Microwave ablation of porcine kidneys in vivo: effect of two different ablation modes ("temperature control" and "power control") on procedural outcome.

PURPOSE: This study was designed to analyze the effect of two different ablation modes ("temperature control" and "power control") of a microwave system on procedural outcome in porcine kidneys in vivo. METHODS: A commercially available microwave system (Avecure Microwave Generator; MedWaves, San Diego, CA) was used. The system offers the possibility to ablate with two different ablation modes: temperature control and power control. Thirty-two microwave ablations were performed in 16 kidneys of 8 pigs. In each animal, one kidney was ablated twice by applying temperature control (ablation duration set point at 60 s, ablation temperature set point at 96°C, automatic power set point; group I). The other kidney was ablated twice by applying power control (ablation duration set point at 60 s, ablation temperature set point at 96°C, ablation power set point at 24 W; group II). Procedural outcome was analyzed: (1) technical success (e.g., system failures, duration of the ablation cycle), and (2) ablation geometry (e.g., long axis diameter, short axis diameter, and circularity). RESULTS: System failures occurred in 0% in group I and 13% in group II. Duration of the ablation cycle was 60±0 s in group I and 102±21 s in group II. Long axis diameter was 20.3±4.6 mm in group I and 19.8±3.5 mm in group II (not significant (NS)). Short axis diameter was 10.3±2 mm in group I and 10.5±2.4 mm in group II (NS). Circularity was 0.5±0.1 in group I and 0.5±0.1 in group II (NS). CONCLUSIONS: Microwave ablations performed with temperature control showed fewer system failures and were finished faster. Both ablation modes demonstrated no significant differences with respect to ablation geometry.

Pharmacological analysis of alpha(2)-adrenoceptor subtypes mediating analgesic, anti-inflammatory and gastroprotective actions.

Our previous findings suggest that alpha(2)-adrenoceptor stimulants induce gastroprotective action, the effect is likely to be mediated by alpha(2B)-adrenoceptor subtype. Clonidine (0.094 micromol/kg p.o.) and rilmenidine (0.014 micromol/kg p.o.) in gastroprotective dose range, as well as ST-91 (2.2 micromol/kg p.o.), a clonidine analogue showing higher affinity to alpha(2B)-adrenoceptor subtype than to alpha(2A)-one, inhibited the carrageenan-induced hyperalgesia in Randall-Selitto test, the antinociceptive action was reversed by yohimbine (5 micromol/kg s.c.) and the alpha(2B)-adrenoceptor antagonist prazosin (0.24 micromol/kg i.p.). Similarly, clonidine and rilmenidine in the same dose range reduced the oedema formation induced by carrageenan, yohimbine and the alpha(2A)-adrenoceptor antagonist BRL-44408 (3 micromol/kg i.p.) inhibited the anti-inflammatory effect; however, prazosin failed to affect it. These results suggest that alpha(2B/C)-like adrenoceptor subtype may be involved in the antihyperalgesic action, but not in the antiphlogistic effect of alpha(2)-adrenoceptor stimulants. The later effect may be mediated by alpha(2A)-like adrenoceptor subtype.