Reconstruction of the human atrioventricular node

Truex, Raymond C.; Smythe, Martha Q.

doi:10.1002/ar.1091580103

Cited by 88 publications

(28 citation statements)

References 15 publications

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“…This is contrary to the current belief that nerves within the AVN are restricted to single nerve fibers 3,13,15,16 and that specialized canine AV junction tissues are devoid of parasympathetic fibers. 16 Clear perinuclear regions were found in the AV bridge myocytes.…”

Section: Discussioncontrasting

confidence: 73%

“…The DAVB is also composed of myocardial fascicles, not single myofibers as previously described, 1,3,[13][14][15][16] and differs from the AVN and PAVB in several major aspects. It is a narrow bundle; its fascicles are the largest (Figures 9 to 11, compare Figures 3D, 6D, and 9D) and are disposed in clusters in transverse sections (Figure 11).…”

Section: Histology Of the Davbmentioning

confidence: 87%

“…The AVN is composed of a meshwork of interwoven myocardial fascicles, not myofibers as previously described. 1,3,[13][14][15][16][17][18] The interwoven AVN meshwork immediately follows the PAVB-AVN junction ( Figure 3A), at which point the AVN is also encased within the central fibrous body (Figures 2B and 2C4). The result of this massive whorl of fascicles can be appreciated in perpendicular sections, where primary fascicles displayed in cross-section are located next to fascicles disposed in the long axis (see Figure 7D).…”

Section: Histology Of the Avnmentioning

confidence: 99%

“…Histological details of myocytes, myofibers, and tissues are also not apparent in orthogonal transverse sections (Table), which are similar to the classic conventional transverse or frontal plane sections. 3,[13][14][15][16][17][18][19]22,23,25 What Is the Atrial or Posterior Input to the AVN? A comparison of histological data for the atrial or posterior input identified by other workers with histological data presented here identifies these structures as ordinary myocardium of the medial atrial wall and, by and large, as various parts of its annular myocardium: terminals of internodal tracts (James,14 Figures 2B, 6, 7, and 9; James, 23 Figures 6C and 6D), the rightward component of the compact AVN (Becker and Anderson, 16 Figure 8A; Inoue and Becker, 19 Figures 2B, 3, and 5 to 7), the overlay and transitional myofibers (James, 14 Figures 2A and 3B; Becker and Anderson, 16 Figure 2A), with the posterior nodal extension and compact AVN (Medkour et al, 24 Figure 2) and the AV nodal ring input being analogous to part or all of the circumferential lamina encircling the tricuspid valve (McGuire et al, 25 Figures 11 and 12) and all of the ordinary atrial myocardium of the AV junction region (Sanchez-Quintana et al, 18 Figure 2).…”

Section: Points Of Controversymentioning

confidence: 99%

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Proximal Atrioventricular Bundle, Atrioventricular Node, and Distal Atrioventricular Bundle Are Distinct Anatomic Structures With Unique Histological Characteristics and Innervation

Racker

Kadish

2000

Circulation

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Background-Direct 3D analysis (ie, stereotaxic analysis of 3 planes) has shown that the atrioventricular (AV) node (AVN) is continuous with only specialized myocardium of the proximal AV bundle (PAVB) and distal AV bundle (DAVB) or His bundle. The purpose of the present study was to determine whether the PAVB, AVN, and DAVB possess histological features distinct from each other and from the ordinary myocardium. Methods and Results-A protocol that preserves the cytoplasmic and interstitial integrity of the tissue and permits serial sections of the AV junction region to be made in 3 orthogonal planes showed that the PAVB, AVN, and DAVB are characterized by myocardium aggregated into fascicles containing Ϸ8 myofibers. Myofibers within the fascicles are coiled or spiraled about each other; and spiraling is most compact in the PAVB. Collagen encases individual fascicles and segregates primary fascicles into secondary fascicles. Fascicles, and not myofibers, are in parallel array in the PAVB, interwoven in the AVN, and parallel in the DAVB. Narrow junctions of parallel fascicles separate the AVN from the PAVB and DAVB. Myocytes, which are largest in DAVB, possess clear perinuclear regions; thin finger-like end processes, which are most numerous in the AVN; uniform, delicate cross-striations; and intercalated disks, which are broader in the PAVB and form short stacks in the AVN. Sheaves of nerve terminals, including boutons, are as found in skeletal muscle. Conclusions-The PAVB, AVN, and DAVB have distinct histological features. Collagen septation of primary and secondary fascicles presents natural barriers within the tissues and to surrounding myocardium and structures. These findings confirm that the AV junction region contains a specialized conduction system that is anatomically isolated from ordinary myocardium.

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Section: Discussioncontrasting

confidence: 73%

Section: Histology Of the Davbmentioning

confidence: 87%

Section: Histology Of the Avnmentioning

confidence: 99%

Section: Points Of Controversymentioning

confidence: 99%

See 2 more Smart Citations

Proximal Atrioventricular Bundle, Atrioventricular Node, and Distal Atrioventricular Bundle Are Distinct Anatomic Structures With Unique Histological Characteristics and Innervation

Racker

Kadish

2000

Circulation

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“…Rather than review all morphological studies performed in this century on the A V nodal area [the early literature has been excellently reviewed by Scherf and Cohen (162)], we focus on recent studies, wh ere, despite some differences in nomenclature, there is agreement about a subdivision of the A V nodal area into several regions (8,10,11,16,19,42,55,99,103,139,145,177,182,191). It may be emphasized that only very time-consuming three-dimensional reconstructions based on serial sections give a complete picture of nodal architecture (11,101,171,177).…”

