Scientific Session 1Renovascular Disease

Designing Renal Artery Protection Devices: Validationof Anatomical Differences in Diseased Renal Arteries.A.H. Pezeshkmehr, Stanford University Medical Center,Stanford, CA, USA 'J.e. Hellinger'S. Cheng'M. Razavi

PURPOSE: It has previously been demonstrated that thereare anatomical differences between normal right and left mainrenal arteries (RA). To further facilitate the design of a distalprotection device (DPD) specific to the renal arterial system,we sought to validate these differences in patients with renalartery stenosis (RAS).

A Pressure-Flow Analysis in RAS: Comparison ofAngiography, MDCTA & Pressurewire PapaverineProvoked Gradients.D.£. Allie, Cardiovascular Institute of the South, Lafayette,LA, USA ·C.J. Hebert 'M.H. Khan'M.A. Khan 'A.A. Allie .e.M.Walker

PURPOSE: The PressureWire (RADI Medical Systems,Wilmington, MA) is accurate in determining functional severityin coronary artery stenosis and beneficial in optimizingcoronary stent outcomes. Stenting in renal artery stenosis(RAS) remains controversial as 30-40% of patients receive noobjective benefit. There is a paucity of data and no consensuscorrelating angiographic RAS, pressure gradients, anddeterminants of physiologic significance in RAS justifyingrevascularization; therefore strategies identifying "which lesionto treat" may optimize renal stenting. Papaverine, an arterialvasodilator, provocation (PP) may hold promise for pressure­flow analysis.

MATERIALS AND METHODS: 89 patients with RAS hadtranslesional systolic pressure gradients (TSPG) obtained usinga 4 F catheter, resting 0.014" PressureWire, and withPressureWire PPusing 30 mg intrarenal injection. All gradientswere compared to digital subtraction angiography (DSA)percent stenosis and 28/89 (31.5%) with 16-channelmultidetector CT angiography (MDCTA). A questionnaireaccompanied all cases asking A) Did PressureWire PPTSPGsignificantly influence procedural decision-making? (yes/no)by B) stenting? (yes/no), or C) not stenting? (yes/no).

RESULTS: 34/89 (38.2%) reported, "yes" PP significantlyinfluenced decision-making, 19/89 (21.3%) did not stent basedon PP confirming < 10 mm Hg pressure gradient where DSA,CTA, and 4-F gradients had predicted significant RAS. 15/89(16.8%) were stented when stenting was predictedpreprocedural. DSA and MDCTA % stenosis did not stronglycorrelate to TSPG by 4-Fr catheters (r2 = 0.224) but didcorrelate with resting PressureWire TSPG (r2 = 0.410) andPressureWire PP (r2 = 0.538).

CONCLUSION: The 0.014" PressureWire with PP is safeand feasible in assessing TSPG in RAS and correlates strongerto DSA and MDCTA than 4-F catheter gradients.PressureWire PP may help optimize renal artery stenting.

Abstract No.3

Prospective Randomized Comparison of MRI versus x­Ray Guided Renal Angioplasty in Swine.JA Gehl, Northwestem University, Chicago, IL, USA ·B.£.Schirf·J.D. Green ·B. Lu ·F.S. Pereles'R.A. Omary, et af.

PURPOSE: MRI-guided balloon angioplasty (PTA) of renalartery stenosis has been shown to be feasible in swine. Directcomparison of MRI with X-ray guidance is required beforethis method can be translated clinically. We tested thehypothesis that the technical success rate, complication rate,and procedure time for MRI and X-ray guided PTA of renalartery stenosis are similar in swine.

