，随机分为心肌梗死后1、2周模型组，②参麦注射液治疗1、2周治疗组，另设两假手术组。多导生理记录仪测量：左室收缩压（LVSP）、左室舒张末压（LVEDP）、左室内压最大上升速率（＋dp／dtmax）和下降速率（-dp／dtmax）以反映左室收缩与舒张功能。测定心脏心脏总重量、左室截面直径，并计算心室重量指数；HE染色、Masson染色、透射电镜观察心结构改变。（2）乳鼠心肌细胞原代培养，AngⅡ诱导凋亡模型。利用荧光染色观察凋亡形态变化；流式细胞仪检测细胞凋亡、心肌细胞线粒体膜电位；激光共聚焦显微镜检测钙离子荧光强度。免疫组化染色检测Bcl-2／Bax、Caspase-3蛋白的表达。     

基于有限元方法的心脏除颤仿真研究

临床动物电击除颤实验无法精确测量放电电场在心脏上的实际分布情况,且存在诸多不便利和不安全因素.鉴于此,提出了一种基于心脏建模及有限元求解的心脏除颤电场分布仿真研究方法,心脏模型包含了完整的心房心室解剖结构和左右心腔,考虑了心肌细胞和血液的电阻率,然后采用有限元方法进行分析,并使用Abaqus集成环境进行求解,求解结果与文献报道的参考标准进行对比.仿真结果在除颤电压阈值和能量阈值方面与目前的植入式心脏复律除颤器( ICD)的临床应用效果具有相当的吻合度,能量阈值相对误差仅为10％,验证了所提出方法的可行性.     

Optimal Transvenous Coil Position on Active-can Single-coil ICD Defibrillation Efficacy: A Simulation Study

The implantable cardioverter defibrillator with an active can and a single coil lead is effective in treating ventricular fibrillation, but the lead placement associated with the high defibrillation efficacy is still controversial and remains largely empirical. In this study, an anatomically realistic finite difference model of the thorax was developed based on MRI cross-sectional images of a human thorax to examine the effect of transvenous coil placement on defibrillation efficacy. Four electrode configurations with the coil was placed, respectively, in the right ventricular (RV) apex, in the middle of RV cavity, along the free wall in RV, or along the septal wall in RV, were simulated and their defibrillation efficacies were evaluated based on a set of metrics including voltage defibrillation threshold, current defibrillation threshold, interelectrode impedance, potential gradient distribution uniformity, current density distribution, and myocardium damage. It was found that the optimal electrode configuration is to position the coil in the middle of the RV cavity. The results were compared with the results from a simplified thoracic model. The comparison indicates that for a given electrode configuration a simplified representation of the thorax may overestimate defibrillation efficacy.     

Role of proximal electrode position in transvenous ventricular defibrillation

Transvenous defibrillation lead systems have been demonstrated to reduce operative morbidity and mortality associated with implantation of cardioverter-defibrillators. To determine the best position for the proximal electrode in transvenous systems, defibrillation thresholds were compared for three positions in a single-pathway, two-lead system. Two defibrillation lead electrodes were transvenously inserted into seven dogs. The distal electrode was positioned in the right ventricular apex. The proximal electrode was randomized to one of three positions: (1) the superior (cranial) vena cava (SVC) at he junction of the right atrium, (2) the left innominate vein at the junction of the SVC, or (3) the external jugular vein. Biphasic defibrillation thresholds for converting electrically induced ventricular fibrillation were determined for the three positions of the proximal electrode in each dog. The innominate vein position resulted in the lowest defibrillation threshold (555±123 V) as compared to the SVC (640±126 V;p=0.0612) and the jugular vein (709±117 V;p=0.0013). Lead impedance gradually increased with increasing dostamce between the two shocking electrodes: 58.4±11.4 Ω for SVC, 76.2±13.8 Ω for innominate vein, and 94.9±10.2 Ω for jugular vein proximal lead electrode position (p<0.05 for all pairwise comparisons). In two-electrode transvenous defibrillation lead systems, positioning the proximal electrode in the left innominate vein produced the lowest defibrillation threshold.     

