Marco Aurelio Grudtner

Efeitos a curto prazo de "stents" não recobertos e recobertos com politetrafluoroetileno em aorta de suínos: um modelo experimental

PURPOSE: To report an experimental study evaluating, through digital morphometry, the intimal thickening of the arterial wall after the implant of auto-expandable stainless steel stents covered or not with polytetrafluoroethylene (PTFE) in the pig aorta. METHODS: In three groups of pigs a 12 F sheath was inserted in distal abdominal aorta. Group I animals (n=5) served as control. Group II animals (n=10) received an auto-expandable uncovered metallic stent. On group III animals (n=10) an auto-expandable stent covered with PTFE was inserted. After four weeks the animals were killed, the specimens were harvested and the intimal thickening was quantified by morphometric analysis. RESULTS: In the comparison among groups I, II and III referring to intimal, medial area and intimal index, it was not observed statistically significant variation. Differences were identified among groups referring to luminal proximal (p=0,036) and distal areas (p=0,044). Through multiple comparison tests for Kruskal-Wallis it was identified a difference between groups I and II. However, when these variables were controlled by weigh factor (luminal area/weigh relation), this difference was not observed anymore. CONCLUSION: In this short term study, the PTFE covering is not associated to further intimal thickening besides that promoted by the metallic mesh in large arteries and in high flow conditions.

Aortomonoiliac Stent-Grafts for Abdominal Aortic Aneurysm Repair: Association with Iliofemoral Crossover Grafts

Purpose: To analyze the outcome of endovascular exclusion of abdominal aortic aneurysm (AAA) using aortomonoiliac stent-grafts. Methods: Fifty-seven consecutive patients (49 men; median age 70, range 56–89) with AAA >5 cm were treated in a 6-year period with the conical ELLA stent-graft. Forty-two (73.9%) patients were classified ASA (American Society of Anesthesiologists) IV and 6 as ASA V. In the majority of cases, the implantation procedure featured device delivery through the external iliac artery, transrenal placement of a bare stent in selected cases, and an iliofemoral crossover graft through a prevesical tunnel. Results: Successful deployment was achieved in 56 (98.2%) patients. Mean time to discharge was 8.7 days (range 2–125). Two patients died in the 30-day period. Nine endoleaks occurred in 8 (14%) patients; 4 required further intervention. Mean follow-up was 35.3 months (range 1–66), during which 5 patients died from unrelated causes. No late endoleak, graft occlusion, device twisting/migration, or aneurysm rupture was observed. No correlation between type I endoleaks and unfavorable proximal neck or iliac artery anatomical characteristics could be found. Primary technical and clinical success rates were 86.0% and 94.7%, respectively. Conclusions: In this approach, the crossover graft remains in a retropubic space and consequently does not have all the disadvantages of a subcutaneously placed prosthesis. The results achieved in this group of high-risk patients support recommendation of this technique as a simple and safe alternative to bifurcated systems.

Análise morfométrica da carótida de suínos submetidos a angioplastia com ou sem implante de stent de cromo-cobalto

Background: Intimal hyperplasia is the most common delayed response to angioplasty. The use of cobalt-chromium stents is well studied in the coronary circulation; however, there are few studies on their use in the carotid and peripheral circulation. Objective: To analyze the intimal reaction in a swine carotid artery undergoing simple angioplasty and angioplasty followed by implantation of cobalt-chromium stent. Materials and methods: We carried out angioplasty in the right common carotid artery and angioplasty with cobalt-chromium stent in the left common carotid artery in eight swine. Four weeks later, all animals were sacrificed for arterial tissue sampling and preparation of histological slides. Slide images were scanned and analyzed using a digital morphometry program. Statistical analysis was performed by mean values and standard deviations of the areas in each group, using the Students t test. A p value of < 0.05 was considered significant. Results: Angioplasty with cobalt-chromium stent implantation resulted in a higher degree of hyperplasia compared with simple angioplasty. The difference was statistically significant when the lumen area, the internal elastic lamina area, and the external elastic lamina area were compared between the two groups. No statistically significant difference was found when the media layers of both groups were compared. Conclusion: Cobalt-chromium stent implantation resulted in more intimal hyperplasia than simple angioplasty, however the stent was not enough to reduce the arterial lumen.

Histological analysis of cobalt–chromium stents with and without Camouflage® polymer coating: experimental porcine carotid artery model:

This study evaluated the arterial response to cobalt–chromium stents with and without polymer coating (Camouflage®, Hemoteq AG, Wuerselen, Germany) implanted in pigs. Cobalt–chromium balloon-expandable stents (4 × 16 mm) were implanted in the common carotid arteries of nine pigs. Histological analysis of endothelialization, inflammation and injury was performed one month later. All stents were successfully deployed, and all but one animal survived the 30 study days. All arteries were patent. Endothelialization was nearly complete in most sections of all carotid stents in both groups. There were mild inflammatory infiltrate and mild-to-moderate injury, which were associated with the stent shafts and not significantly different between groups. Our findings suggest that, in porcine carotid arteries, the histological response to balloon-expandable cobalt–chromium stents coated with polymer (Camouflage®, Hemoteq AG) is similar to the response to non-coated cobalt–chromium stents.