4
Sunday, March 3, 1996 II II 136 justifying the investment in the simulator, re- ducing complications, and improving the qual- ity of health care. Selected Bibliography Cuschieri A. Whither minimal access surgery: tribulations and expectations. Am J Surg 1995; 169:9-19. Dent T. Training, credentialing and granting of privileges for laparoscopic general surgery. Am J Surg 1991; 161:399-403. Gupta SC, Klein SA, Barker JH, Franken RJPM, Banis Jc. Introduction of new technology to clinical practice: guide for assessment of new VR applications. J Med VR 1995; 1:16- 20. Hoffman HM. Virtual reality meets medical education. In: Morgan K, Satava RM, Sieburg HB, Mathieu R, Christensen JP, eds. Interactive Technology and the New Paradigm for Healthcare. Washington, DC: lOS Press, 1995; 130-136. Jackson BG, Rosenberg LB. Force feedback and medical simulation. In: Morgan K, Satava RM, Sieburg HB, Mathieu R, Christensen JP, eds. Interactive Technology and the New Paradigm for Healthcare. Washington, DC: lOS Press, 1995;147-15I. Krueger MW. Olfactory stimuli in virtual reality for medical applications. In: Morgan K, Scientific Session 5 Covered Stents for Occlusive Disease Moderator: Alan H. Matsumoto, MD, Charlottesville, VA Room 608 25-1:30 pm Physical Properties of PTFE Bypass Material after Radial Dilation F. Palmaz, San Antonio, TX· Ie. Palmaz, MD • E.A. Sprague, PhD PURPOSE: To evaluate the performance charac- teristics of 3- and 6-mm PTFE vascular graft af- ter radial dilation comparable to that used in endovascular applications. MATERIALS AND METHODS: PTFE conduits with inner diameters of 3 and 6 mm were radi- ally expanded to three, four, and five times the original diameter with angioplasty balloons. In- ner and outer diameters, wall thickness, and in- Satava RM, Sieburg HB, Mathieu R,Christensen JP, eds. Interactive Technology and the New Paradigm for Healthcare. Washington, DC: lOS Press, 1995; 180-18I. Lnderquist A, Ivancev K, Wallace S, Enge I, Laerum F, Klbenstvedt AN. The acquisition of skills in interventional radiology by supervised training on animal models: three- year multicenter experience. Cardiovasc Intervent Radiol 1995; 18:209-211. Merril JR, Merril GL, Raju R, et al. Photorealistic interactive three-dimensional graphics in surgical simulation. In: Morgan K, Satava RM, Sieburg HB, Mathieu R, Christensen JP, eds. Interactive Technology and the New Paradigm for Healthcare. Washington, DC: lOS Press, 1995; 244-252. Merril JR, Preminger GM, Babayan R, Roy RT, Merril GL. Surgical simulation using virtual reality technology: design, implementation, and implications. (Reprint from Surgical Technology International III.) Rheingold H. Virtual Reality. New York: Simon and Schuster, 199I. Rosenberg LB. How to assess the quality of force-feedback systems. J Med VR 1995; 1: 12-15. ternodal distance were measured, and water entry pressure test and longitudinal and radial tensile strength tests were performed. RESULTS: After dilation, the 3- and 6-mm PTFE conduits foreshortened 3.3% and 3.2%, and the wall thickness decreased 35% and 46%, respec- tively. Both had radial recoil averaging 24.7% and 27%, respectively. The average internodal distance decreased insignificantly (3% and 5%). Correspondingly, water entry pressure in- creased 1% and 24%, respectively. Radial ex- pansion resulted in a 49% and 50.4% decrease in the longitudinal tensile strength and a 34.4% and 12.4% decrease in radial tensile strength, respectively. CONCLUSIONS: Radial dilation of PTFE grafts to three to five times the original diameter results in moderate elastic recoil and negligible fore- shortening, but the wall thickness decreases al- most by half. The porosity of the graft is not

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Page 1: Scientific Session 5 Covered Stents for Occlusive Disease

Sunday, March 3, 1996

II

II

136

justifying the investment in the simulator, re­ducing complications, and improving the qual­ity of health care.

