肝移植术中血管超声检查在血管并发症预防和诊断中的价值

目的 探讨肝移植术中血管超声检杳在预防和诊断血管并发症中的价值.方法 肝移植术中对116例患者进行血管超声检查,检测血管吻合后肝动脉峰值流速和门静脉流量.以肝动脉峰值流速2>30 cm/s为正常肝动脉标准,以门静脉流量2>800ml/min为正常门静脉标准.结果 在116例患者中,有14例肝动脉峰值流速<30 cm/s,其中9例通过应用利多卡因腹腔于根部浸润、罂粟碱及盐酸消旋山莨菪碱肝动脉内注射,解除血管痉挛后,肝动脉峰值流速达到正常标准,但术后仍有3例患者发生肝动脉并发症;另5例经过上述处理,肝动脉峰值流速仍<30 cm/s,故采用供者髂内动脉对受者腹主动脉与供者肝动脉进行搭桥吻合,吻合后测肝动脉峰值流速2>30 cm/s,术后未发生肝动脉并发症.116例患者中,有5例门静脉流量<800 ml/min,其中4例经证实存在门腔分流,行门腔分流静脉结扎后,门静脉流量达到正常标准,但术后仍有1例发生门静脉血栓;另1例存在门静脉Ⅲ级血栓,血栓切除后进行门静脉端端吻合,门静脉流量仍达不到标准,故利用供者髂静脉通过胰腺前胃十二指肠后与受者肠系膜上静脉远端进行搭桥吻合,术中测量门静脉流量达到正常标准,术后未发生门静脉并发症.结论 肝移植术中血管超声检查对血管并发症具有较高的预防和诊断价值.对术中超声检查提示异常的患者,术后应该严密监测,以尽早发现可能出现的血管并发症并进行相应治疗.     

Flow- and pressure-adapted portal arterialization in dogs

The effects of portal arterialization after portacaval shunt were studied in dogs. Flow- and pressure-adapted portal arterialization was performed by mounting a Teflon cuff on an autogenous vein bypass graft between the hepatic stump of the portal vein and the right renal artery. Immediately following operation, the total hepatic blood flow and intrahepatic portal venous pressure were within normal range. Eight weeks after operation, the intrahepatic portal venous pressure remained within the preoperative range, while total hepatic blood flow had increased double or triple. However, structual change due to increased flow was absent in the liver, even sixteen months after operation. Body weight, liver enzyme chemistry, ICG clearance rate, and amino acid metabolism were well maintained for the entire period of investigation. These findings suggest that sequelae such as hepatic encephalopathy and impaired hepatic metabolism after portacaval shunt can be avoided by portal arterialization, in the presence of an appropriate flow and pressure.     

Flow- and pressure-adapted portal arterialization in dogs

The effects of portal arterialization after portacaval shunt were studied in dogs. Flow- and pressure-adapted portal arterialization was performed by mounting a Teflon cuff on an autogenous vein bypass graft between the hepatic stump of the portal vein and the right renal artery. Immediately following operation, the total hepatic blood flow and intrahepatic portal venous pressure were within normal range. Eight weeks after operation, the intrahepatic portal venous pressure remained within the preoperative range, while total hepatic blood flow had increased double or triple. However, structural change due to increased flow was absent in the liver, even sixteen months after operation. Body weight, liver enzyme chemistry, ICG clearance rate, and amino acid metabolism were well maintained for the entire period of investigation. These findings suggest that sequelae such as hepatic encephalopathy and impaired hepatic metabolism after portacaval shunt can be avoided by portal arterialization, in the presence of an appropriate flow and pressure.     

Left renal vein ligation for large splenorenal shunt during liver transplantation

Adequate hepatopetal portal vein blood flow is obligatory to ensure proper liver function after liver transplantation. Large collateral veins as shunts impair portal vein flow and even cause hepatofugal blood flow and portal steal syndrome. In particular, splenorenal shunts in liver transplant recipients can lead to allograft dysfunction and possible allograft loss or hepatic encephalopathy. Restoration of portal flow through left renal vein ligation (LRVL) is a treatment option, which is much easier compared to splenectomy, renoportal anastomosis and shunt closure, but bears the risk of moderate and temporary impairment of renal function. In addition, a patent portal vein is mandatory for LRVL. However, although LRVL has been reported to be an effective, safe and easy method to control portacaval shunts and increase hepatopetal flow in some studies, indications and safety are still not clear. In this review, we summarize existing studies on LRVL during liver transplantation.     

