Animal Experiments on an Antithrombogenic Small-Caliber Vascular Prostheses and Vascualr Patch: Observation in Canine Models / 대한흉부외과학회지

BACKGROUND: Although a variety of synthetic vascular grafts are available in modern vascular surgery, no ideal prosthesis has yet been developed. Small-caliber vascular grafts with low flow, as used in the lower extremity, continue to become thrombosed at unacceptable rates. We have developed and evaluated the new antithrombogenic blood contacting surfaces in canine model. MATERIAL AND METHOD: Two new antithrombogenic blood contacting surfaces(Polyvinylalcohol-Polyurethane(PVA-PU) blend and natural Graphite-Polyurethane(G-PU) blend) have been developed and evaluated in canine model, using vascular grafts and patches. The luminal surfaces of the test vascular grafts(5 mm ID) were fabricated by dipping a glass rod in PVA-PU blend solution(50 % PVA) using phaseseparation method. Mongrel dogs of either sex weighing 18-22 kg were anesthetized by endotracheal intubation using halothane and their lungs were ventilated with a volume-cycled ventilator. Maintenance anesthesia with 0.5-1.0% halothane and supplemental oxygen was used. Two pairs were used for comparison in the bilateral femoral arteries for both vascular grafts(PVA-PU vs. PU) and vascular patches(G-PU vs. PU). Bilateral groin incisions were made and the arteries were exposed and clamped. After an excision of 1 cm of the artery between clamps, a graft of 2.5 cm in length was implanted end-to-end using 6-0 polypropylene suture. The vascular patch was implanted as a form of on-lay patch. Animals were sacrificed at 1, 2, 4, 6, 8 and 16 weeks for vascular grafts and 1, 2, 4 and 6 weeks for vascular patches. RESULT: The vascular grafts of PVA-PU blends showed patent lumina in the 2 and 16 weeks animals, while those of PU showed a patent lumen in 2 weeks animal. PVA-PU graft of 16 weeks showed a fairly clean luminal surface. A light microscopic finding of this graft demonstrated good tissue infiltration through porosity. The animals with vascular patches showed patent arteries in both groups except 2 weeks animal. Scanning electron microscopy of the luminal surfaces of G-PU patches in 4 and 6 weeks animals showed endothelial cell covering with microvilli. PU patches showed qualitatively less endothelial cell covering. CONCLUSION:In conclusion, PVA-PU and G-PU blends can be a promising blood contacting surfaces for application in a synthetic vascualr graft. However,further animal study is needed to determine the real long-term effects of these methods of surface modifications.

Effects of verapamil in cardioplegic perfusates on the ischemic myocardium in isolated rat heart / 대한흉부외과학회지

Using isolated rat heart preparations, we observed the protective effects of verapamil cardioplegia on ischemic myocardial injury. Isolated rat hearts were subjected to global ischemia at 25degrees C. Twenty four isolated Sprague Dawley rat hearts underwent 30 minutes of the retrograde nonworking perfusion with Krebs-Henseleit buffer solution followed by 25degrees C cardioplegic solution(St. Thomas' Hospital Cardioplegic Solution) for 60 minutes. Before ischemic arrest, rat hearts were treated with cold cardioplegic solution in control group(n=12) and cold cardioplegic solution with verapamil(1mg/L) in experimental group(n=12). After 60 minutes of ischemia, hemodynamic and biochemical parameters such as heart rate, left ventricular pressure(LVP), +dp/dt max, coronary flow and creatine phosphokinase(CPK) were measured before giving cardioplegia and 30 minutes after reperfusion. Verapamil group exhibited greater recovery of heart rate, LVP, +dp/dt max, coronary flow and CPK than control group(p<0.05).

Surgical Treatment of Thymoma / 대한흉부외과학회지

Between January 1986 and December 1995, 24 patients were treated surgically for thymoma. There were 17 males and 7 females, and their ages ranged from 23 to 69 years old and mean age was 49 years. Thymomas were associated with fourteen my asthenia gravis, and classified histologically as lymphocytic in 12 patients, mixed in 8, epithelial in 4, and classified clinically as stage I in 11, stage II in 4, stage III in 8 and stage VI in 1 patient. Eleven patients with non-invasive thymoma had received surgical resection, and 10 out of 13 patients with invasive thymoma were able to undergo complete resection. A partial resection or tissue biopsy followed by radiation or chemotherapy was done with the remaining three patients. Three died, four had improvement of symptom, two had relapse and fifteen had no symptom during follow up ranged from 25 days to 60 months. In fourteen cases of thymoma with myasthenia gravis, one died due to myasthenic crisis, two showed symptom aggravation, six had less medical treatment and five patients had medical treatment as same as dosage received preoperatively.