The Japanese Contribution

Masayasu Hiraoka

Department of Cardiovascular Diseases,Medical Research Institute, Tokyo Medical and Dental University,
Tokyo, Japan

Correspondence: M Hiraoka, Department of Cardiovascular Diseases, Medical Research Institute,
Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
E-mail: hiraoka.card@mri.tmd.ac.jp, phone +81-3-5803-5829, fax +81-3-5684-6295

1.    Introduction

Electrocardiology has been one of the most prominent fields in cardiovascular medicine in Japan. After the electrocardiogram (ECG) became a popular method for cardiac diagnosis, its clinical utility, as well as the theoretical basis of lead fields together with vectorcardiographic studies received wide interest and popularity among clinicians and researchers. The introduction of microelectrode techniques gave a strong impact to clarifying unresolved problems in cardiac electrical activity and electrocardiology. The background of cellular physiology in Japan later made a significant advance through the application of the patch clamp technique to isolated single cardiac myocytes, and shed light on clarifying the issues at the single channel level. Body surface mapping also made a considerable advance in Japan with theoretical, technical and clinical refinement in 1980s, in which the method later came into routine use after standardization for general application.

2.    The Era prior to the Founding of the International Society of Electrocardiology (ISE)

The first international contribution by Japan to electrocardiology was the discovery by Tawara, at the beginning of the 20^th century, of the A-V node and its extended conduction system in the ventricle. After the ECG became a useful tool for cardiac diagnosis, many Japanese physicians and researchers worked on the problems of lead fields, vectorcardiography, clinical electrocardiography and mechanisms of arrhythmias including atrial flutter and fibrillation. The people who contributed in this era included N. Kimura, Takayasu, and E. Kimura.

In the 1950s, the microelectrode method became a popular means of studying cardiac electrical activity at the cellular level and of clarifying unresolved problems in electrocardiography, including arrhythmias. The pioneers of microelectrode techniques included Matsuda, Irisawa, and Gotoh.

3.    The Initiation of the Japanese Contribution to ISE

Sano, who was one of the pioneers in the area of basic electrophysiology using the microelectrode technique as well as being a clinical electrocardiographer utilizing vectorcardiography in theoretical and clinical ways, started to join the meetings of ISE and its forerunner in the late 1960s. He contributed to various areas of basic electrophysiology, as well as to theoretical and clinical electrocardiography. Among numerous contributions, Sano clarified S-A conduction, intra-atrial conduction routes, unique features of action potentials in the A-V nodal cells, and anisotropic conduction properties of ventricular muscles. He first recorded intra-cellular action potentials in fibrillating cardiac cells, and demonstrated longitudinal dissociation of the His bundle and many other arrhythmic mechanisms in the experimental as well as the clinical situation using His bundle electrocardiography. With respect to theoretical and clinical electrocardiology, he first recorded P waves in the vectorcardiogram in health and disease, invented the spatial velocity ECG and studied its clinical utility. He also studied vectorcardiographic characterization and the mechanism of U waves etc. Soon after joining ISE, he became a council member of the Society and contributed to the development of the Society in the 1970s. He was nominated as the President of the 9^th International Congress on Electrocardiology to be held in 1982, Japan, but he died of stomach cancer in 1979.

After the untimely death of Sano, Ueda became a council member of the ISE, took over his presidency, and organized the 9^th International Congress in Tokyo, 1982. Ueda, physician, cardiologist, electrocardiographer, and a great teacher of medicine, first published a monograph of the electrocardiogram in Japan as early as 1939. He also made a classification of the WPW syndrome into type A, B and C (Ueda 's classification). The 9^th Congress in Tokyo attracted over 600 attendees with a high quality of scientific presentation and discussion. The Congress also impressively demonstrated the high quality of Japanese scientific work in electrocardiology to other ISE members, thereby engendering great success of the first ISE congress held outside Europe and North America.

In the same era as that of Sano and Ueda, Yamada worked in the fields of vectorcardiography, body surface mapping and basic electrophysiology. His most remarkable achievements were noted in a proposal for preferential conduction pathways in the atria, reproduction of ECG wave forms by a solution of the forward problem, and development of a body surface potential mapping system and its clinical application. His invention of body surface mapping equipment with 87 electrodes became the standard approach to recording maps for widespread clinical use in Japan. He played a primary role in the establishment of the Japanese Society of Electrocardiology and, as a leader of this field, trained many students as excellent electrophysiologists and electrocardiographers such as Yasui, Okajima and Toyama (a council member of ISE), who frequently appeared at ISE Congresses and stimulated their development.

Harumi, a student of Ueda, was involved in numerous scientific achievements contributing to analysis of vectorcardiograms and body surface maps, computer analysis of ECG waveforms, mechanistic clarification of the genesis of arrhythmias, as well as electropharmacology. In particular, he clarified the theoretical and experimental basis for the genesis of T waves by combining vectorcardiographic observations and computer simulation. He contributed to the clinical application of body surface mapping and analysis of inverse problems. He and his group developed computer simulation models of ECG waveforms and various types of arrhythmias, including ventricular fibrillation. He started to attend the International Congress on Electrocardiology as early as 1970 and became a council member of ISE in 1982. Since then, he continuously appeared at every Congress and played a central role in the promotion of ISE. He served as the general secretary at the 9^th Congress held in Tokyo and as the president at the 21^st Congress in Yokahama, in 1994, both of which brought great success for scientific achievement and development in Electrocardiology. He was the president of ISE from 2000 to 2001, contributing greatly to the development of the Society. He was also one of the founders of the Japanese Society of Electrocardiology, which now consists of over 2000 members who regularly participate in an extremely active programme.

Hiraoka, a student of Sano, became a council member in 1990 and served as a secretary general at the 21^st Congress in Yokohama being nominated as the president of the 31^st Congress to be held in Kyoto in 2004. He contributed to various areas of basic electrophysiology and ion channel works using the patch-clamp technique. He also worked on body surface maps of P waves in health and disease, and clarified the mechanisms of arrhythmias at the cellular level as well as clinical arrhythmias. His recent contribution has clarified ion channel gene mutation as the pathogenesis of inherited arrhythmic disorders including long QT syndrome, Brugada syndrome and idiopathic ventricular fibrillation.