MATERIALS AND METHODS: We surgically inducedbilateral renal artery stenosis in 11 pigs using reverse cableties. After one week recovery, we inserted femoral arterialsheaths and performed baseline X-ray digital subtractionangiography. We transfelTed each animal to a 1.5-T SiemensSonata MRI scanner and prospectively randomized whichartery received MRI-guided PTA. Under MRI-guidance,devices were tracked using both active and passive techniques,and vascular depiction was generated using catheter-directedmagnetic resonance angiography (MRA). We dilated stenosesusing 5-6 mm diameter balloon catheters and performed 3Dcatheter-directed Gd-enhanced MRA. Each animal was thentransported to the X-ray angiography suite, where PTA wasperformed on the contralateral artery. Under intention to treat,we compared the technical success rate (residual stenosis <50%), complication rate, and time for each guidance method.We measured stenoses using imaging workstation software.We compared success and complication rates usingMcNemar's test and procedure times using a paired t test.Alpha was set at 0.05.

MATERIALS AND METHODS: Multidetector-row computedtomographic angiograms in patients with right (N=27), left(N=27), or bilateral (N=16) RAS were retrospectivelyanalyzed. Exams were performed on 8 or 16 channel MDCTusing similar scan technique: 1.35-1.375 pitch, 0.5-0.6 gantryrotation, 1.25 mm slice thickness, and 0.8 mm reconstructioninterval. 120 cc of nonionic contrast medium was administeredat 4.0 cc/sec. In all cases, MPR images were processed on anAdvantage Windows 4.1 workstation (GE Medical Systems,Milwaukee, WI). Three anatomical parameters were measured:1) segment one (Rl) distance, defined as the distance of themain renal artery to its first order bifurcation; 2) DPDdeployment diameter, defined as the Rl diameter 5 mmproximal to the bifurcation; and 3) RA cannulation angle, definedas the RA origin angle in the coronal plane. Paired student t­

test was applied to determine statistical significance.

RESULTS: For the right RA (N=43), mean Rl distance,deployment diameter, and cannulation angle were 48 ± 13.4mm (range 15-69 mm), 5.8 ± 1.1 mm (range 3-9 mm), and 54.3± 16° (range 22-90°), respectively. For the left RA (N=43),mean Rl distance, deployment diameter, and cannulation anglewere 35 ± 12.4 mm (range 8.6-58 mm), 6 ± 1.4 mm (range 3.2­9.5 mm), and 70 ± 19° (range 25-106°), respectively.Differences between light and left Rl distances, as well as thecannulation angles, achieved statistical significance (p<.OO1).There was no statistical difference based on the degree of rightor leftRAS.

CONCLUSION: Irrespective of the degree of RAS, right andleft main renal arteries demonstrate anatomically different R 1distances and cannulation angles. These data are importantfor designing a renal DPD which can have universal patientapplication.

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Abstract No.2

Abstract No.1

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Friday, April 1, 200512:30 PM - 2:00 PMModerator(s): Timothy P. Murphy, MD

Marc R. Sapoval, MD

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CONCLUSION: Excimer laser-assisted renal angioplasty is asafe and feasible treatment for RA ISR. Debulking RA ISRmay allow lower pressure BA with less potential for a repeat"stem sandwich."

A Novel Model of Hypertension and Uremia in Pigs.J.D. Gordon, Mayo Clinic, Rochester, MN, USA'S. Misra'L.Lerman

PURPOSE: Large animal models have been developed tounderstand the mechanisms responsible for hemodialysis graftfailure. However, all current research has been conducted inanimals with normal kidney function. We report a novel

RESULTS: Procedural success was 43/44 (97.7%). No patientdeveloped a > 10% increase in serum CR. TPG improvedfrom mean 30 mm Hg (range 18-55 mm Hg) to mean 4 mm Hg(range 0-7 mm Hg). Percent stenosis improved from mean78% (range 70-95%) to mean 10% (range 0-20%). 6/44 (13.6%)required a "stent sandwich" but with experience, the repeatstent rate decreased to < 10% (l of last 16). 4/32 (12.5%)developed RAre-ISR (> 60%) at 6-month DU and had repeatELRA without stenting for an 87.5%, 6-month freedom fromrestenosis rate.

