Fuminori Moriyasu

Experiences of 120 microsurgical reconstructions of hepatic artery in living related liver transplantation

BACKGROUNDnWe reviewed 120 microsurgical reconstructions of a hepatic artery in living related liver transplantation and discussed the problems encountered.nnnMETHODSnFrom January 1991 to July 1994 we performed a series of 105 living related liver transplantations on children with end-stage liver disease. Arterial reconstruction was performed under the optical field of a continuous zoom magnification of approximately 10 times with an operating microscope.nnnRESULTSnTwenty-six percent of the graft arteries were less than 2 mm in diameter. The time required for an arterial reconstruction was 49.5 +/- 1.8 minutes. In 15 of the 31 cases in which there were two graft arteries, two arterial reconstructions were required. The caliber differences between the graft artery and the recipient artery in 30 instances was dealt with by cutting an undersized artery obliquely (17 instances), by fish-mouth method (10 instances), by end-to-side anastomosis (1 instance), or by funnelization method (2 instances). In one case we performed an intimal dissection of a recipient hepatic artery and substituted a splenic artery. Consequently, hepatic arterial thrombosis occurred in only two cases (1.7%).nnnCONCLUSIONSnMicrosurgical technique has overcome the high risk of hepatic arterial thrombosis in cases of fine graft arteries, enabled the reconstruction of arteries with caliber difference, and decreased arterial complications with its delicate manipulation.

Analysis of flash echo from contrast agent for designing optimal ultrasound diagnostic systems

Microbubble-based contrast agents can enhance echoes in areas of low blood flow, but the bubbles are extremely sensitive and collapse easily when exposed to ultrasound (US) irradiation. An experimental study of bubble collapse was carried out to design new functions for US diagnostic systems to detect echoes from microbubbles more efficiently. For contrast agent (Levovist) solution, a high-intensity, but momentary, echo (flash echo), was observed in the first frame image after a several-second suspension of transmission, but was not seen in the second frame image. These flash echo signals were analyzed and categorized based on microscopic observation, and the results showed that the longevity of the microbubbles was reduced by conditions such as B-mode imaging. Next, a numerical simulation of the bubbles in liquid was performed under the same conditions as in the in vitro experiment. The results showed that even bubbles less than 1 microm in diameter expand and collapse within one pulse drive, which would generate flash echoes. The flash echo imaging system described here permits flexible intermittent scanning with variable intervals, with a variable number of frames at the trigger, and with simultaneous monitoring at low power output. Animal experiments were also conducted to evaluate the system. As the interval between frames was increased, the flash echoes gradually increased, and perfusion in the parenchyma was clearly observed with an interval of 4 s.

Measurement of Portal Vascular Resistance in Patients With Portal Hypertension

Portal vascular resistance was measured percutaneously in 60 patients with chronic liver disease and in 5 control subjects. The portal vascular resistance (PVR) was calculated, using the following equation, from the portal blood flow (QPV), portal venous pressure (PPV), and hepatic venous pressure (PHV): PVR = (PPV - PHV)/QPV. The portal blood flow was measured using an ultrasonic Doppler duplex system, and the portal venous and hepatic venous pressures were measured using percutaneous transhepatic catheterization and venous catheterization, respectively. The wedged hepatic venous pressure was measured by occluding the hepatic venous branch using a balloon catheter. The portal vascular resistance was 0.25 +/- 0.13 mmHg X ml-1 X min X kg body weight (mean +/- SD, n = 5) in the control group, 0.64 +/- 0.29 mmHg X ml-1 X min X kg body wt (n = 13) in the chronic active hepatitis group, 1.34 +/- 0.79 mmHg X ml-1 X min X kg body wt (n = 30) in the cirrhosis group, and 0.85 +/- 0.69 mmHg X ml-1 X min X kg body wt (n = 13) in the idiopathic portal hypertension group.

