Balloon Angioplasty for Low Flow AccessBalloon Angioplasty for Low Flow Access

Dheeraj K. Rajan MD, Dheeraj K. Rajan MD, FRCPC, FSIRFRCPC, FSIR

Division of Vascular and Interventional Division of Vascular and Interventional RadiologyRadiology

University of Toronto – University Health University of Toronto – University Health NetworkNetwork

Angioplasty – The Gold StandardAngioplasty – The Gold Standard

• Goal is to relieve the stenosis

• Venous stenoses associated with dialysis access is typically unyielding often requiring high pressure balloons

• Following PTA, recurs in a short period of time

• Complications of PTA

Balloon versus patch angioplasty as an adjuvant Tx to surgical thrombectomy of hemodialysis grafts.

• Case control study of PTA and patch angioplasty pts

• RESULTS: 10 patencies of patch & PTA group: 86% vs 77% at 1 mo, 45% vs 40% at 3 mos, 17% vs 28% at 6 mos

• No statistically signif diff btw the 2 groups

• CONCLUSION: Balloon angioplasty offers advantages to patch angioplasty, with similar patency rates. We recommend balloon angioplasty as a comparable method to salvage dialysis access grafts

• DOQI guideline percutaneous

Patch Angioplasty is SurgeryPatch Angioplasty is Surgery

Bitar G et al. Am J Surg 1997;174:140-2.Slide courtesy of Ziv Haskal

AngioplastyAngioplasty

• The potential long-term patency rate following PTA is (possibly) well established.

• Published series consistently report 40% to 50% 6-month unassisted patency rates from PTA. Long-term unassisted patency after surgical revision is less well established due to reporting of cumulative patency.

AVG 10 Patency after PTA 38-63% 6 mo. (retrospective series)

Probably more accurate

23-41% 6mo. (prospective series)

Prospective

Levels of evidence: Levels of evidence: Access InterventionsAccess Interventions

Slide courtesy Ziv Haskal

Advances – What Advances?Advances – What Advances?

• K/DOQI recommends 50% 6 month primary patency following angioplasty

• Technical success <30% residual stenosis

• New devices – do they improve patency?

• Is there any value in prophylactic intervention?

• The future?

PTA Resistant StenosesPTA Resistant Stenoses

• Lesions resistant to PTA overall 10-15%– Clark, JVIR 2002; 51

– Rajan, Radiology 2004; 508

• 55% of dialysis stenoses required inflation pressures > 15 atm when grafts/fistulas were combined– Trerotola, JVIR 2005; 1613.

• Lesion most difficult to treat is the cephalic arch

Lay JP et al. Clin Radiol 1998; 53:608-611.Lay JP et al. Clin Radiol 1998; 53:608-611. Clark TW et al. J Vasc Interv Radiol 2002; 13:51-59.Clark TW et al. J Vasc Interv Radiol 2002; 13:51-59. Manninen HI et al. Radiology 2001; 218:711-718.Manninen HI et al. Radiology 2001; 218:711-718. Turmel-Rodrigues et al. Nephro Dial Transplant 2000; 15:2029-2036Turmel-Rodrigues et al. Nephro Dial Transplant 2000; 15:2029-2036

PatenciesPatencies

What else has been tried?What else has been tried?

Conquest versus regular PTAConquest versus regular PTA

• Grafts

• 55 PTA’s each group

• No difference in patency

• Only venous anastomosis grafts

• 10-20% stenoses require pressure >15 atm

• Slow inflation & deflation

• 1ATM every 3-5 sec.

• Atherotomes descend within the folds of balloon material

• Minimizes atherotome exposure to healthy tissue

• Device should not exceed 10 inflation /deflation cycles

Cutting Balloon Folding DesignCutting Balloon Folding Design

Cutting BalloonCutting Balloon

JVS -2014JVS -2014

• 623 patients – mixed grafts and fistulas

• At venous anastomosis at 6 and 12 months primary assisted patency significantly better– 86 vs 63; 56 vs 37%

• Really treatment area primary patency– Not access circuit or secondary

• Ultrasound follow-up monthly

Cutting Balloon - AgainCutting Balloon - Again

• Autogenous fistulas

• USED if conventional PTA did not work

• 71/516 randomized to HPTA vs. cPTA

• Six month f/u angio

• 66% versus 40% at 6 months

• JVIR 2014; 190

Nitinol StentsNitinol Stents• Since 1991, >10% of PTA procedures associated

with stent placement• Chan 2008

– 25% versus 3% primary patency 6 mts– AVG’s

• Retrospective with 64 patients– Centrally: 14.9 months

• 12 month: 67% – Mean primary patency peripheral: 8.9 months

• 12 month: 20%– Almost all were severely stenosed at 6 mts

Vogel, JVIR 2004: p1051-1060

39% 6-month 10 patency for stents73% 6-month 10 patency for PTA

p = 0.028

Kariya S, et al. Cardiovasc Intervent Radiol (2009) 32:960–966

Stent UsageStent Usage

• No definite conferred long term benefit over PTA

• Can convert focal lesion to lesion length of the stent

• Used as bailout for:– Rupture– Reobtruction– Recoil– ? rapid recurrence of stenosis (<3 mts K/DOQI)

Novel TechnologiesNovel Technologies

• Cryotherapy

• Gene therapy

• Drug eluding stents

• Brachytherapy

• Atherectomy catheters

• Dissolving stents

Brachytherapy cont…Brachytherapy cont…

Dosing scheme:Dosing scheme: 18.4 Gray 18.4 Gray at 0.5mm into the vein wallat 0.5mm into the vein wall

Treatment times: Treatment times: 214 to 214 to 323 seconds323 seconds

BrachytherapyBrachytherapy

• Novoste Bravo trial• Beta radiation source• Trial cancelled

– Switched study population inclusion criteria part way through trial

• 42% target lesion primary patency end point at 6 months as compared to 0% of the control group (P = 0.015) - did not translate into an improvement in secondary patency at either 6 or 12 months.

