title: Patent side branches do not affect coronary blood flow in internal thoracic artery-left anterior descending anastomosis: an experimental study.
abstract: BACKGROUND
  It has been reported that large side branches of internal thoracic artery grafts may steal flow from the coronary circulation. Material an.
  
  
  METHODS
  To assess the importance of the side branches, we measured the proximal and distal flow and pressures (mean subclavian artery pressure and mean arterial anastomotic pressure) at baseline and during infusion of adenosine (0.5 mg/kg/min) in 10 Landrace pigs in which an internal thoracic artery-left anterior descending anastomosis was constructed without interruption of the side branches. The difference between proximal and distal flow was considered to represent the blood flow of the internal thoracic artery side branches. Measurements were then repeated after surgical occlusion of all the side branches.
  
  
  RESULTS
  At baseline, blood flow of the side branches represented 18% of the total flow in the proximal internal thoracic artery, and this percentage remained constant under the infusion of adenosine, which caused a 220% increase of the cardiac index and a 368% increase of the proximal flow. The infusion reduced the gradient along the left internal thoracic artery (mean subclavian artery pressure-mean arterial anastomotic pressure) from 15 to 10 mm Hg (P =.02) as the result of a lower mean subclavian artery pressure, although the mean arterial anastomotic pressure remained constant. Interruption of all the side branches resulted in a small and not significant increase in distal flow even after adenosine infusion.
  
  
  CONCLUSIONS
  These observations suggest that blood flow in the side branches is minimal either at baseline and under combined systemic and coronary vasodilation. Clinically significant flow steal from the coronary circulation to the internal thoracic artery side branches seems then unlikely.
authors.affiliation: Departments of Cardiac Surgery and Anesthesiology, Catholic University, Rome, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Pragliola
authors.forename: M
authors.initials: M
authors.lastname: Gaudino
authors.forename: G
authors.initials: G
authors.lastname: Bombardieri
authors.forename: C
authors.initials: C
authors.lastname: Barilaro
authors.forename: P
authors.initials: P
authors.lastname: Bruno
authors.forename: C
authors.initials: C
authors.lastname: Varano
authors.forename: T
authors.initials: T
authors.lastname: Santoro
authors.forename: G
authors.initials: G
authors.lastname: Possati
mesh_terms: D000714:Anastomosis, Surgical / Q000009:adverse effects* / Q000379:methods*; D000818:Animals; D003097:Collateral Circulation / Q000502:physiology*; D001026:Coronary Artery Bypass / Q000009:adverse effects* / Q000379:methods*; D003326:Coronary Circulation / Q000502:physiology*; D003971:Diastole; D004195:Disease Models, Animal; D005260:Female; D006439:Hemodynamics; D006801:Humans; D019060:Minimally Invasive Surgical Procedures / Q000009:adverse effects* / Q000379:methods*; D013552:Swine; D013599:Systole; D013895:Thoracic Arteries / Q000503:physiopathology* / Q000637:transplantation*; D014654:Vascular Patency / Q000502:physiology*