Home About us Contact
|
Home About us Contact | ||
|
|
||
Portal Blood Flow (portal + blood_flow)
Selected AbstractsHepatic arterial buffer response in patients with advanced cirrhosisHEPATOLOGY, Issue 3 2002Veit Gülberg 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 (RI) of the hepatic artery. A total of 366 patients with cirrhosis (Child-Pugh class A, 106; class B, 168; class C, 92) underwent duplex Doppler ultrasonographic examination with determination of RI and maximal flow velocity in the portal vein before and 1 month after TIPS placement. Portosystemic pressure gradient was determined before and after TIPS placement. In 29 patients with hepatofugal portal blood flow, RI was significantly lower than in 337 patients with hepatopetal flow (0.63 ± 0.02 vs. 0.69 ± 0.01; P < .001). TIPS induced a significant decrease of the RI in patients with hepatopetal flow (RI, 0.69 ± 0.01 before vs. 0.64 ± 0.01 after TIPS; P = .001) but not in patients with hepatofugal flow (RI, 0.63 ± 0.02 before vs. 0.63 ± 0.02 after TIPS; NS). This response was not dependent on the Child-Pugh class. In conclusion, our results suggest that some degree of HABR is preserved even in patients with advanced cirrhosis with significant portal hypertension. [source] Regulatory processes interacting to maintain hepatic blood flow constancy: Vascular compliance, hepatic arterial buffer response, hepatorenal reflex, liver regeneration, escape from vasoconstrictionHEPATOLOGY RESEARCH, Issue 11 2007W. Wayne Lautt Constancy of hepatic blood flow (HBF) is crucial for several homeostatic roles. The present conceptual review focuses on interrelated mechanisms that act to maintain a constant HBF per liver mass. The liver cannot directly control portal blood flow (PF); therefore, these mechanisms largely operate to compensate for PF changes. A reduction in PF leads to reduced intrahepatic distending pressure, resulting in the highly compliant hepatic vasculature passively expelling up to 50% of its blood volume, thus adding to venous return, cardiac output and HBF. Also activated immediately upon reduction of PF are the hepatic arterial buffer response and an HBF-dependent hepatorenal reflex. Adenosine is secreted at a constant rate into the small fluid space of Mall which surrounds the terminal branches of the hepatic arterioles, portal venules and sensory nerves. The concentration of adenosine is regulated by washout into the portal venules. Reduced PFreduces the washout and the accumulated adenosine causes dilation of the hepatic artery, thus buffering the PF change. Adenosine also activates hepatic sensory nerves to cause reflex renal fluid retention, thus increasing circulating blood volume and maintaining cardiac output and PF. If these mechanisms are not able to maintain total HBF, the hemodynamic imbalance results in hepatocyte proliferation, or apoptosis, by a shear stress/nitric oxide-dependent mechanism, to adjust total liver mass to match the blood supply. These mechanisms are specific to this unique vascular bed and provide an excellent example of multiple integrative regulation of a major homeostatic organ. [source] Disagreement between acute and chronic haemodynamic effects of nadolol in cirrhosis: a pathophysiological interpretationALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2005C. MERKEL Summary Background :,The acute effects of , -blockers may be different from chronic; mechanisms underlying this difference are poorly elucidated. Aim :,To assess portal pressure and its pathophysiological determinants after acute and chronic administration of nadolol. Methods :,In 24 patients with cirrhosis and portal hypertension hepatic venous pressure gradient, portal blood flow and resistance to portal blood flow were measured before, 60,90 min after acute administration of nadolol, and after 1 month. Patients were good-responders if hepatic venous pressure gradient was ,12 mmHg, or decreased by at least 20%. Results :,Eleven and 13 patients were good- and poor-responders to acute administration, respectively. Acute poor-responders showed a lower decrease in portal blood flow (P = 0.04) and a less evident decrease in mean arterial pressure (P < 0.001). Eleven and 13 patients were good- and poor-responders to chronic administration, respectively. Chronic poor-responders showed a larger increase in resistance to portal blood flow compared with good-responders (P = 0.01). Disagreement between acute and chronic effects was seen in 12 patients: six were acute good-responders chronic poor-responders and six