家兔心室肌细胞动作电位时间与心率关系的探讨

在麻醉后自然呼吸条件下同步记录了40只家兔不同心率时的心电图和心室肌细胞的跨膜动作电位。对126个单位的记录进行了测量和统计学分析后,找出了动作电位时间(APD)与窦性心周期时间(SCL)之间的定量关系,求出了相应的直线回归方程式。利用这些方程式可消除SCL对APD的影响,从而可以研究某些因素是直接影响APD,还是通过SCL间接影响APD,因此具有一定的实用价值。     

Relationship between action potential duration of ventricular cells and heart rate of rabbit under natural breathing

Summary The ECG and transmembrane action potentials of the ventricular cells of 40 albino rabbits at various heart rates under natural breathing were simultaneously recorded. After statistical analysis of the records of 126 units, quantitative relationships between action potential durations (APDs) and heart rates were found and regression equations were obtained by linear regression. In order to eliminate the effect of heart rates on APDs, the correction formulas on APDs were also worked out. After correction the effect of sinus cycle length (SCL) on APDs could be eliminated. This study has provided a practical method for the study of the effect of different agents on the APDs of ventricular cells under more natural condition. Though the regression equations and correction formulas can only be applied in rabbits under natural breathing, this method might be adopted to work out the corresponding regression equations and correction formulas for other experimental animals. Therefore it has practical significance in a rather broad field.     

Effects of high potassium and high calcium on the action potential of the ventricular cells of the tortoise heart

Summary Using floating microelectrode, we have been able to record the transmembrane potential of the ventricular cells of in-situ perfused heart of the tortoise and observed the effects of high potassium and high calcium on it. It was found that high potassium(8.0 mM) could lower resting potential (Rp), reduce action potential amplitude (APA), and shorten action potential duration at 50% and 90% of repolarization (APD₅₀, APD₉₀). High calcium (3.2 mM) could lower RP, increase overshoot (OS), shorten APD, but had no significant influence on APA. It could antagonize the effect of high potassium on heart rate (slowing heart rate) and APA, but act synergistically with high potassium on shortening of APD. The influence on heart rate indicates that there is an antagonistic effect on the pacemaker cell of the sinus venosus between potassium and calcium.     

心房颤动对QT间期的影响

对30例房颤病人的50个心动每一QT间期与前一RR间期、平均QT与平均RR进行了相关性研究。结果表明:平均QT与平均RR呈线性相关,QT=169+0.253RR(P<0.001,r=0.892)。各心动的QT与前一RR也呈线性正相关,其平均回归斜率为0.081。每例各心动QT和前一RR的回归斜率与平均RR则呈线性负相关(r=-0.620,p<0.05)。30例的QT较同一平均心室率时窦性心律延长,除3例外其余仍在Lepeshkin报道正常范围,而平均QT与RR回归线高于Ahave报道的冠心病患者窦性心律的回归线。作者认为,QT间期不仅受病因、心室率的影响,而且受心律影响,故不宜单纯用Bazett公式纠正房颤病人(尤其在快速房颤时)的QT间期。     

Comparison of effects of magnesium valproate and sodium valproate on the action potential of isolated papillary muscle from guinea pigs and dogs

Summary A comparison of the effects of magnesium valproate (MV) and sodium valproate (SV) on the action potential of isolated papillary muscle from guinea pigs and dogs was made in this study. The results in both animals were as follows: MV and SV induced a slight reduction of slope plateau of action potential and prolongation of action potential duration (APD).What is more, APD₅₀ and APD₉₀ were prolonged significantly, thus the ratio of APD₉₀/APD₂₅ was increased. The effective refractory period (ERP) was prolonged significantly. MV or SV showed no effects on action potential amplitude, overshoot, resting potential and phase o upstroke velocity. The above results suggested that MV and SV might play an. antiarrhythmic role and that their effects were analogic. The mechanism of MV and SV inducing significant prolongation of APD₅₀, APD₉₀, and ERP, might be closely related to the slow-down of the velocity of K⁺ efflux during plateau and repolarization of phase 3 by radical of valproate and the slow-down of velocity of K⁺ efflux of repolarizalion of phase 3 in particular. These results showed that there was no difference in SV and MV action on guinea pigs and dogs.     

