title: Epicardial intimal thickening in transplant coronary artery disease and resistance vessel response to adenosine: a combined intravascular ultrasound and Doppler study.
abstract: BACKGROUND
  Transplant coronary artery disease is the major factor limiting long-term survival after cardiac transplantation. Both intravascular ultrasound imaging (IVUS) and intracoronary flow studies have been used to assess the morphologic and functional importance of the disease. However, the impact of epicardial intimal thickening, as quantitated by IVUS, on the resistance vessel response to adenosine has not been explored.
  
  
  RESULTS
  Seventy-six coronary arteries without angiographically overt coronary disease (diameter stenosis visually, < or =50%) were studied with both IVUS and intracoronary Doppler in 54 patients 0.5 to 127 months after transplantation. Mean intimal index and mean lumen cross-sectional area (CSA) were determined by IVUS, and the average was obtained for every coronary artery. Coronary flow average peak velocity (APV) was obtained by Doppler before and after administration of 16 microg adenosine to calculate coronary flow velocity reserve (CFVR) and coronary vascular resistance index (CVRI). The hyperemic pressure-flow velocity ratio (hyperemic mean aortic pressure/hyperemic APV) as an index of minimal coronary resistance was further derived. The intimal index (mean, 20.0+/-10%) did not correlate with either CFVR (mean, 2.9+/-0.7, r=.12) or CVRI (mean, 0.33+/-0.1, r=.16). However, a significant correlation between the intimal index and the hyperemic pressure-flow velocity ratio (mean, 1.52+/-0.47 mm Hg/cm/s, r=.74, P<.0001) was found. The hyperemic pressure-flow velocity ratio was not influenced by the presence or absence of left ventricular hypertrophy or a mild acute rejection period (International Society for Heart and Lung Transplantation grades IA and IB).
  
  
  CONCLUSIONS
  This study shows that in patients without angiographically overt coronary disease, the degree of epicardial intimal thickening as quantified by IVUS did not predict the adenosine vasodilator response, when determined by commonly used parameters such as CFVR and CVRI. The hyperemic pressure-flow velocity ratio best reflected the functional significance of transplant coronary artery disease.
authors.affiliation: Department of Internal Medicine, Klinikum Innenstadt, University of Munich, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Klauss
authors.forename: K
authors.initials: K
authors.lastname: Ackermann
authors.forename: K H
authors.initials: KH
authors.lastname: Henneke
authors.forename: C
authors.initials: C
authors.lastname: Spes
authors.forename: T
authors.initials: T
authors.lastname: Zeitlmann
authors.forename: F
authors.initials: F
authors.lastname: Werner
authors.forename: E
authors.initials: E
authors.lastname: Regar
authors.forename: J
authors.initials: J
authors.lastname: Rieber
authors.forename: P
authors.initials: P
authors.lastname: Uberfuhr
authors.forename: B
authors.initials: B
authors.lastname: Reichart
authors.forename: K
authors.initials: K
authors.lastname: Theisen
authors.forename: H
authors.initials: H
authors.lastname: Mudra
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D000293:Adolescent; D000328:Adult; D001783:Blood Flow Velocity / Q000187:drug effects; D017023:Coronary Angiography; D003326:Coronary Circulation / Q000187:drug effects*; D003327:Coronary Disease / Q000473:pathology*; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000187:drug effects / Q000473:pathology*; D016027:Heart Transplantation / Q000009:adverse effects*; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000209:etiology; D008875:Middle Aged; D015203:Reproducibility of Results; D014463:Ultrasonography
chemical_list: D000241:Adenosine