title: Coronary pressure and flow relationships in humans: phasic analysis of normal and pathological vessels and the implications for stenosis assessment: a report from the Iberian-Dutch-English (IDEAL) collaborators.
abstract: Our understanding of human coronary physiological behaviour is derived from animal models. We sought to describe physiological behaviour across a large collection of invasive pressure and flow velocity measurements, to provide a better understanding of the relationships between these physiological parameters and to evaluate the rationale for resting stenosis assessment.
  
  
  
  Five hundred and sixty-seven simultaneous intracoronary pressure and flow velocity assessments from 301 patients were analysed for coronary flow velocity, trans-stenotic pressure gradient (TG), and microvascular resistance (MVR). Measurements were made during baseline and hyperaemic conditions. The whole cardiac cycle and the diastolic wave-free period were assessed. Stenoses were assessed according to fractional flow reserve (FFR) and quantitative coronary angiography DS%. With progressive worsening of stenoses, from unobstructed angiographic normal vessels to those with FFR ≤ 0.50, hyperaemic flow falls significantly from 45 to 19 cm/s, Ptrend < 0.001 in a curvilinear pattern. Resting flow was unaffected by stenosis severity and was consistent across all strata of stenosis (Ptrend > 0.05 for all). Trans-stenotic pressure gradient rose with stenosis severity for both rest and hyperaemic measures (Ptrend < 0.001 for both). Microvascular resistance declines with stenosis severity under resting conditions (Ptrend < 0.001), but was unchanged at hyperaemia (2.3 ± 1.1 mmHg/cm/s; Ptrend = 0.19).
  
  
  
  With progressive stenosis severity, TG rises. However, while hyperaemic flow falls significantly, resting coronary flow is maintained by compensatory reduction of MVR, demonstrating coronary auto-regulation. These data support the translation of coronary physiological concepts derived from animals to patients with coronary artery disease and furthermore, suggest that resting pressure indices can be used to detect the haemodynamic significance of coronary artery stenoses.
authors.affiliation: Imperial College London, London, UK.
authors.forename: Sukhjinder S
authors.initials: SS
authors.lastname: Nijjer
authors.affiliation: VU University Medical Centre, Amsterdam, The Netherlands.
authors.forename: Guus A
authors.initials: GA
authors.lastname: de Waard
authors.affiliation: Imperial College London, London, UK.
authors.forename: Sayan
authors.initials: S
authors.lastname: Sen
authors.affiliation: Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: Tim P
authors.initials: TP
authors.lastname: van de Hoef
authors.affiliation: Imperial College London, London, UK.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Petraco
authors.affiliation: Cardiovascular Institute, Hospital Clínico San Carlos, Madrid, Spain.
authors.forename: Mauro
authors.initials: M
authors.lastname: Echavarría-Pinto
authors.affiliation: Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: Martijn A
authors.initials: MA
authors.lastname: van Lavieren
authors.affiliation: Amphia Hospital, Breda, The Netherlands.
authors.forename: Martijn
authors.initials: M
authors.lastname: Meuwissen
authors.affiliation: VU University Medical Centre, Amsterdam, The Netherlands.
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Danad
authors.affiliation: VU University Medical Centre, Amsterdam, The Netherlands.
authors.forename: Paul
authors.initials: P
authors.lastname: Knaapen
authors.affiliation: Cardiovascular Institute, Hospital Clínico San Carlos, Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Escaned
authors.affiliation: Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: Jan J
authors.initials: JJ
authors.lastname: Piek
authors.affiliation: Imperial College London, London, UK.
authors.forename: Justin E
authors.initials: JE
authors.lastname: Davies
authors.affiliation: VU University Medical Centre, Amsterdam, The Netherlands n.vanroyen@vumc.nl.
authors.forename: Niels
authors.initials: N
authors.lastname: van Royen
mesh_terms: D001783:Blood Flow Velocity; D003251:Constriction, Pathologic; D017023:Coronary Angiography; D003326:Coronary Circulation; D023921:Coronary Stenosis; D003331:Coronary Vessels; D053805:Fractional Flow Reserve, Myocardial; D006801:Humans
keywords: Autoregulation; Microvascular resistance; Physiological lesion assessment; Stenosis