title: Assessment of microcirculatory remodeling with intracoronary flow velocity and pressure measurements: validation with endomyocardial sampling in cardiac allografts.
abstract: BACKGROUND
  Intracoronary physiology techniques have been validated extensively for the assessment of epicardial stenoses but not for the lone study of coronary microcirculation. We performed a comparison between 4 intracoronary physiological indices with the actual structural microcirculatory changes documented in transplanted hearts.
  
  
  RESULTS
  In 17 cardiac allograft patients without coronary stenoses, ECG, intracoronary Doppler flow velocity, and aortic pressure were digitally recorded before and during maximal hyperemia with a dedicated system. Postprocessing of data yielded 4 indices of microcirculatory status: coronary flow velocity reserve (2.13+/-0.59), instantaneous hyperemic diastolic velocity pressure slope (2.33+/-1.25 cm x s x (-1)mm Hg(-1)), coronary resistance index (1.65+/-0.88 mm Hg x cm(-1) x s(-1)), and coronary resistance reserve (2.36+/-0.65). Quantitative morphometry was performed in endomyocardial biopsies during the same hospital intake; arteriolar obliteration (76.57+/-6.95%) and density (2.00+/-1.22 arterioles per 1 mm(2)) and capillary density (645+/-179 capillaries per 1 mm(2)) were measured. Univariate regression analysis between intracoronary measurements and histological findings revealed that instantaneous hyperemic diastolic velocity-pressure slope correlated with arteriolar obliteration (r=0.58, P=0.014) and capillary density (r=0.60, P=0.012). Statistical adjustment revealed an independent contribution of arteriolar obliteration (beta=0.61, P=0.0009) and capillary density (beta=-0.60, P=0.0008) to instantaneous hyperemic diastolic velocity-pressure slope values, resulting in an excellent predictive model (r=0.84, P=0.0002). Coronary resistance index correlated only with capillary density (r=0.70, P=0.019). Relative indices (coronary flow velocity reserve and coronary resistance reserve) did not correlate significantly with arteriolar obliteration, capillary density, or arteriolar density.
  
  
  CONCLUSIONS
  Intracoronary indices derived from pressure and flow, particularly instantaneous hyperemic diastolic velocity-pressure slope, appear to be superior to coronary flow velocity reserve in detecting structural microcirculatory changes. Both arteriolar obliteration and capillary rarefaction seem to influence microcirculatory hemodynamics independently.
authors.affiliation: Cardiovascular Institute, Hospital Clínico San Carlos, Madrid, Spain. escaned@secardiologia.es
authors.forename: Javier
authors.initials: J
authors.lastname: Escaned
authors.forename: Alex
authors.initials: A
authors.lastname: Flores
authors.forename: Pablo
authors.initials: P
authors.lastname: García-Pavía
authors.forename: Javier
authors.initials: J
authors.lastname: Segovia
authors.forename: Jesús
authors.initials: J
authors.lastname: Jimenez
authors.forename: Paloma
authors.initials: P
authors.lastname: Aragoncillo
authors.forename: Clara
authors.initials: C
authors.lastname: Salas
authors.forename: Fernando
authors.initials: F
authors.lastname: Alfonso
authors.forename: Rosana
authors.initials: R
authors.lastname: Hernández
authors.forename: Dominick J
authors.initials: DJ
authors.lastname: Angiolillo
authors.forename: Pilar
authors.initials: P
authors.lastname: Jiménez-Quevedo
authors.forename: Camino
authors.initials: C
authors.lastname: Bañuelos
authors.forename: Luis
authors.initials: L
authors.lastname: Alonso-Pulpón
authors.forename: Carlos
authors.initials: C
authors.lastname: Macaya
mesh_terms: D000328:Adult; D001160:Arterioles / Q000473:pathology; D001783:Blood Flow Velocity; D001794:Blood Pressure; D002196:Capillaries / Q000473:pathology; D003326:Coronary Circulation; D003971:Diastole; D004699:Endocardium / Q000473:pathology; D005260:Female; D016027:Heart Transplantation; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology; D008297:Male; D055806:Microvessels / Q000503:physiopathology*; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology; D011237:Predictive Value of Tests; D014184:Transplantation, Homologous; D014655:Vascular Resistance; D055815:Young Adult