Co2 Laser Soldering of Microvascular Anastomosis Controlled by a Temperature Regulation Fiberoptic System

Eyal Gur M.D
Department oF Plastic Surgery, Faculty of Medicine,
Tel Aviv University

Introduction – aims of the research.
Researchers in the applied physics group, researchers have been developing, for the last few years, a system of bonding tissues based on controlled heating. The system includes a CO₂ laser which heats a spot on an incision, a fiberoptic radiometer which measures the temperature of the heated spot on the incision and a computer which controls the heating and stabilizes the temperature. At the beginning our group used a "laser welding" system -heating the incision itself. We later switched to "laser soldering" - heating an incision covered by a layer of biological solder (e.g. albumin). In other experiments we welded skin, a cornea and a bladder, whereas in the present research we tried to widen the scope by using a system for soldering blood vessels. The aim was to start a research project for soldering blood vessels in small animals and continue in soldering of blood vessels in large animals. Bonding small blood vessels, as accepted in clinical microsurgery, is similar to bonding blood vessels in rats. Bonding larger blood vessels is similar to bonding blood vessels in pigs.

Experiments in bonding blood vessels
During the research year, experiments were carried out with Dr. Eyal Gur and Dr. Dudi Leshem of the Plastic Surgery Department of Ichilov hospital in Tel Aviv. The research was carried out in the Animal House in Tel Aviv University with the help of the veterinary Dr. Noam Kariv. We obtained permission to carry out experiments only on small animals (rats).

The plan for the experiments was to make a longitudinal incision in a coronary artery in a rat and to try to bond this incision with the aid of controlled heating. Already at the beginning of the research it became clear to us that soldering blood vessels is much more difficult than welding the tissues mentioned above. The problems that arose were as follows:

1. In the abovementioned tissues there was very little blood present, and there was no need to stop the flow of blood. In the case of blood vessels it is, of course, necessary to stop the flow of blood from both sides of the incision with the aid of clamps. This is the usual procedure when blood vessles are sutured clinically. When the clamps are used, the walls of the blood vessels are not stretched, of course. In the case of suturing this is not much of a problem. In the case of soldering it is much more difficult to keep the sides of the incision approximated.
2. Immediately after the soldering, the clamps stopping the flow of blood were released and the blood pressure in the blood vessel rose. Therefore the immediate strength of the bond is of major importance especially in comparison with the other experiments mentioned above.
3. The incisions in the present experiments were much smaller than in the previous experiments and the heating system heated a much larger area than is desirable.

Results of the experiments.
At the beginning we failed in our efforts to bond blood vessels and in the few experiments in which it seemed that we had succeeded, the animals finally died. After several months of strenuous experimentation, the physicians finally succeeded in soldering longitudinal incisions in blood vessels. They even succeeded in cutting blood vessels into two and in bonding them together again thereafter with the help of the laser soldering system (i.e. anastomosis). The mortality rate of the animals was still high but in some of the rats the soldering succeeded. After several days the animals were sacrificed and upon examination it was found that the bonding did not open. Summary.

During the year of research, exploratory experiments were carried out, which proved the feasibility of laser soldering for bonding tissues and the latent potential in this technique for microsurgery. On the other hand, technical difficulties were encountered. We plan to continue with the research, to improve the performance of the system and to advance to experiments on much larger animals (rabbits and pigs). This is important for surgery on larger blood vessels in humans. In addition, it will probably be easier to solder blood vessels in large animals. The accumulated experience will help in experiments on blood vessels in small animals which we plan to continue, and for the anticipated use of this method clinically in microsurgery.