教学实践过程中关于结间束存在与否的思考

心传导系统是人体内重要的控制心节律性活动的解剖学结构,并且在多种疾病的发生、发展和治疗过程起关键作用。本团队在人体解剖学课程教学实践过程中发现教师和学生容易对结间束是否存在的问题产生疑惑。现就与结间束的提出和争议相关的关键人物和历史事件按照时间顺序进行梳理,并就目前相关国内权威教科书和国内外专著关于结间束的阐述进行整理,以期对结间束是否存在的科学问题进行初步探究。     

体视显微镜下检查成人心房室传导轴

目的:建立一套采用体视显微镜检查房室传导轴的新方法,并结合组织学方法对房室传导轴的形态进行初步探究。方法:采用8例成人心进行实验,先在体视显微镜下行解剖检查,再用组织学方法,观察房室传导轴的特定形态。结果:新方法能全部(8/8)成功地检查房室传导轴,并获得它们的巨微解剖立体形态学资料,1~2个组织块(10张切片/组织块)即可获得足够的组织学信息;8例房室结头部与扩展区之间没有成形的绝缘膜,使得房室结头部不易被解剖分离;8例房室结在平行于心内膜切面上均为椭圆形;具有房室环形态学特征的传导组织和结间束在人心常规组织切片上得到体现。结论:新方法能准确、简便地定位房室传导轴,而且能获得传导轴的巨微解剖资料,为心脏病理学及法医学检查传导系统提供帮助。     

人心房室结和房室束的光镜观察

本文对13例人心标本房室结和房室束的形态及位置,作了连续切片观察。1.房室结为一扁长形结构,其横切面呈右侧微凸的三角形,有时切面呈梭形或半卵圆形。成人房室结大小为3.5×3.3×1.1 mm~3。有5例房室结表面的右心房心内膜隆起。2.房室结位于二尖瓣与三尖瓣附着缘之间的房室隔内,成人房室结距冠状窦口1.8～5.8 mm,距右心房心内膜0.3～0.7 mm,距三尖瓣隔侧瓣上缘3.3～7.5 mm。结左侧紧贴中心纤维体。3.房室结可分为浅、深两部,浅部纤维纵行止于结的下端。1例深部又分为上、下两部。在结表面右心房心内膜隆起的标本上,结右侧的心房肌覆盖层止于心内膜。结的上缘、右侧面及后缘与房肌相连。4.成人房室束长5.7～7.9 mm,直径1.1～1.5 mm。房室束前部有7例在肌性室间隔顶部;3例在肌性室间隔左侧;2例在肌性室间隔肌肉内部。1例经行特殊,由肌性室间隔顶部至其左侧,最后至肌性室间隔内部偏右侧而终止。     

儿童心脏右房室瓣解剖类型调查

目的为临床儿童心脏右房室瓣病变的诊治提供解剖学资料。方法对135例出生1 d至15岁儿童心脏标本的右房室瓣主瓣和副瓣的形态进行观测。结果主瓣类型分为二尖型、三尖型、四尖型和五尖型。主瓣分为内瓣、前瓣、后瓣和外瓣、后内瓣、前外瓣和后外瓣。主瓣形状分为三角形、半椭圆形、半圆形、长方形和梯形。40例有副瓣,其中33例有两个副瓣,7例有1个副瓣。副瓣分为前内副瓣、后内副瓣、前外副瓣和后外副瓣。右房室环形状可分为椭圆形、圆形、三角形和肾形,其中椭圆形最多见。结论主瓣和副瓣都有明显位置,它们可以密闭心室与心房的交通,使血液不能逆流入心房。了解儿童右房室瓣的解剖类型可供手术时参考。     

人心房室隔内正常或异常兴奋传导的解剖学基础

文中着重综述了有关房室隔、房室交点区解剖学研究进展以及房室交接区各部有关双路、多路或环路兴奋传导的肌纤维变异。结合Ｊａｍｅｓ关于结间束的观点，提出从窦房结到房室结可能有６条传导兴奋的解剖学基础的设想，以供临床工作者参考。文中对房室隔和房室交点区的概念与Ｓｅａｌｙ前、后间隔区的概念作了扼要的比较，指出二者间的异同。介绍了文献中关于间隔房室副束的位置和形态特点，并提出进一步研究的建议     

