title: Alpha-adrenergic receptor blockade and hyperaemic response in patients with intermediate coronary stenoses.
abstract: BACKGROUND
  Maximal hyperaemia is paramount in the diagnosis of patients with coronary artery disease. However in these patients, enhanced alpha-adrenergic microvascular vasoconstriction may preclude adenosine to induce maximal hyperaemia.
  
  
  OBJECTIVE
  To assess the presence and the clinical relevance of residual microvascular resistance after administration of adenosine.
  
  
  RESULTS
  Fractional flow reserve (FFR, calculated by coronary pressure measurements during adenosine-induced hyperaemia) was assessed in 85 patients with an intermediate coronary stenosis (mean diameter stenosis of 50+/-1%) and normal left ventricular function which were divided into the following three groups: (a) 33 patients before and after IC bolus of phentolamine, an alpha1-, alpha2-adrenergic blocker; (b) 32 patients before and after IC bolus of urapidil, a selective alpha1-adrenergic blocker; (c) 20 patients before and after IC bolus of saline. Since minimal luminal diameter remained unchanged before and after phentolamine (1.46+/-0.06 vs. 1.47+/-0.06 mm, ns), urapidil (1.46+/-0.06 vs. 1.39+/-0.08, ns), and saline (1.56+/-0.08 vs. 1.55+/-0.08, ns), changes in FFR reflects changes in microvascular resistance. Overall, phentolamine and urapidil induced a slight but significant decrease in FFR (phentolamine: 0.79+/-0.02 vs. 0.77+/-0.02, p<0.05; urapidil: 0.78+/-0.02 vs. 0.75+/-0.02, p<0.05). However, only 6 patients showed a change in FFR from > or = 0.75 to <0.75 and no patients showed a change in FFR from > or = 0.80 to <0.75 that could have influenced clinical decision making. Saline did not induce any change in FFR. Phentolamine and urapidil induced only transient and negligible haemodynamic changes in heart rate and blood pressure.
  
  
  CONCLUSIONS
  The administration of alpha-adrenergic blockers in addition to adenosine unmasks a small, yet clinically irrelevant, degree of residual microvascular tone. The consequential changes in FFR values do not significantly affect clinical decision making.
authors.affiliation: Cardiovascular Center Aalst, Onze Lieve Vrouw Clinic, Moorselbaan 164, B-9300 Aalst, Belgium.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Barbato
authors.forename: Jozef
authors.initials: J
authors.lastname: Bartunek
authors.forename: Wilbert
authors.initials: W
authors.lastname: Aarnoudse
authors.forename: Marc
authors.initials: M
authors.lastname: Vanderheyden
authors.forename: Frank
authors.initials: F
authors.lastname: Staelens
authors.forename: William
authors.initials: W
authors.lastname: Wijns
authors.forename: Guy R
authors.initials: GR
authors.lastname: Heyndrickx
authors.forename: Nico H J
authors.initials: NH
authors.lastname: Pijls
authors.forename: Bernard
authors.initials: B
authors.lastname: De Bruyne
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000627:therapeutic use*; D001794:Blood Pressure / Q000502:physiology; D003324:Coronary Artery Disease / Q000473:pathology / Q000503:physiopathology; D003326:Coronary Circulation / Q000502:physiology; D023921:Coronary Stenosis / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D005260:Female; D006801:Humans; D006940:Hyperemia / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010646:Phentolamine / Q000627:therapeutic use*; D010879:Piperazines / Q000627:therapeutic use*
chemical_list: D000317:Adrenergic alpha-Antagonists; D010879:Piperazines; C015568:urapidil; D010646:Phentolamine