（Anton E. Becker）／はじめに
Cardiac surgeons today should be well aware of the fact that there is a conduction system in the heart which allows spread of electrical activation from the atrial pacemaker site to the ventricles. It would be rather shocking if this was not the case.
However, if one comes to think about it our knowledge of the cardiac conduction system does not date back that long. It is of historical interest that Japanese researchers have played an important role in unraveling some of the mysteries of the underlying anatomy. The most prominent in this context has been Sunao Tawara（1873-1952）, whose epic work in 1906 unequivocally showed the location of the atrioventricular（AV）node - node of Tawara - in the normal human heart and with the bundle of His connecting the node to the ventricles. However, the precise location of node and bundle in hearts with congenital malformations, such as ventricular septal defects, tetralogy of Fallot and atrioventricular septal defects, remained uncertain and had as yet to be determined. For a long time though the need to do so was not very pressing because it took a while before surgeons were able to operate inside the heart. And, indeed, it was because of technical achievements and, in particular, the advents in operative techniques for congenital heart malformations that the need to understand better where precisely the AV node and His bundle were positioned became urgent.
It was in the sixties of the last century that such icons as Maurice Lev and Jesse Edwards, with their co-workers, started to study the anatomic relationship between the AV conduction system and defects in the ventricular septum, prompted by the high degree of postoperative conduction interferences. Those early studies clearly revealed that complete heart block, right bundle branch block and postoperative ventricular pump failure were almost invariably due to surgical trauma to the AV conduction system. It also appeared from those initial studies that the precise relationship between the anatomic location of the AV conduction axis and the ventricular septal defect varied according to the exact position of the defect. In other words, the early studies made it crystal clear that in depth knowledge of the intricate anatomy of congenitally malformed hearts was a necessity to operate safely inside those hearts without causing damage to AV conduction.
It is in the context of this historical background that Hiromi Kurosawa - together with his wife Satoko - visited me in Amsterdam, The Netherlands. Just like my senior colleagues in the USA, we also had gathered a collection of congenital heart specimens which we preserved for scientific purposes and Hiromi was welcome to take advantage of that. He spent two years with us and performed a meticulous anatomic study of the AV conduction system in normal hearts and in hearts with congenital malformations. Specimens were extensively documented photographically, where after the area of the anticipated AV conduction tissue was removed en bloc and subsequently serially sectioned for microscopic evaluation. The data so obtained allowed a precise reconstruction of the AV conduction axis in relation to the defects in the same specimen. By superimposing the AV node and bundle on the gross photographs and by performing sham operations on the same specimens he made it perfectly clear to any young surgeon where to put stitches and where not. His observations were of direct value in the operating theater and certainly contributed to diminish postoperative conduction defects. After Hiromi had left Amsterdam for Tokyo he continued his work in the field of AV conduction, organized seminars, produced teaching videos and became a much respected expert internationally.
This volume reflects his vast experience in the field and should be on the shelf of each surgeon operating on hearts. As a colleague and personal friend I feel honored and privileged to have been asked to write a foreword.
Anton E. Becker, MD, PhD
Emeritus professor of Cardiovascular Pathology,
Academic Medical Center, University of Amsterdam,
「病気を診ずして病人を診よ」（東京慈恵会医科大学学祖・高木兼寛先生）の教えに沿いfor the patientsに徹して本書をまとめたが，刺激伝導系の幅広い多様性を論理的に理解する上で，心臓外科医ばかりでなく小児科医，麻酔医，その他の心臓病医療にかかわるspecialistのprofound knowledgeの一端になれば幸甚である．
本書は盟友Becker教授との共著“Atrioventricular conduction in congenital heart disease. Surgical anatomy”（Springer-Verlarg. Tokyo, Berlin, New York 1987）をもとに，その後の25年におよぶ臨床経験の知見を加えた構成になっている．今でも未解決の課題が多々あり，genuineなtextbookをめざしてさらなる研究が必要であり，今後の心臓発生学，心臓病理学，小児循環器学，先天性心臓外科学の発展に期待したい．