title: Phasic changes in arterial blood volume is influenced by collateral blood flow: implications for the quantification of coronary stenosis at rest.
abstract: BACKGROUND
  The systolic to diastolic arteriolar blood volume (aBV) ratio derived using myocardial contrast echocardiography (MCE) can identify the presence of coronary stenosis at rest. There are some patients with moderate to severe coronary stenosis who nonetheless exhibit a normal systolic to disatolic aBV ratio.
  
  
  OBJECTIVE
  To test the hypothesis that collateral blood flow influences the systolic to diastolic aBV ratio. MCE-defined phasic changes in aBV were recorded at baseline and up to 2 degrees of non-critical stenosis in 12 dogs. Measurements were made from MCE-defined collateralised and non-collateralised portions of the left anterior descending arterial bed.
  
  
  RESULTS
  Increases in both systolic and diastolic aBV were noted in the non-collateralised region with increasing degrees of stenosis. Although these increases in the absolute values did not reach statistical significance, the systolic to diastolic aBV signal ratio in the non-collateralised bed increased significantly between stages (analysis of variance, p = 0.003). In comparison, in the collateralised bed neither the absolute systolic nor diastolic aBV signals changed with increasing degrees of stenosis. Consequently, the aBV signal ratio between systole and diastole also did not change in this bed.
  
  
  CONCLUSIONS
  Phasic changes in aBV are influenced by the degree of collateral blood flow. Thus, if the region of interest is not placed in the centre of the vascular bed, the degree of stenosis may be underestimated by the systolic to diastolic aBV ratio. On the other hand, as extensive collateralisation may indicate excellent prognosis, this ratio may provide prognostic information independent of the coronary anatomy.
authors.affiliation: Division of Cardiovascular Medicine, Oregon Health & Science University, Portland, OR 97239, USA.
authors.forename: Marco
authors.initials: M
authors.lastname: Pascotto
authors.forename: Kevin
authors.initials: K
authors.lastname: Wei
authors.forename: Antonio
authors.initials: A
authors.lastname: Micari
authors.forename: Thanjavur
authors.initials: T
authors.lastname: Bragadeesh
authors.forename: Norman Craig
authors.initials: NC
authors.lastname: Goodman
authors.forename: Sanjiv
authors.initials: S
authors.lastname: Kaul
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity; D001810:Blood Volume / Q000502:physiology; D003097:Collateral Circulation / Q000502:physiology*; D003326:Coronary Circulation / Q000502:physiology*; D023921:Coronary Stenosis / Q000175:diagnosis / Q000503:physiopathology*; D003971:Diastole / Q000502:physiology; D004285:Dogs; D012146:Rest; D013599:Systole / Q000502:physiology