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Abstract No.6

method of creating uremia and hypertension in pigs byembolizing the kidney with a percutaneous catheter techniqueusing polyvicryl acrylide (PVA) particles.

MATERIALS AND METHODS: Ten castrated juvenile malepigs weighing 30 kg to 40 kg underwent embolization of 1.5kidneys using PYA particles. Central renins (IVC, left andright renal veins) were measured before and after embolization.The angiogram and renin procedures were repeated at day 28.Peripheral blood collections (BUN, creatinine, potassium,renins) and blood pressure measurements were obtained beforeand after embolization, and on days 3 (D3), 7 (D7), 14 (D 14),21 (D2l), and 28 (D28).

Efficacy ofRenal Artery Stenting in Patients with ChronicRenal Insufficiency.D.N. Ishimitsu, University ofHawaii John A. Bums School ofMedicine, Honolulu, HI, USA 'H.e. Yoon

PURPOSE: To determine whether renal artery stenting is aneffective treatment for delaying the progression of renaldysfunction in patients with obstructive renovascular diseaseand chronic renal insufficiency.

RESULTS: Values are expressed as means with standarddeviations. Statistical comparison between different periodswas performed using the Student t test. A P value of < .05 wasconsidered statistically significant. Five of the 10 animalsdied prior to completing the 4-week study. The mean BUNprior to embolization was 7.86, and immediately after, theBUN increased to 10.5. The mean BUN rose to 68 by D3 andremained elevated at a mean of 60 at D7. The BUN decreasedto 27.2 by D14 and plateaued at 24.5 by D28. The sametrends were observed for the serum creatinine, potassium,central and peripheral renins. The P values were statisticallysignificant (p<. 05) through D28 for BUN and D21 forcreatinine. The mean arterial pressure (MAP) increasedsignificantly from baseline by D3. The animals remainedhypertensive for the first two weeks after embolization andreturned to baseline by D21 to D28. By D28-35, the averageweight of the embolized kidney was 47.3 g while the averageweight of the partially embolized kidney was 128.8 g (control88.38 g).

CONCLUSION: Our study has created an elegant reversiblemodel of acute renal failure superimposed with chronic renalfailure and hypertension. This model will be used to closelysimulate the physiology of hemodialysis graft failure enablingan understanding of the mechanisms involved.

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MATERIALS AND METHODS: From December 2000 toAugust 2004, 44 patients (28 men, 16 women, average age,67.5 ± 10.6 years) underwent renal artery stenting. Theelectronic medical records of these patients were reviewedretrospectively to analyze the effect of the procedure onpreserving renal function as measured by serum creatininelevels. All patients had a serum creatinine ~ 1.2 mg . dL'! andobstructive renovascular disease. The inverse serum creatininevalues were plotted over time, and the slopes obtained for the6-month period prior to the procedure and the 6-month post­procedure interval were compared using a paired t-test.

RESULTS: Before renal artery stenting, there were 23 patientswith increasing creatinine values as evidenced by a negativeslope (mean, -0.00098 ± 0.00095 dL· mg!· d'!) and 21 patientswith stable creatinine values (mean, 0.00042 ± 0.00055 dL .mg'!· d'!). The mean of the pre-stent slopes for the combined44 patients was -0.00032 ± 0.0011 dL· mg! . d'!. After stenting,the mean of the slopes for the entire patient populationincreased to 0.00069 ± 0.0042 dL . mg'! . d'l, P = 0.054. In

Abstract No.4

Abstract No,S

RESULTS: We successfully dilated 9/11 renal arteries (82%)under MRI-guidance and 11/11 arteries (100%) under X-rayguidance. This difference was not statistically significant(p=0.5). Complications (dissections) occurred in 3/11 (27%)and 1/11 (9%) arteries under MRI and X-ray-guidance,respectively, which was not statistically significant (p=0.5).Mean MRI-guided PTA procedure time was 46 minutes longerthan X-ray guided PTA, which was statistically significant(p=O.O I).

