左旋四氢巴马汀治疗心律失常的临床观察

<正> 左旋四氢巴马汀(L-Tetrahydropalmatine,L-THP),亦称颅通定,是从罂科紫堇属植物延胡索中提出的一种生物碱,是中药延胡索的有效成份。L-THP是良好的中枢抑制剂。已公认的药理作用有镇痛、镇静、催眠和解痉。近来文献报道:L-THP还具有抗心律失常的作用。动物试验发现,L-THP能对抗氯化钙、哇巴因、氯仿、肾上腺素等诱发的心律失常,并能使血压下降,心肌耗氧量减少。但临床应用效果如何,文献少见报道。本文对20例心律失常病人,给予L-THP治疗一个月,旨在初步观察L-THP     

苄基四氢巴马汀抗实验性心律失常的作用

苄基四氢马汀(B-THP)1mg/kg有对抗氯仿所致的小鼠室颤作用,5mg/kg可使哇巴因引起的豚鼠心律失常量和致死量增加。并有减轻氯仿-肾上腺素所致的心律失常作用,在麻醉大鼠,ivB-THP10mg/Kg可明显降低氯化钙所致的室颤发生率和死亡率,但对乌头碱引起的大鼠心律失常无拮抗作用。麻醉大鼠的心电图结果表明,B-THP静脉恒速灌注有减慢大鼠心率、延长Q-T间期的作用。iv3mg/kg B-THF在抗哇巴因引起的心律失常时对其血流动力学变化无明显影响。     

普伐他汀对兔急性心肌缺血室性心律失常的影响

目的观察普伐他汀对兔急性心肌缺血室性心律失常的影响并探讨其作用机制。方法将36只家兔随机分为对照组、缺血再灌组和普伐他汀组，每组各12只。制备冠脉灌流的兔左心室楔形心肌块的灌注模型，采用浮置玻璃微电极法同步记录楔形心肌块心内膜、心外膜心肌细胞跨膜动作电位和跨室壁心电图。观察各组缺血30 min和再灌注15 min时的QT间期和内、外膜心肌细胞跨膜动作电位时程以及跨室壁复极离散度（TDR），同时记录各组缺血和再灌注时室性心律失常的诱发率。结果①缺血状态下缺血再灌组较对照组TDR和心律失常的诱发率显著增加（均P〈0.01），普伐他汀组和缺血再灌组与对照组相比，TDR和心律失常的诱发率显著减少（均P〈0.05），对照组、缺血再灌组和普伐他汀组室性心律失常的诱发率分别为0/12、9/12、2/12。②再灌注状态下缺血再灌组和普伐他汀组TDR和室性心律失常的发生率差异均无显著性意义（均P〉0.05）。结论普伐他汀可显著降低兔急性缺血心肌跨室壁复极离散度和室性心律失常发生率，并能够改善缺血心肌的各项异常电生理指标。     

跨室壁复极离散度对扩张型心肌病患者室性心律失常的预测价值

目的:探讨跨室壁复极离散度(TDR)预测扩张型心肌病患者室性心律失常(VA)的价值。方法:测定全部156例扩心肌病患者心电图导联TpTe和TpTe/QT的参考值范围,分析其与室性心律失常的关系。结果:扩心肌病患者TpTe和TpTe/QT的参考值范围分别为:69～97ms,0.20～0.24;两者预测室性心律失常敏感度、特异度、阳性预测值、阴性预测值和阳性似然比分别为:48.3%、42.5%、35.7%、55.5%、0.84和74.2%、89.4%、82.1%、84.0%、7。结论:跨室壁复极离散度增大是室性心律失常的重要原因,TpTe值对室性心律失常的预测价值较小,而TpTe/QT有较大的预测价值。     