Selected BibliographyCuschieri A. Whither minimal access surgery:

tribulations and expectations. Am J Surg

1995; 169:9-19.Dent T. Training, credentialing and granting of

privileges for laparoscopic general surgery.

Am J Surg 1991; 161:399-403.Gupta SC, Klein SA, Barker JH, Franken RJPM,

Banis Jc. Introduction of new technologyto clinical practice: guide for assessment ofnew VR applications. J Med VR 1995; 1:16­20.

Hoffman HM. Virtual reality meets medicaleducation. In: Morgan K, Satava RM,Sieburg HB, Mathieu R, Christensen JP,eds. Interactive Technology and the New

Paradigm for Healthcare. Washington, DC:lOS Press, 1995; 130-136.

Jackson BG, Rosenberg LB. Force feedback andmedical simulation. In: Morgan K, SatavaRM, Sieburg HB, Mathieu R, ChristensenJP, eds. Interactive Technology and theNew Paradigm for Healthcare. Washington,DC: lOS Press, 1995;147-15I.

Krueger MW. Olfactory stimuli in virtual realityfor medical applications. In: Morgan K,

Scientific Session 5Covered Stents for Occlusive DiseaseModerator: Alan H. Matsumoto, MD,Charlottesville, VARoom 608

25-1:30 pm

Physical Properties of PTFE Bypass Materialafter Radial DilationF. Palmaz, San Antonio, TX· Ie. Palmaz, MD• E.A. Sprague, PhD

PURPOSE: To evaluate the performance charac­teristics of 3- and 6-mm PTFE vascular graft af­ter radial dilation comparable to that used inendovascular applications.

MATERIALS AND METHODS: PTFE conduitswith inner diameters of 3 and 6 mm were radi­ally expanded to three, four, and five times theoriginal diameter with angioplasty balloons. In­ner and outer diameters, wall thickness, and in-

Satava RM, Sieburg HB, MathieuR,Christensen JP, eds. InteractiveTechnology and the New Paradigm forHealthcare. Washington, DC: lOS Press,1995; 180-18I.

Lnderquist A, Ivancev K, Wallace S, Enge I,

Laerum F, Klbenstvedt AN. The acquisitionof skills in interventional radiology bysupervised training on animal models: three­year multicenter experience. CardiovascIntervent Radiol 1995; 18:209-211.

Merril JR, Merril GL, Raju R, et al. Photorealisticinteractive three-dimensional graphics insurgical simulation. In: Morgan K, SatavaRM, Sieburg HB, Mathieu R, ChristensenJP, eds. Interactive Technology and theNew Paradigm for Healthcare. Washington,DC: lOS Press, 1995; 244-252.

Merril JR, Preminger GM, Babayan R, Roy RT,Merril GL. Surgical simulation using virtualreality technology: design, implementation,and implications. (Reprint from SurgicalTechnology International III.)

Rheingold H. Virtual Reality. New York: Simonand Schuster, 199I.

Rosenberg LB. How to assess the quality offorce-feedback systems. J Med VR 1995; 1:12-15.

ternodal distance were measured, and waterentry pressure test and longitudinal and radialtensile strength tests were performed.

RESULTS: After dilation, the 3- and 6-mm PTFEconduits foreshortened 3.3% and 3.2%, and thewall thickness decreased 35% and 46%, respec­tively. Both had radial recoil averaging 24.7%and 27%, respectively. The average internodaldistance decreased insignificantly (3% and 5%).Correspondingly, water entry pressure in­creased 1% and 24%, respectively. Radial ex­pansion resulted in a 49% and 50.4% decreasein the longitudinal tensile strength and a 34.4%and 12.4% decrease in radial tensile strength,respectively.

CONCLUSIONS: Radial dilation of PTFE grafts tothree to five times the original diameter resultsin moderate elastic recoil and negligible fore­shortening, but the wall thickness decreases al­most by half. The porosity of the graft is not

Page 2: Scientific Session 5 Covered Stents for Occlusive Disease

Sunday, March 3, 1996

significantly atJected by dilation, but the longi­tudinal tensile strength decreases to half andthe radial strength to a third of the undilated

control samples.