Vascular complications in living related liver transplantation detected with intraoperative and postoperative Doppler US

BACKGROUND/AIMSnThe purpose of this study was to clarify changes in the graft hemodynamics induced by vascular complications in living related liver transplantation.nnnMETHODSnThis study included 46 pediatric recipients who underwent partial liver transplantation from living related donors. The blood flow was evaluated in the portal system, the hepatic artery and the hepatic vein with serial intra- and post-operative Doppler ultrasound (US).nnnRESULTSnIn 12 patients, intraoperative Doppler US showed a decrease in portal venous inflow (< 9 ml.min-1.kg-1) toward the liver graft and could act as a guide for ligation of collaterals in seven patients, portal re-construction in two, thrombectomy in one and relief of hepatic venous outflow obstruction in two for increasing the portal venous inflow. In five patients, intraoperative Doppler US showed poor arterial inflow, i.e. dampened arterial waveforms which involved both low pulsatility index (< 0.90) and low peak-systolic velocity (< 31 cm/s). In three of them, the waveform was more pulsatile after re-anastomosis or relief from stretching of the hepatic artery. The remaining two patients developed hepatic artery thrombosis. Most of the hepatic venous outflow obstruction (four of five patients) had flat waveforms, low flow velocity (< 10 cm/s) of the hepatic vein, and poor portal inflow (flow velocity < 14 cm/s). Postoperative Doppler US showed hepatic venous outflow obstruction in three patients, hepatic artery thrombosis in three (twice in one patient), portal vein stenosis in two and portal vein thrombosis in one. These complications were successfully managed with surgical procedures in three patients, transhepatic angioplasty in three and conservative treatments in four. Six patients died of non-vascular complications.nnnCONCLUSIONSnSerial intra- and post-operative Doppler US was a useful technique for making an early diagnosis of abnormal hemodynamics of the graft circulation. Furthermore, intraoperative Doppler US could assess reconstructed vessels objectively and would reduce the incidence of vascular complications following transplantation.

Gray scale second harmonic imaging of the liver: A preliminary animal study

Gray scale second harmonic imaging (2.5 MHz/5.0 MHz) was evaluated in preliminary animal studies with a new ultrasound contrast agent (FS069). FS069 was administered intravenously in 10 rabbits (6 with normal liver, and 4 with implanted VX-2 tumors) and two woodchucks with hepatocellular carcinomas. The vasculature (including tumor vessels) and liver parenchyma were clearly enhanced at a low dosage (optimal dose was from 0.1 to 0.2 mL/kg) in all cases. Enhancement was reproducible and generally dose-dependent. Tumors were enhanced well during the early phase and tumor enhancement disappeared earlier than that of surrounding normal liver. Arterial phase and portal phase were easily distinguished and patterns of enhancement were diagnostic of the tumors. Gray scale second harmonic imaging is useful in the detection of hepatic tumors and in diagnosis of their hemodynamics.

Quantitative measurement of portal blood flow in patients with chronic liver disease using an ultrasonic duplex system consisting of a pulsed doppler flowmeter and B-mode electroscanner

SummaryPortal blood flow (PBF) can be measured quantitatively using a B-mode combined pulsed Doppler (BCD) system. This system combines a real time B-mode linear type electroscanner and a pulsed Doppler (D-mode) flowmeter. Since both modes are displayed in realtime, Dopper blood flow signals can be retrieved at will from any depth. The blood flow velocity determined by the Doppler spectrogram and the vascular cross-sectional area measured from the B-mode tomographic image enables the quantitative calculation of blood flow volume. Using this system,PBF was measured quantitatively in 88 healthy adults, 54 patients with chronic hepatitis, 65 with cirrhosis of the liver, 27 with primary hepatoma and 12 with idiopathic portal hypertension (IPH). Results ofPBF volume measurement were as follows: 889±284 ml/min (mean ± S.D.) for healthy adults, 851 ± 237 ml/min for patients with chronic hepatitis, 870 ± 289 ml/min for cirrhosis of the liver, 966 ± 375 ml/min for primary hepatoma and 1,047 ± 381 ml/min forIPH.These preliminary results demonstrated that this ultrasonic Duplex system is clinically useful to determine the quantitative amount of PBF.

