Biomedical Engineering Reference
In-Depth Information
welding is an exciting new approach. Since tissue welding is heat activated,
microwaves could be used.
Previous Approaches to Anastomosis
As stated before, laser welding has
been used to create vascular anastomoses. Successful laser tissue welding
relied on precise apposition of the tissue edges and avoidance of thermal
injury due to excess energy delivery and nonspecific absorption. Early dis-
ruption due to the diminished strength of welds immediately after their
creation has prevented more widespread use of this technology. A laser-
fibrinogen-reinforcing suture anastomosis does not require as precise an
apposition as does an anastomosis primarily made by laser. (The biological
solder fills in the spaces between the tissues to be welded.) The addition of a
fibrinogen solder has been shown to increase the strength of such welds.
It is believed that the main problem with these tissue welds is the small
surface area available for bonding (Fig. 6.20). The initial approach was to
increase the surface area for the anastomoses and to control heating with
microwave energy (Fig. 6.21). The solder was placed not only between the two
arteries but also from a sleeve around the vessel. This approach provided the
greater surface area. The biological solder would be activated by microwave
energy applied via a catheter within the arteries. This approach required that
the biological solder have some intrinsic strength and the microwave energy
would be selectively absorbed by the biological solder.
Artery 2
Artery 1
Only this small surface area is available for bonding
FIGURE 6.20
Small surface area available for bonding.
Artery 2
Artery 1
Biological solder
FIGURE 6.21
Sleeve around vessels to provide greater surface area.
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