Hepatic interstitial laser photocoagulation: demonstration and possible clinical importance of intravascular gas.

PURPOSE

To investigate gas formation during hepatic interstitial laser photocoagulation (ILP).

MATERIALS AND METHODS

In vitro, ILP was performed with a neodymium yttrium aluminum garnet laser on a piece of liver in a water bath. In vivo, nine pigs underwent 24 ultrasound (US)-monitored ILP procedures. Fiber tips were more than 1 cm from (n = 16) or adjacent to (n = 8) intrahepatic veins. The gas production seen on US images was graded on a scale of 0 to 4. Precordial Doppler US was performed in all cases.

RESULTS

In vitro, smoke bubbles emanated from the vessels during ILP. In vivo, US showed intravascular gas production during nine of 15 exposures of at least 500 seconds duration. Gas production scores of 2 or more were recorded for nine exposures. Intracardiac gas was identified on eight precordial Doppler US recordings. All animals survived.

CONCLUSION

Gas was detected in the heart during some ILP exposures. Patients with a probe-patent foramen ovale (24% prevalence) could be at risk for paradoxic air embolus during ILP.