Scientific Session 16 Peripheral Vascular Disease: Evaluation, Recanalization Techniques

2:47 pm

Abstract No. 120

3:45 pm

Abstract No. 121

Thin-Section Multidetector cr Angiography of Renal Artery Stents. I v Behm; Duke University Medical Center, Durham, Ne, USA • R.C. Nelson· TP. Smith • IF. Zidar • D.M. Delong

The Effect of "Kissing" Aorto-lliac Stents on Laminar Blood Flow. M.B. Saker, Northwestern Univel'sity, Chicago, IL, USA· G. Gordon • R.K. Ryu • H.E. Chrisman • H. Chen • RA. Omary, et al.

PURPOSE: To compare stent lumen diameter by multidetector CT angiography and conventional catheter angiography following renal artery stent placement.

PURPOSE: Recent studies suggest that "kissing" stents placed at the aorto-iliac bifurcation may be prediSposed to failure due to laminar flow disruption and accelerated neointimal hyperplasia. To test this hypothesis, we measured the effect of "kissing" metallic stents on laminar flow using a dynamic in vitro aorto-i1iac flow phantom..

MATERIALS AND ME1HODS: CT angiography (CTA) was performed within 24 hours of renal artery stent placement or diagnostic angiography in 14 consecutive patients (7 men, 7 women; ages 43 - 83 years) with a total" of 16 stents. CTA was performed on a GE LightSpeed QXli multidetector scanner. 135-175 cc of Isovue 370 was administered intravenously at 5cc/sec with a scan delay of 14-30 seconds as detelmined by a timing bolus. A volumetric data set was acquired through the renal arteries in the axial plane using 4 x 1.25 mm collimation, a pitch of 3:1, a table speed of 3.75 mm/gantry rotation, a rotation speed of 0.8 seconds and a field of view of 20 cm. Sections were reconstructed at 0.5 mm intervals. Direct comparison of stent lumen diameter on CTA as determined by curved MPR in the axial and coronal plane was made to the post-stent angiogram. RESULTS: All 16 stents were patent on both CTA and catheter angiography. The mean stent lumen diameter as determined by CTA for the curved MPR in the axial plane was 4.3 mm (S.D. 1.1) and the curved MPR in the coronal plane was 4.5 mm (S.D. 1.0). The mean stent lumen diameter as determined by catheter angiography was 5.9 mm (S.D. 1.1). The CTA lumen was less than the catheter angiogram by a mean of -1.1 mm for the curved axial and -0.9 mm for the curved coronal (p= 0.004 and 0.001 respectively). The 95% confidence intelval for the difference in means for catheter angiogram compared to curved MPR in the axial and coronal plane was (-1.6, -0.6) and (-1.3, -0.5) respectively. The diameter on catheter angiography was greater than CTA in 13 of 16 stents. CONCLUSION: CTA produced interpretable multi planar images of the renal artery even with a metallic stent in place. Compared to catheter angiography, intrastent luminal diameter differed from catheter angiography possibly due to beam hardening.

Scientific Session 16 Peripheral Vascular Disease: Evaluation, Recanalization Techniques Moderator: Mahmood Razavi, MD Dieter Liermann, MD

Tuesday, March 6,2001 3:45 pm-5:15 pm

MATERiALS AND METHODS: We conslnlCted a three -dimensional glass phantom of the aorto-iliac bifurcation to mimic human internal diameters, aorto-i1iac bifurcation area ratios, and bifurcation angles. Steady state physiologic flow rates were achieved via gravity to an open system. We controlled hemodynamic factors to model human mean arterial pressure and blood Viscosity. We detected flow by adding hollow 50-100 micron sized glass beads to a glyceroVwater solution and using a slit lamp. 35-mm photographs and video were then serialJy taken of the blood flow through the bifurcation phantom, with and withollt "kissing" 10 x 40 mm Wallstents. RESULTS: In the absence of stents, laminar flow was readily detected at the bifurcation in the flow phantom. After adding "kissing" stents, we detected no laminar flow. The accumulation of glass beads in the space between the vertex of the "kissing" stents and the glass phantom flow divider revealed disrupted laminar flow. CONCLUSION: Placement of metallic "kissing" stents at the bi[-urcation of a dynamic aorto-i1iac flow phantom disrupts normal laminar flow. This in vitro finding may partially explain the mechanism of early failure of "kissing aorto-i1iac stents in humans. further in vivo study of these effects is warranted.

