Carlos E. Encarnacion

Stenting of the iliac arteries with the palmaz stent: Experience from a multicenter trial

Balloon-expandable, intraluminal stenting of the iliac arteries with the Palmaz stent was the subject of a multicenter study for 4 years. A total of 486 patients underwent 587 procedures. Four hundred and five patients had unilateral and 81 had bilateral iliac stent placements. Follow-up ranged from 1 to 48 months (mean 13.3±11 months). Sustained clinical benefit of the treated patients was obtained in 90.9% at 1 year, 84.1% at 2 years, and 68.6% at 43 months. Angiographic patency rate was 92%. Diabetes mellitus and poor runoff had significant negative influence on the clinical outcome. The 10% incidence of procedural complications was not altered by operator experience.

Iliac Artery Stent Placement with the Palmaz Stent: Follow-up Study

PURPOSE The long-term efficacy of iliac artery stent placement with the Palmaz stent was evaluated for treatment of limb ischemia. PATIENTS AND METHODS Iliac stent implantation for limb ischemia was performed on 108 limbs in 83 patients. Eighty patients (96.4%) were followed up clinically from 1 to 70 months (mean, 25.8 months), and 30 patients (37.5%) were followed up with angiography from 1 to 48 months (mean, 10.4 months). Patients were classified into six categories by using an ischemic ranking profile. Clinical success was defined as a minimum one-category improvement from preprocedure ranking. RESULTS The clinical success rate was 98.9% immediately after the procedure and 86.2% at 48 months. Long-term success was statistically more common in patients with higher preprocedure and lower postprocedure ischemic ranking, and in patients without diabetes. Arteriography demonstrated a primary patency rate of 87.5% at latest follow-up, with five occlusions (12.5%) and only two (5.0%) restenoses. Average stenosis was 17.8% at 6 months and 24.7% at 2 years. Stent restenosis was statistically more common with a higher postprocedure pressure gradient. The complication rate was 9.7%, and 30-day mortality was 1.2%. CONCLUSION Long-term clinical and angiographic follow-up demonstrates iliac artery stent placement with the Palmaz stent is safe and efficacious for treatment of limb ischemia.

Aortic bifurcation stenosis: treatment with intravascular stents.

Balloon-expandable intravascular stents were employed to correct atherosclerotic stenosis of the aortic bifurcation. The devices were placed in the proximal iliac arteries with the cephalic end of the stents contacting in the midline. This arrangement provided an adequate lumen for the distal portion of the aortic wall and the proximal iliac arteries. Six of seven patients who received this form of treatment had hemodynamic and clinical improvement of their vascular insufficiency at an average follow-up of 1 year.

Influence of Anatomic Distribution of Atherosclerosis on the Outcome of Revascularization with Iliac Stent Placement

PURPOSE To determine the influence of clinical and angiographic variables, including the anatomic disease pattern, on the outcome of iliac stent placement. PATIENTS AND METHODS The 455 patients of the study population were divided in three groups according to the anatomic distribution of their peripheral atherosclerosis lesions. Pattern type 1 (focal aortoiliac and/or common iliac lesion) included 180 patients (39.6%), type 2 (external iliac lesion) comprised 58 patients (12.8%), and type 3 (multilevel lesions) included 217 patients (47.7%). RESULTS Complete relief of symptoms immediately after revascularization was observed in 88.3% and 85.4% of patients with pattern type 1 and 2, respectively, compared to 60.1% with type 3 (P < .05). The persistence of clinical benefit at 36-month follow-up was 91.6%, 97.9%, and 60.8% in disease patterns 1, 2, and 3, respectively. The overall 1-year mortality rate was 3% with type 1 lesions, 5.7% with type 2, and 9.7% with type 3. On multivariate logistic regression, the presence of a disease pattern type 3 was the most powerful indicator (P < .001) of early unsatisfactory clinical outcome in iliac stent placement. Unexpectedly, female gender was predictive of unsatisfactory clinical outcome (P < .01) and higher periprocedural complications (P < .001) following iliac stent revascularization. CONCLUSIONS Pattern type classification helps identify patients at higher risk for cardiovascular morbidity and mortality. Ideal candidates for iliac stent placement are patients with pattern type 1 or 2 disease.

