title: Acute absolute vasodilatation is associated with a lower vascular wall stiffness in pulmonary arterial hypertension.
abstract: BACKGROUND
  Acute vasoreactivity testing (VT) is considered mandatory in the diagnostic work-up of patients with pulmonary arterial hypertension (PAH). We studied the relation between the acute absolute arterial vasodilatation and the severity of vascular remodeling estimated by intravascular ultrasound (IVUS) in patients with idiopathic PAH.
  
  
  METHODS
  Simultaneous right heart catheterization and IVUS of the pulmonary artery (PA) were performed both in basal conditions and during short-term intravenous epoprostenol infusion in nineteen idiopathic PAH patients. Pulmonary vascular resistance (PVRi) and capacitance indexes (stroke volume/pulse pressure, Cp), were calculated. Local pulsatility was estimated by IVUS (IVUSp) (systolic-diastolic lumen area/diastolic lumen area×100; sA-dA/dA) and PA stiffness was assessed by the elastic modulus (E: pulse pressure/IVUSp).
  
  
  RESULTS
  Epoprostenol infusion (11±2ng/kg/min) determined a real vasodilatation (increment of dA>10%) in six patients. This vasodilation group presented on average significantly higher cardiac index, stroke volume index and Cp, and lower PVRi and IVUSp (P<0.05), with a lower E (P=0.08). Three patients were responders according to the actual criteria, but only one showed a real vasodilator response. Baseline E below the median value (≤190mm Hg) was able to differentiate patients with an acute vasodilator response (sensibility 83%, specificity 73%, area under ROC 0.81; P<0.05). Neither E nor vasodilator response is correlated with delta mean PA pressure and PVRi.
  
  
  CONCLUSIONS
  Patients with higher IVUSp and lesser E displayed an absolute PA vasodilation during VT with epoprostenol. The patients with a positive VT according to actual criteria do not necessarily have a real vasodilatation on intravascular ultrasound.
authors.affiliation: Depto de Fisiopatología, Hospital de Clínicas, Universidad de la República, Montevideo, Uruguay. jgrig@fmed.edu.uy
authors.forename: Juan C
authors.initials: JC
authors.lastname: Grignola
authors.forename: Enric
authors.initials: E
authors.lastname: Domingo
authors.forename: Rio
authors.initials: R
authors.lastname: Aguilar
authors.forename: Manuel
authors.initials: M
authors.lastname: Vázquez
authors.forename: Manuel
authors.initials: M
authors.lastname: López-Messeguer
authors.forename: Carlos
authors.initials: C
authors.lastname: Bravo
authors.forename: Antonio
authors.initials: A
authors.lastname: Roman
mesh_terms: D000328:Adult; D000368:Aged; D006328:Cardiac Catheterization / Q000379:methods; D011464:Epoprostenol / Q000494:pharmacology; D065627:Familial Primary Pulmonary Hypertension; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000175:diagnosis* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000187:drug effects / Q000502:physiology*; D059289:Vascular Stiffness / Q000187:drug effects / Q000502:physiology*; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*
chemical_list: D011464:Epoprostenol