婴幼儿和法洛氏四联症房室结和房室束的外科解剖及计算机三维重建Ⅱ.光镜形态与计算机三维重建

15例人心房室结和房室束的连续切片观察表明:多数成人房室结细胞排列较致密,结内结缔组织较多,有明显的脂肪浸润;另一例房室结仅由纵行细胞组成的松散样结构.婴幼儿房室结细胞有的排列松散,有的排列致密,易形成细胞岛和Mahaim束,结内结缔组织较少,未见脂肪浸润,法四房室结细胞排列致密.同时,在VAX-11/730主机和S-600图象处理系统下,用Fortran-77编制的软件包,对一例正常婴幼儿的房室结和房室束进行了三维重建,在彩色监视器的屏幕上显示了不同角度的房室结和房室束及其毗邻结构,并用透明法处理显示了它们之间的位置关系.     

山羊房室结、房室束及束支的形态学增龄改变

目的 :探讨山羊房室结组织的年龄变化规律。方法 :光镜、电镜观察和图像分析。结果 :老年羊房室结内一般心肌细胞增加 60 % ,细胞间质增多 3 0 % ,胶原纤维增多 2 0 % ,出现脂肪细胞。电镜下老年羊房室结细胞内可见较多的脂褐素 ,线粒体紊乱脱嵴 ,溶酶体膜破裂溶解。结论 :随着年龄增长 ,羊房室结、房室束和束支的组织学和亚显微结构出现一系列变化     

婴幼儿和法洛氏四联症房室结和房室束的外科解剖及计算机三维重建Ⅰ.位置与毗邻

通过对15例人心(成人5例,婴幼儿5例,法四5例)房室结和房室束的连续切片观察和图像分析,表明:15例房室结均位于Koch三角内.与成人相比,婴幼儿房室结位置相对较高,法四房室结位置偏低,其结前部紧靠三尖瓣隔瓣根部.婴幼儿房室束多位子三尖瓣隔瓣附着缘以上的房室肌隔内或室嵴顶部,而法四房室束起始部紧邻三尖瓣隔瓣根部的深面,其余部份可位:室嵴左侧,室缺的后下缘;房室束可直接位于室缺游离缘的心内膜下,或距室缺游离缘(可为肌性或腱性)1.88-2.14mm处.为临床小儿心外科手术提供了直接的形态学依据.     

Arterial vascularisation of the atrioventricular node

The aim of this study was to define the anatomic characteristics of the principal arterial source of the atrioventricular node, known as the artery of the atrioventricular node. Forty hearts were studied by various anatomic and radiologic methods dissection, injection-dissection, injection-corrosion and injection-radiography, but only 23 results were interpretable. The right coronary artery represented the commonest arterial source of the atrioventricular node (21/23 hearts) but numerous variations in the origin and topography of the nodal artery were found.     

成人心传导系统的超微结构

目的　进一步观察成人心传导系统的超微结构。方法　对窦房结、房室结采用纵切法 ,分别于其头、体、尾部切取 1mm3 组织各两块 ;房室束分叉部采用横切法切取其分叉部的近、远段组织各两块 ,用透射电镜观察。结果　 (1)窦房结头部或头体交界部见P细胞 3～ 4个环抱成团 ,团内细胞互相广泛连接 ,构成一个电传导装置 ;(2 )窦房结和房室结可见有功能下降的明细胞与代偿性功能增强的暗细胞相并列 ;(3)结细胞退行性变与纤维组织增生并举 ;(4)窦房结的退行性变化从外侧部、尾部开始。结论　推测窦房结的头部和头体交界部可能是窦房结的起搏中心     