CONCLUSION: MRI- and X-ray-guided renal PTA havesimilar success and complication rates in swine. However,procedure times significantly differ. Improvements in MR!­compatible devices and in spatio-temporal resolution are stillrequired before clinical translation. [Cope]

Excimer Laser Angioplasty in RA In-Stent Restenosis: ASafety & Feasibility Report with 6-Month Follow-Up.D.E. Allie, Cardiovascular Institute of the South, Lafayette,LA, USA 'C.J. Hebert'M.H. Khan 'M.A. Khan ,e.M. Walker

PURPOSE: Renal artery (RA) in-stent restenosis (ISR) ratesof 11-39% represent a significant therapeutic dilemma.Conventional repeat balloon angioplasty (BA) in RA ISRresults in 36-67% re-restenosis rates. A consensus treatmentremains undefined. The photoablative "debulking" potentialof this technology makes excimer laser renal angioplasty(ELRA) an attractive treatment option for RA ISR.

MATERiALS AND METHODS: Between November 2001and May 2004, 44 patients with RA ISR (> 60%) diagnosedby duplex ultrasound (DU) underwent ELRA. Quantitativetransstenotic assessment included pre and postproceduralangiography and pullback catheter pressure gradients (TPG).RA sizes treated included 5 mm 23/44 (52.2%), 6 mm 15/44(34.1 %) and 7 mm 6/44 (13.6%). Techniques used include:2.0 mm eccentric catheter (model CVX-300, Spectranetics,Colorado Springs, CO), 4 antegrade ablations each at 90°angles (360° total ablation), and low pressure « 6-8atmospheres) BA sized to the stent. Follow up: I-week andI-month serum creatinine (CR) and 32/44 (72.7%) 6-monthDU.

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CONCLUSION: Weight based sodium bicarbonate infusionbefore and after radiographic contrast administration isaccompanied by a low incidence of CIN over a broad range ofbaseline SCr.

both the negative and non-negative pre-stent slope subsets,post-stent mean slope increased (mean, 0.00036 ± 0.0018 dL. mg~l . d~l, P = 0.0039 in negative pre-stent slope subset;mean, 0.0011 ± 0.0058 dL . mg~l . d~l, P = 0.30 in non-negativepre-stent slope subset).

CONCLUSION: While mean slopes increased over the entirepatient population and both patient subsets after stenting,the increase only reached significance in the subset of patientswith rising serum creatinine values. This suggests that declinein renal function was slowed by renal artery stenting in thosewith worsening renal insufficiency. It remains unclear whetherstenting is of benefit to those with chronic renal insufficiency,but with stable serum creatinine values.

Prevention of Contrast Induced Nephropathy withProphylactic Intravenous Sodium Bicarbonate Infusion.O.S. Aassar, Carolinas Medical Center, Charlotte, NC,USA ·GJ. Menen 'M.J. Kelley ,v.P. Antonacci 'A. V. Moore 'WP.Burgess

PURPOSE: To determine the incidence of contrast inducednephropathy (CIN) in patients undergoing prophylacticsodium bicarbonate administration. To stratify the risk ofCIN as a function of baseline serum creatinine (SCr).

MATERIALS AND METHODS: 338 patients with SCr greaterthan or equal to 1.1 undergoing contrast radiographic studiesusing ioparnidol received a weight based intravenous infusionof sodium bicarbonate before and after contrast administration.The infusion consisted of 154 mEqlL of sodium bicarbonatein dextrose and H20, mixed in the hospital pharmacy byadding 154 mL of 1000 mEqlL sodium bicarbonate to 846 mlof 5% dextrose in Hp, slightly diluting the dextroseconcentration to 4.23%. The initial infusion was 3 mL/kg perhour for 1 hour immediately before contrast injection; theinfusion was continued at a rate of ImL/kg per hour duringcontrast administration and for 6 hours afterwards. Contrastvolume was recorded. SCr was measured at baseline and 1and 2 days after contrast, and until any increase of SCrresolved. The incidence ofCIN, defined as an increase of25%or more in baseline SCr within 2 days ofcontrast, was measured.Baseline SCr was divided into four strata and the relativeincidence of CIN for each group was obtained.