彩色多普勒超声在检测正常移植肝脏及其并发症中的应用价值

目的 探讨彩色多普勒超声在检测正常移植肝脏及并发症中的应用价值。方法 用彩色多普勒超声观察41例肝移植患者肝脏动、静脉血流变化及胆管、肝实质声像图改变。主要观察最大血流速度、时间平均血流速度、阻力指数及胆管的内径。结果 41例中17例（41．5％）发生移植物排斥反应，其彩色多普勒显像（CDFI）显示13例（76．4％）门静脉平均血流速度减低；15例（88．25％）肝静脉波幅降低，呈单相锯齿波或负二相波；9例（52．9％）肝动脉阻力指数升高；5例（29．4％）胆管轻度扩张。41例中5例（12．2％）肝动脉血栓形成，主要表现为门静脉周围检测肝动脉血流信号消失。检测中要注意操作技术及一些假阳性和假阴性影响因素。肝移植术后3例（17．3％）早期轻度胆管扩张，2周内恢复。20例（48．8％）胆管扩张明显并逐渐加重，原于胆管狭窄（2例）、胆管结石（15例）及其他（3例）。结论 彩色多普勒显像技术对正常移植肝脏的确定及并发症的检出具有重要价值；对提高术后存活率有重要意义。     

Haemodynamic and metabolic consequences of reversed portal venous blood flow after side-to-side portacaval shunt in the dog

The immediate haemodynamic and metabolic effects of reversed portal blood flow after side-to-side portacaval shunt were studied in 9 normal anaesthetized dogs, and compared to those observed after end-to-side shunt in the same animals. Blood flow in the hepatic artery (HA) and portal vein (PV) was measured using electromagnetic flowmeters. The magnitude of the HA hyperaemic response to side-to-side shunt was similar to that found after end-to-side shunt, but approximately one-third of the flow left the liver via the PV. There was no significant correlation between the HA response and the magnitude of reversed PV flow after side-to-side shunt. Despite fairly well preserved total hepatic oxygen consumption in both groups, there was a statistically significant decrease in the side-to-side series; moreover, only 13% of the total hepatic oxygen consumption was derived from blood draining the liver via the PV. It is concluded that the substantial quantity of portally drained blood after side-to-side shunt traverses metabolically inefficient pathways in the liver, and may have a detrimental influence on long-term liver function.     

Severe fatty change of the graft liver caused by a portosystemic shunt of mesenteric varices

Portosystemic shunt is a common complication in patients with portal hypertension. Mesenteric varix is one of the collaterals that can cause post-transplant liver dysfunction. In this case report, a 45-year-old woman underwent living relative donor liver transplantation for alcoholic cirrhosis. Although the early postoperative course was uneventful, she was readmitted for treatment of liver hypofunction. Fatty change in the graft liver was confirmed by histopathology of the biopsy specimen. The venous phase of a superior mesenteric angiogram revealed large-caliber mesenteric varices comprising portosystemic venous shunts. Surgery was performed to ligate the shunts. The intraoperative color Doppler ultrasonography showed hepatofugal portal blood flow, which was corrected to hepatopetal blood flow by clamping the shunt vessels. The portal pressure was moderately elevated from 13.6 cm to 21.8 cm H(2)O. Two shunt vessels were ligated and divided. Her liver function returned to nearly normal thereafter. We recommend that descending collaterals be divided during liver transplantation.     

Utility of Doppler Ultrasonography in Liver Transplantation With Celiac Axis Compression Syndrome: A Case Report

BackgroundCeliac axis compression syndrome (CACS) blocks adequate hepatic arterial flow and is a risk factor for hepatic artery thrombosis after liver transplantation. We report a case of living donor liver transplantation in a 65-year-old Brazilian male with liver cirrhosis of Child-Pugh class C and hepatocellular carcinoma caused by hepatitis C virus infection.ResultsThe patient underwent living donor liver transplantation using the graft of his 34-year-old daughter. Stenosis of the celiac artery was detected on preoperative computed tomography (CT), and CACS was suspected. Maintaining blood supply through the hepatic artery to prevent potential graft loss is essential in liver transplantation. A decrease in common hepatic artery (CHA) flow due to CACS could disturb graft blood supply or lead to hepatic artery thrombosis. In this case, we confirmed CACS through dynamic CT and used intraoperative Doppler ultrasonography (US) to plan the surgical procedure. Three types of hepatic artery reconstruction have been described in liver transplantation for CACS, namely the release of the median arcuate ligament (MAL), aorto-hepatic graft reconstructions, and reconstruction preserving the gastroduodenal artery (GDA) without MAL release. We found that clamping the GDA completely abolished hepatic inflow, but clamping the CHA did not change the hepatic inflow. Therefore, we performed arterial reconstruction without division of the GDA. The patient's postoperative course was good, with excellent hepatic artery flow, as assessed by Doppler US.ConclusionsPreoperative dynamic CT evaluation, adequate preparation of surgical procedures, and intraoperative evaluation by Doppler US is recommended in liver transplantation patients with CACS.     