药物致尖端扭转型室性心动过速的发生机制

目的探讨药物致尖端扭转型室性心动过速(Tdp)的发生机制。方法建立冠状动脉灌注的犬左室心肌楔形组织块模型,同步记录左心室内膜、中层、外膜心肌细胞的动作电位及跨壁心电图,观察不同浓度D-Sotalol对动作电位时间(APD)、QT间期、跨壁复极离散度(TDR)、早期后除极(EAD)及Tdp发生的影响。结果浓度为0～100μmol/L的D-Sotalol呈剂量依赖性地延长各层细胞APD,尤以中层细胞最为显著(P<0.05),因而增加TDR;D-Sotalol在中层细胞可诱发EAD,触发室性早博并形成跨壁折返导致Tdp。结论 D-Sotalol在中层细胞诱发EAD、R on T室性早博是其致Tdp的始动因子,在TDR增加的基础上形成跨室壁折返是Tdp得以维持的关键。     

消旋四氢巴马汀的降压作用

静脉注射消旋四氢巴马汀(dl-THP)对麻醉大鼠可引起快速、剂量依赖性降压作用,腹腔注射和灌胃给药同样可产生明显的降压作用。给麻醉兔椎动脉注射dl-THP对血压无明显影响。结果表明dl-THP对麻醉大鼠有可靠的降压效应,并提示其降压作用部位可能不在中枢。     

抗心律失常肽对蛋白激酶C激动剂致心律失常作用的影响

目的 观察抗心律失常肽对蛋白激酶C激动剂致心律失常作用的影响并探讨其作用机制.方法 制备左室楔形心肌块灌注模型,随机分为①正常组;②佛波酯(PMA)组:PMA 0.5 μmol/L;③抗心律失常肽(AAP10)组:PMA 0.5 μmol/L +AAP10 0.5 μmol/L.同步记录心内膜、心外膜心肌细胞跨膜动作电位及跨室壁心电图,给予程序性期前刺激诱发室性心动过速(室速)的发生.通过免疫印迹法(Western blot)检测心肌细胞缝隙连接蛋白43(Cx43)总量及其 S368位点去磷酸化水平的变化.结果 与正常对照组相比,PMA组QT间期[(260±25) ms vs.(302±21) ms,P＜0.01]显著缩短,Tp-e(同一心搏T波顶点至终点的间期)[(61±13) ms vs.(51±7) ms,P＜0.01]及Tp-e/QT[(0.24±0.05) vs.(0.17±0.02),P＜0.01]显著增大,Cx43的总量(P＜0.05)及 S368位点去磷酸化水平(P＜0.01)显著减少,室速诱发率(70% vs.0%,P＜0.05)明显增加.与PMA组相比,AAP10组QT间期[(241±22) ms vs.(260±25) ms,P＞0.05]及S368位点去磷酸化水平(P＞0.05)无明显改变,但Cx43的总量(P＜0.05)明显增加,Tp-e[(41±6) ms vs.(61±13) ms,P＜0.01]及Tp-e/QT[(0.17±0.03) vs.(0.24±0.05),P＜0.01]显著减小,且室速诱发率(20% vs.70%,P＜0.05)明显降低. 结论 AAP10通过阻止PMA对缝隙连接的下调而减少PMA诱导的兔室性心律失常的发生.     

T波峰末间期在122例冠心病室性心律失常患者中的观察

目的 探讨冠心病(CHD)心电图T波峰末间期与室性心律失常的关系.方法 122例冠心病患者按照有无室性心动过速或室颤发生,分为A组为恶性心律失常组与B组为非恶性心律失常组,测定每位患者心电图T波峰末间期即Tp_Te值,以及超声心动图舒张末期内径(LVEDD)和LVEF.结果 恶性室性心律失常组的Tp_Te、(LVEDD)值明显高于非恶性室性心律失常(P＜0.05),而射血分数(LVEF)值明显低于非恶性室性心律失常组(P＜0.05).Tp_Te与LVEDD显著正相关(r＝0.72,P＜0.01),与LVEF显著负相关(r=-0.68,P＜0.01).两组用药前、后Q-T间期\Q-Td、Tp-Te、Tp-Ted的比较:A、B两组患者治疗前、后Q-T间期\Q-Td、Tp-Te、Tp-Ted之间的比较有显著差异(P＜0.05)(P＜0.01).结论 Tp_Te可能反映心室跨壁复极离散度的变化,能预测CHD患者恶性室性心律失常的发生,对评价心功能不全的预后也有一定价值.     