Take Home Points:1. PTFE dilated before or during endovascular

applications has minimal foreshortening, sig­nillicant wall thinning, and moderate elastic

recoil.

2. Although porosity is not affected by radial

dilation, both radial and longitudinalstrength are decreased. These changesshould be considered during calculations of

the endurance requirements of PTFE for en­

dovascular use.

26-1:45 pm

PTFE-covered versus Uncovered Palmaz Stents:Impa.ct on Intimal HyperplasiaML Marin, MD, New York, NY. Fj. Veith, MD

•J. Cynamon, MD· L.A. Sanchez, MD· R.T

Lyon. AiD

PURPOSE: Neointimal hyperplasia within intra­

vascular stents used in the treatment of focalcommon iliac artery occlusive disease continues

to be a cause of restenosis.

MATljRIALS AND METHODS: Nine patients who

received endovascular stented grafts for thetreatment of long-segment iliac occlusive dis­

ease underwent follow-up arteriography be­tween 4 and 6 months after their primary pro­cedure; this allowed an assessment of the

proximal iliac stent anastomosis. Each graft was

cons1TUcted of a 30-mm Palmaz stent, one-halfof which was contained within a 6-mm polytet­rafluoroethylene graft. All stents were deployedby using an 8-mm balloon. The region of thestent in each follow-up angiogram was magni­fied five times to permit accurate measurementof luminal diameter of covered and uncoveredparts.

RESULTS: A transition zone from the uncoveredto the covered areas of each stent was identi­fied. The mean luminal diameter within the

stent was significantly greater in covered C7.5± 0.14) compared with uncovered (6.8 ±0.31) portions (P < .05).

CONCLUSION Partially covered intravascularstents used to anchor endovascular grafts in the

treatment of aortoiliac occlusive disease is a

unique model for assessing the effects of an

extrinsic stent covering on arterial healing.

These data suggest that a nonporous stent cov­ering may inhibit stent-related restenosis.

Take Home Points:1. Control of intimal hyperplasia.

2. Stented grafts for the treatment of aortoiliacocclusive disease.

3. Etiology of failure of stented grafts.

27-2:00 pm

Endovascular Aorto-Iliac Grafts Combinedwith Standard Infrainguinal Arterial Bypassesin the Management of Limb-threateningIschemia: Preliminary Report

J. Cynamon, MD, Bronx, NY. C. W. Baka!, MD• ML Marin, MD· Fj. Veith, MD· Tj. Di

Bartho!omeo, MD • E. Casado, MD· et a!

PURPOSE Occlusive disease of the aortoiliacsegment may lead to limb-threatening ischemia

if there is coexisting disease in the femoral,

popliteal, or tibial arteries. This report summa­rizes the technical feasibility and early results of

placement of aortoiliac endovascular stentedgrafts (ESGs) in combination with conventional

surgical reconstructions for the treatment ofmultilevel arterial occlusive disease.

MATERIALS AND METHODS: Seventeen pa­tients with multilevel aorto-ilio-femorallimb­

threatening occlusive disease underwentinsertion of an ESG to treat long-segment oc­clusive disease followed by a conventional sur­

gical bypass. Conventional surgical bypasses

were constructed from polytetrafluoroethylene(n = 15) or saphenous vein (n = 2) as follows:femoral-popliteal (n = 12), femoral-tibial (n =

2), or contralateral femoral (n = 3) arteries.

RESULTS: Technical success was achieved in 17of 18 procedures (94%). The I-year primaryand secondary cumulative patency rates forESGs were 94% ± 10 and 100%, respectively.The 1- and 2-year patency rates for the extra­

vascular grafts were 92% ± 10 and 100%, re­

spectively. There were no deaths and 1 patient

lost his limb at 16 months.

CONCLUSION ESGs in combination with con­ventional surgical infrainguinal bypasses are

technically feasible and safe for the treatmentof limb-threatening occlusive disease and have

demonstrated encouraging early patency.