Influence of spontaneous portosystemic collateral pathways on portal hemodynamics in living-related liver transplantation in children: Doppler ultrasonographic study

We investigated the influence of spontaneous portosystemic collateral pathways on the portal hemodynamics and examined the necessity for ligating these vessels in pediatric liver transplantation from living donors. We assessed portal blood flow before, during, and after surgery in 82 pediatric recipients (mean age, 4.2 years), using Doppler ultrasonography. When blood flow in the reconstructed portal vein was decreased (< 10 ml/min/kg body weight) and portosystemic collaterals persisted during surgery, those vessels were ligated and Doppler flowmetry was examined again. Spontaneous portosystemic collaterals were detected at one or more sites in 67 patients before transplantation. These collaterals had been ligated in 17 patients before intraoperative flowmetry. Among the remaining 50 patients, initial Doppler studies revealed a decrease in portal blood flow in 22 patients. Nine patients had hepatofugal splenic venous flow and 6 had no significant flow signals from the intrahepatic portal vein. Ligation of collaterals resulted in a remarkable increase in portal blood flow in 20 patients, all of whom are alive. The remaining 2 patients died of graft failure due in part to portal hypoperfusion. On the other hand, the collaterals were not ligated in 24 patients because adequate portal blood flow was confirmed by intraoperative flowmetry. Postoperatively, flow signals from the unligated collateral vessels gradually diminished, but they still persisted in 3 patients at 12 months after transplantation. Hepatofugal blood flow through the portosystemic collateral pathways may persist after implantation of a normal graft. If the patent collaterals significantly reduce the effective portal blood flow, these vessels should be ligated in order to avoid graft failure.

Hemodynamics of splenic artery aneurysm

Blood flow volume of the portal venous system of 3 patients with splenic artery aneurysm, an uncommon disease, was measured using an ultrasonic duplex system. A huge increase in splenic blood flow volume was found in each case. A large portasystemic shunt through which the portal blood flowed hepatofugally was present in 2 cases. We suspect the shunt is partially responsible for an increase in splenic blood flow volume, which would lead to the formation of splenic artery aneurysm together with portal hypertension.

Liver-type arginase in serum during and after liver transplantation: a novel index in monitoring conditions of the liver graft and its clinical significance.

We quantified liver-type arginase in sera of 47 patients undergoing partial liver transplantation with use of an ELISA method. The level of liver-type arginase fluctuated slightly beyond the normal range in successful liver recipients, while it changed more drastically or precipitously in unsuccessful ones, accompanying or unaccompanying elevation of AST and ALT levels. A higher elevation pattern of the arginase level (above 100 ng ml-1) was observed in each of the unsuccessful recipients with critical condition, except for one patient. Other hepatic markers (LDH, ALP, and T-BIL) remained relatively unchanged until the terminal stage of deceasing patients. The finding that the liver-type arginase emerged in large quantity in the blood stream immediately after reperfusion of the liver graft indicates that the enzyme leaks out of hepatocytes damaged, presumably, by storage in the absence of circulation. A half-life of the liver-type arginase in the human blood was estimated to be 1 h, that is clearly shorter than that of AST. The short half-life of the arginase appears to be ascribable, at least partly, to formation of an immune complex with circulating autoantibody which appears in many liver recipients. These results suggest that liver-type arginase behaves uniquely in the serum among many hepatic enzymes, and could serve as a distinct marker of hepatic lesions, particularly during and after liver transplantation.

Intraoperative measurement of the graft oxygenation state in living related liver transplantation by near infrared spectroscopy

Abstract Graft oxygenation plays an important role in successful liver transplantation. Intraoperative changes in the oxygenation state of the liver graft were measured by near infrared spectroscopy in 28 cases of living related liver transplantation. Oxygen saturation of hemoglobin in the liver (hepatic SO2) changed from 81.2%± 1.5% (mean ± SEM) before donation (in the donor) to 49.7%± 4.2% after portal reflow, to 58.4%± 5.0% after arterial reflow, and then to 71.4%± 3.9% before closure. Mean hepatic SO2 was positively correlated with portal flow rate as measured by duplex Doppler sonography. Cases with low portal flow rate showed a high coefficient of variation (SD/mean) of hepatic SO2, indicating heterogeneous tissue oxygenation. Though graft size was expected to affect the graft oxygenation state, hepatic SO2 was fairly independent of the graft‐to‐recipient weight ratio. In two cases with markedly low hepatic SO2, postoperative graft dysfunction occurred. This study suggest that the method of near infrared spectroscopy is reliable and useful for assessing the graft oxygenation state in liver transplantation.