Comparison of portal flow distribution after portacaval and mesocaval shunts

The distribution of portal flow between the hepatic and systemic circulations was assessed in dogs using gamma-labeled radioactive microspheres. In control dogs all flow went to the liver. After side-to-side portacaval shunt, no flow went to the liver with all the injected microspheres entering the systemic circulation and becoming lodged in the lung. In contrast, interposition mesocaval and portacaval shunts resulted in preservation of 23 to 70% of hepatic portal blood flow.     

Significance of selective arteriographic patterns in the celiac axis and superior mesenteric artery in portal hypertension

Selective celiac and superior mesenteric arteriographies were performed in patients with portal hypertension. An arterioarterial (A-A) shunt between the superior mesenteric artery and the celiac axis via pancreatic arcades was found in fifteen of forty-three patients with associated massive splenomegaly. A mild A-A shunt disappeared after portacaval anastomosis alone, whereas a prominent A-A shunt was reduced but persisted. The persisting A-A shunt disappeared after splenectomy. These findings led us to suggest that the paucity of the blood flow in the common hepatic artery concomitant with increased splenic arterial flow to the massively enlarged spleen may result in a compensatory supply to the liver from the superior mesenteric artery via the shunt.     

Hemodynamic Changes in Blood Flow Through the Denervated Liver in Pigs

We investigated the effects of liver denervation on hemodynamic circulation in seven anesthetized pigs. Simultaneous measurements of the hepatic artery and portal vein were performed with an ultrasound Doppler flow meter before and after liver denervation. Neither resting systemic nor hepatic hemodynamics changed following liver denervation. However, temporary occlusion of the portal vein resulted in a significant increase in hepatic artery flow in the innervated liver (from 123 ± 15 ml/min to 177 ± 17 mu/min, p <. 01), whereas, in the denervated liver, a significant decrease was observed (from 128 ± 11 ml/min to 106 ± 19 mu/min. p >. 05). Thus, the reciprocity between the hepatic artery and portal vein in the innervated liver disappeared in the denervated liver. The absence of an increase in the hepatic artery flow during portal vein occlusion might intensify symptoms of portal vein thrombosis in liver transplantation. In the denervated liver, a significant decrease also occurred in systolic blood pressure and central venous pressure from 1 to 3 min after portal vein occlusion. Since the liver plays a crucial role in the maintenance of cardiovascular homeostasis during blood loss, it is likely that denervation at the porta hepatis induced a lack of vasoconstriction in the portal territory. Liver denervation might further exacerbate this response to hypotension. The current study confirms that the hepatic nerves play an important role in hepatic arterial and portal venous interactions aimed at maintaining a constant blood flow through the liver. We also suggest that the hepatic nerves are important for cardiovascular homeostasis.     

彩色多普勒超声对肝移植术后11例血管并发症的诊断

目的评价彩色多普勒超声对肝移植术后血管并发症的诊断意义。方法回顾性分析和总结11例肝移植术后血管并发症的彩色多普勒超声检查资料,检测指标包括肝动脉及左右分支的峰值速度、阻力指数、加速度及加速时间,门静脉平均流速。结果5例经手术或造影证实为动脉并发症(血栓形成2例,肝动脉狭窄2例,肝动脉痉挛1例),彩色多普勒超声表现有肝动脉狭窄处的高速高阻血流并伴有湍流,而狭窄远端肝内动脉峰值速度<40cm/s,阻力指数<0.5,加速时间>0.08s,加速度<300cm/s2,2例肝动脉血栓形成肝门部无动脉血流信号;6例为门静脉并发症(3例门静脉狭窄,3例门静脉血栓形成)。结论彩色多普勒超声对肝移植术后血管并发症的诊断具有重要的指导意义。     

