Introduction to microsurgery: an emerging discipline in biomedical research.

Using microsurgical techniques, biomedical researchers are able to perform procedures that would otherwise be impossible on small laboratory animals. The authors provide a primer on learning microsurgical technique, from correct posture and hand position, to understanding lenses and proper handling of surgical needles and suture material.

Microsurgical instrumentation and suture material.

Microsurgery requires specialized instruments and very fine suture material. The authors describe microsurgical instruments and suturing materials available for small animal microsurgery.

US-guided percutaneous laser ablation of liver tissue in a chronic pig model.

The authors evaluated the safety of ultrasound (US)-guided percutaneous ablation of liver tissue using a neodymium-yttrium-aluminum-garnet (Nd:YAG) laser fiber placed through a skinny needle. The US appearance of the lesion was correlated with the pathologic findings in 19 pigs killed at 1-7 weeks. A 20-gauge needle was percutaneously placed in the liver, and a fiber with a 0.5-cm cladding-stripped tip was inserted. The Nd:YAG laser was fired for 6 minutes at 1-4 W. The early sonographic appearance was recorded, and the US appearance before the pigs were killed was correlated with the gross and histopathologic findings. There were no cases of abdominal bleeding or infection. Mild transient changes in liver function were seen. An initial strong echogenic focus decreased slightly in echogenicity for 10 minutes and then stabilized. Over 1-7 weeks, the 1-cm-diameter lesion decreased in size and developed an echogenic rim that correlated with a peripheral zone of inflammatory repair around a small central cavity and zone of necrosis. US-guided laser ablation of liver tissue is safe in this pig model, and the US appearance corresponds to a process of repair and removal of necrotic liver tissue.

Animal model for fluoroscopically guided laser application in the biliary tree.

The purpose of this project was to develop an animal model for a fluoroscopically guided application of the contact neodymium-yttrium aluminum garnet (Nd-YAG) laser in the bile duct and identify the factors affecting the extent of damage to the duct wall. This model permits cholangiographic visualization of the duct during laser application. Laser damage is limited by using contact probes and firing the laser while slowly pulling the probe proximally into the duct. Sixteen common bile duct laser burns were produced in 14 dogs. Power settings of 8-25 W were used. The tension of the contact probe along the duct wall, termed "wall tension," was varied through intraoperative manipulation in order to mimic a variety of ductal geometries that might be encountered in clinical use. The authors produced duct damage ranging from a superficial burn to perforation. Power and wall tension were the most important factors in determining the depth and circumference of damage, and the use of 15 W or less did not perforate the duct.