3:56 pm

Abstract No. 122

Where is the Folding Point of lliofemoral Artery during Flexion of the Hip Joint? JR. Won, Ajou University, School ofMedicine, Suwon, South Korea • IK. Kim • D. Y. Lee PURPOSE: Periarticular stents may be of greater risk for neointimal hyperplasia and eventual occlusion than those deployed in immobile vessels. The purpose of this study is to investigate the folding point of iliofemoral artery (IFA) during flexion of hip joint and its relationship with the location of hip joint. MATERIALS AND ME1HODS: Forty-eight patients undergoing femoral artery catheterization (right:left = 25:23) were evaluated. The patients ranged in ages from 16 to 75 years (mean 52). Measurement of IFA contralateral

849

to femoral access was done using a marked vessel sizing catheter. Fluoroscopic images of the catheter inserted side of the hip joint was obtained in antero~pos~ terior (AP) and lateral projection with hip extension and in lateral projection with hip flexion. The angle of IFA was measured in lateral projection with hip extension. The folding point of the IFA with hip flexion on lateral projection was compared with AP projection. The relationship between the location of cavity of the hip joint and the folding point of IFA was also evaluated in AP projection.

RESULTS: The folding point of IFA on A.P projection with hip flexion was located 43.6±15.5mm cranial to the hip joint cavity and 6.9±16.8mm caudal to sacroiliac joint caviLy. With increasing age, the folding point was noted to be more cranially located to the hip joint cavity (p=O.019). The angle of IFA on lateral projection with hip extension was 140.8°±25.5°. As the age increased, the angle decreased (p
4,07 pm

Abstract No. 123

"Kissing" Aorto·lUac Stent Placement: Effect of Intra~aortic Stent Length on Patency. M.B. Saker, Northwestern University, Chicago, IL, USA· H.B. Chrisman. R.K. Ryu • RA. Omary • AA. Nemcek, Jr. • R. V Vogelzang PURPOSE: Bilateral "kissing" stent placement across the aorto-iliac bifurcation is an accepted treatment option for atherosclerotic occlusive disease that is unresponsive to primary percutaneous transluminal balloon angioplasty (PTA). Studies suggest that a significant subset of patients relUrn within two years with occlusion of the stents. We tested the hypothesis that longer aortic Slent length is associated with reduced long-term patency in patients who receive bilateral aOrloiliac kissing stent placement.

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MATERIALS AND MEJHODS, Between 1994 and 1998, 3] patients with occlusive disease or the aorto-i1iac bifurcation, were treated with aorto-iliac "kissing" stent placement. Stents were implanted primarily in occluded vessels or secondarily after failed PTA. We retrospectively performed clinical and imaging follow-up.Patency was determined by symptOm assessment and ankle brachial pressure index, and confirmed angiographically in those patients that became symptomatic.The angiographic studies were reviewed and categorized into those with stents protruding <4cm or>4cm into the aona. Mean interval follow-up was 18 months (range 2 to 60 months).We assessed statistical significance of the difference in Olltcome proportions

using the chi~square test. The null hypothesis was rejected at the p<0.05 level. RESULTS: A total of 10/31 C32%)"kissing" stt~nt failures occurred within the first 18 months post implantation, mOSI of them within the first 12 months, 7/10 (23% of total). Five out of 6 (83%) of patients with intra-aortic stent extension equal or >4cm failed vs. 5/25 (20_%) of failures noted in patients with intra-aortic stent extension less than 4cm. This difference was statistically significant (p - 0.025). CONCLUSION· Following bilateral aortoiliac kissing stent placement, the placement of longer aortic portions is associated with reduced patency. We recommend minimizing the length of stent protruding into the aorta during the treatment of these patients with severe bilateral aOl1oiliac atherosclerosis.