灯盏花素对家兔肥厚心肌室性心律失常的影响

目的观察口服灯盏花素对家兔肥厚心肌室性心律失常的影响,探讨灯盏花素抗心律失常的作用机制。方法 30只家兔随机分为假手术组、心肌肥厚组和灯盏花素组,每组10只。假手术组开腹但不行腹主动脉缩窄术;心肌肥厚组和灯盏花素组采用腹主动脉缩窄术制备家兔心肌肥厚模型;灯盏花素组自手术后第2天开始喂服灯盏花素,每只每日1片,喂养8周。制备兔左心室楔形心肌块,利用浮置玻璃微电极法同步记录楔形心肌块内、外膜心肌细胞跨膜动作电位和跨壁心电图;测心脏质量(HW)、体质量(BW)和左心室游离壁厚度(LVT)。观察各组QT间期和内、外膜心肌细胞跨膜动作电位以及跨室壁复极离散度(TDR),程序电刺激诱发室性心律失常,记录跨膜动作电位复极90%的时程(APD90),早期后除极(EAD)和尖端扭转性室性心动过速(Tdp)的发生率。结果心肌肥厚组与灯盏花素组HW、HW/BW及LVT值与假手术组相比均明显升高(P<0.05);灯盏花素组HW、HW/BW及LVT值与心肌肥厚组相比均明显减小(P<0.05)。心肌肥厚组与灯盏花素组QT间期及内、外膜心肌APD90较假手术组明显延长(P<0.05);灯盏花素组QT间期及内、外膜心肌APD90与心肌肥厚组相比明显缩短(P<0.05)。假手术组、心肌肥厚组和灯盏花素组TDR分别为(55±17)、(99±12)和(68±11)ms,3组间比较差别有统计学意义(P<0.05)。灯盏花素组EAD和Tdp的发生率明显低于心肌肥厚组(P<0.05)。结论肥厚心肌TDR增大,心律失常的发生率显著升高。灯盏花素可减少TDR,明显降低EAD和Tdp的发生率。     

Effect of autonomic nervous system on the transmural dispersion of ventricular repolarization in intact canine

Therecentstudieshavefoundasub populationofcells ,namedmidmyocardiumcells(Mcell) ,withuniqueelectrophysiological propertiesinthedeepsubepicardiumoftheventricleofhuman ,canineandotheranimals .TheresearcherssuggestedthattheMcellsnotonlyformthecellularbasisof…     

Effect of Calcium-Channel Antagonist on Repolarization Heterogeneity of Ventricular Myocardium in an in Vitro Rabbit Model of Long QT Syndrome

Intracellular Ca2＋ and Ca2＋-dependent signaling molecule play an essential role in the genesis of long-QT （LQT） syndrome-related ventricular arrhythmias. The effect of calcium-channel antagonist verapamil on repolarization heterogeneity of ventricular myocardium was assessed in an in vitro rabbit model of LQT syndrome. By using the monophasic action potential （MAP） recording technique, MAPs of epicardium, mid-myocardium and endocardium were simultaneously recorded by specially designed plunge-needle electrodes across the left ventricular free wall in rabbit hearts purfused by Langendorff method with standard Tyrode＇s solution. Bradycardia was induced by com- plete ablation of atrioventricular node. A catheter was introduced into the right ventricle to pace at the cycle lengths （CLs） of 1500, 1000, and 500 ms, successively. Quinidine （2 μmol/L） prolonged QT interval and ventricular MAP duration （MAPD）, and increased transmural dispersion of repolarization （TDR） in a reverse rate-dependent fashion in isolated rabbit heart. No polymorphic ventricular tachycardias were induced under this condition. The effective free therapeutic plasma concentrations of verapamil （0.01--0.05μmol/L） used in this experiment had no effect on quinidine-induced changes of QT interval, MAPD and TDR. This study demonstrated that, in this model of LQT syndrome, blockade of calcium-channel with verapmil had no effect on quinidine-induced changes of repolatiation heterogeneity of ventricular myocardium.     

