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  • 1
    Electronic Resource
    Electronic Resource
    The Tendons of Todaro and the “Triangle of Koch”: (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 10 (1999), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Todaro's Tendons and the “Triangle of Koch.”Introduction: There is growing use of the Todaro tendon and triangle of Koch as anatomic icons for invasive cardiac electrophysiologists. Reasons exist to doubt this validity. Methods and Results: Histologic sections were prepared from 96 anatomically normal human hearts. The study area extended from the crista supraventricularis to the eustachian valve and included the AV node and His bundle. This encompasses any tendon of Todaro. Because the purported triangle of Koch includes the tendon of Todaro, all of Koch's available publications were examined. The tendon of Todaro is absent in only one fourth of infant hearts, hut in two thirds of adult hearts. Tendons present were less often single than double or more, rarely exceeded 4 mm in length, and were seldom 〉 1 mm in diameter. Tendons usually originated from the central fibrous body and ended in the eustachian valve. Their origin most often was over the His bundle or its junction with the AV node, rather than the AV node. Tendons were primarily composed of collagen. Koch never described any triangle or acknowledged existence of tendons of Todaro. Conclusion: Todaro tendons are too often absent (or multiple) to warrant use as anatomic landmarks. Without this side of the supposed triangle of Koch, the entire tendon and triangle concept collapses and should be abandoned. There are numerous far more constant anatomic landmarks available to orient one to the human AV node and His bundle; these are briefly reviewed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8167.1999.tb00207.x
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  • 2
    Electronic Resource
    Electronic Resource
    Long Reflections on the QT Interval: (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 7 (1996), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The Gordon K. Moe Lecture. This review of accumulated knowledge about the long QT syndromes begins with an iteration of the original papers and then proceeds to a broader historic reflection that includes my personal work as well as many studies by others. Next come reflections upon the current status of knowledge on the subject, combined with comments about remaining challenges and questions grouped as follows: (1) morphologic abnormalities of the cardiac conduction system and their pathophysiologic significance in the long QT syndromes; (2) cardioneuropathy in the pathogenesis of long QT syndromes; (3) variability of QT prolongation, including consideration of peripheral and central dysautonomic conditions with certain diagnostic and therapeutic implications; (4) some caveats about the popular use of left cervical sympathectomy to treat symptomatic individuals with long QT syndrome, emphasizing hazards for future electrical instability of the heart; (5) consideration of genetic influences in the long QT syndromes, a field holding great promise as well as fraught with many puzzling dilemmas; and (6) apoptosis and the pathogenesis of the long QT syndromes, based upon personal observations previously made with electron microscopic studies of the sinus node and now including new immunohistochemical evidence expanding the relevance of this novel viewpoint. These intentionally provocative presentations are made to stimulate physicians and other scientists to consider these several different perspectives in planning future studies aimed at better understanding of one of the most challenging medical entities facing cardiology today.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8167.1996.tb00581.x
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  • 3
    Electronic Resource
    Electronic Resource
    NORMAL AND ABNORMAL CONSEQUENCES OF APOPTOSIS IN THE HUMAN HEART (1998)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 60 (1998), S. 309-325 
    Details
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Notes: Abstract Knowledge about apoptosis has become essential for understanding many aspects of cardiac structure and function. In the human heart there are major periods of morphogenesis that begin only after birth, and some of these processes recur intermittently for many years. Although the exact mechanisms by which these events are initiated or terminated remain poorly understood, it is clear that their benefits may be mirrored in destructive effects. In this review, selected examples include normal morphogenesis of the cardiac conduction system and the normal postnatal involution of the right ventricle, both of which are mediated by apoptosis. Destructive counterparts include familial heart block ending in fatal arrhythmias, similar results in the long QT syndrome, and the pathogenesis of both Uhl's anomaly and arrhythmogenic right ventricular dysplasia; in each apoptosis is an important factor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.physiol.60.1.309
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  • 4
    Electronic Resource
    Electronic Resource
    Distribution of cholinesterase within the sinus node and AV node of the human heartThis work was supported in part by grants from the Michigan Heart Association and the U. S. Public Health Service. (1966)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 155 (1966), S. 151-161 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Distribution of cholinesterase within the sinus node, AV node and His bundle of the human heart was studied utilizing acetylthiocholine as the substrate. Cholinesterase is present in large amounts in the conduction system tissue, much smaller amounts in right atrial myocardium and was not observed in ventricular myocardium. The sinus node artery was devoid of cholinesterase, as was the sarcolemma and nucleus of cells in the conduction system. Cholinergic nerve endings stained the most heavily of all tissue studied and were more numerous in the sinus node than the AV node. Stellate-shaped cells previously suggested to be the pace-making site in the sinus node were found to contain abundant cholinesterase. Fibers in the AV nodal bypass tract, which lies between the AV node and right atrial endocardium, also contain cholinesterase. Within individual cells of the sinus node cholinesterase could be identified within myofibrils, with periodic absence in the linear staining most likely corresponding to the Z bands. Other organelles within the cells also contained cholinesterase, but their precise definition was impossible with the present technics. Possible functional significance of these histochemical observations were discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091550203
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  • 5
    Electronic Resource
    Electronic Resource