4,18 pm

Abstract No. 124

Endovascular Placement of a New Self-expanding Nitinol Coil Stent (Intracoiil"M) for the Treatment of FemoropopliteaJ Occlusive Disease. T Jahnke, Department of RadioLogy University HospitaL, KieL, Germany.]. Brossmann • G. Voshage • S. Muller-HuJsbeck • ]. Grimm. M. HeLler PURPOSE: Prospective two center study to evaluate safeLy and effectiveness of a new self-expanding nitinol coil stent in patients with infrainguinal occlusive disease. MATERIALS AND MElHODS· The INTRACOIL™ nitinol stem (IntraTherapeutics, St. Paul, Minnesota, USA) was used in 29 patients, 7 female and 22 male (mean age: 63 years, range 43-81 y) presenting with high-grade stenoses (n=15) or short occlusions « 3cm, n=14) of the superficial femoral (n=24) or popliteal artery (n=5). Indica cion for stent placement was significant reSidual stenosis (> 500/0) or dissection following angioplasty. Follow-up evaluations with measurement of the doppler-ankle-brachial index (ABO, assessment of clinical stage and color-coded duplex sonography were carried out at discharge and 1, 3, 6, 12 and 18 months thereafter.

RESULTS: Initial technical success was achieved in all patients. In 8/29 patients more than one 40-mm long device had to be implanted for total lesion coverage, the lOtal number of stents deployed was n=40. Stent placemenl induced an initial improvement of the mean ABI from 0,54 ± 0,2 to 0.92 ± 0,12 (p< 0,0n. So far 13 patients have been followed up for at least 12 months, mean follow-up is 10,6 ± 4,9 months (range 6-18). Pri· mary patency rates at 6 and 12 months were 90,5 % (SE~6,6) and 81,3 (SE~10,J) respectively. Secondary patency rate at 12 months was 100 %. CONCLUSION Endovascular placement of the INTRACOIL™ self-expanding nitinol sten[ for the treatment of infra inguinal occlusive disease shows promising initial success rates and very good mid-term results.

4:29 pm

Abstract No. 125

Optimized Dynamic High-resolution Gd-enhanced MRA Compared to 2D-TOF MRA for the Identification of Occult Distal Runoff Vessels. A. Sa/vi, University 0/ Iowa College a/Medicine, Iowa City, lA, USA • Mj. Shara/uddin • A.H. Stolpen • YM. Dang • S. Sun • K.A. Youse/, et al. PURPOSE: We prospectively evaluated an optimized multiphase high-resolution Gd-enhanced 3D MRA (HRGd-MRA) and standard 2D-TOF MRA, in their ability to delineate occult distal calf and pedal vessels. MATERlALS AND METHODS: Twelve patients with severe limb-threatening PVD underwent both HR-Gd-MRA and 2D-TOF MRA to identify angiographically-occult targets for distal bypass. Imaging was performed on a 1.5T system, with either knee or head coil. The HR-GdMRA sequence (TR:6.8, TE:2.3, FA:250, FOV:300x188 mm2, matrix:200x512, slice thickness: 2-3 mm) allowed acquisition of multiple consecutive coronal partitions, each in 18-25 sec. A standard 2D-TOF MRA sequence was also obtained using the same coil with (TR:25, TE:9.0, FA:35, FOV:165x220 mm2, matrix:160x256, slice thickness: 3 mm, with interleaved saturation band). RESULTS: HR-Gd-MRA allowed significantly faster imaging time and larger FOV than 2D-TOF MRA (p<.OOOl). All segments seen on 2D-TOF were visualized on HR-GdMRA, and, when the same area of coverage was compared between the 2 modalities, significantly more primary segments were well-seen on HR-Gd-MRA (p<.05). In addition, DSA HR-Gd-MRA aUowed better visualization of tl1e pedal arch and demonstrated far more sidebranches than 2D-TOF-MRA (p<.OOOl). A very high rate of artifacts that adversely affected image interpretation occurred with 2D-TOF-MRA compared to HR-Gd-MRA (14 limbs versus 2 limbs, p<.0005). Bolus mistiming with HR-Gd-MRA occurred in one patient (2 limbs) resulting in suboptimal mask acquisition, but the study remained diagnosrjc. Quality and diagnostic confidence was judged satisfactory in all limbs on HR-Gd-MRA, compared to 12 limbs with 2D-TOF (p<.OOOl). HR-Gd-MRA findings were used to successfully plan revascularization in 14 limbs. CONCLUSION HR-Gd-MRA clearly identified more distal target vessels with greater confidence than 2D-TOF. Optimized HR-Gd-MRA may should replace 2D-TOF as the gold-standard examination for evaluation of occult ankle/foot runoff.

