Development of collateral circulation following distal embolization of hepatic artery in pigs

Effect of Repeated Normothermic Ischaemia on Normal Liver Parenchyma

Hepatic ischaemia was induced in 8 mesenterico-cavally shunted pigs. The hepatic artery was occluded with biodegradable starch microspheres and the portal vein with a balloon catheter. The liver was kept ischaemic for 90 minutes at the beginning, and 90 minutes at the end, of a 24-hour period. At histopathologic examination 6 of the livers had multiple, small areas of necrosis. The total volume of these necroses accounted for no more than 10 to 15 per cent of each liver. No necrosis was evident in 2 livers. Thus normothermic Ischaemia for 2 periods of 90 minutes each within a 24-hour period caused minimal damage to the liver. An alternative treatment in patients with liver tumours could therefore be simultaneous occlusion of the hepatic artery and the portal vein.

Intra-Arterial Injection of Adriamycin/Mitomycin C Lipiodol Suspension in Liver Metastases

Intra-arterial injection of a suspension of adriamycin and/or mitomycin C in Lipiodol was performed in 17 patients with hepatic metastases, which at angiography were poorly vascularized. Accumulation of Lipiodol in the tumors was demonstrated at computed tomography (CT) in 15 of 17 patients examined within one week. Follow-up with CT showed that Lipiodol remained in the tumor during the first month in 94 per cent, after 2 months in 31 per cent, and after 3 months in 17 per cent. In the non-tumor part of the liver Lipiodol disappeared earlier, and one month after injection it could no longer be traced on CT. In 8/17 cases (47%) CT, after intra-arterial injection of Lipiodol, gave superior information compared with CT after intravenous contrast enhancement. Tumor response was achieved in 9 of 16 cases. Particularly in metastases originating from cancer of the colon and stomach response was observed with a decrease in tumor size in 8 of 10 patients.

Antitumor effect of arterial administration of a medium-chain triglyceride solution of an angiogenesis inhibitor, TNP-470, in rabbits bearing VX-2 carcinoma

Using rabbits bearing VX-2 carcinoma on the inner side of the leg, we examined the antitumor activity of a medium-chain triglyceride (MCT) solution of an angiogenesis inhibitor, TNP-470 (AGM-1470, 6-O-(N-chloroacetylcarbamoyl)-fumagillol), following administration into the femoral artery feeding the tumor. The MCT solution of TNP-470 (1 and 5 mg) strongly suppressed tumor growth following a single intra-arterial (i.a.) injection 2 or 3 weeks after tumor inoculation. Moreover, remarkable regression of well-developed tumors, those 4 weeks after inoculation, was obtained by i.a. injection of the MCT solution containing 20 mg of TNP-470 without any influence on body weight. The antitumor effects were potentiated by coadministration of doxorubicin or mitomycin C (MMC) in the solution or microspheres containing MMC. In a shell-less chorioallantoic membrane (CAM) assay, angiogenesis was inhibited when a droplet of the MCT solution containing 25 micrograms of TNP-470 was placed on the CAM for 2 days, suggesting that the prolonged antitumor effect resulted from the inhibition of tumor neovascularization by sustained drug release from the preparation. These results indicate that i.a. injection of the MCT solution of TNP-470 is promising for treating well-developed tumors.

The protective effect of portoarterial shunts after experimental hepatic artery embolization in rats with liver cirrhosis

PURPOSE

The role of the portal system after hepatic artery embolization (HAE) was examined.

METHODS

Using a Wistar strain rat model of liver cirrhosis, the route and occurrence of portoarterial (PA) shunts before and after HAE by scanning electron microscopic (SEM) and histologic methods were evaluated. HAE was performed with iodized oil and gelatin sponge particles.

RESULTS

In the SEM study, PA shunts did not develop in normal rats regardless of whether they did (n = 10) or did not have HAE (n = 5). The cirrhotic rat model showed PA shunts in both HAE (n = 5) and non-HAE (n = 5) animals. PA shunts were established via the peribiliary plexus and direct arterioportal anastomosis. In the histologic study, the occurrence of PA shunts in liver cirrhosis was significantly increased by HAE (HAE = 6, non-HAE = 6, p < 0.01).