    Anatomy of the A-V node of the dogSupported in part by grants from the U. S. Public Health Service (H-7108) and the Michigan Heart Association. (1964)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 148 (1964), S. 15-27 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The A-V node of the dog is composed of closely interwoven fibers which frequently connect with each other within a sparse collagen framework. Fibers from the interatrial septum enter the posterior half of the node along its superior and posterior margins, while the anterior half of the node is isolated from such connections. In addition there are fibers from the interatrial septum which bypass these marginal atrionodal junctions and instead enter the convex surface of the node, which lies beneath the right atrial endocardium. These bypassing fibers circumvent most of the interweaving fibers within the A-V node. At the posterior margin of the node, lying between it and the coronary sinus, there are ganglia and nerves, with the nerve fibers extending anteriorly through the A-V node into the A-V bundle. The only major anatomic difference between the human and canine A-V nodes is their arterial blood supply, that of man being derived from one source originating from the right coronary artery and that of the dog being from two sources, both of which originate from the left coronary artery.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091480103
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  • 6
    Electronic Resource
    Electronic Resource
    Anatomy of the sinus node, av node, and his bundle of the heart of the sperm whale (Physeter macrocephalus), with a note on the absence of an os cordis (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 242 (1995), S. 355-373 
    Details
    ISSN: 0003-276X
    Keywords: Cardiac conduction in whales ; Coupled relaxation oscillators ; Whale cardiac rhythm ; Death of beached whales ; Comparative cardiac anatomy ; Whale Purkinje cells ; Whale working cardiocytes ; P cells of whale heart ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Background: Atrioventricular (AV) conduction time in large whales is only slightly greater than in smaller mammals even though their hearts are enormously larger. Little is known of the detailed histology or cytology of the conduction system of large whales. Such knowledge could be useful in defining the nature of cardiac rhythm and conduction of the whale as well as smaller mammals including humans.Methods: We studied hearts from seven sperm whales. After fixation in formaldehyde and later dissection, specimens were prepared for histological examination.Results: Cell size, histological organization, and innervation of the sperm whale's sinus node, AV node, and His bundle are similar to most mammalian hearts, except the sinus node is substantially larger. There is no central fibrous body between the atrial and ventricular septa, and the whale has no os cordis. Only the upper quarter of the interventricular septum is fully formed; below that there is only a thin layer of fatty connective tissue between the two ventricles.Conclusions: Given our morphological findings, we believe that the whale's comparatively short AV conduction time may be best explained by the sinus node and AV node functioning as coupled relaxation oscillators. Absence of an os cordis or central fibrous body or strong attachment between the two ventricles may pose both electrophysiological and hemodynamic hazards when the whale is no longer in its normally buoyant aquatic environment. © 1995 Wiley-Liss, Inc.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092420309
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  • 7
    Electronic Resource
    Electronic Resource
    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 (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 235 (1993), S. 74-86 
    Details
    ISSN: 0003-276X
    Keywords: Chicken atrioventricular valves ; Chicken cardiac conduction system ; Chicken AV Purkinje ring ; Chicken middle bundle branch ; Chicken left para-aortic muscle arch ; Muscular right AV valve ; Tricuspid fibrous left AV valve ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: 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.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092350108
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  • 8
    Electronic Resource
    Electronic Resource
    Cardiac conduction system in the chicken: Gross anatomy plus light and electron microscopy (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 236 (1993), S. 493-510 
    Details
    ISSN: 0003-276X
    Keywords: Chicken sinus node ; Chicken AV Purkinje-ring ; Chicken AV node ; Chicken His bundle ; Chicken middle bundle branch ; Ultrastructure chicken conduction system ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Twenty-three chicken hearts were used to study the cardiac conduction system by light and electron microscopy. In addition to a sinus node, atrioventricular node (AVN), His bundle, left and right bundle branches (LBB, RBB), the chicken also has an AV Purkinje ring and a special middle bundle branch (MBB). The sinus node lies near the base of the lower portion of the right sinoatrial valve. The AV node is just above the tricuspid valve and anterior to the coronary sinus. The His bundle descends from the anterior and inferior margin of the AV node into the interventricular septum, then dividing into right, left and middle branches some distance below the septal crest. The middle bundle branch turns posteriorly toward the root of the aorta. The AV Purkinje ring originates from the proximal AV node and then encircles the right AV orifice, joining the MBB to form a figure-of-eight loop. The chicken conduction system contains four types of myocytes: (1) The P cell is small and rounded, with a relatively large nucleus and sparse myofibrils. (2) The transitional cell is slender and full of myofibrils. (3) The Purkinje-like cell resembles the typical Purkinje cell, but is smaller and darker. (4) The Purkinje cell is found in the His bundle, its branches, and the periarterial and subendocardial Purkinje network. © 1993 Wiley-Liss, Inc.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092360310
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  • 9
    Electronic Resource
    Electronic Resource
    Classification of triatrial heartsFrom the Division of Cardiovascular Diseases, Henry Ford Hospital, Dertoit 2, Michigan. Supported in part by grants from the U. S. Public Health Service (H-5197) and the Michigan Heart Association. (1962)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 143 (1962), S. 79-91 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091430108
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  • 10
    Electronic Resource
    Electronic Resource
    Anatomy of the human sinus nodeFrom the Division of Cardiovascular Diseases, Henry Ford Hospital, Detroit, Michigan. Supported in part by grants from the U. S. Public Health Service (H-5197) and the Michigan Heart Association.A portion of this material was presented at the annual meeting of the American Association of Anatomists, March 21-24, 1961, Chicago, Illinois. (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 141 (1961), S. 109-139 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091410205
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