高频起搏犬房颤模型心房重塑及窦房结和房室结功能的变化

 目的:持续高频起搏犬左心房,观察房颤(AF)发生率、心房重塑以及窦房结、房室结传导功能。方法: 健康比格犬15只随机分为起搏组(P组,n=9)和对照组(N组,n=6)。2组均在左心房心外膜缝合固定一起搏电极,P组以400 min-1的频率起搏,N组不起搏。采用程序起搏技术测定电生理参数。结果: (1) 4周后P组阵发性AF和持续性AF的诱发率与N组比较差异均有统计学意义（分别P<0.05,P<0.01）,P组第2周2只犬自发AF,第4周AF诱发率达100%,且持续性AF的发生率高。 (2) P组4周后心房有效不应期(AERP)在不同基本起搏周期(250 ms、300 ms和350 ms)时均较N组缩短 (P<0.05);房室结文氏点(AVN-Wen) 较N组有意义延长［(294.44±26.03)min-1 vs (328.33±24.01)min-1, P<0.05］;房室结有效不应期(AVERP)在不同起搏周期均明显延长 (P<0.01)。(3) 与N组比较,P组4周后窦房结恢复时间（SNRT）和校正恢复时间（cSNRT）均延长（P<0.01）;P波时限2组比较差异没有统计学意义(P>0.05)。(4) P组2周后心脏超声与N组比较显示左心房前后、上下、左右径都有明显增大(P<0.01),右心房上下增大(P<0.05)。结论: 持续４周心房高频起搏后房颤发生率高,心房肌、窦房结和房室结电生理发生特征性的相应改变,左、右心房不同程度扩大,提示电重塑、结构重塑与房颤的发生关系密切。     

Histological organization of the right and left atrioventricular valves of the chicken heart and their relationship to the atrioventricular purkinje ring and the middle bundle branch

In the avian heart the right and left atrioventricular (AV) valves not only exhibit their own special anatomical characteristics, but they also are in close proximity to the conduction system. The right AV valve is a single, spiral plane of myocardium, in remarkable contrast to the fibrous structure characteristic of the mammalian tricuspid valve. A ring of Purkinje tissue encircles the avian right AV orifice and connects to the muscular valve. The chicken has no crista supraventricularis, its right AV valve serving that function as well as opening and closing the right AV orifice. The left AV valve consists of three leaflets instead of the two typical of mammalian hearts. Its anterior and posterior leaflets are small; its large aortic (medial) leaflet merges with the bases of both the left and noncoronary cusps of the aortic valve by fibrous tissue, resembling that of the mammalian heart. However, unlike in mammals, there is a slim cylinder of continuous myocardium coursing parallel to this fibrous junction. This unusual arc of myocardium in the chicken serves to complete an entire subaortic ring of myocardium and is thus potentially capable of constricting the outflow tract of the chicken's left ventricle. The middle bundle branch connects with both the muscle arch and the AV Purkinje ring. Thus the myocardium in or near both AV valves (and the left ventricular outflow tract) in the chicken heart is so arranged that it may receive direct early activation from the conduction system. ©1993 Wiley-Liss, Inc.     

人胚心静脉窦和传导系统的早期发育

目的 探讨早期人胚心静脉窦及传导系的发生发育机制. 方法 用抗α-平滑肌肌动蛋白(α-SMA)、抗α-横纹肌肌动蛋白(α-SCA)和抗结蛋白(DES)抗体对29例C10～C16期人胚心连续切片行免疫组织化学染色. 结果 人胚发育C12～C13期,系统静脉汇集形成的静脉窦出现于心包腔尾端原始横膈间充质中,静脉窦壁间充质细胞逐渐分化为α-SCA阳性的静脉窦心肌细胞.C14期,心包腔的扩张使静脉窦进入心包腔内,参与了右心房的形成.DES阳性传导系心肌的分化始于C10期心房室管右侧壁,随发育逐渐向室间沟心肌扩展,发育为房室传导系的希氏束、左右束支及心室腔面的小梁心肌.在心房,DES表达首先出现于C11期心房背侧壁,在C13期,可见静脉窦左背侧壁α-SCA、α-SMA、DES阳性心肌带与左心房底部、房室管背侧壁相延续,这条心肌带可能参与了人胚心静脉窦至房室管传导系的发育.C14～C16期,DES强阳性染色从窦房结经左、右静脉瓣及心房的背、腹侧壁延伸至房室管右侧壁,可能是原始的心房传导通路. 结论 心包腔尾端原始横膈间充质是人胚静脉窦心肌发生区,原始横膈间充质细胞逐渐分化为心肌细胞,添加到人胚心管静脉端,形成心静脉窦心肌.人胚心传导系心肌的分化始于房室管,随心管发育逐渐向动、静脉端扩展,在C16期,已分化为形态清晰可辨的DES阳性胚胎心传导系.     