CONCLUSION

The development of PA shunts, which help perfuse liver parenchyma, may explain why HAE can be safely performed in patients with liver cirrhosis.

Scanning electron microscopy of intrahepatic microvasculature casts following experimental hepatic artery embolization

The initial site of occlusion of the intrahepatic microvasculature in rats following hepatic artery embolization was studied by scanning electron microscopy of microvasculature casts. The rats were divided into four groups: embolization with gelatin powder (n = 3), polyvinyl alcohol (n = 3, 125-150 microns), gelatin sponge (n = 3, 212-250 microns), and ionized oil. Not only the hepatic arteries but also vessels in the peribiliary plexus were occluded. However, the size of the hepatic arteries and vessels of the peribiliary plexus occluded correlated with the size of the embolic material, except in the case of the gelatin powder which occluded vessels smaller than the particle size.

Hemobilia in childhood

During a 10-year period we have encountered three cases of hemobilia among children after blunt abdominal trauma. All patients had the classical symptoms with varying degrees of severity. One of the patients, a 5-year-old boy, had several episodes of severe gastrointestinal bleeding, abdominal pain, and jaundice during a 2-month period. He was treated with selective arterial embolization of the left hepatic artery. The symptoms ceased instantly, and the patient has remained healthy during an observation period of more than 2 years. In cases of hemobilia, selective arterial embolization is a safe method with no serious complications. Arterial collaterals develop very quickly and the risk of liver dysfunction is small. We suggest that embolization of hepatic arteries may be the treatment of choice even in small children with hemobilia.

Effects of superselective arterial embolization and chemoembolization on energy charge and total blood flow of the rat liver

The superselective transcatheter arterial embolization (TAE) and chemoembolization (TAC) of the periphery of the left and median lobes of the rat liver were performed using 1.5 mg of gelatin sponge dissolved in saline solution and mitomycin (MMC) at a dose of 1.6 mg/kg b.wt. The energy charge (EC) of the embolized and chemoembolized lobes decreased after the embolization but was restored 3 h later. The total hepatic blood flow (THBF) was reduced to about one half and required 1 week to be restored to the preembolization levels in both groups. Microscopic centrilobular necrosis and vacuolization were found. The addition of MMC did not produce marked untoward effects. Thus, the normal liver is able to restore its energy pool despite a reduction in the THBF after superselective arterial embolization, and this recovery is not altered even by the use of a high dose of MMC.

Occurrence of an intrahepatic porto-arterial shunt after hepatic artery embolization with Gelfoam powder in rats and rabbits

Postmortem perfusion studies were carried out following hepatic artery embolization (HAE) with Gelfoam powder in rats (n = 17) and rabbits (n = 10). The inflow of barium particles into the hepatic arteries after portal vein injection (porto-arterial shunt: P-A shunt) was analyzed by stereomicroscopic and histologic examinations. A P-A shunt was observed in 12 of 17 rats (71%) following HAE (embolization group). The difference in occurrence rates of P-A shunt between control (1/12 = 9.2%) and embolization groups was statistically significant (chi 2, p less than 0.01) in rats. In rabbits, a P-A shunt was seen in only one of 10 animals in the embolization group. P-A shunting may have an important role in reconstructing the blood supply to hepatic tumors after HAE, and administration of anticancer drugs via the portal vein following HAE might be effective. However, the differences among different species of animals should be considered before clinical application.

Liver necrosis after hepatic dearterialization in pigs

In nine pigs, the livers were dearterialized by a combination of distal occlusion of the hepatic artery with Ivalon (polyvinyl alcohol foam) particles of 150-250 mu and proximal occlusion of the common hepatic artery with Gianturco coils. Necrosis of at least 90% of the liver developed in eight pigs. One pig with less extensive liver necrosis had developed an effective collateral circulation to a large part of the liver. Patency of the portal venous system did not prevent extensive infarction of dearterialized liver tissue.