Das Reizleitungssystem des Säugetierherzens
Das Reizleitungssystem des Säugetierherzens (English: "The Conduction System of the Mammalian Heart") is a scientific monograph published in 1906 by Sunao Tawara. It has been recognized by cardiologists as a monumental discovery,[1] and a milestone in cardiac electrophysiology".[2]
The monograph revealed the existence of the
Background
Prior to Tawara's discoveries, it was assumed that electrical conduction through the
However, Tawara postulated that ventricular contraction occurs in the opposite manner, with the apex contracting earlier than the base. He also believed that the heart's electrical conduction was not slow but rapid. Working under the guidance of his mentor,
The implications of his work were immediately recognized by Aschoff, who arranged for it to be published in the form of a monograph.[1]
Discoveries
Tawara's monograph, titled "Das Reizleitungssystem des Säugetierherzens" (English: "
- The Bundle of His is divided into 2 bundle branches that are connected with a fanlike group of “subendocardially scattered characteristic muscular bundles”.[1]
- Purkinje cells act as a pathway for the "atrioventricular connecting system".[1]
- The atrioventricular connecting system starts in the bundle branches, and descends into the terminal ends of the Purkinje fibers.[1]
Tawara commented that the system represents a transporting or conducting pathway, and "because the pathway is not a ductal, but a continuously related protoplasmic cord, conduction of excitation impulses surely must take place there."[1]
Influences
On 26 September 1905, shortly before the monograph was due to be published, Ludwig Aschoff wrote an article about Tawara's work. It was subsequently read by the Scottish cardiologist James Mackenzie and forwarded to anatomist Arthur Keith, who was attempting to confirm the existence of the Bundle of His. Despite putting in his best efforts, he failed to locate the structure. On 15 January 1906, Keith wrote a letter to Mackenzie and acknowledged his skepticism about its existence: "I have given up the search for His' bundle—having come to the conclusion that there is not and never was any such thing.”[4]
- Verification of the Bundle of His (1906)
In response to Arthur Keith's skepticism, Mackenzie forwarded Aschoff's article about Tawara's findings, which stimulated Keith's renewal of his studies on the cardiac conduction system.[5] Despite having written a letter to The Lancet about his failure to locate the Bundle of His and his increasing doubts about its existence, Keith (with his student Martin Flack) later reported that they had succeeded in locating the structure by following the detailed descriptions and figures in Tawara's monograph.[6] In a paper published in The Lancet on 11 August 1906, they acknowledged the monograph's high degree of accuracy:
- "We take this opportunity of clearly stating that although some of our observations are new our work is in the main but a verification of the accurate and complete monograph published recently by Tawara, a Japanese working in the laboratory of Professor Aschoff of Marburg."[7]
- Discovery of the sinoatrial node (1907)
Encouraged by their initial success and inspired by Tawara's discovery of the atrioventricular node, Keith and Flack extended their studies and eventually discovered the sinoatrial node in 1907.[4] They wrote that they were examining other regions of the heart for "peculiar musculature" similar to the one discovered by Tawara.[8]
- Theoretical basis for the electrocardiogram(1908)
In 1908, the Dutch physiologist Willem Einthoven referred to Tawara’s monograph as the anatomical basis for interpreting the electrocardiogram.[3] In his monograph, Tawara theorized about the velocity of the excitatory process in the conduction system and the mode of ventricular contraction. Together with his anatomic findings and physiological assumptions, it contributed to the rapid popularization of electrocardiography.[9]
- Other influences and reviews
In 1909, the American pathologist
- "The main advance was made by Tawara, working under the direction of Aschoff. In his book, Das Reizleitungssystem des Saugetierherzens, a complete account of the junctional tissues was given, and the anatomy of the whole system and the connections with the network of Purkinje were described in great detail and in many species of animals. These observations upon the anatomy have received complete confirmation by the more recent writings."[11]
In his autobiography published in 1950, Arthur Keith explained how he had systematically searched for Tawara's system to verify its components:
- "I was able in heart after heart to verify the existence of Tawara’s system. The auricles, I found, were joined to the ventricles by an elaborate system which, beginning in a root like structure in the auricular septum, ended as an arborescence in the ventricles. The ‘bundle of His’ was but a small segment of the Tawara system."[1]
Acknowledging the significance and implications of these discoveries, Keith commented: "With the discovery of the conducting system of Tawara, heart research entered a new epoch."[12]
Shortly before his death,
See also
- Electrical conduction system of the heart
References
- ^ PMID 16769927.
- PMID 16969729.
- ^ .
- ^ PMID 17890694.
- PMC 6655567.
- PMID 17420362.
- .
- PMID 17232727.
- PMID 16567300.
- PMID 20180918.
- ^ Lewis, Thomas (1911). The Mechanism of the Heartbeat. London: Shaw & Sons. p. 3.
- PMID 17420362.
It was no exaggeration for Keith to state, "With the discovery of the conducting system of Tawara, heart research entered a new epoch."
- PMID 18147204.