| Project/Area Number |
12670692
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Circulatory organs internal medicine
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| Research Institution | Showa University |
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Principal Investigator |
SAITO Tsukasa Showa University, School of Medicine, Assistant Professor, 医学部, 講師 (40205662)
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| Co-Investigator(Kenkyū-buntansha) |
INOUE SHIN Showa University, School of Medicine, Associate Professor, 医学部, 助教授 (00201335)
SAKAI Tetsuo Showa University, School of Medicine, Istructor, 医学部, 助手 (60281367)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2001: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2000: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Keywords | pulmonary vein / atrial fibrillation / ectopic automaticity / morphology |
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| Research Abstract |
Electrophysiologic studies have shown that spontaneous initiation of atrial fibrillation by ectopic beats may originate from within pulmonary veins. The anatomic substrate is as yet unknown. Human autopsy hearts were studied and classified two groups ; with atrial arrhythniias, with no history of atrial arrhythmias. The muscle fiber arrangement of the left atrial wall and pulmonary veins was dissected. Microscopical observation and threedimensional reconstruction of the fiber arrangement in the myocardial sleeves were performed.
The length of the sleeves was largest in the left superior pulmonary veins (14.5mm). There were no statistically significant differences between uniform and nonuniform muscle fiber arrangements. Microscopic evaluation revealed myocardial sleeves positioned on the adventitial side of the pulmonary vein, separated from the muscular media of the pulmonary vein by a fibrofatty tissue plane. The most distal zone of the myocardial sleeves showed increasing fibrosis with encapsulation of small groups of within fibrous tissue. There were considerable heterogeneity in cellular morphology in myocardium of pulmonary veins. There was no relationship with presence or absence of atrial arrhythmias. Three-dimensional reconstruction revealed nonuniform muscle fiber arrangements.
The observation that the peripheral zones of myocardial sleeves are associated with increasing connective tissue deposition between myocardial muscle groups, suggests degenerative changes which from the histologic viewpoint fits with progressive ischemia. These changes in the myocardial sleeves could provide the basis for progressive electrical uncoupling of side-to-side connections, the generation of ectopic beats and micro-reentry and, hence, for atrial arrhythniias. And heterogeneity in cellular morphology in myocardium of pulmonary veins might be related in arrhythmogenesis in these area.
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