LIVER HEMODYNAMIC CHANGES BEFORE AND AFTER RADIO-FREQUENCY ABLATION ASSESSED BY DOPPLER ULTRASOUND

Purpose: Radio-frequency ablation (RFA) is now well accepted as an effective local treatment opportunity in patients with nonresectable hepatic malignancies. Experimental and clinical evidence has shown that hyperthermia is relatively safe for hepatic vasculature outside the ablated area due to the cooling effect of the blood stream. On the other hand, the precise liver hemodynamic actions of the generated heat are not well established. The AIM of the study is to evaluate the hemodynamic liver changes related to RFA.

Methods and Materials: Sixty three malignant nodules(41 metastatic, 22 Hepatocellular Carcinoma-HCC) in 48 patients undergoing Ultrasound(US)-guided RFA were investigated prospectively. Liver hemodynamics was evaluated by Doppler US (color, power, pulse) examinations of the portal vein(PV), hepatic artery(HA), hepatic veins(HV) both in the peritumoral zone and at the main branches. Observations were conducted prior to, up to 1 hour after and on 1-st and 7-th days post-RFA.

Results: No significant spectral changes, neither thrombosis were observed in HV or inferior v.cava. HA revealed significantly reduced RI 1h post-RFA (from mean 0,684 to 0,651, p<0,05) assessed at the main trunk and segmental peritumoral branches when possible. HA changes were less pronounced in patients with HCC and cirrhosis. Portal blood flow was the most affected with increased mean velocity (18,3cm/s vs. 26,8cm/s) without marked changes in vessel diameter after the ablation procedure. In all cases the hemodynamic alterations of HA and PV returned to pretreatment values on the 1-th day post-RFA. In the peritumoral zone in 7 pts with HCC and cirrhosis were observed portal vessels with reversed flow, in 2 more the portal spectrum was arterialized, probably due to cirrhotic–related collateral shunting, which persisted to 7-th day post-RFA. In one case on the 1-st day after the ablation Doppler US revealed segmental portal thrombosis in the vicinity of the tumor zone.

Conclusions: 1.Doppler US is useful in evaluating liver hemodynamic changes related to RFA. 2. Major vascular complications are rare after RFA. 3. Increased hepatic blood flow measured in PV and HA is observed transiently after RFA. 4. Peritumoral vascular changes are more distinct in patients with cirrhosis/HCC and affect mostly the portal flow.