| Co-Investigator(Kenkyū-buntansha) |
IKEDA Kozue Yamagata Univ. Sch. of Med. Assistant, 医学部, 助手 (30184419)
TONO-OKA Ichiro Yamagata Univ. Sch. of Med. Assistant, 医学部, 助手 (70164001)
太田 郁郎 山形大学, 医学部, 助手 (70143097)
KUBOTA Isao Yamagata Univ. Sch. of Med. Instructor, 医学部, 助教授 (30161673)
TSUIKI Kai Yamagata Univ. Sch. of Med. Associate Professor, 医学部, 助教授 (30004683)
YAMAKI Michiyasu Yamagata Univ. Sch. of Med. Assistant (40191217)
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| Research Abstract |
The purpose of this study is to investigate the mechanism of exercise- induced ST elevation in patients previous myocardial infarction. We approached this problem by canine experiment of 1-month old infarction and by exercise test in patients with previous myocardial infarction.
Experimental Study: We constructed experimental myocardial infarction in 6 mongrel dogs by ligation of the left anterior descending artery. One month after, epicardial mapping of 60 leads was performed during the right atrial pacing. The frequency of pacing increased from 120 bpm, by 20 bpm for each 3 min, until 240 bpm. The electrocardioraphic data was simultaneously recorded by CD-0055 and transmitted to a personal computer, PC9801. For each lead, timeintegrals from the onset of QRS to the offset of QRS, from the offset of QRS to the offset of T, and from the onset of QRS to the offset of T (AQRS, ASTT, AQRST, respectively) were calculated. Infarcted area was determined by staining with nitroblue tetrazolium.
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n the infarcted area, AQRS was significantly decreased and ASTT was significantly increased by the increase of heart rate. Also, the amplitude of Q wave increased significantly. AQRST showed no significant changes. On the other hand,in the non-infarcted area, none of AQRS, ASTT or AQRST changed significantly.
Clinical Study: We performed body surface electrocardiographic mapping in 68 patients with previous myocardial infarction, before and after the symptom limited treadmill exercise. The ECG mapping data was recorded by HPM5100 or VCM3000. For each lead, AQRS, ASTT, and AQRST were calculated. In the Infarcted area, AQRS decreased significantly, and ASTT and AQRST increased significantly by exercise. Also, the amplitude of Q wave increased significantly.
These results demonstrated that the decrease of AQRS was associated with the increase of ASTT both in the right atrial pacing and exercise test in chronic myocardial infarction. We conclude that changes in the ventricular depolarization (QRS) by the increased heart rate contributed to the exerciseinduced elevation of ST segment in the chronic myocardial infarction. Less
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