Defibrillation of the heart: insights into mechanisms from modelling studies

Despite its critical role in restoring cardiac rhythm and thus in saving human life, cardiac defibrillation remains poorly understood. Further mechanistic inquiry is hampered by the inability of presently available experimental techniques to resolve, with sufficient accuracy, electrical behaviour confined to the depth of the ventricles. The objective of this review article is to demonstrate that realistic 3-D simulations of the ventricular defibrillation process in close conjunction with experimental observations are capable of bringing a new level of understanding of the electrical events that ensue from the interaction between fibrillating myocardium and applied shock. The article does this by reviewing the results of two studies, one on vulnerability to electric shocks and another on defibrillation. An overview of the modelling tools used in these studies is also provided.     

Temporal stability and precision of ventricular defibrillation threshold data.

Over 200 measurements of the minimum damped sinusoidal current and energy for transchest electrical ventricular defibrillation (ventricular defibrillation threshold) were made to determine the stability and precision of threshold data in 15 pentobarbital-anesthetized dogs. Threshold was determined by repeated trials of fibrillation and defibrillation with successive shocks of diminishing current, each 10% less than that of the preceding shock. The lowest shock intensity that defibrillated was defined as threshold. In three groups of five dogs each, threshold was measured at intervals of 60, 15, and 5 min over periods of 8, 5, and 1 h, respectively. Similar results were obtained for all groups. There was no significant change in mean threshold current with time. Owing to a decrease in transchest impedance, threshold delivered energy decreased by 10% during the first hour of testing. The standard deviations for threshold peak current and delivered energy in a given animal were 11% and 22% of their respective mean values. Arterial blood pH, Pco2, and Po2 averaged change of pH, PCO2 and PO2 were not significantly different from zero. The data demonstrate that ventricular defibrillation threshold is a stable physiological parameter that may be measured with reasonable precision.     

Patient-Specific Computational Analysis of Transvenous Defibrillation: A Comparison to Clinical Metrics in Humans

The goal of this study is to assess the predictive capacity of computational models of transvenous defibrillation by comparing the results of patient-specific simulations to clinical defibrillation thresholds (DFT). Nine patient-specific models of the thorax and in situ electrodes were created from segmented CT images taken after implantation of the cardioverter-defibrillator. The defibrillation field distribution was computed using the finite volume method. The DFTs were extracted from the calculated field distribution using the 95% critical mass criterion. The comparison between simulated and clinical DFT energy resulted in a rms difference of 12.4 J and a 0.05 correlation coefficient (cc). The model-predicted DFTs were well matched to the clinical values in four patients (rms = 1.5 J; cc = 0.84). For the remaining five patients the rms difference was 18.4 J with a cc = 0.85. These results suggest that computational models based soley on the critical mass criterion and a single value of the inexcitability threshold are not able to consistently predict DFTs for individual patients. However, inspection of the weak potential gradient field in all nine patients revealed a relationship between the degree of dispersion of the weak field and the clinical DFT, which may help identify high DFT patients.     

Comparison of the efficacy of oral capecitabine versus bolus 5-FU in preoperative radiotherapy of locally advanced rectal cancer

The effects of treatment with oral capecitabine vs. bolus 5-FU, administered concurrently with preoperative radiotherapy, were compared in the treatment of locally advanced rectal cancer (LARC). One hundred and twenty-seven patients with LARC received concurrent preoperative chemoradiation using two cycles bolus 5-FU (500 mg/m2/day) plus leucovorin (LV, 20 mg/m2/day) (Group I). Another LARC group received concurrent chemoradiation using two cycles 1,650 mg/m2/day of oral capecitabine and 20 mg/m2/day of LV (Group II, 97 patients). Radiation was delivered to the primary tumor at 50.4 Gy in both groups. Definitive surgery was performed 6 weeks after the completion of chemoradiation. A pathologic complete remission was achieved in 11.4% of patients in Group I and in 22.2% of patients in Group II (p= 0.042). The down-staging rates of the primary tumor and lymph nodes were 39.0/ 68.7% in Group I and 61.1/87.5% in Group II (p=0.002/0.005). Sphincter-preserving surgery was possible in 42.1% of patients in Group I and 66.7% of those in Group II (p=0.021). Grade 3 or 4 leucopenia, diarrhea, and radiation dermatitis were statistically more prevalent in Group I than in Group II, while the opposite was true for grade 3 hand-foot syndrome. Preoperative chemoradiation using oral capecitabine was better tolerated than bolus 5-FU and was more effective in the promotion of both down-staging and sphincter preservation in patients with LARC.