Section: Different Eell Types Within the A V Nodementioning

confidence: 99%

Morphology and electrophysiology of the mammalian atrioventricular node

Meijler

Janse

1988

Physiological Reviews

204

146

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The AV node of those mammalian species in which it has been thoroughly investigated (rabbit, ferret, and humans) consists of various cell types: transitional cells, midnodal (or typical nodal cells), lower nodal cells, and cells of the AV bundle. There are at least two inputs to the AV node, a posterior one via the crista terminalis and an anterior one via the interatrial septum, where atrial fibers gradually merge with transitional cells. The role of a possible third input from the left atrium has not been investigated. Since the transition from atrial fibers to nodal fibers is gradual, it is very difficult to define the "beginning" of the AV node, and gross measurements of AV nodal length may be misleading. Histologically, the "end" of the AV node is equally difficult to define. At the site where macroscopically the AV node ends, at the point where the AV bundle penetrates into the membranous septum, typical nodal cells intermingle with His bundle cells. A conspicuous feature, found in all species studied, is the paucity of junctional complexes, most marked in the midnodal area. The functional counterpart of this is an increased coupling resistance between nodal cells. An electrophysiological classification of the AV nodal area, based on transmembrane action potential characteristics during various imposed atrial rhythms (rapid pacing, trains of premature impulses), into AN (including ANCO and ANL), N, and NH zones has been described by various authors for the rabbit heart. In those studies in which activation patterns, transmembrane potential characteristics, and histology have been compared, a good correlation has been found between AN and transitional cells, N cells and the area where transitional cells and cells of the beginning of the AV bundle merge with midnodal cells, and NH cells and cells of the AV bundle. Dead-end pathways correspond to the posterior extension of the bundle of lower nodal cells and to anterior overlay fibers. During propagation of a normal sinus beat, activation of the AN zone accounts for at least 25% of conduction time from atrium to His bundle, the small N zone being the main source of AV nodal delay. Cycle length-dependent conduction delay is localized in the N zone. Conduction block of premature atrial impulses can occur both in the N zone and in the AN zone, depending on the degree of prematurity. Several factors determining AV nodal conduction delay have been identified.(ABSTRACT TRUNCATED AT 400 WORDS)

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The AV junction region of the heart: A comprehensive study correlating gross anatomy and direct three-dimensional analysis. Part I. Architecture and topography

Racker

1999

Anat. Rec.

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There is little detailed knowledge of the architecture of the AV junction region, the cytoarchitecture of the AV node or of its atrial connections. In the present study, the gross anatomy and topography of intracardiac structures in 21 adult canine hearts were photographically compared in whole and dissected hearts and tissue blocks and serial histologic sections made in three orthogonal planes. There are seven major new findings: 1) A coronary sinus fossa exists at the crux of the heart. It separates the right medial atrial wall (MAW) superoposterior region from the left atrium, its floor is the coronary sinus, and it carries the medial atrionodal bundle and proximal AV bundle on its right wall. 2) The posterior MAW forms two isolated bridges of myocardium as it surrounds the coronary sinus ostium, is isolated from the sinus venarum with crista terminalis and interatrial septum-by the floor of the inferior vena cava, and the narrow bridges link the posterior atrial wall to the mid MAW. 3) The tendon of Todaro has both epicardial and endocardial exposures, terminates in the superoposterior MAW and its medial aspect is adjacent sequentially to the medial atrionodal bundle and proximal AV bundle. 4) Only ordinary myocardium contacts the anulus fibrosus. 5) The ventricular septum's shoulder is humped shape posteriorly, is completely overlaid by anular myocardium and the medial leaflet and is joined by struts of papillary muscle. 6) The membranous septum joins the anterior ventricular septum to the crista supraventricularis, forms part of the posterior noncoronary and right aortic valve sinus walls and encases the right bundle branch. 7) The specialized conduction tissues, the superior, medial and lateral atrionodal bundles, the proximal AV bundle, AV node, distal AV bundle and right bundle branch are subjacent to MAW epicardium outside the right atrium, share regular intracardiac relationships with topographic landmarks and the medial atrionodal bundle, terminal superior atrionodal bundle, the proximal AV bundle and AV node are aligned to the medial leg of Koch's triangle. Thus, atrial myocardium of the AV junction region is that of the MAW. The floor of the inferior vena cava forms a natural barrier to impulse transmission along the full extent of the posterior MAW. The specialized tissues are outside of the MAW. Anatomic landmarks form reliable topographic landmarks for the specialized AV junction region tissues. A knowledge of the association of the specialized conduction tissues with specific regions of the MAW is useful in localizing the tissues and along with the coronary sinus fossa provides several extracardiac approaches.

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Reconstruction of the human atrioventricular node

Cited by 88 publications

References 15 publications

Proximal Atrioventricular Bundle, Atrioventricular Node, and Distal Atrioventricular Bundle Are Distinct Anatomic Structures With Unique Histological Characteristics and Innervation

Proximal Atrioventricular Bundle, Atrioventricular Node, and Distal Atrioventricular Bundle Are Distinct Anatomic Structures With Unique Histological Characteristics and Innervation

Morphology and electrophysiology of the mammalian atrioventricular node

The AV junction region of the heart: A comprehensive study correlating gross anatomy and direct three-dimensional analysis. Part I. Architecture and topography

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