急性心肌梗死患者急性期体表心电图T波峰末间期与恶性室性心律失常的关系研究

目的探讨急性心肌梗死患者体表心电图T波峰末间期(TpTe)与急性期室性心律失常的关系。方法102例接受直接PCI(pPCI)治疗的急性心肌梗死患者中,共有46例出现室性心动过速(VT)和心室纤颤(VF),作为病例组。其余56例未出现室性心律失常,作为对照组。测量并比较两组pPCI前后12导联心电图的QT、TpTe、QT离散度(QTd)及经心率校正的QT间期(QTc间期)、TpTe(TpTec)。研究室性心律失常与QTc和TpTec各时段上限值的相关性并比较不同梗死部位的QT及TpTe值。结果 pPCI治疗前两组对象的QT间期、QTd间差异无统计学意义(P>0.05),但QTc和TpTec间差异有统计学意义(P<0.05)。经pPCI治疗后第3天,两组间QT和QTd间差异仍无统计学意义,而QTc、TpTe和TpTec间差异有统计学意义(P<0.05)。pPCI治疗后1周TpTe、QTc和TpTec间差异仍有统计学意义(P<0.05)。两组pPCI治疗前后的RR间期无差异(P>0.05)。QTc间期各时段上限值与VT+VF的发生率无相关性(r=0.376,P>0.05)。TpTe及TpTec间期各时段上限值与VT+VF的发生率呈正相关(r=0.677,P<0.05;r=0.698,P<0.05)。结论在急性期出现VT和VF的急性心肌梗死患者与不出现室性心律失常的患者相比,TpTe和TpTec明显延长,但QT和QTd则无明显差异。TpTe可能预示着心肌梗死急性期恶性心律失常。     

Cardiac electrophysiological differences between Kunming and C57BL6/J mice

Objective To investigate the alterations of cardiac electrophysiological properties and substantial mechanism and find the stable arrhythmia mouse model in Kunming (KM) and C57BL6/J (C57) mice.Methods...     

海训对指战员心血管系统及相关指标影响的研究

目的:探讨海训对指战员心血管系统及常规心电图、心率变异性和QTd的影响。方法:用常规方法检测某部指战员海训前的血压、心率,通过常规心电图、24h动态心电图(Holter),分别在海训前、海训结束后检测HRV时域指标和QTd并加以分析比较。结果:海训结束后指战员的心率减慢、舒张压值降低与海训前相比差异显著(P<0.05),收缩压较训练前则元显著差异(P>0.05)。常规心电图的轻度异常率为46％。,HRV时域指标明显降低(P<0.05);QTd则稍延长,但无显著差异(P>0.05)。相关性分析提示QTd和HRV指标之间无相关关系。结论:海训可显著改善指战员心血管系统功能,但长期超强度海训可导致心电活动异常发生率增高。     

阻塞性睡眠呼吸暂停低通气综合征患者昼夜心室复极参数变化研究

背景阻塞性睡眠呼吸暂停低通气综合征（OSAHS）是一种常见的睡眠呼吸疾病,越来越多的研究表明OSAHS与心血管疾病具有显著相关性,是心律失常、高血压、冠心病等心血管疾病的独立危险因素,但其具体机制仍未完全阐明。相关证据表明,Tp-e间期、QT间期和Tp-e/QT等心室复极参数可能与心律失常甚至心源性猝死有关。然而截止到目前,对OSAHS相关心律失常及心电参数变化的研究相对较少。目的研究OSAHS患者昼夜心室复极参数变化。方法选取2020年6月至2021年7月在郑州大学第一附属医院接受多导睡眠监测、符合纳入及排除标准的OSAHS患者159例,并根据疾病的严重程度进一步分为轻-中度OSAHS组（78例）与重度OSAHS组（81例）;选取51例未患疾病的健康者为对照组。测量并计算所有参与者的日间和夜间Tp-e间期、QT间期、Tp-e/QT。结果对照组与轻-中度OSAHS组、重度OSAHS组之间的日间Tp-e间期、夜间Tp-e间期、日间Tp-e/QT、夜间Tp-e/QT比较,差异均有统计学意义（P<0.05）。日间Tp-e间期、夜间Tp-e间期、日间Tp-e/QT、夜间Tp-e/QT在三组间有逐渐延长的趋势（P<0.05）;三组日间及夜间QT间期比较,差异无统计学意义（P>0.05）。OSAHS患者日间静息状态及夜间阻塞性呼吸暂停期的Tp-e间期、QT间期、Tp-e/QT比较,差异均有统计学意义（P<0.05）;夜间阻塞性呼吸暂停期的Tp-e间期、QT间期、Tp-e/QT均较日间静息状态有所延长,差异有统计学意义（P<0.05）。OSAHS患者夜间Tp-e间期（rs=0.221,P=0.005）、夜间Tp-e/QT（rs=0.298,P<0.001）均与AHI呈正相关。结论OSAHS患者夜间阻塞性呼吸暂停期心室复极参数较日间静息状态下延长,昼夜变化显著,为今后OSAHS合并心律失常的研究提供了新的思路。     

