title: Hemodynamic responses to acute and gradual renal artery stenosis in pigs.
abstract: BACKGROUND
  Reduction of renal blood flow (RBF) due to a renal artery stenosis (RAS) can lead to renal ischemia and atrophy. However in pigs, there are no data describing the relationship between the degree of RAS, the reduction of RBF, and the increase of systemic plasma renin activity (PRA). Therefore, we conducted a study in order to measure the effect of acute and gradual RAS on RBF, mean arterial pressure (MAP), and systemic PRA in pigs.
  
  
  METHODS
  RAS was induced experimentally in six pigs using an occluder placed around the renal artery downstream of an ultrasound flow probe. The vascular occluder was inflated gradually to reduce RBF. At each inflation step, percentage of RAS was measured by digital subtraction angiography (DSA) with simultaneous measurements of RBF, MAP, and PRA. Data were normalized to baseline values obtained before RAS induction. Piecewise regression analysis was performed between percentage of RAS and relative RBF, MAP, and PRA, respectively.
  
  
  RESULTS
  In all pigs, the relationship between the degree of RAS and RBF was similar. RBF decreased over a threshold of 42% of RAS, with a rapid drop in RBF when RAS reached 70%. PRA increased dramatically over a threshold of 58% of RAS (+1,300% before occlusion). MAP increased slightly (+15% before occlusion) without identifiable threshold.
  
  
  CONCLUSIONS
  This study emphasizes that the relation between the degree of RAS and RBF and systemic PRA is not linear and that a high degree of RAS must be reached before the occurrence of significant hemodynamic and humoral effects.
authors.affiliation: Département de Néphrologie, Hôpital Edouard Herriot, Hospices Civils de Lyon, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Rognant
authors.forename: Olivier
authors.initials: O
authors.lastname: Rouvière
authors.forename: Marc
authors.initials: M
authors.lastname: Janier
authors.forename: Quoc Hung
authors.initials: QH
authors.lastname: Lê
authors.forename: Paul
authors.initials: P
authors.lastname: Barthez
authors.forename: Maurice
authors.initials: M
authors.lastname: Laville
authors.forename: Laurent
authors.initials: L
authors.lastname: Juillard
mesh_terms: D000208:Acute Disease; D015901:Angiography, Digital Subtraction; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D002908:Chronic Disease; D004195:Disease Models, Animal; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006977:Hypertension, Renal / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D008955:Models, Cardiovascular; D012078:Renal Artery Obstruction / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D012079:Renal Circulation / Q000502:physiology*; D012083:Renin / Q000097:blood; D034421:Sus scrofa; D014463:Ultrasonography
chemical_list: D012083:Renin