137

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138

Take Home Points:1. The combination of endovascular and con­

ventional bypass grafts is technically feasi­ble.

2. This modality is used for limb-threateningischemia.

3. Primary and secondary patency rates arepromising.

28-2:15 pm

Percutaneous Treatment of FemoropoplitealOcclusions with Use of Covered CraggEndoprostheses

J. Link, MD, Kiel, Gennany· S. Mueller­Huelsbeck, MD· J. Brossmann, MD· H.

Schwarzenberg, MD· M. Heller, MD

PURPOSE: To evaluate the effectiveness of per­cutaneous treatment of femoropopliteal occlu­sions with Dacron-covered Cragg endopros­theses.

MA TERlALS AND METHODS: In a period of 20months, 26 patients (17 men, 9 women) aged43-84 years (mean, 64 years) who presentedwith long-distance occlusion of the femoropop­liteal artery (mean, 8 cm) and poor results afterPTA were treated with percutaneous placementof covered Cragg endoprostheses. Follow-upranged from 1 to 20 months (mean, 9 mo) andconsisted of Doppler US after 1, 3, 6, and 12months and arterial angiography after 6months.

RESULTS: Immediate technical success wasachieved in 96% of cases. The ankle-brachialindex improved from 0.43 to 0.82 after the in­tervention. Nineteen of 26 endoprostheses(73%) were patent at the most recent DopplerUS follow-up. Angiography after 6 months hasbeen performed in 15 patients and has re­vealed a patency rate of 60%. In 6 patients,there were concentric stenoses at the marginsof the endoprostheses. One-third of the pa­tients had local pain and fever after the inter­vention, which lasted up to 4 weeks.

CONCLUSION Initial results of this minimallyinvasive technique are promising. Restenosis atthe margins of the covered Cragg endopros­theses is a problem and has to be investigatedin long-term follow-up studies. There seems tobe an unclear reaction against the coverage ofthe endoprosthesis.

29-2:30 pm

Silicone-coated Intravascular Stents: Use in theTreatment of Arteriovenous FistulasG.K. Geremia, MD~ Chicago, IL· B. Silver, MD• M. Haklin, MD· M. Bakon, MD· LB.

Brennecke, DVM, PhD· J. Douglas, MD

PURPOSE: The purpose of this study was toobserve the effectiveness of silicone-coated me­tallic stents in treatment (closure) of experi­mentally created arteriovenous fistulas.

MATERIALS AND METHODS: Experimental arte­riovenous fistulas between the carotid arteryand jugular vein,S mm in diameter, were cre­ated in five mongrel dogs weighing 30-40 kg.A single silicone-coated stent was deposited in­travascularly into the carotid artery so that it layacross the fistula hole. Angiography and Dopp­ler US were performed before, immediately af­ter, and 4 and 8 weeks after stent placement.

RESULTS: Complete closure of the fistula wasdemonstrated immediately after the stent wasdeposited in all cases. The parent carotid arterywas widely patent immediately after and 4weeks after stent placement; 250/0-50% narrow­ing of the carotid lumen was seen at the proxi­mal and distal ends of the stent 8 weeks afterstent placement. Histopathologic study revealeda solid area of collagen and fibrosis betweenthe carotid artery and jugular vein.

CONCLUSION Nonporous stents may have arole in the definitive, acute management ofsome fistulas. Further research is necessary,however.

Take Home Points:1. Silicone-coated stents were effective in the

acute treatment of arteriovenous fistulas.

2. Significant reactive fibrosis was seen at theends of the stent.

3. Coated stents may playa role in the treat­ment of selected arteriovenous fistulas.

30-2:45 pm

Endoluminal Bypass Grafting in Leg Arterieswith Use of the Cragg Endopro System 1: Aseries of 105 PatientsM. Henry, MD, Essey Les Nancy, France· M.Amor, MD· I. Henry, MD· M. Allaoui, MD· C.

Amicabile, MD· E. Le Borgne, PhD· et al

PURPOSE: To evaluate a new expandable ni­tinol stent covered with a polyester woven fab-

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Sunday, March 3, 1996

ric, Ithe Cragg Endopro System 1, which ena­bles percutaneous bypass graft placement iniliac and femoropopliteal arteries.