4:40 pm

Abstract No. 126

Endovascular Placement of HemobahnTM StentGrafts for the Primary Treatment of Infra-inguinal Occlusive Disease. j. Brossmann, Department 0/Radiology, University Hospital,. Kiel, Germany • T.jahnke • R. Andresen. S. Muller-Hiilsbeck • j. Grimm • M. Heller PURPOSE: Prospective multicenter trial to evaluate safety, effectiveness and patency rates of "intention-to-

treat" stent-graft placement using the HEMOBAHN™ self-expanding endoprosthesis in patients with femoropopliteal occlusive disease MATERiAL AND METHODS: During an 18-months period a total of 48 HEMOBAHN™ stent-grafts (w.L. Gore, Flagstaff, Arizona, USA) were used in 41 patients presenting with primary occlusions (n=30) or high-grade stenoses (n=l1) of the superficial femoral artelY (SFA). 11 female and 30 male (mean age: 61,8 ± 7,6 years) were treated. Mean lesion length was 8,9 ± 4,5 em. Preinterventional run-off status of lower leg arteries was 2,3 ± 0,7. FoJlow-up evaluations with assessment of Rutherford clinical stage, color-coded duplex sonography and MR-imaging and were carried out at discharge and 1, 3, 6, 12 and 18 months thereafter. RESULTS: Initial technical success was achieved in all patients. Stent-graft placement induced an initial improvement of the doppler ankle-brachial index from 0,55 ± 0,2 to 0,89 ± 0,15 (p
4:51 pm

Abstract No. 127

Endothelial Dysfunction of Canine Hind limb Arteries After the Endovascular Induction of Diabetes Mellitus. A. Eclavea, Indiana University Medical Cent€1~ Indianapolis, IN, USA • A.1. Salis • C.S. Packer • N.H. Patel • R.G. Peterson • T.C.johnson, et at. PURPOSE: Endothelial dysfunction may be a factor in diabetic atherosclerosis. Acetylcholine (ACh) induced arterial relaxation is dependent on endothelial nitric oxide (NO). Impaired endothelium-dependent relaxation in diabetics may contribute to me predominately infrapopliteal atherosclerotic disease. MATl:-7?IALS AND j\1ETHODS: Diabetes was created by intra-arterial streptozotocin and alloxan infusion. Saphenous arterial rings were cut from dogs 2-3 years after diabetes induction and from controls. Po was defined as peak force to 120 mM potassium chloride (KC!). Rings were exposed to ACh at peak norepinephrine ( E) contractions. Force produced was normalized to tissue cross sectional area (mN/cm2). Relaxation half times (tl!2) were measured after high K+ washout and during ACh-induced relaxations. Student'S [-test was used to

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compare control and diabelic Po, PNE and tll2 values (p<0.05 considered significant). RESULTS: Nejther force production rates nor PNE values were different for control and diabetic arteries (0.015±0.004 g/s;n~4 vs 0.017±0.005g/s;n~3 and 570±133 m!\/cm2;n~4vs 865±198 mWcm2;n~2, respectively). Force production rates to KCl appear to be twice as fast in diabetics compared wilh controls (0.466±0.442 gls;n=3 vs 0.277±0."152 gls;n=4) while mean diabetic Po appears to be half that of the control (1139±77 mN/cm2;n='2 vs 2845±802 mN/cm2;n=4). Relaxation tll2 in response to ACh was 3 times greater in diabetics compared with controls (295±85s;n=2 vs 95±9s;n=4, p<0.03). Relaxation rates of KCI contractions were not different (p>0.05). CONCLUSION: The endothelium was intact in diabetic

hind limb aneries, yet the rate of ACh-induced relaxation was significantly slower. Impaired relaxation is not due to altered smooth muscle since KCl-induced contractions relax normally. Preliminary dara suggests diabetic endothelial dysfunction that specifically affects the NO pathway. 5,02 pm

