Hepatic arterial buffer response in patients with advanced cirrhosis

Abstract

Hepatic arterial buffer response (HABR) is considered an important compensatory mechanism to maintain perfusion of the liver by hepatic arterial vasodilation on reduction of portal venous perfusion. HABR has been suggested to be impaired in patients with advanced cirrhosis. In patients with hepatopetal portal flow, placement of a transjugular intrahepatic portosystemic shunt (TIPS) reduces portal venous liver perfusion. Accordingly, patients with severe cirrhosis should have impaired HABR after TIPS implantation. Therefore, the aim of this study was to investigate the effect of TIPS on HABR as reflected by changes in resistance index ( H epatic arterial buffer response (HABR) is an intrinsic regulatory mechanism of the liver to maintain total hepatic blood flow when portal perfusion decreases. Increased hepatic arterial blood flow mediated by adenosine washout in the portal triad 1-3 and independent of hepatic oxygen supply or demand compensates for the reduced portal tributary blood flow (for review, see Lautt 4,5 ). This phenomenon has been shown under various experimental conditions such as endotoxinemia 6 or portal vein ligation 7 and in the clinical setting after liver transplantation. 8 Just recently, maintenance of HABR has been shown in an animal model of cirrhosis (namely, CCl 4 -induced cirrhosis in the rat). 9,10 Thus far, it is not clear whether HABR is preserved in patients with cirrhosis and whether it is dependent on the stage of liver disease. Several studies have shown an increased hepatic arterial resistance in patients with cirrhosis. This was related to the degree of portal hypertension, 11,12 portal resistance, 12,13 and Child-Pugh score, 12 respectively. In contrast to these observations, Kleber et al. 14 recently reported an increased hepatic arterial flow volume and decreased pulsatility index of the hepatic artery in Child-Pugh class C patients. In this study, intra-arterial infusion of adenosine induced an increase in hepatic arterial blood flow that was independent of Child-Pugh class, suggesting that HABR may be independent of the stage of liver disease.Hepatofugal portal venous blood flow has been reported in 2% to 15% of patients with cirrhosis. [15][16][17] According to the HABR hypothesis, this condition should be a strong stimulus for hepatic arterial vasodilation. Similarly, the transjugular intrahepatic portosystemic shunt (TIPS) procedure results in a decreased portal perfusion fraction of total liver blood flow. 18 Therefore, assuming an impaired HABR in patients with advanced cirrhosis, hepatic arterial blood flow should increase less and the decrease in resistance of the hepatic artery should be lower after the TIPS procedure than in patients with compensated cirrhosis.To test this hypothesis, we compared the hepatic arterial resistance index (RI) in cirrhotic patients with hepatopetal and hepatofugal portal venous blood flow. Furthermore, the effects of TIPS on RI were examined in both groups of patients using duplex Doppler ultrasonography. Patients and MethodsPatients. A...

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