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The Necrotizing Effect of Pulse Cryocycling on Liver Tissue
Doron Kopelman, MD;
Gregory Shpoliansky, MD;
Ofer Ben-Izhak, MD;
Assaf Zaretzki, DVM;
Rona Shofti, DVM;
Diana Gaitini, MD;
Moshe Hashmonai, MD
Arch Surg. 2004;139:245-250.
Hypothesis Repeated cycles of freezing improve the necrotizing effect of cryosurgery. We investigated whether multiple, very short periods of freezing and thawing (pulse cryocycling) enlarged the area of cell cryonecrosis within the iceball, compared with the standard method of cryocycling.
Design Liver cryonecrosis was produced in 3 groups of rabbits by means of 2 cycles of 5-minute freezing processes, each followed by 5 minutes of spontaneous thawing. In the control group (group 1), the freezing periods were uninterrupted. In the pulse cryocycling groups, the freezing periods consisted of repeated episodes of freezing and active thawing of 15 seconds (group 2) or 30 seconds (group 3) each. The edges of all lesions were visually marked. The correlation between marking and borders of the cryolesion were examined ultrasonographically. All animals were killed on the following day, and the liver was harvested and examined histologically.
Setting Animal experimental laboratory.
Results Complete liver cell demise was observed up to the edge of the cryolesions in all 3 groups of animals. However, a thin, sharply bounded intermediate zone of incomplete tissue destruction was observed at the border of the cryolesions, which was relatively thicker in group 2.
Conclusions In our study, pulse cryocycling had no advantage compared with regular cryocycling, which obtained optimal results in normal liver tissue. However, compared with the 30-second cycles, the 15-second pulse cycling yielded poorer results.
From the Department of Surgery B, Haemek Medical Center (Drs Kopelman and Shpoliansky), the Departments of Pathology (Dr Ben-Izhak) and Radiology (Dr Gaitini), Rambam Medical Center, and the Faculty of Medicine, Technion–Israel Institute of Technology (Drs Kopelman, Shpoliansky, Ben-Izhak, Zaretzki, Shofti, Gaitini, and Hashmonai), Haifa, Israel.
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