Microbubbles in the Pulmonary Artery Generated During Experimental Hepatic Radiofrequency Ablation Is Correlated with Increased Pulmonary Arterial Pressure

Abstract

Microbubbles in hepatic veins during hepatic radiofrequency (RF) ablation is a well-known observation. In this experimental study, we examined the association between microbubbles in the pulmonary artery and alterations in mean pulmonary arterial pressure (MPAP) during hepatic RF ablation with a perfusion electrode system. Sixteen domestic pigs were included in the study. Twelve animals were randomly assigned to RF ablation with maintained (n = 6) or interrupted (n = 6) hepatic inflow. Four animals were assigned to a control group where interruption of hepatic inflow but no RF ablation was performed. Microbubbles in the pulmonary artery were recorded by transesophageal echocardiography and scored according to the number of bubbles per heart cycle. Mean pulmonary arterial pressure was continuously registered by a pulmonary artery catheter. The association between the microbubble score and increase in MPAP during ablation was examined using Spearman's rank correlation coefficient. Echocardiographic recordings were acquired in 9 of 12 animals in the two treatment groups. Microbubbles in the pulmonary artery were present in four animals in each treatment group. Mean pulmonary arterial pressure increased from a baseline value of 17.7 mm Hg +/- 2.3 to a maximum value of 29.7 mm Hg +/- 7.7 during ablation (P = .018). A significant association was found between the microbubble score and increase in MPAP (P = .001). Microbubbles were detected in the pulmonary artery during hepatic RF ablation both during maintained and interrupted hepatic inflow. A strong association was found between microbubbles in the pulmonary artery and increased MPAP. The clinical implications of our findings are to be determined.