氟西汀对抑郁大鼠心脏电生理的影响

目的 研究抑郁刺激对大鼠心脏电生理影响,以及氟西汀的干预作用。方法 将60只雄性SD大鼠随机分为3组,即对照组（CTL,n=20）、抑郁组（CUMS组,n=20）和氟西汀组FLX组（n=20）。氟西汀给药方式为灌胃;慢性温和不可预见刺激建立抑郁模型,行为学评价包括糖水消耗实验和强迫游泳进行评估抑郁模型;利用Langendorff装置维持体外心脏循环进行心脏电生理研究,记录心房和心室组织ERP、APD₉₀,并用Burst程序刺激心房和心室,诱发心律失常。结果 1与正常对照组比较,糖水偏好百分比降低、强迫游泳静止时间延长;氟西汀组行为学评价分数有所改善。差异均有统计学意义（P<0.05）;2抑郁组的心房和心室ERP小于正常组与氟西汀组,而APD₉₀大于其余两组,差异有统计学意义（P<0.05）;3抑郁组房颤诱发率（100%）明显高于对照组（0）、氟西汀组（40%）,心室颤动诱发率在对照组、抑郁组和氟西汀组分别为：0、80%和40%,抑郁组心房颤动诱发率高于心室。结论 抑郁刺激诱发心脏心房和心室组织发生电生理改变,采用抗抑郁药物进行干预,有改善作用,证明抑郁与心血管疾病之间存在密切关系。     

冠心病合并2型糖尿病患者Tp-e间期与Tp-e/QT比值的研究

目的探讨2型糖尿病合并冠心病患者QT间期、Tp-e间期和Tp-e/QT检测的临床价值。方法随机选取冠心病合并2型糖尿病50例,分别与年龄、性别与之匹配的体检组、2型糖尿病、冠心病患者各50例进行比较,分别测量四组V4导联QT间期、Tp-e间期、计算Tp-e/QT。结果 (1)冠心病合并2型糖尿病组与体检组对比QT间期、Tp-e间期和Tp-e/QT比值差异有统计学意义(P0.05)。(2)冠心病合并2型糖尿病组与2型糖尿病组、冠心病组对比,Tp-e间期和Tp-e/QT比值均显著高,差异有统计学意义(P0.05)。(3)冠心病合并2型糖尿病组与冠心病组、2型糖尿病组比较,QT间期差异无统计学意义(P0.05)。结论 Tp-e间期与Tp-e/QT比值比QT间期在预测室性心律失常更有价值;Tp-e间期和Tp-e/QT可作为冠心病合并2型糖尿病患者发生恶性心律失常的预测指标。     

单相动作电位测定槐定，硫酸镁对兔心脏触发性心律失常的抑制作用

在氯化铯引起的兔触发性心律失常模型上，通过单相动作电位（Monophasic action potential,MAP)测定，观察了槐定和硫酸镁对触发性心律失常的抑制作用。结果显示：（1）静脉注射氯化铯后QT间期延长，心律减慢，单相动作电位90％复极间期（MAPD90）延长，出现早期后除极（Early afterdepolarization,EAD),由EAD诱发心律失常，发生率100％，其中室性心动过速为50％。（2）静脉注射槐定和硫酸镁后，EAD振幅（EADA）均减小，心律失常发生率分别为30％和25％（与对照组比两者均P＜0．05），无一例发生室性心动过速。     

