Local infusion of the nitric oxide donor Sin-1 after angioplasty. Effects on intimal hyperplasia in porcine coronary arteries.

PURPOSE: To investigate the development of intimal hyperplasia in response to percutaneous transluminal coronary angioplasty (PTCA) followed by local delivery of the nitric oxide (NO) donor 3-morpholino-sydnonimine (SIN-1). MATERIAL AND METHODS: Overdilation PTCA was performed in coronary arteries in 20 healthy pigs. One of the dilated segments was additionally treated with local delivery of SIN-1 for 10 min. Segments distal to the treated part of the arteries served as controls. Arteries were radiographically depicted and analyzed after 1 and 8 weeks for actin, myosin and intermediate filaments (IF), nitric oxide synthetase (NOS) and histological evaluation. RESULTS: Segments treated with PTCA+SIN-1 showed a significantly (p=0.03) larger luminal diameter compared with PTCA only treated segments. The luminal loss after SIN-1 was not significant compared with the diameter prior to treatment. Endothelial NOS content was significantly lower in the PTCA+SIN-1 group compared with the PTCA group after 1 (p=0.03) and 8 weeks (p=0.013). IF/actin ratio after 1 week was significantly increased in PTCA-treated segments compared with untreated controls (p=0.004), and compared with PTCA+SIN-1-treated segments (p=0.004). CONCLUSION: PTCA-induced intimal hyperplasia was potently inhibited by local delivery of the NO donor SIN-1. Momentary events at the time of injury play a significant role in the development of intimal hyperplasia and long-lasting down-regulation of the endothelial NOS expression after SIN-1 exposure is suggested. The IF/actin ratio can be useful as an early marker of intimal hyperplasia.

Long-term results of combined surgical and radiological intervention in complicated aortic dissection type-A. A case report.

We report the long-term results of combined surgical and radiological intervention in a patient with complicated aortic dissection, type-A. Following surgical graft-repair of a dissected part of the ascending aorta, embolization of the splenic artery, and stenting of the major abdominal arteries and of the left renal artery, was performed. The patient was able to return to normal active life, and all stented arteries remained patent after 32 months. A stent that was mispositioned across the aortic lumen did not cause any symptoms.

Double-balloon catheter for isolated liver perfusion: an experimental study.

PURPOSE: Further development of a previously described interventional method for isolated liver perfusion (ILP) with a new double-lumen balloon catheter, and evaluation of the side-effects of such isolation. METHODS: In six pigs a double-balloon occlusion catheter was placed via the transjugular approach with its tip in the portal vein. One of the balloons was positioned in the inferior vena cava (IVC), cranial to the origin of the hepatic veins and the other balloon in the portal vein. By the transfemoral approach, a single-balloon occlusion catheter was placed in the IVC caudal to the origin of the hepatic veins. A third catheter was placed by the transfemoral route with the occlusion balloon in the proper hepatic artery. After inflation of all balloons 99Tc(m)-labelled human serum albumin was recirculated through the liver. The isolation was evaluated by repeated measurement of radioactivity levels in peripheral blood. Laboratory tests of liver and pancreas function, and hemoglobin, were taken before, at the end of, and 3 days after the procedure. Blood gases were tested at the beginning and end of the procedure. RESULTS: One pig died during the procedure due to technical failure and was excluded from the study. In the other pigs leakage from the isolated liver to the systemic circulation increased slowly, up to 9.7% (mean) during 30 min of recirculation of the perfusate through the liver. Laboratory tests were normal in all pigs except insignificant acidosis directly after the procedure and the slight elevation of s-ALAT after 3 days. CONCLUSIONS: Only minor leakage from the liver to the systemic circulation was noted during ILP performed with a new, double-balloon catheter. There were no serious side effects.

A new stent designed for carotid artery application. An experimental study.

PURPOSE: To evaluate a new stent developed for treating arterial stenoses located adjacent to the bifurcation of the carotid artery. MATERIAL AND METHODS: Eight 4-cm-long nitinol stents, each with a diameter of 6 mm in its distal half and 9 mm in its proximal half, were tested in 4 pigs. In each animal, the abdominal aorta was catheterized through the left common carotid artery, and 2 stents were inserted into the right and left iliac arteries, respectively, with the wider portion in the common iliac artery and the narrower portion in the corresponding external iliac artery. The pigs were killed after 24 hours, or 1, 4 or 8 weeks, following control angiography. The arteries were examined macroscopically and by scanning electron microscopy. RESULTS: All stents remained in the intended position, fitting the arterial wall, following successive expansion to their maximum diameter and after 4 weeks were completely covered by endothelium. The arteries remained patent, with preserved flow to the side branches through the stent mesh. A small thrombus was found in I artery CONCLUSION: In animal experiments, the new stent was safely inserted over the arterial bifurcation, remained in place and was covered by endothelium while flow through side branches was preserved.

Differences in endothelial injury after balloon angioplasty, insertion of balloon-expanded stents or release of self-expanding stents: An electron microscopic experimental study.