were acute poor-responders chronic good-responders. Acute good-responders chronic poor-responders patients had the smallest decreases in portal blood flow and in mean arterial pressure after acute administration, while acute poor-responders chronic good-responders showed the largest (P = 0.05 and 0.01). Conclusions :,Disagreement between acute and chronic effects of nadolol on hepatic venous pressure gradient is common. The mechanism responsible is complex, the acute effect being mainly modulated by arterial hypotension and the chronic effect by changes in portal resistance. [source] Continuous infusion of prostaglandin E1 via the superior mesenteric artery can prevent hepatic injury in hepatic artery interruption through passive portal oxygenationLIVER INTERNATIONAL, Issue 2 2000Tsutomu Sato Abstract:Aims/Background: Hepatic artery interruption (HAI) causes severe ischemic liver damage, especially following hepatopancreatobiliary surgery. In order to inhibit a decrease in oxygen delivery after HAI, continuous infusion of PGE1 via the superior mesenteric artery (SMA) was administered in pigs and changes in hepatic blood flow and oxygen delivery were investigated. Furthermore, its effectiveness in the prevention of liver injury was evaluated by histology and serum enzyme levels. Methods: Animals were subjected to HAI without PGE1 infusion (control group n=6) and to continuous infusion of PGE1 (0.02 ,g/kg/min) into the SMA (PGE1 group n=6). Results and Conclusion: PGE1 infusion via the SMA not only increased the portal blood flow but also elevated the oxygen content of the portal blood. The reduction in oxygen delivery to the liver was 50% in the control group, and only 13% in the PGE1 group. Serum aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) levels 24 h after HAI in the control group were 3415±1283 IU/L and 9839±2959 respectively while in the PGE1 group they were 939±426 IU/L and 5510±1545 IU/L respectively. Histological examination showed massive necrosis in the control group at 72 h but only focal liver cell necrosis in the PGE1 group. Based on this finding and the fact that this treatment can be performed easily and safely, continuous infusion of PGE1 via the SMA may be a useful intervention to prevent severe liver damage after hepatic artery interruption. [source] A caspase inhibitor, IDN-6556, ameliorates early hepatic injury in an ex vivo rat model of warm and cold ischemia,LIVER TRANSPLANTATION, Issue 3 2007Niel C. Hoglen This study examined the efficacy of the caspase inhibitor, IDN-6556, in a rat model of liver ischemia-reperfusion injury. Livers from male Sprague-Dawley rats were reperfused for 120 minutes after 24 hours of 4°C cold storage in University of Wisconsin solution. Portal blood flow measurements estimated sinusoidal resistance, and bile production, alanine aminotransferase activities, and Suzuki scores were evaluated as parameters of hepatocyte/liver injury. Treated livers were exposed to 25 or 50 ,M of IDN-6556 in University of Wisconsin storage solution and/or the perfusate. All treatment regimens with IDN-6556 significantly improved portal blood flow measured at 120 minutes, and significant improvements were seen as early as 30 minutes when inhibitor was also present in the perfusate (P < 0.01). All treatment groups with IDN-6556 significantly increased bile production by 3-4-fold compared with controls (P < 0.01), and reductions in alanine aminotransferase activities were seen within 90 minutes of reperfusion (P < 0.05). These data were confirmed by improved Suzuki scores (less sinusoidal congestion, necrosis, and vacuolization) in all treated groups. Livers from the IDN-6556,treated groups had markedly reduced caspase activities and TUNEL (terminal deoxynucleotidyl transferase dUTP nick-end labeling)-positive cells, suggesting reductions in apoptosis. IDN-6556 present in cold storage media ameliorated liver injury due to cold ischemia and reperfusion injury and may be a rational therapeutic approach to reduce the risk of liver ischemia in the clinical setting. Liver Transpl 13: 361,366, 2007. © 2007 AASLD. [source] Management Options to Treat Gastrointestinal Bleeding in Patients Supported on Rotary Left Ventricular Assist Devices: A Single-Center ExperienceARTIFICIAL ORGANS, Issue 9 2010Helen M. Hayes Abstract Gastrointestinal (GI) bleeding in ventricular assist devices (VADs) has been reported with rotary devices. The pathophysiological mechanisms and treatments are in evolution. We performed a retrospective review of GI bleeding episodes for