title: Renovascular impedance correlates with portal pressure in patients with liver cirrhosis.
abstract: OBJECTIVE
  To prospectively evaluate, in patients with liver cirrhosis, the correlation between the renovascular impedance measured by using color flow and pulsed wave Doppler ultrasonography (US) and the portal pressure measured by using the hepatic venous pressure gradient (HVPG).
  
  
  METHODS
  The study was approved by the senior staff committee (comparable to institutional review board) of the university hospital, and written informed consent was obtained from all patients. Thirty-one patients with cirrhosis (22 men, nine women; mean age, 57.6 years +/- 8.8 [standard deviation]) and esophageal varices were consecutively enrolled in the study. Having fasted, the patients underwent color flow and pulsed wave Doppler US of the right interlobar renal artery (RRA) and the left interlobar renal artery (LRA). The resistance index (RI) and pulsatility index (PI) were determined. On the same day, with fluoroscopic guidance, a 5-F balloon-tipped catheter was advanced, via the right basilic vein, into the right hepatic vein; HVPG was calculated as the difference between the wedged and free hepatic pressures. All measurements were performed in triplicate, and permanent tracings were recorded. Correlations were made by using the Pearson test. The positive predictive value of renovascular impedance for detection of severe portal hypertension was determined.
  
  
  RESULTS
  Mean RI and PI values were 0.67 +/- 0.07 and 1.21 +/- 0.25, respectively, for the RRA, and 0.68 +/- 0.07 and 1.24 +/- 0.26, respectively, for the LRA. All patients had portal hypertension (mean HVPG, 19.3 mm Hg +/- 4.7; range, 11.5-33.5 mm Hg). Neither portal pressure nor renal impedance correlated with Child-Pugh score for cirrhosis. Renal artery impedance indexes correlated with the HVPG (for RRA RI: R = 0.424, P = .03; for RRA PI: R = 0.402, P = .04; for LRA RI: R = 0.352, P = .05; for LRA PI: R = 0.393, P = .02). A higher-than-normal renal impedance had a high positive predictive value (RRA RI and PI, 100%; LRA RI, 92%; LRA PI, 84%) for the detection of severe portal hypertension.
  
  
  CONCLUSIONS
  Renovascular impedance had a direct correlation with HVPG.
authors.affiliation: Dipartimento di Medicina Interna, Cardioangiologia, Epatologia, Università di Bologna, Policlinico S. Orsola-Malpighi, via Albertoni 15-40138 Bologna, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Berzigotti
authors.forename: Andrea
authors.initials: A
authors.lastname: Casadei
authors.forename: Donatella
authors.initials: D
authors.lastname: Magalotti
authors.forename: Nicola
authors.initials: N
authors.lastname: Castaldini
authors.forename: Francesco
authors.initials: F
authors.lastname: Losinno
authors.forename: Cristina
authors.initials: C
authors.lastname: Rossi
authors.forename: Marco
authors.initials: M
authors.lastname: Zoli
mesh_terms: D000328:Adult; D000368:Aged; D004932:Esophageal and Gastric Varices / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D006801:Humans; D006978:Hypertension, Renovascular / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008103:Liver Cirrhosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D017082:Portal Pressure; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D018615:Ultrasonography, Doppler, Color; D018617:Ultrasonography, Doppler, Pulsed; D014655:Vascular Resistance