PURPOSE: To evaluate which of six different commonly available stents inserted into an artery without percutaneous transluminal angioplasty (PTA) causes the least endothelial damage. To compare the degree of endothelial injury after insertion of such a stent with injury caused by PTA. METHODS: Twelve healthy pigs were used in the experiments. In the first part of the study six different types of stents were inserted into the common iliac arteries. In the second part of the study self-expanding stents with large spaces between the wires were used. PTA was performed in the contralateral iliac artery. The pigs were killed immediately after the procedure and resected specimens examined after fixation, using scanning electron microscopy. RESULTS: All procedures but two were accomplished successfully. More endothelium was preserved after insertion of self-expanding stents with large spaces between the wires, compared with stents with small spaces and balloon-expanded stents. After insertion of self-expanding stents with large spaces, 50.1% +/- 16.4% of the endothelium remained intact, compared with only 5.6% +/- 7.7% after PTA. The difference was statistically significant (p < 0.001). CONCLUSION: Self-expanding stents with large spaces between the wires, inserted without PTA, cause less damage to the endothelium than other stents and significantly less damage than PTA.

Electrolytic stent in the normal bile duct. An experimental study.

PURPOSE: To evaluate and compare changes in the bile-duct wall after the insertion of electrolytic and nonelectrolytic stents. MATERIAL AND METHODS: The electrolytic stents were composed of 3 different layers (iron, isolating polyethylene and tantalum) and were implanted surgically in the bile duct of 8 healthy pigs. The nonelectrolytic stents were also composed of 3 layers (2 layers of tantalum and an isolating layer of polyethylene) and were implanted surgically in the bile ducts of 9 healthy pigs. After an observation time of 8 weeks, the pigs were killed and the bile ducts were excised and sent for histopathological examination. RESULTS: One pig was killed after the procedure owing to postoperative complications; all the other pigs survived without complications. Migration of the stent to the bowel occurred in 4 pigs. A slight inflammatory reaction was seen at histopathological examination in 6 pigs with the electrolytic stent and in 6 pigs with the nonelectrolytic stent. There was no difference in the specimens from pigs with electrolytic and nonelectrolytic stents. CONCLUSIONS: The electrolytic stents did not cause more changes in the normal bile-duct wall than the nonelectrolytic stents.

Treatment of adenocarcinoma of the liver with mitomycin, hyaluronidase, and ethanol: an experimental study in the rat.

PURPOSE: To evaluate the effect of intratumorally injected ethanol, mitomycin, mitomycin with hyaluronidase, and hyaluronidase on tumor growth in an experimental model. METHODS: A suspension of 1 x 10(6) cells of chemically induced adenocarcinoma was implanted into the liver of 52 rats. Seven days later the rats were divided into groups according to treatment and injected via a midline laparotomy with ethanol, mitomycin, mitomycin with hyaluronidase, or hyaluronidase. A control group was treated with saline. The rats were killed 7 days after treatment. The tumor growth ratio was calculated, and the results compared for the different groups. Wilcoxon's rank sum test was used for statistical evaluation. RESULTS: The tumor growth ratio was significantly reduced after injection of mitomycin (p < 0.01) but not after ethanol. Hyaluronidase alone did not reduce the tumor growth ratio and had no synergetic effect with mitomycin. CONCLUSION: In an animal model intratumoral treatment of adenocarcinoma of the liver with mitomycin was significantly more efficient than similar treatment with saline or ethanol.

Proliferative response in smooth muscle cells after angioplasty or insertion of self-expanding stents. An experimental study in pigs.

PURPOSE: Evaluation of the early proliferative reaction of smooth muscle cells (SMC) in the media of the artery following percutaneous transluminal angioplasty (PTA), compared with the reaction on insertion of self-expandable stents. MATERIAL AND METHODS: In 6 healthy pigs, one iliac artery was overdilated with an 8-mm diameter angioplasty balloon. A self-expanding Nitinol stent, OD 8 mm, was inserted into the contralateral iliac artery without previous dilatation. The nuclei of the proliferating SMC in the media of the artery were labelled by intravenous administration of 5-bromo-2-deoxy-uridine and cells in S-phase counted 24 h after the procedure. RESULTS: The mean number of proliferating nuclei of the SMC increased significantly more after PTA (p < 0.05) than after the insertion of a stent. CONCLUSION: Early proliferative reaction of the SMC is more pronounced after PTA than after insertion of the self-expanding stent.

Isolated liver perfusion using percutaneous methods: an experimental study in the pig.

PURPOSE: To develop a method for isolated perfusion of the liver using radiological methods. METHODS: Twenty-one pigs, weighing about 20 kg, were divided into three groups. By transjugular and transfemoral approaches two occlusion balloons were placed in the inferior vena cava cranial and caudal, respectively, to the origin of the hepatic veins. One occlusion balloon was placed transfemorally in the common hepatic artery. Another occlusion balloon was inserted in the main branch of the portal vein via the transjugular-transhepatic approach in 11 pigs (groups 1 and 2), and in 10 pigs (group 3) by a percutaneous transhepatic route. After inflation of the balloons, patency of the isolated liver circulation was evaluated by recirculation of 99Tcm-labelled human albumin during 30 min. Blood tests were obtained after 1, 3, 5, 10, 15, and 30 min to evaluate leakage from the liver to the systemic circulation. RESULTS: Increasing leakage to the systemic circulation from the isolated liver circulation was observed in groups 1 and 2. In the third group the leakage was less than 10%. CONCLUSION: In an experimental animal model, isolated perfusion of the liver with minor leakage to the systemic circulation may be achieved using radiological methods.

Electrochemical and megavolt treatment of rat tumours.

In a series of experiments, an electrolytic method of tumour destruction has been developed. When tested clinically, no tumour has been totally destroyed but substantial necroses have been achieved. To make the electrolytic method more effective it can favourably be combined with radiotherapy. This has been done experimentally with good results. It is likely that the intense inflammation around the chemical destruction creates a radio-sensitising effect.