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Hepatic interstitial laser photocoagulation: demonstration and possible clinical importance of intravascular gas
D E Malone1, L Lesiuk, A P Brady
1Department of Radiology, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada.
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.