JaLCDOI 10.18926/AMO/32442
FullText URL fulltext.pdf
Author Saito, Daiji| Yasuhara, Koichiro| Takeda, Kou| Hyodo, Tatsuo| Fujii, Akinobu| Uchida, Toshiaki| Abe, Yukihiro| Haraoka, Shoichi| Nagashima, Hideo|
Abstract <p>The effects of intravenous infusion of isoproterenol on stenosis resistance were studied in the anesthetized open-chest dog. The circumflex coronary artery (LCx) was isolated near its origin and an electromagnetic flow transducer was placed around the vessel for measuring coronary flow. A polyethylene catheter was inserted into the small branch of LCx for monitoring distal coronary pressure. LCx was constricted with a thick cotton string to a degree of obstruction that eliminated reactive hyperemia following a 20-second coronary occlusion. The coronary resistance across the stenotic segment (RL) was calculated as the pressure gradient across the stenosis divided by coronary flow. Isoproterenol was infused intravenously in a dose to keep the heart rate at a level 25-30% above the control with and without coronary constriction. For maintaining the ascending aortic pressure at the pre-isoproterenol level, the descending thoracic aorta was constricted with a tape. In the absence of coronary constriction, the vascular resistance of large coronary arteries was not affected by isoproterenol with a significant increase in coronary flow. In the presence of coronary stenosis, isoproterenol markedly increased RI regardless of additional aortic constriction. The magnitude of the increase in RL during aortic constriction varied directly with the percent increase in the pressure gradient across the coronary stenosis. Pacing-tachycardia essentially did not affect RL. These results suggest that isoproterenol increased the vascular resistance of the stenotic segment with fixed caliber.</p>
Keywords coronary cinstriction open-chest dog distal coronary pressure
Amo Type Article
Published Date 1983-02
Publication Title Acta Medica Okayama
Volume volume37
Issue issue1
Publisher Okayama University Medical School
Start Page 59
End Page 66
ISSN 0386-300X
NCID AA00508441
Content Type Journal Article
language 英語
File Version publisher
Refereed True
PubMed ID 6846053
Web of Science KeyUT A1983QD83600007
JaLCDOI 10.18926/AMO/32419
FullText URL fulltext.pdf
Author Saito, Daiji| Abe, Yukihiro| Takeda, Koh| Hyodo, Tazuo| Tani, Hideki| Ohnishi, Shigeru| Haraoka, Shoichi| Nagashima, Hideo|
Abstract <p>Stress-induced changes in the resistance due to coronary arterial stenosis of a fixed diameter and in the myocardial blood flow distal to the stenosis were investigated in the open-chest dog. Myocardial blood flow in the inner and outer third of the left ventricular wall was continuously measured with heated cross-thermocouples. The circumflex coronary artery was constricted with a thick string so that myocardial reactive hyperemia was nearly eliminated. Without constriction, a 15-second occlusion of the artery produced no significant changes in the resistance of large coronary arteries. On the contrary, in the presence of coronary constriction, a brief coronary occlusion caused a sustained decrease in distal coronary pressure and subendocardial myocardial flow during reactive hyperemia, while coronary flow returned quickly to the pre-occlusion level with significant reactive hyperemia of subepicardial flow. This change resulted in a long-lasting increase in the stenosis resistance. These results suggest that stenosis resistance changes dynamically, resulting in additional myocardial ischemia especially in the subendocardial myocardial layers.</p>
Keywords stenosis resistance coronary constriction transient myocardial ischemia myocardial flow
Amo Type Article
Published Date 1983-10
Publication Title Acta Medica Okayama
Volume volume37
Issue issue5
Publisher Okayama University Medical School
Start Page 423
End Page 429
ISSN 0386-300X
NCID AA00508441
Content Type Journal Article
language 英語
File Version publisher
Refereed True
PubMed ID 6650224
Web of Science KeyUT A1983RN98400006