Radio-frequency tissue ablation of the liver: effects of vascular occlusion on lesion diameter and biliary and portal damages in a pig model.

The aim of this study was to assess the effect of vascular occlusion on radio-frequency (RF) lesion size and on potential associated biliary and portal lesions. Radio-frequency lesions using a 1-cm exposed-tip cooled electrode were created in pig liver. Liver perfusion was modified by arterial embolization (n=2), left portal clamping (n=2), and both (n=2). Two pigs were used as controls. Two weeks after, control portography was performed, animals were killed, and ex-vivo cholangiography was carried out. Pathological studies evaluated the lesion surface and associated portal and biliary damages. A mathematical regression model showed that portal occlusion increased by 43 mm2 (+40%) the surface of RF lesions, arterial occlusion by 135 mm2 (+126%), and associated occlusion by 466 mm2 (+435%). Biliary stenoses were found in 4 cases (two arterial occlusions, one portal occlusion, and one associated occlusion). One case of partial portal vein thrombosis was found in one case of portal occlusion and resolved at 2 weeks. Ischemic damages adjacent to RF lesions were found in cases of combined occlusions. The reduction of liver perfusion increases significantly the size of RF lesions but is associated with a risk of biliary, portal, or parenchymal complications.

Intrahepatic hemodynamic changes following portal vein embolization: a prospective Doppler study.

The aim of this study was to describe the intrahepatic hemodynamic modifications induced by right portal vein embolization (RPVE) using Doppler ultrasound. Eighteen patients with hepatocellular carcinoma (n = 8), liver metastases (n = 9), or multiple adenomas, underwent RPVE 1 month before right hepatectomy in order to increase the size of future remnant liver. Doppler ultrasound was performed before and 1 month after RPVE. The portal vein flow and the hepatic artery resistive index in right and left lobes (segments V and III) were calculated. We recorded simultaneously artery and portal vein of segment III to measure the arterioportal ratio calculated as follows: (maximal arterial systolic velocity minus maximal portal vein velocity)/maximal arterial systolic velocity. Results were compared in cirrhotic patients (group A) and in healthy liver patients (group B). In both groups, portal flow was not significantly modified following RPVE. In the left lobe, in both groups the hepatic artery resistive index was not significantly modified. In group B, the arterioportal ratio decreased significantly (0.71 +/- 0.18 and 0.42 +/- 0.23, respectively, before and after embolization; p < 0.01), whereas it was not statistically modified in group A (0.75 +/- 0.17 and 0.69 +/- 0.14, respectively, before and after embolization). The right hepatic arterial resistive index decreased significantly in both groups after embolization (0.74 +/- 0.07 to 0.66 +/- 0.07, p<0.05; and 0.66 +/- 0.07 to 0.61 +/- 0.06, p < 0.05, respectively, before and after RPVE for groups A and B). Total portal flow was unchanged after RPVE (750 +/- 337 ml/mn and 696 +/- 231 ml/mn, respectively, before and after RPVE). The hepatic artery resistive index was unchanged before and after embolization in the left lobe (0.75 +/- 0.13 and 0.74 +/- 0.14, respectively), but significantly decreased in the right lobe (0.7 +/- 0.08 and 0.62 +/- 0.06 respectively, p < 0.05). The left arterioportal ratio decreased significantly from 0.76 +/- 0.17 to 0.52 +/- 0.23 after PVE, p < 0.02). Our study confirms that right portal occlusion induces a decrease in hepatic artery resistive index in the right lobe and does not modify total portal flow. The left and right lobes of the liver have separate arterioportal regulation.

Doppler sonography of the inferior mesenteric artery: a preliminary study.

The purposes of this study were to look for the inferior mesenteric artery in patients undergoing abdominal sonography, to determine in what percentage of patients it is visible, and to characterize Doppler flow patterns of the inferior mesenteric artery in fasting patients without intestinal vascular disease. The inferior mesenteric artery was sought in 100 consecutive fasting adults (mean age, 54 years; 63 women, 37 men), as follows: the infrarenal aorta was scanned in a transverse plane; the origin of the inferior mesenteric artery was identified on the left anterolateral surface of the aorta; the inferior mesenteric artery was then traced caudally along the left side of the aorta. The inferior mesenteric artery and the superior mesenteric artery were studied with Doppler sonography in 50 different subjects without clinical or Doppler sonographic evidence of abdominal vascular disease (mean age, 44.9 years; 17 men, 33 women). Pulsed Doppler samples were taken within the inferior mesenteric artery in sagittal planes. The resistive index was calculated from the superior mesenteric artery and the inferior mesenteric artery. The inferior mesenteric artery was detected in all but eight patients (92%). In seven patients obesity prevented visualization. The eighth patient had undergone abdominal surgery on the previous day, limiting the sonographic examination. The diastolic flow in the inferior mesenteric artery was less than that in the superior mesenteric artery in all patients. The resistive index was 0.959 +/- 0.045 in the inferior mesenteric artery and 0.856 +/- 0.046 in the superior mesenteric artery (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)