MATERIALS AND METHODS: A total of 105symptomatic patients (91 men, 14 women;mean age, 63 years ± 3; range, 38-88 years)with predominantly lengthy stenotic (n = 49)or occlusive (n = 49) lesions or aneurysms (n= 7) in iliac (n = 38), femoral (n = 62), orpopliteal (n = 5) arteries received 154 stents.Mean length of femoropopliteallesions was15.3 cm ± 2.1 (range, 4-30 cm) and of iliac le­sions was 10.1 cm ± 0.9 (range, 3-15 cm).Mean percentage stenosis was 89% ± 2. Allstents were placed with a percutaneous ap­proach (femoral, 86; popliteal, 19) through7-9-·P introducers and needed to be further ex­panded with balloon dilation.

RESULTS: Immediate technical success wasachieved in 104 of 105 patients. Complicationswere: acute thromboses: 7 (3 cured by fibrino­lysis, 4 requiring surgery), late thromboses: 14(3 recovered by new PTA). Twenty-seven pa­tients had fever and pain in the leg during sev­eral days. Over 18-month follow-up, all iliacstents remained patent, nine restenoses oc­curred at femoral level, and seven were curedwith repeat angioplasty. Primary (PI) and sec­ondary (PII) patencies at 18-month follow-upwere: iliac artery: PI and PH = 100%; femoralartery, global: PI = 59%, PH = 81%; femoralartery stenoses: PI = 46%, PH = 76%; femoralartery occlusions: PI = 670/0, PH = 84%; arteriallesions < 15 cm: PI = 60%, PH = 90%; and le­sions > 15 cm: PI = 55%, PH = 64%.

CONCLUSION The Cragg Endopro System 1seems to be safe and effective in long lesionsand aneurysms. Mid- and long-term results ofthis percutaneous bypass are encouraging com­pared with results of surgical bypasses.

Scientific Session 6Renal Arterial Disease/InfertilityModerator: Lindsay S. Machan, MD,

Vancouver, Be, Canada

Room 611

31-1:30 pm

&perimentaJ Endovascularly Induced Stenosisof the Renal Artery in Normo- andHypercholesterolemic RabbitsA.F. Le Blanche, MD, Paris, France· M.

Sibony, MD· A. Kollar, MD· j.R. Bigot, MD·F.P. Boudghene, MD

PURPOSE: To evaluate a new model of endo­vascular-induced stenosis of the renal artery innormo- and hypercholesterolemic rabbits.

MATERIALS AND METHODS: Eleven normo­and 13 hypercholesterolemic New Zealandmale rabbits weighing an average of 3.5 kg(range, 2.9-4.7 kg) were anesthetized and cath­eterized after denudation of the right femoralartery. Aortograms were acquired. Overdilationof the right renal artery was followed by pull­ing back the 2 X 20-mm balloon catheter in­flated at 5 atm. Six weeks later, the animalswere examined with angiography and killed;10% buffered formalin was infused in vivo formacro- and microscopic studies of the aorta, re­nal arteries, and kidneys.

RESULTS: Of the normocholesterolemic rabbits,one died of retroperitoneal hematoma within48 hours. Ten renal arteries had circumferentiallesions of intimal hyperplasia 000%), eight hadlesions of remodeling (80%), and seven had astenosis (70%) visible on arteriograms. Of thehypercholesterolemic rabbits, three died of aor­tic dissection within 72 hours. Only five sten­oses of the renal artery (50%) were shown onangiograms. The arterial wall contained little in­timal hyperplasia and no remodeling.

CONCLUSION A new, low-cost model of steno­sis of the renal artery was successfully devel­oped in rabbits. Stenoses with remodeling aremore reproducible in normocholesterolemicrabbits.

Take Home Points:1. An endovascular-induced model of stenosis

of the renal artery is feasible and reproduci­ble in low-cost, small animals.

2. Intimal hyperplasia and remodeling are ob­tained.

139