Comparison of Near-Infrared Spectroscopy and Laser Doppler Flowmetry for Detecting Decreased Hepatic Inflow in the Porcine Liver

Hepatic artery and portal vein thrombosis are devastating complications of partial liver transplantation. Early detection of inflow complications is important, as re-reconstruction can salvage the graft. Near-infrared spectroscopy or laser Doppler flowmetry can be used to detect tissue oxygenation or microcirculation on the liver surface. The aim of this study was to examine which of these two methods better detects changes in hepatic inflow. Sangen-strain pigs (n = 5) were used. The tips of the near-infrared spectroscopy and laser Doppler flowmetry probes were placed separately on the surface of the right liver. Inflow to the liver was controlled during the following seven conditions: control (not clamped), half- and totally clamped portal vein, half- and totally clamped hepatic artery, and half- and totally clamped portal vein and artery. Tissue blood flow was calculated using laser Doppler flowmetry. Oxyhemoglobin, deoxyhemoglobin, and the tissue oxygenation index were measured and calculated using a near-infrared spectroscopy system. The tissue blood flow and oxygenation index could not be used to differentiate between the half-clamped portal vein, half-clamped hepatic artery, and totally clamped portal vein conditions. The oxyhemoglobin minus deoxyhemoglobin value was significantly decreased after half or total clamping of the portal vein or hepatic artery (p <. 001 for each condition). The findings of the present study indicate that near-infrared spectroscopy was more sensitive than Doppler flowmetry for detecting changes in hepatic tissue inflow from the liver surface.     

Effects of portacaval shunt and hepatic artery ligation on liver surface oxygen tension and effective hepatic blood flow

Liver surface oxygen tension (LSOT) and nutrient hepatic blood flow (NHBF) were measured in rats 1 hr and 1 week after sham operation, portacaval shunt (PCS), and hepatic artery ligation (HAL). LSOT was measured using a heated Clark electrode (37 deg) and was expressed as percentage of rectus muscle O2 tension to correct for changes in systemic oxygenation. Nutrient hepatic blood flow (NHBF) was measured using steady-state, low-dose galactose clearance pharmacokinetics. Acutely, we found a close correlation between LSOT and nutrient hepatic blood flow after both hepatic artery ligation and portacaval shunt. At one week after hepatic artery ligation, LSOT and nutrient hepatic blood flow made parallel increases. However, 1 week after portacaval shunt, LSOT increased while nutrient hepatic blood flow remained reduced. The divergence in these results between the two methods of producing hepatic hypoperfusion, implies that LSOT recovers via a different mechanism after portacaval shunt. Recovery of LSOT at one week probably reflects normalization of hepatic O2 delivery after hepatic artery ligation and impaired oxygen utilization after portacaval shunt.     

How rapidly do hyperinsulinaemia and hyperglucagonaemia develop after portacaval shunting?

Elevation of serum insulin and plasma glucagon have been reported during and immediately after clinical and experimental liver transplantation and in patients with cirrhosis and surgically created or spontaneous portacaval shunts. There is controversy about the relative roles of portal diversion and impaired liver function in the genesis of these elevated levels of pancreatic hormones. End-to-side portacaval shunt was made in normal pigs which were fitted with catheters which allowed transhepatic sampling during and for 4 hr after the operation. Within 5 min of opening the shunt, there was a sixfold increase in portal venous insulin concentrations but hepatic clearance of insulin and the arterial concentration were unaltered. The increase in insulin was sustained for 2 hr. A twofold increase occurred within 1 hr in portal venous glucagon concentration which appeared to be predominantly of pancreatic origin and which continued for the 4 hr of the study. Hepatic glucose uptake did not occur after portacaval shunting despite levels of glucose elevated two-fold by iv infusion. There were no changes in aspartate aminotransferase, hepatic tissue energy charge, or total adenine nucleotides, suggesting that hepatic function was intact. It is concluded that portal diversion results in an increase in insulin and glucagon secretion and in the absence of hepatic uptake of glucose. This is a novel observation with relevance especially in liver transplantation when portal diversion for at least 1 hr forms part of the procedure.(ABSTRACT TRUNCATED AT 250 WORDS)     