冠心病患者QT间期动态变化

采用动态心电图对３０例冠心病患者和３０例正常人的ＱＴ间期进行了个体和群体两个层次的动态分析，在一定的心率范围内，ＱＴ间期与ＲＲ间期呈良好的线性关系，冠心病患者的回归斜率大于正常人回归斜率。用二段直线拟合方法，能消除过长ＲＲ间期对ＱＴ－ＲＲ线性关系的干扰。用此法求得的主回归线斜率能较好地区别正常人与冠心病患者，其敏感性、特异性均为８６．７％。     

心室复极间期的迷走神经调节

目的：观察迷走神经刺激对兔心室肌复极间期的调节作用。方法：分离、结扎并剪断兔双侧颈迷走、交感神经,电刺激迷走神经外周端。心室复极时程以体表心电图（ECG）II导联QT间期、心外膜电图（EPG）的QT间期及采用玻璃微电极技术记录的动作电位时程（APD90,APD50）表示。结果：刺激迷走神经时,在自然心率状态下,ECG II导联及EPG中QT间期、APD均明显延长;起搏消除HR影响后,迷走神经刺激使QT间期及APD缩短。结论：迷走神经兴奋使非起搏状态下心室肌复极延缓,而使起搏状态下心室肌的复极加速。     

急性颅脑损伤患者心率变异性的临床分析

为了解急性颅脑损伤病人伤后早期心率变异性的改变及其与QT离散度的相关性 ,对 60例急性颅脑损伤(损伤组 )病人和对照组 ( 30例 )的 2 4h心电图 (Holter) ,应用美国DMS分析软件进行心率变异性的时域分析。结果 :①损伤组颅脑损伤后早期心率变异性时域分析的各项参数指标均降低 (P <0 .0 1 ) ;②损伤组正常R R间距标准差(SDNN)与QT离散度呈正相关 (P <0 .0 5)     

不同负荷频发室性期前收缩患者血尿酸、QTCB、左室心肌质量指数比较分析

目的通过比较不同负荷频发室性期前收缩(premature ventricular contraction,PVC)患者血尿酸(uric acid,UA)、左室心肌质量指数(left ventricular myocardial mass index,LVMI)、校正QT间期(correct QT interval by Bazett,QTCB),探讨期前收缩负荷与这些指标之间的关系。方法入选期前收缩频次大于360次/h或8 640次/24 h室性心律失常患者67例,研究对象均行24h动态心电图监测及空腹接受化验检查,将入选患者分为期前收缩负荷<10%(低负荷组)、10%～20%(中等负荷组)、>20%(高负荷组),比较3组间生物化学指标、LVMI、心电图指标等分析其相关性。结果高负荷组QTCB、LVMI、UA水平明显高于低负荷组(P<0.01),经多元线性回归分析结果得出回归方程Y=0.029X1+0.045X2-12.558,F=10.037,P<0.001(Y=期前收缩负荷,X1=UA,X2=QTCB),标准化回归系数UA为0.357,QTCB为0.295。结论 PVC患者随着期前收缩负荷的增加,QTCB延长、左室肥厚程度加重,UA水平升高,并且对期前收缩负荷的影响UA比QTCB大。     

射频消融对心率、QT间期及QT离散度的影响

目的 探讨导管射频消融术(RFCA)对心率、QT间期、QT离散度(QTd)的影响。方法 时比分析50例阵发性室上性心动过速(SVT)患者RFCA术前、术后的PP(RR)间期、QT间期、QTd变化。结果 RFCA术后PP(RR)间期明显缩短，心率加快；QT间期随心率加快而缩短；经心率校正后的QT间期、QTd与术前相比差异无显著性。结论 RFCA可导致窦性心率加快，对校正的QT间期、QTd无明显影响。     

