title: Vein graft function improvement after percutaneous intervention: evaluation with MR flow mapping.
abstract: OBJECTIVE
  To provide functional reference values in single and sequential vein grafts by using magnetic resonance (MR) flow mapping and to examine the effect of percutaneous intervention (PCI) on coronary artery bypass graft function.
  
  
  METHODS
  Fast MR flow mapping at baseline and during adenosine-induced stress was performed in 39 nonstenotic single vein grafts and 20 nonstenotic sequential vein grafts, as well as in 15 stenotic vein grafts before and 7.3 weeks +/- 1.5 after successful PCI. We evaluated the following parameters (in terms of mean values +/- SDs): average peak velocity (APV) at baseline, stress APV, and velocity reserve. Parameters in nonstenotic single and sequential vein grafts were compared by means of unpaired two-tailed Student t testing. To evaluate changes in velocities before and after PCI, a paired two-tailed Student t test was used. P <.05 was considered to indicate a statistically significant difference.
  
  
  RESULTS
  Reference values in single vein grafts for baseline APV, stress APV, and velocity reserve were 8.6 cm/sec +/- 3.4, 20.2 cm/sec +/- 9.5, and 2.4 +/- 0.8, respectively. In sequential vein grafts, significantly higher values for baseline APV (12.2 cm/sec +/- 5.0) and stress APV (27.2 cm/sec +/- 10.6) but a similar velocity reserve (2.3 +/- 0.7) were found. Significant improvements were observed after PCI in baseline APV (before PCI: 9.2 cm/sec +/- 6.6; after PCI: 12.9 cm/sec +/- 7.9; P =.008) and stress APV (before PCI: 12.9 cm/sec +/- 6.3; after PCI: 27.1 cm/sec +/- 13.9; P <.001). No improvement in velocity reserve was observed.
  
  
  CONCLUSIONS
  Significantly higher absolute velocity and flow values were observed in sequential versus single vein grafts, underscoring the need for separate functional reference values for different graft types. Graft function showed significant improvement after PCI to the point that it was restored or nearly restored to reference values.
authors.affiliation: Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, C5-P, 2300 RC Leiden, the Netherlands.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Langerak
authors.forename: Hubert W
authors.initials: HW
authors.lastname: Vliegen
authors.forename: J Wouter
authors.initials: JW
authors.lastname: Jukema
authors.forename: Aeilko H
authors.initials: AH
authors.lastname: Zwinderman
authors.forename: Hildo J
authors.initials: HJ
authors.lastname: Lamb
authors.forename: Albert
authors.initials: A
authors.lastname: de Roos
authors.forename: Ernst E
authors.initials: EE
authors.lastname: van der Wall
mesh_terms: D000241:Adenosine / Q000009:adverse effects; D000368:Aged; D015906:Angioplasty, Balloon, Coronary; D001783:Blood Flow Velocity; D001026:Coronary Artery Bypass; D003326:Coronary Circulation / Q000502:physiology; D005260:Female; D006083:Graft Occlusion, Vascular / Q000175:diagnosis; D006801:Humans; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging; D008297:Male; D012016:Reference Values
chemical_list: D000241:Adenosine