Experimental study of the effect of autonomic nervous system on the transmural dispersion of ventricular repolarization under acute myocardial ischemiain vivo

Summary The effect of the autonomic nerves on the transmural dispersion of ventricular repolarization (TDR) under acute myocardial ischemia in intact canine was investigated. Using the monophasic action potential (MAP) recording technique, MAPs of the epicardium (Epi), midmyocardium (Mid) and endocardium (Endo) were recorded simultaneously by specially designed plunge-needle electrodes at the left ventricular free wall under acute myocardial ischemia in 12 open-chest dogs. MAPD₉₀ and TDR among three myocardial layers as well as the incidence of the early afterdepolarization (EAD) before autonomic nervous stimulation and during autonomic nervous stimulation were compared. It was found that 10 min after acute myocardial ischemia, TDR was increased from 55±8 ms to 86±15 ms during sympathetic stimulation (P<0.01). The TDR (53±9 ms) during parasympathetic stimulation was not significantly different from that of the control (55±8 ms) (P>0.05). The EAD was elicited in the Mid of 2 dogs (16%) 10 min after acute myocardial ischemia, but the EAD were elicited in the Mid of 7 dogs (58%) during sympathetic stimulation (P<0.01). It was concluded that: (1) Sympathetic stimulation can increase the transmural dispersion of repolarization and induce early afterdepolarizations in the Mid under acute myocardial ischemia, which provide the opportunity for the ventricular arrhythmia developing; (2) Parasympathetic stimulation has no significant effect on the transmural dispersion of repolarization under myocardial ischemia. Zhang Cuntai, male, born in 1963, Associate Professor     

Effect of Autonomic Nervous System on the Transmurai Dispersion of Ventricular Repolarization in Intact Canine

Summary: The effect of the autonomic nerves on the transmural dispersion of ventricular repolarization in intact canine was investigated. By using the monophasic action potential (MAP) recording technique, monophasic action potentials (MAPs) of the epicardium (Epi), midmyocardium (Mid)and endocardium (Endo) were recorded simultaneously by specially designed plunge-needle electrodes at the left ventricular free wall in 12 open-chest dogs. MAPD90 and transmural dispersion of repolarization among three myocardial layers as well as the incidence of the EAD before autonomic nervous stimulation and during autonomic nervous stimulation were compared. The results showed that the MAPD90 of Epi, Mid and Endo before autonomic nervous stimulation were 278±11 ms,316± 16 ms and 270± 12 ms respectively, the MAPD90of Mid was significantly longer than that of Epi or Endo (P＜0.01). MAPD90 of Epi, Mid and Endo were shortened by 19±4 ms, 45±6 ms,18± 3 ms respectively during sympathetic stimulation. Compared with that of the control, the transmural dispersion of repolarization during sympathetic stimulation was shortened from 44 ± 4 ms to 15±3 ms (P＜0. 01), but early afterdepolarizations were elicited in the Mid of 5 dogs (41 0%)during sympathetic stimulation. Parasympathetic stimulation did not significantly affect the MAPD90 in the three layers. It is concluded that there is the transmural dispersion of ventricular repolarization in intact canine. Sympathetic stimulation can reduce transmural dispersion of repolarization, but it can produce early afterdepolarizations in the Mid. Parasympathetic stimulation does not significantly affect the transmural dispersion of ventricular repolarization.     

复极时程和跨室壁复极离散在尖端扭转型室性心动过速中的作用

目的:探讨复极时程和跨室壁复极离散(TDR)在尖端扭转型室性心动过速(TdP)发生的作用. 方法:32只兔随机等分为4组,低浓度索他洛尔组(10 μmol/L),高浓度索他洛尔组(100 μmol/L),低浓度奎尼丁组(1 μmol/L),高浓度奎尼丁组(10 μmol/L). 采用Langendorff技术离体兔心脏灌流,同步记录用药后三层心肌的单相动作电位(MAP)和TDR,观察早期后除极(EAD)、TdP的发生情况. 结果:索他洛尔浓度依赖性地延长三层心肌MAP时程(MAPD)和TDR,高浓度索他洛尔组诱发EAD,TdP分别为8只和6只,而低浓度组诱发EAD,TdP分别为4只和0只. 奎尼丁浓度依赖性地延长三层心肌MAPD,但逆浓度依赖性地延长TDR,高浓度奎尼丁组诱发EAD,TdP分别为7只和1只,而低浓度组诱发EAD,TdP分别为6只和4只. 结论:与TdP的发生密切相关的主要是TDR,而不是复极时程.     

