Sunao Tawara 田原 淳, (1873 – 1952) was a Japanese pathologist.
Knowledge of the conduction system of the heart was greatly advanced by Tawara’s work carried out in the laboratory of Ludwig Aschoff (1866 – 1942) in Marburg at the beginning of this century.
In the laboratory, Tawara had two research projects. The first concerned myocarditis, whilst the other involved the study of the conduction system. He published the manuscript for cardiac conduction [Das Reizleitungssystem des Säugetierherzens] with a forward by Aschoff; the second project was published with Aschoff as co-author shortly after Tawara had returned home [“Current Theories Concerning the Pathological and Anatomical Basis of Cardiac Failure”]
- Born 5 July 1873
- 1904-1906 Research pathologist in Aschoff’s laboratory, Marurg
- 1908-1933 Professor of Pathology at the University of Kyushu
- Died 19 January 1952 in Fukuoka, Kyushu
Tawara node (1906)
The atrioventricular node [AV node; Node of Tawara; Aschoff-Tawara node]
Tawara’s 1906 monograph, ‘Das Reizleitungssystem des Säugetierherzens‘ [The Conduction System of the Mammalian Heart] established the link between the bundle of His and the Purkinje fibers by discovering the left and the right bundle branch, the interposed components between them, and by identifying the Purkinje fibers as the terminal ramifications of these components. Tawara added another component, the atrioventricular node, and defined these components as a system – the conduction system of the heart.
Tawara explained the conduction system as a closed system, like that of an anatomic tree rooted in the atrial septum, with the stem and the main branches located in the ventricular septum. The peripheral branches extend to the papillary muscles and the parietal walls, and that the smallest ramifications of the Purkinje fibers ultimately spread, as the terminal ramifications of the conduction system, to all the parts of the ventricles.
The AV node is sometimes referred to as the Aschoff-Tawara node. However, although Tawara’s work on the conduction system was carried out in Aschoff’s laboratory and under his guidance, Aschoff did not claim to be a co-author of the monograph, only providing the foreword to Tawara’s work.
Key Medical Contributions
Tawara made significant contributions to the knowledge of the cardia conducting system. These findings had been overlooked for the best part of a century before the work of Koso Suma brought many of the findings to light. Suma summarises Tawara’s contribution to the conduction system as:
- Identification of the atrioventricular node with a reticular formation at the sites where the atrioventricular conduction system originates
- Precise description of the courses of the right and the left bundle
- Identification of the false tendons as parts of the conduction system
- Identification of the Purkinje fibers as the terminal ramifications of the conduction system
- Precise description of the histology of each part of the conduction system
- Precise estimation of the conduction velocity of excitation in the conduction system and of the excitatory process and the mode of contraction of the ventricles.
Tawara produced detailed photographic and illustrated images to demonstrate the conduction system. Below is a macroscopic image of the left ventricle of the human heart. The anterior wall of the left ventricle was cut from just below the aortic valve toward the cardiac apex at the line between the anterior and the posterior papillary muscles and opened toward the right and the left. The entire course of the left bundle branch and its terminal ramifications are illustrated.
Stimulations for further advancements
Tawara’s work had a significant impact on the progress of cardiology.
Tawara’s discovery of the atrioventricular node stimulated Keith and Flack to search for such a peculiar tissue in another region of the heart, as it was believed at that time that the heart beat was initiated in the musculature surrounding the terminal part of the superior vena cava. In 1907, Arthur Keith (1866-1955) and Martin Flack (1882-1934) reported the existence of the sino-atrial node in the vertebrate heart.
In 1903, Willem Einthoven (1860 – 1927) published a paper reporting the recording of the ECG with a string galvanometer developed by himself. This attracted little attention from the medical profession. However, following the publication of the paper, “More about the electrocardiogram,” Einthoven was besieged by visitors and received correspondence from individuals all over Europe who wanted to see or learn about the new instrument. In this publication, Einthoven referred to the contributions of Sunao Tawara 田原 淳, (1873 – 1952) as the theoretical basis for interpreting electrocardiogram.
Nach den Untersuchungen Tawara’s besteht das atrioventrikulare Verbindüngsbfindel aus einem System vonMuskelfasern, die einen sich baumförmig verzweigenden Strang bilden…Völlig in glbereinstimmung mit diesem anatomischen Bau ist die Fortpfianzung der Kontraktionswelle im Herzen, wie dieselbe aus tier Form des Elektrokardiogrammes abgeleitet werden muss.Einthoven 1908: 576
According to Tawara’s study, the atrioventricular connecting bundle consists of a system of muscle fibers which form a tree-like ramified cord…The mode of propagation of the contraction wave in the heart, as it must be deduced from the form of the electrocardiogram, is in complete accordance with this anatomical structure.Einthoven 1908: 576
- Tawara S. Das Reizleitungssystem des Säugetierherzens: Eine anatomisch-pathlogische Studie über das Atrioventrikularbündel und die Purkinjeschen Fäden. Jena, Verlag von Gustav Fischer, 1906. [Suma K. Conduction System Of The Mammalian Heart, The: An Anatomico-histological Study Of The Atrioventricular Bundle And The Purkinje Fibers. [English translation] 2000]
- Aschoff L, Tawara S. Die heutige Lehre von den pathologisch-anatomischen Grundlagen der Herzschwäche; kritische Bemerkungen auf Grund eigener Untersuchungen. 1906.
- Tawara S. Anatomisch-Histologische Nachprüfung der Schnittführung an der von Prof. H.E. Hering übersandten Hundeherzen. Arch ges Physiol Mensch Thier 1906; 111:300–302
- Tawara S. Über die sogenannten abnormen Sehnenfäden des Herzens. Ziegl Beitr Path Anat 1906; 39:563–584.
- Fye WB. The origin of the heart beat: a tale of frogs, jellyfish, and turtles. Circulation. 1987;76(3):493-500.
- Ehrlich W. The discovery of the cardiac conduction system: the testimony of the authors. Perspect Biol Med. 1992;35(4):487-498.
- Suma K. Tawara S. Conduction System Of The Mammalian Heart, The: An Anatomico-histological Study Of The Atrioventricular Bundle And The Purkinje Fibers. [English translation] 2000
- Suma K. Sunao Tawara: a father of modern cardiology. Pacing Clin Electrophysiol. 2001;24(1):88-96.
- Loukas M, Linganna S, Chiba A, Tubbs RS. Sunao Tawara, a cardiac pathophysiologist. Clin Anat. 2008;21(1):2-4.
- Bibliography. Tawara, Sunao 1873-1952. World Cat Identities
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