title: Concurrent assessment of epicardial coronary artery stenosis and microvascular dysfunction using diagnostic endpoints derived from fundamental fluid dynamics principles.
abstract: BACKGROUND
  Simultaneously measured pressure and flow distal to coronary stenoses can be combined, in conjunction with anatomical measurements, to assess the status of both the epicardial and microvascular circulations.
  
  
  RESULTS
  Assessments of coronary hemodynamics were performed using fundamental fluid dynamics principles. We hypothesized that the pressure-drop coefficient (CDPe; trans-stenotic pressure drop divided by the dynamic pressure in the distal vessel) correlates linearly with epicardial and microcirculatory resistances concurrently. In 14 pigs, simultaneous measurements of distal coronary arterial pressure and flow were performed using a dual sensor-tipped guidewire in the setting of both normal and disrupted microcirculation, with the presence of epicardial coronary lesions of lt; 50% area stenosis (AS) and > 50% AS. The CDPe progressively increased from lesions of < 50% AS to > 50% AS and had a higher resolving power (45 +/- 22 to 193 +/- 140 in normal microcirculation; 248 +/- 137 to 351 +/- 140 in disrupted microcirculation) as compared to fractional flow reserve (FFR) and coronary flow reserve (CFR). Strong multiple linear correlation was observed for CDPe with combined FFR and CFR (r = 0.72; p < 0.0001). Further, the ratio of maximum pressure drop coefficient evaluated at the site of stenosis and its theoretical limiting value of minimum cross-sectional area was also able to distinguish different combinations of coronary artery diseases.
  
  
  CONCLUSIONS
  The CDPe can be readily obtained during routine pressure and flow measurements during cardiac catheterization. It is a promising clinical diagnostic parameter that can independently assess the severity of epicardial stenosis and microvascular impairment.
authors.affiliation: Department of Mechanical Engineering, University of Cincinnati, Cincinnati, Ohio 45221-0072, USA. rupak.banerjee@uc.edu
authors.forename: Rupak K
authors.initials: RK
authors.lastname: Banerjee
authors.forename: Koustubh D
authors.initials: KD
authors.lastname: Ashtekar
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Effat
authors.forename: Tarek A
authors.initials: TA
authors.lastname: Helmy
authors.forename: Edward
authors.initials: E
authors.lastname: Kim
authors.forename: Eric W
authors.initials: EW
authors.lastname: Schneeberger
authors.forename: Roy A
authors.initials: RA
authors.lastname: Sinha
authors.forename: William M
authors.initials: WM
authors.lastname: Gottliebson
authors.forename: Lloyd H
authors.initials: LH
authors.lastname: Back
mesh_terms: D000800:Angioplasty, Balloon; D000818:Animals; D023921:Coronary Stenosis / Q000503:physiopathology*; D003627:Data Interpretation, Statistical; D004195:Disease Models, Animal; D023381:Endpoint Determination; D006439:Hemodynamics / Q000502:physiology*; D008833:Microcirculation / Q000502:physiology; D008863:Microspheres; D055806:Microvessels / Q000503:physiopathology*; D008955:Models, Cardiovascular; D012039:Regional Blood Flow / Q000502:physiology*; D013552:Swine