title: Functional diagnosis of coronary stenoses using pressure drop coefficient: a pilot study in humans.
abstract: OBJECTIVE
  Myocardial fractional flow reserve (FFR) in conjunction with coronary flow reserve (CFR) is used to evaluate the hemodynamic severity of coronary lesions. However, discordant results between FFR and CFR have been observed in intermediate coronary lesions. A functional parameter, pressure drop coefficient (CDP; ratio of pressure drop to distal dynamic pressure), was assessed using intracoronary pressure drop (dp) and average peak velocity (APV). The CDP is a nondimensional ratio, derived from fundamental fluid dynamic principles. We sought to evaluate the correlation of CDP with FFR, CFR, and hyperemic stenosis resistance (HSR: ratio of pressure drop to APV) in human subjects.
  
  
  METHODS
  Twenty-seven patients with reversible perfusion defects based on SPECT were consented for the study before cardiac catheterization. Distal coronary pressure and APV were measured simultaneously for each coronary lesion using a Combowire(©) during cardiac catheterization. Reference diameter, minimal lumen diameter, and %AS were obtained by quantitative coronary angiography. Maximum hyperemia was induced by IV adenosine (140 µg/kg/min). CDP was calculated as, (Δp)/(0.5 × ρ × APV(2) ). The density of blood (ρ) was assumed to be 1.05 gm/cm(3) .
  
  
  RESULTS
  The functional index, CDP, when correlated simultaneously with FFR and CFR, was found to have a significant correlation (r = 0.61; P < 0.05). Similarly a significant correlation was achieved when CDP was correlated with HSR (r = 0.91; P < 0.001). This is consistent with the definition of CDP, which is a functional parameter that includes both pressure and flow information.
  
  
  CONCLUSIONS
  CDP, a nondimensional parameter combining simultaneous measurements of pressure drop and velocity data, can accurately define the severity of coronary stenoses and could prove advantageous clinically.
authors.affiliation: School of Dynamic Systems, Mechanical Engineering Program, University of Cincinnati, Cincinnati, Ohio; Veteran Affairs Medical Center, Cincinnati, Ohio.
authors.forename: Kranthi K
authors.initials: KK
authors.lastname: Kolli
authors.forename: Tarek A
authors.initials: TA
authors.lastname: Helmy
authors.forename: Srikara V
authors.initials: SV
authors.lastname: Peelukhana
authors.forename: Imran
authors.initials: I
authors.lastname: Arif
authors.forename: Massoud A
authors.initials: MA
authors.lastname: Leesar
authors.forename: Lloyd H
authors.initials: LH
authors.lastname: Back
authors.forename: Rupak K
authors.initials: RK
authors.lastname: Banerjee
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Effat
mesh_terms: D000241:Adenosine / Q000008:administration & dosage; D061605:Administration, Intravenous; D062186:Arterial Pressure; D001783:Blood Flow Velocity; D006328:Cardiac Catheterization / Q000295:instrumentation; D062906:Cardiac Catheters; D017023:Coronary Angiography; D003326:Coronary Circulation; D023921:Coronary Stenosis / Q000175:diagnosis* / Q000503:physiopathology; D003331:Coronary Vessels / Q000503:physiopathology*; D004867:Equipment Design; D005260:Female; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D009820:Ohio; D010865:Pilot Projects; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D014665:Vasodilator Agents / Q000008:administration & dosage
chemical_list: D014665:Vasodilator Agents; D000241:Adenosine
keywords: cardiac hemodynamics; catheterization; coronary disease; stenosis