CONCLUSION: Most patients have limited understanding of their risk factors for atherosclerotic vascular disease. Our data serves as a baseline upon which to compare the utility of methods used to improve patient awareness and education. Risk Factor

Nl1mrer(%)

Total cholesterol

57(7]%;

Re~u1ar exercise

47 (59%)

RMI> 25

46 (58%)

RecentJcl1rrent smoker 3D r)Ho/c) Hyoertension lJiabctcs

9 fl1 %) 7(9%)

Abstract No. 128

Patient Awareness of Risk Factors for Atherosclerosis Among Those Undergoing AngiograpWc Evaluation of Peripheral Vascular Disease. C. Yoon, University of Utah, Salt Lake City, UT, USA • G.E. Morgan. C. Parr. FI Miller PURPOSE: \'(le are aware of no published information about patient awareness of risk factors associated with peripheral vascular disease. The purpose of this study was to evaluate patient knowledge of atherosclerotic disease risk factors among those scheduled for catheter angiography.

MATERIALS AND METHODS: Patients undergoing angiographic evaluation for atherosclerotic vascular disease completed a questionnaire describing their risk factors for atherosclerosis. Modifiable risk factors analyzed included smoking, hypertension, diabetes, body mass index, serum lipid levels, and regular exercise. This information was then compared with data from the physical examination and the patient's medical record. A simple scoring method was used to assess patient knowledge. RESULTS: There were 52 males and 28 females (average

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greater than 130 but did not report having diabetes. The prevalence of risk factors among these 80 patients is presented in the Table. The average number scored was 3.5 with a stand.ard deviation of 1.0. The m<;>de and median values were 3 and 3 respectively. No patient scored zero points, and only 1 patient received aU 6 points (1%). Two patients scored 1 point (3%), 9 scored 2 (11%), 30 scored 3 (38%), 25 scored 4 (31%), and 13 scored 5 points (16%).

age 61.9 + 15.3 years). Most patients did not know their total cholesterol level. Only 23 were aware of their lipid panel results. Less than half of all patients reported a regular pattern of exercise even among those who did not have claudication. More than half of the patients were overweight. There were 30 recent or current smokers. Nine patients had high blood pressure by our measurements but did not report having hypertension. Seven patients had routine fasting serum glucose levels

Scientific Session 17 Hemodialysis Interventions: Native Fistulae Moderators: Stephen Quinn, MD Iuc Turmel-Rodrigues, MD

Tuesday, March 6, 2001 3:45 pm-5:15 pm Abstract No. 129

"Swing Point Stenoses" in Hemodialysis Arteriovenous Fistulae. A. Falk, Mt. Sinai Medical Center, New York, NY, USA. V. Teodorescu • H. Mitty .]. Urlbam .]. Vassalotti • J. Gullet; et al. PURPOSE: To prospectively evaluate the efficacy of PTA for treatment of stenoses found at the surgical mobilization site ("swing point") of veins used to create hemodialysis arteriovenous fistulae (AVF) that fail to mature or are failing.

MATERIALS AND METHODS.. Iletween Febmary 1999

and August 2000, 71 consecutive hemodialysis patients (37 male and 34 female; age range 21-92 years; mean age, 56.3 years) with AVF that failed to mature or were failing were studied. All AVF were evaluated initially by ultrasound to define the site of pathology. The AVF were cannulated under sonographic guidance in a retrograde fashion and fistulography was performed to image the inflow artery, anastomosis, oULflow and central veins. PTA was performed at stenotic sites. Prospective data collection included demographic informalion,