A macroscopic anatomical investigation of atrioventricular bundle locational variation relative to the membranous part of the ventricular septum in elderly human hearts

Although several gross anatomical investigations on the cardiac conducting system have been published, most have presented gross anatomical observations after histological confirmation. This is because of the difficulty in dissecting the conducting system itself. Additionally, the conducting system has hitherto been represented schematically and/or histologically, even in recent regional anatomical color atlases of the heart. Therefore most researchers and clinicians rarely view a conducting system at the macroscopic level. In this study we reveal the detailed-gross anatomical architecture and normal variations in the conducting system using 105 elderly human hearts. In particular, we focused on the location of the atrioventricular bundle relative to the membranous part of the interventricular septum because it has commonly been used as a landmark to identify the conducting system. Consequently we found locational variations in the atrioventricular bundle to be relatively more frequent in 56 cases (53.3%), in contrast to 49 (46.7%) ordinary cases in which this bundle ran just along the lower border of the membranous part of the interventricular septum. In the former cases we also emphasized the clinical significance of the naked atrioventricular bundle running on the membranous part of the interventricular septum in 22 cases (21.0%). Some types of lower atrioventricular bundle variation would be important for cardiac surgery, especially the operation of the interventricular septal defect and can be explained from the developmental viewpoint, i.e., the atrioventricular bundle has its origin in the mixture of specialized myocardinal rings.     

Characteristics of the delayed rectifier K current compared in myocytes isolated from the atrioventricular node and ventricle of the rabbit heart

The delayed rectifier potassium current (I _K) is known to be important in action potential repolarisation and may contribute to the diastolic pacemaker depolarisation in pacemaker cells from the heart. In this study, using whole-cell patch clamp, we investigated the characteristics of I _K in morphologically normal cells from the atrioventricular node (AVN) and ventricle of the rabbit heart. Cells were held at −40 mV and 5 μM external nifedipine was used to block L-type calcium current (I _Ca,L). Significant I _K was observed with pulses to potentials more positive than −30 mV. The steady-state activation curve in both cell types showed maximal activation at between + 10 and + 20 mV. Half-maximal activation of I _K occurred at −4.9 and −4.1 mV with slope factors of 8.3 and 12.4 mV in ventricular and AVN cells, respectively. Using pulses of increasing duration, significant I _K tails after repolarisation from + 40 mV were observed with pulses of 20 ms and increased with pulses up to 100–120 ms in both cell types. Pulses of longer duration did not activate further I _K and this suggested that only the rapid component of I _K, called I _Kr, was present in either cell type. Moreover, I _K tails after pulses to all potentials were blocked completely by E-4031, a selective blocker of I _Kr. The reversal potential of I _K varied with the concentration of external K. Superfusion of AVN cells with medium containing 4, 15 and 40 mM [K⁺]_o resulted in reversal potentials of −81, −56 and −32 mV, respectively, which are close to values predicted if the I _K channel were highly selective for K. The time constants for deactivation of I _K in ventricle and AVN on return to −40 mV after a 500-ms activating pulse to + 60 mV were 480 ms and 230 ms, respectively. The faster deactivation of I _K in AVN cells was a distinguishing feature and suggests that there may be differences in the I _Kr channel protein between ventricular and AVN cells. Received: 24 July 1995 /Received after revision: 20 October 1995 /Accepted: 23 October 1995