肝移植围手术期门静脉血栓的处理

目的 探讨肝移植围手术期门静脉血栓（PVT）的处理。方法 回顾性分析中国医科大学附属第一医院1995年5月至2008年6月实施的194例肝移植病人临床资料,术前存在PVT 24例,其中Ⅰ级12例,Ⅱ级9例,Ⅲ级2例,Ⅳ级1例。术中采取不同门静脉重建方式,结扎术前存在的门腔分流和粗大的侧支循环。术后根据凝血酶原时间（PT）,应用普通肝素或低分子质量肝素预防性抗凝。术中、术后应用多普勒超声监测门静脉血供。结果 术后PVT发生率2.58%（5/194）。1例PVT经外科门静脉取栓、重新吻合治愈,3例置管溶栓、支架植入治愈,另1例仅表现肝功能轻度异常,未特殊处理。与PVT相关病死率为0。其余病例随访6~ 104个月,未见PVT。结论 理想的门静脉重建方式、结扎门腔存在的分流和术后有效的抗凝可以减少PVT的发生,多普勒超声监测能早期发现PVT,挽救移植物,避免再移植。     

Transient hepatofugal portal blood flow after hepatectomy in a patient with cirrhosis: Report of a case

We report herein the case of a 60-year-old man who developed hepatic failure with simultaneous transient hepatofugal portal blood flow after undergoing hepatectomy for hepatocellular carcinoma accompanied by cirrhosis with a splenorenal shunt. The transient hepatofugal portal blood flow was detected by color Doppler ultrasonography. Following this case report, the possibility of a relationship between hepatofugal portal blood flow, portal-systemic shunts, and postoperative hepatic failure is discussed.     

Budd-Chiari syndrome: portacaval shunt and subsequent liver transplantation

The Budd-Chiari syndrome (BCS) is caused by hepatic venous outflow obstruction, which often leads to death as a result of portal hypertension and liver failure. Therapeutic approaches vary widely from conventional medical therapy to liver transplantation. If and when a patient suffering with BCS needs surgery remains a matter of contention. However, it is well accepted that portacaval shunt surgery and orthotopic liver transplantation represent efficient surgical treatments of this condition. We report on a patient with an eventful course after BCS was diagnosed. After portacaval shunt surgery the patient had acute liver failure and had a successful orthotopic liver transplantation.     

Risk factors for intraoperative portal vein thrombosis in pediatric living donor liver transplantation

Pathologic changes of the recipient native portal venous system may cause thrombosis of the portal vein, especially in pediatric living donor liver transplantation (LDLT). This study assessed the utility of Doppler ultrasound (US) for the detection of intraoperative portal vein occlusion and identification of predisposing risk factors in the recipients. Seventy-three pediatric recipients who underwent LDLT at Chang Gung Memorial Hospital, Taiwan, from 1994 to 2002 were included. Preoperative and intraoperative Doppler US evaluation of the portal vein was performed. Age, body weight, native liver disease, type of graft, graft recipient weight ratio (GRWR), type of portal anastomosis, portal velocity, portal venous size and presence of portosystemic shunt were analyzed for statistical significance of predisposing risk factors. Eight episodes of intraoperative portal vein thrombosis, with typical findings of absent Doppler flow in portal vein and prominent hepatic artery with a resistant index lower than 0.5 (p < 0.001), were detected during transplantation, which was then corrected by thrombectomy and re-anastomosis. Children age < or =1 yr (p = 0.025), weight < or =10 kg (p = 0.024), low portal flow < or =7 cm/s (p = 0.021), portal venous size < or =4 mm (p = 0.001), and GRWR >3 (p < 0.017) were all risk factors for intraoperative portal vein thrombosis. Doppler US is essential in the preoperative evaluation, early detection and monitoring of outcome of the portal vein in liver transplant.     

Percutaneous control of a portacaval H-graft: Description of a new device and its initial clinical application

A percutaneously-controlled inflatable cuff which can change the diameter of a portacaval H-graft has been developed and used in 10 patients. When inflated, the cuff narrows the H-graft to increase portal pressure and reduce shunting. Use of the cuff has been of clinical significance in 3 of 7 long-term surviving patients. Narrowing the shunt improved the clinical state in 2 patients with encephalopathy, and reopening a closed shunt improved ascites in the third patient. Duplex ultrasound and deep Doppler have demonstrated an alteration of hepatic portal blood flow following inflation of the cuff after 6 months. It is concluded that further development of this controlled portacaval H-graft is warranted.