Experimental Study of the Effect of Autonomic Nervous System on the Transmural Dispersion of Ventricular Repolarization under Acute Myocardial Ischemia in Vivo

The electrophysiologic heterogeneity of the ven-tricular myocardium is an important factor of devel-oping ventricular arrhythmia.Under the pathologiccondition,thedistribution and thefunction of the au-tonomic nerves,especially the sympathetic nerve,can produce the heterogeneity in the myocardium,which can accelerate the electrophysiologic hetero-geneity of the ventricular myocardium.Acute my-ocardial ischemia can induce the dysfunction of theautonomic nerve endings,resulting in the hetero-gene…     

Effect of Lidocaine and Amiodarone on Transmural Heterogeneityricular Repolarization in Isolated Rabbit Hearts Model of Sustained Global Ischemia

To study the effect of of lidocaine and amiodarone on the transmural heterogeneity of ventricular repolarization in isolated rabbit hearts model of sustained global ischemia and to explore the mechanisms underlying the antiarrhythmic activity of lidocaine and amiodarone, rabbits were randomly divided into 4 groups: control group, ischemia group, lidocaine group and amiodarone group. By the monophasic action potential (MAP) recording technique, MAPs of recorded across the left ventricular free wall in rabbit hearts perfused transmural dispersion of repolarization (TDR) and arrhythmic induced by ischemia. Our results showed that TDR of three myocardial layers in ischemia group were significantly lengthened after ischemia. TDR was increased from 17.5±3.9 ms to 31.2±4.6 ms at the time that concided with the onset of sustained ventricle arrhythmic. Amiodarone could decrease TDR, but lidocaine could increase TDR at initial ischemia, and no significant difference was found at other ischemia time points. 5 cases had ventriclar arrhythmia in ischemia group (62.5 %), but no case in lidocaine group (P<0.01) and only 1 case in amiodarone group had ventrilar arrhythmia (P< 0.01). No significant difference was found between amiodarone group and lidocaine group. It is concluded that TDR of of three myocardial layers increases significantly at ischemia and it is closely associated with development of ventricular arrhythmia, and amiodarone could decrease TDR, but lidocaine could increase TDR at initial ischemia and has no effects at other ischemia time points.     

Changes of monophasic action potential duration and effective refractory period of three layers myocardium of canine during acute ischemia in Vivo

Summary The effect of acute ischemia on the electrophysiological characteristics of the three layers myocardium of caninein vivo was investigated. Twelve canines were divided into two groups randomly: acute ischemia (AI) group and sham operation (SO) group. By using the monophasic action potential (MAP) technique, MAP and effective refractory period (ERP) of the three layers myocardium were measured by specially designed plunge needle electrodes and the transmural dispersion of repolarization (TDR) and transmural dispersion of ERP (TDE) were analyzed. The results showed that in the AI group, MAP duration (MAPD) was shortened from 201.67±21.42 ms to 169.50±13.81 ms (P<0.05), but ERP prolonged to varying degrees and TDE increased during ischemia. In the SO group, MAPD and ERP did not change almost. Among of the three layers myocardium of canine, MAPD was coincident in two groups. It was concluded that during acute ischemia, MAPD was shortened sharply, but there was no significant difference among of the three layers myocardium. The prolonged ERP was concomitant with increased TDE during acute ischemia, which may play an important role in the occurrence of arrhythmias induced by acute ischemia. These findings may have important implications in arrhythmogenesis. ZHANG Fanzhi, male, born in 1973, M. D., Ph. D.