糖尿病大鼠心肌电学的改变与腺苷的作用

目的:探讨糖尿病心肌病的心肌电生理改变以及腺苷(ADO)对其电生理的可能作用.方法:以SD雄性大鼠复制糖尿病模型,选择健康成年SD雄性大鼠作为对照组,6周时记录大鼠体表心电图和右心室乳头肌跨膜电位,观察ADO对跨膜电位的影响.结果:大鼠糖尿病成模后第6周,体表心电图QT间期和右室乳头肌动作电位时程(APD)各水平均明显长于对照组大鼠(P＜0.01);而静息膜电位(RP)、动作电位幅度(APA)和超射值(OS),以及0期去极化最大速率(Vmax)均无明显变化.经10～400 μmol/L ADO灌流,糖尿病组大鼠和对照组大鼠右心室乳头肌跨膜电位各参数均无明显作用,当ADO浓度增加到500 μmol/L时,对照组大鼠右心室乳头肌APD30、APD50、APD70及APD90轻度缩短(P＜0.05),而对糖尿病组大鼠APD无明显影响.结论:糖尿病大鼠右室乳头肌动作电位时程和QT间期明显延长,而ADO(10～500 μmol/L)对糖尿病大鼠过长的ADP无明显缩短作用.     

QT间期离散度与心肌梗塞预后的关系

目的探讨ＣＴ间期离散度对急性心肌梗塞近期预后的预测价值．方法计算方法：每导联均测ＱＴ间期３～５个．取均值．则ＱＴ间期离散度（ＱＴｄ）＝ＱＴｍａｘ－ＱＴｍｉｎ，用心率校正后的ＱＴ间期（ＱＴｃ）的离散度（ＱＴｃｄ）＝ＱＴｃｍａｘ－ＱＴｃｍｉｎ．结果急性心肌梗塞组与对照组ＱＴｃ、ＱＴｄ．ＱＴｃｄ值比较有显著差异（Ｐ＜０．００１）．梗塞组有无恶性心律失常及猝死者ＱＴｃ、ＱＴｄ、ＱＴｅｄ对比有显著差异（Ｐ＜０．０１）．当ＱＴＣ≥４４０ｍｓ，ＱＴｄ、ＱＴＣｄ≥６０ｍｓ时发生恶性心律失常及猝死的诊断正确指数ＱＴｃｄ与ＱＴＣ、ＱＴｄ比较有明显差异（Ｐ＜０．０５）．但ＱＴｄ与ＱＴＣ比较无明显差异（Ｐ＞０．０５）．结论ＱＴ离散度能更好反映心室复极过程，尤其是用心率校正后的ＱＴ离散度，对判断急性心肌梗塞近期预后具有重要指导价值．     

QT hysteresis in long-QT syndrome children with exercise testing

Background Congenital long QT syndrome (LQTS) is an inherited ion channel disorder resulting in abnormal cardiac repolarization that can cause syncope and sudden death associated with a prolonged rate-corrected QT interval and polymorphic ventricular tachycardia. Several studies in adults showed that LQTS patients have altered QT adaptation to heart rate changes compared with normal subjects which forming a “hysteresis loop” in the QT-circle length plot. This study was to observe the QT interval changing during exercise testing in children long QT syndrome (LQTS) patients, explore the new diagnosis methods of LQTS. Methods The subjects were divided into 3 groups according to 1993 LQTS diagnostic criteria. Group 1: LQTS group (n=17) who scored &gt; or = 4 points indicating definite LQTS. Group 2: Middle group (n=16), patients who have prolonged QT interval but scored 1.5 to 3.5. Group 3: Normal control group (n=18). The average age of all study population is (12.3±5.8) years. No case had beta-adrenergic antagonists administration before exercise testing. All subjects were underwent tread mill exercise testing and electrocardiograph in whole exercise testing and recovery were recorded. QT and heart rate changing during whole exercise testing period were recorded. △QT, the QT interval at 1, 2, 4, 6 minutes into recovery subtract from the QT interval at a similar heart rate during exercise, were calculated.Results In all three groups, QT intervals were shortening with the increasing of heart rate, but QTc had no significant change. △QT at 1 minute ((45±11) ms), 2 minutes ((37±15) ms), 4 minutes ((23±12) ms) into recovery in LQTS group were significantly greater than that of the other two groups (P&lt;0.05, P&lt;0.01, P&lt;0.01, respectively). There was no △QT significant difference between middle group and normal control group at recovery time. During the recovery phase in LQTS group, the QT interval remained shortened despite a decelerating heart rate, forming a hysteresis “loop” in the curve relating the QT interval to the cycle length．Conclusions In children LQTS patients, there is significant QT hysteresis loop in the relation of QT interval with heart rate during recovery of exercise testing, which could be useful to the early diagnosis for LQTS.