Use of Stents Covered with Polytetrafluoroethylene in Experimental Abdominal Aortic Aneurysm

PURPOSE To establish the effectiveness of covered stents in the treatment of aortic aneurysms, to investigate the histopathologic healing patterns of the device, and to determine the long-term endurance and integrity of modified polytetrafluoroethylene (PTFE). MATERIALS AND METHODS Experimental aneurysms were created in dogs by enlarging the aortic lumen with a patch of abdominal fascia. After 5 months, eight animals underwent an endoluminal bypass. The bypass device consisted of a 6-cm-long stent covered with thin PTFE. After surgery, the animals were killed at 3, 6, and 12 months in groups of three, three, and two, respectively. Specimens were processed for luminal surface studies and cross-sectional histologic study. Explanted PTFE material was analyzed for its physical characteristics and performance and was compared with retained control samples. RESULTS Before the animals were killed, aortography showed patent bypass conduits in all animals, although two of eight had leaks into the aneurysmal sac. Endothelialized neointima largely covered the luminal surface of the PTFE stent. The percentage of prosthetic surface covered by tissue did not change from 3 months to 1 year. Physical testing of the explanted PTFE material showed no structural deterioration and no change in the internodal distance. Thickness and axial tensile strength varied 12% and 17% from controls, respectively. CONCLUSION Thin-walled PTFE seems to have physicochemical characteristics that make this material adequate for endovascular use. Though limited, this study supports the establishment of preliminary clinical evaluation of metallic stents combined with PTFE for the treatment of abdominal aortic aneurysm.

Oral contraceptives and venous thromboembolism: a case-control study designed to minimize detection bias.

Background: Previous epidemiologic studies of venous thromboembolism and oral contraceptive use are susceptible to bias in the detection of venous thromboembolic events. This case-control study uses a unique design to minimize the influence of detection bias. Methods: Nonpredisposed women younger than the age of 40 years who underwent pulmonary angiography, lower extremity venography, or lower extremity duplex Doppler sonography at a large urban hospital were classified into a case group or control group based on results of their diagnostic studies. Medical records were reviewed for a history of current oral contraceptive use. Results: Fifty-seven women met the study criteria during the 11-year study period. Seven of 9 women in the case group and 17 of 48 women in the control group were currently using oral contraceptives (odds ratio 6.38; 95 percent confidence limits 1.19, 34.2). Conclusions: The association previously noted between venous thromboembolism and oral contraceptive use is not due to bias in the detection of venous thromboembolic events.

Polytetrafluoroethylene-encapsulated Stent-Grafts: Use in Experimental Abdominal Aortic Aneurysm

PURPOSE To evaluate expanded polytetrafluoroethylene (ePTFE) encapsulated stents for the treatment of aortic aneurysms with emphasis on the blood and tissue-material interactions. MATERIALS AND METHODS Experimental aortic aneurysms were created in dogs by enlarging the aortic lumen with an abdominal fascial patch. Twenty animals underwent endoluminal repair after allowing the surgically created aneurysm to heal for 2 months prior to transluminal aneurysmal exclusion. The device used consisted of an 8-cm-long ePTFE encapsulated stent graft. The animals were killed in groups at 1 week and at 1, 2.25, 6, and 12 months. Specimens were processed for histologic and luminal surface studies. RESULTS Before the animals were killed, aortography demonstrated two thrombosed aortae in the 6-month group and two endoleaks in the 12-month group. Endothelialized neointima extended into the proximal and distal portions of the prosthetic lumen, with minimal cell coverage in the center of the graft. The overall percent surface area covered by endothelialized neointima was 22% +/- 6% at 6 months and 18% +/- 10% by 1 year (P = .75). Histologic examination demonstrated minimal tissue penetration into the ePTFE. CONCLUSION Transluminal exclusion of abdominal aortic aneurysms by encapsulated stent-graft is easily accomplished. With this device, tissue coverage and penetration of the stent graft is limited and does not tend to increase with time.

Jejunal phlebectasia presenting with massive gastrointestinal hemorrhage.

Our case report illustrates the clinicopathologic features of this rare vascular lesion and highlights that phlebectasia should be considered as a cause of gastrointestinal bleeding of undetermined etiology in adult patients.