title: Effect of systemic blood pressure on microcollateral circulation evaluated by real-time contrast echocardiography.
abstract: BACKGROUND
  In acute myocardial infarction, residual collateral-derived myocardial blood flow (CBF) within the ischemic area is one of the major determinants of infarct size. Management of systemic blood pressure (sBP) related to maintain collateral circulation is still difficult. The aim of this study was to reveal the influence of sBP on the rescue of area at risk by collateral circulation.
  
  
  METHODS
  Real-time myocardial contrast echocardiography just after the onset of complete occlusion of the left circumflex coronary artery was performed in collateral-rich open-chest dogs. The video intensity of the ischemic area was evaluated during the occlusion and the CBF (A x beta) was calculated from a replenishment curve: y = A (1 - e(-beta t)). To analyze the effect of sBP on the collateral circulation, sBP was altered by infusion of nitroglycerin or etilefrine hydrochloride. To evaluate the defect size (%DS), every end-systolic myocardial contrast echocardiography image after left circumflex coronary artery occlusion was converted into binary images using custom offline software.
  
  
  RESULTS
  The %DS increased and CBF slightly decreased at low sBP. The %DS decreased and CBF increased at high sBP. At excessively high sBP, %DS increased and CBF decreased again.
  
  
  CONCLUSIONS
  Real-time myocardial contrast echocardiography, which is a useful noninvasive method to evaluate the collateral perfusion quantitatively, has a crucial role in the decision of patient treatment and management strategy of acute myocardial infarction.
authors.affiliation: School of Allied Health Sciences, Osaka University, Faculty of Medicine, Osaka, Japan. ishikura@sahs.med.osaka-u.ac.jp
authors.forename: Fuminobu
authors.initials: F
authors.lastname: Ishikura
authors.forename: Ayako
authors.initials: A
authors.lastname: Miki
authors.forename: Akiko
authors.initials: A
authors.lastname: Iwata
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Toshida
authors.forename: Masahiro
authors.initials: M
authors.lastname: Shakudo
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Asanuma
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kitakaze
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Shinozaki
authors.forename: Hidezo
authors.initials: H
authors.lastname: Mori
authors.forename: Shintaro
authors.initials: S
authors.lastname: Beppu
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003097:Collateral Circulation / Q000187:drug effects; D003326:Coronary Circulation / Q000187:drug effects; D004285:Dogs; D004452:Echocardiography / Q000295:instrumentation / Q000379:methods; D005039:Etilefrine / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D008833:Microcirculation / Q000000981:diagnostic imaging / Q000187:drug effects; D005996:Nitroglycerin / Q000494:pharmacology*; D012307:Risk Factors; D013997:Time Factors; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D014665:Vasodilator Agents; D005996:Nitroglycerin; D005039:Etilefrine