all VADs implanted at our institution. Five male patients experienced GI bleeding,age 63.6 ± 3.64 years. VAD type VentrAssist n = 1, Jarvik 2000 n = 2, and HeartWare n = 2. All patients were anticoagulated as per protocol with antiplatelet agents (aspirin and/or clopidogrel bisulfate [Plavix] and warfarin (therapeutic international normalized ratio 2.0,3.5). There was no prior history of gastric bleeding in this group. Ten episodes of bleeding requiring blood transfusion occurred in five patients. Some patients had multiple episodes (1 × 5, 1 × 2, 3 × 1). The events occurred at varying times post-VAD implantation (days 14, 21, 26, 107, 152, 189, 476, 582, 669, and 839). Octreotide (a long-acting somatostatin analogue that reduces splanchnic arterial and portal blood flow) was administered subcutaneously or intravenously. Three patients received infusions of adrenaline at 1 µg/min to enhance pulsatility. Anticoagulation was interrupted during bleeding episodes but successfully introduced post bleeding event. GI bleeding is a significant complication of VAD therapy. In this article, we discuss diagnosis and management options. [source] Dysplastic nodules frequently develop into hepatocellular carcinoma in patients with chronic viral hepatitis and cirrhosisCANCER, Issue 3 2006Masahiro Kobayashi M.D. Abstract BACKGROUND Advances in imaging technology have enhanced the detection of small nodular lesions during the course of chronic liver disease. METHODS Between 1995 and 2002, the authors examined 154 consecutive patients with small hepatic nodules without hepatocellular carcinoma (HCC) over a median duration of 2.8 years. The median size of these nodules was 14 mm (range, 7,40 mm). The initial histopathologic diagnosis included high-grade dysplastic nodule (HGDN) (n = 13), low-grade dysplastic nodule (LGDN) (n = 42), and regenerative nodule (RN) (n = 99). RESULTS A total of 29 (18.8%) nodules developed into HCC during the observation period. Cumulative HCC development rates at the first, third, and fifth year were 46.2%, 61.5%, and 80.8% for HGDN; 2.6%, 30.2%, and 36.6% for LGDN; and 3.3%, 9.7%, and 12.4% for RN, respectively. The rate of HCC development was significantly higher in the HGDN group than for other types (P < 0.001). Multivariate analysis disclosed that histopathologic diagnosis (P < 0.001) and findings on computed tomographic arterial portography (CT-AP) (P = 0.004) were significantly associated with future HCC development. The hazard ratios of HGDN and LGDN were 16.8 (95% confidence interval [CI], 6.19,45.6) and 2.96 (95% CI, 1.20,7.31), respectively. A decrease in portal blood flow also showed a significantly high hazard ratio of 3.04 (95% CI, 1.42,6.50). Approximate annual development rate to HCC was 20% in patients with HGDN and 10% in LGDN. CONCLUSION HGDN should be considered a precancerous lesion when it appears during follow-up of chronic viral hepatitis or cirrhosis. Reduced portal blood flow in the nodule on computed tomography-AP is also an important predictor for development of hepatocellular carcinoma. Cancer 2006. © 2005 American Cancer Society. [source] Hepatic venous outflow reconstruction in adult living donor liver transplants without portal hypertensionCLINICAL TRANSPLANTATION, Issue 2 2004Diego Bogetti Abstract:, Graft congestion is one of the causes of poor graft function in segmental liver transplantation. Three factors are implicated in segmental graft congestion: graft size, hepatic venous outflow and portal inflow. The graft size must be matched to the body weight, which is conventionally done by using graft to body weight ratio. Hepatic blood outflow must be optimized by hepatic vein reconstruction, which can be complicated. High portal blood flow has been shown to be detrimental to small-for-size grafts. These factors are strictly connected to each other. They can all contribute to graft congestion and poor function, while one factor can compensate for the others and decrease congestion. Ideally, all the accessory veins should be reconstructed, if possible, to maximize the outflow. In the absence of portal hypertension and with an adequate sized graft, complex venous reconstruction may not be necessary. We present a case report of an adult living donor liver transplant with the favorable conditions of normal portal pressure and a large sized graft, but complicated by the presence of several accessory hepatic veins. A simple hepatic vein anastomosis was sufficient for adequate outflow and prompt graft function. [source] | ||||||||||||||||||||||