RESULTS: For the 338 patients, the mean baseline SCr was1.77 (± 0.52, range 1.1- 5.2) and contrast volume was 145 mL(± 65, range 42-520 mL). The overall incidence ofCm for all338 patients was 3%. None of the patients with SCr ;:::0: 2.5developed CIN.

Scientific Session 2Oncologic Interventions:Percutaneous Ablation

Abstract No.8

Abstract No.9

Friday, April 1, 200512:30 PM - 2:00 PMModerator(s): Debra A. Gervais, MD

Bradford J. Wood, MD

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Intraoperative RFAofUnresectable Liver Metastases fromColorectal Cancer: Long-Term Results in 49 Patients.Y.J. Kim, UCLA David Geffen School ofMedicine, Los Angeles,CA, USA-S.S. Raman'N.c. YU'L.L. Boyadzhyan·J.S.Economou 'D.S.K Lu

PURPOSE: To evaluate long-term results of intraoperativeradiofrequency ablation (RFA) for patients with livermetastases from colorectal cancer.

MATERIALS AND METHODS: Between March 1998 andJuly 2003, 161 metachronous colorectal liver-confinedmetastases in 49 patients (mean age, 62 years) deemedunsuitable for surgical resection underwent intraoperativeultrasound-guided RFA. At the time of treatment, all patientshad metastatic disease confined to the liver. Lesion size rangedfrom 0.3 to 10 cm (mean ± SD, 2.4 ± 1.8) with the largestlesion in each patient from I to 10 cm (4.29 ± - 2.16). Nineteen(39%) patients of 49 patients had one, nine (18%) had two,six (12%) had three, and seven (14%) had four metastases.The remaining eight (16%) had five or more metastases. Eleven(22%) patients underwent concurrent hepatic resection and37 (76%) patients received concurrent transarterial chemo­infusion pump placement. Overall survival rates and diseasefree survival rates were calculated with the Kaplan-Meiermethod.

RESULTS: Of 49 patients, three (6%) patients underwentRFA with intention of debulking at laparotomy. Of 46/49(94%) patients who underwent RFA with curative intention,complete ablation was achieved in all but one (98%) patient,based on CT or 'MR imaging one day after RFA. The mediansurvival time was 31 months. Overall estimated 1-,2-,3-, and4-year survival rate were 87%, 64%, 41 %, and 30%,respectively. Of 44 patients in whom complete ablation wasonce achieved, the estimated 1-, 2-, 3-, and 4- year disease freesurvival rate were 58%,36%,25%, and 12%. There are two(4%) complications related with RFA, including hepaticabscess and biloma. There was no significant survival differencebetween RFA + hepatic resection and RFA alone group(p=0.69). Intraarterial chemo-infusion therapy was notassociated with overall survival difference (p=0.49).

CONCLUSION: Intraoperative RFA is an effective treatmentof hepatic metastases from colorectal carcinoma.

Abstract No.7

2.Q,;SGr:>2.5 SGQ2.556 402.18(0.14) 3.17(0.76)1.8%(1) 0%(0)

Incidence of GIN for 4 Strata of Baseline SGrStratum SGr :>1.5 1.5:>Sc,,;2.0n 127 115Mean SGr (SD) 1.26 (0.14) 1.65 (0.14)GIN % (n) 3.9% (5) 3.5% (4)

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Risk Factors of Local Recurrence Following PercutaneousRF Ablation Used for the Treatment of Hepatoma.H. Takaki, Mie University, Tsu, Mie, Japan 'K. Yamakado'M.Akebosi 'A. Nakatsuka 'K. Takeda

PURPOSE: This study was retrospectively undertaken toevaluate risk factors of local recurrence followingradiofrequency (RF) ablation used for the treatment ofhepatomas (HCCs).

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