• Misra S, KI 2006 (70) p 2006

CryoplastyCryoplastyPolarCath SystemPolarCath System

Nitrous Oxide Coolant

CryoplastyCryoplasty

• Stenosis or thrombosis increased from 3 weeks to 16 weeks

• Only 5 patients– Am J Kidney Dis, 2005; 45(2): e27-32.

• 20 patients– 35% technical success

• 25% 6 month patency• Associated with severe pain

– Gray JVIR 2008

Atherectomy DevicesAtherectomy Devices

• SilverHawk/TurboHawk/DiamondBack– T – Designed to cut through CTO’s (hard plaque)– S – Everyday plaque with no thrombus and/or calcified

plaques– No iliac indication; for above/below knee– Preserves treatment options

• Atherectomy– Limited studies – three– 5/13 (38%) patent at 6 mts– largest study– expensive

Bioabsorbable StentsBioabsorbable Stents

• Constructed of polylactic acid

– Two layers : anti-proliferation drug that absorbs and second is made of a harder crystalline matrix of PLA which dissolves in two years

• Biodegradable magnesium alloy dissolves in months

• Also a vehicle for delivery of nanoparticles

Drug Eluding BalloonsDrug Eluding Balloons

• Targeted delivery of drugs to vascular wall or perivascular region– Antigrowth factors– Angiogenesis factors– Gene therapy– Injection of cells– Local delivery

concentrations can be 500x greater than systemic therapy

Drug Eluding BalloonsDrug Eluding Balloons

• InPact Admiral Balloon (paclitaxil)

• 40 patients (only AVF’s) randomized 1:1

• No defined prospective F/U

• TLR-free survival was significantly superior in the PCB group 308 d vs 161 d.

• However, device success rates were 100% in the HPB group and 35% in the PCB group

• JVIR 2015 – in press

Drug Eluding BalloonsDrug Eluding Balloons

• Adventitial delivery• 130 micron needle• Controlled localized delivery• Reduced toxicity

Drug Eluding BalloonsDrug Eluding Balloons

• Questions to be answered– Drug dose– Pre PTA or Post PTA– Duration of dwell time

Question Should be PTA versus Stent GarftsQuestion Should be PTA versus Stent Garfts

• No definite evidence that proves stents are better than angioplasty for patency for peripheral and central lesions

• Stents do improve technical success with some evidence of improved effect (Vogel, JVIR 2005)

• Early randomized studies demonstrate clear patency advantage of stent grafts

Viabahn

Flair

Fluency

Viatorr

Self-expanding ePTFE Covered Stents

Slide courtesy Bart Dolmatch

(Core Lab Analysis)

N Engl J Med 2010;362(6):494-503 N Engl J Med 2010;362(6):494-503

Survival Free from Treatment Area Primary Patency Failure

Log-Rank p=0.003 Log-Rank p=0.003 Wilcoxon Wilcoxon p=0.008p=0.008

FLAIR study

AVG functions 5 years after placement.

2 mos 29 mos

s berman

Of course, this is achievable with PTA, isn’t it?

Revise TrialRevise Trial

• Presented at SIR• Gore Viabahn device for venous anastomotic stenosis• Six month primary patency significantly different• Secondary patency the same• Renova

– 12-month ACPP for the stent graft group was significantly better than the PTA group, 24.1% vs. 10.3% (p=0.005), respectively.

Literature (Cephalic Arch)Literature (Cephalic Arch)

• Randomized Study • Stent versus stent graft• 25 patients• Six month primary patency was 82% in the stent graft

group and 39% in the bare stent group. • One-year primary patency was 32% in the stent graft

group and 0% in the bare stent group• Historical PTA 42% and stent 39% (Rajan vs.

Shemesh) • Shemesh, JVS 2008 48(6): 1524-1531

Another Study:Another Study:

• 14 patients mature brachiocephalic fistulas. • Five were randomized to angioplasty (PTA) and 9 to stent

grafting. • Technical success 100%• Mean patency in PTA group 100 days (56-154 days) vs 300

days (201-504 days) for SG• Primary access circuit patency at 6 and 12 months:

– PTA: 0%– Stent graft: 67 and 22% (95% CI: 42-100; 6-75) p<0.01

• Primacy target lesion patency at 3, 6 and 12 months– PTA: 60% (CI 29-100%), 0% and 0% – SG: 100%, 100% and 29% (CI: 9-93%) (p<0.01)

Surgical InterventionSurgical Intervention

• Anatomic bypasses• Turn down cephalic vein to basilic or axillary

vein• Autologous or artificial bypass

• Patch• Skilled motivated surgeons needed• Literature

• Not much short, medium or long term data published

LiteratureLiterature

• Transposition of cephalic vein to axillary or basilic vein• 13 Patients• Six month primary patency rate of angioplasty before the

surgical revision of 8%• Six month primary patency rate following surgical revision of

69% at 6 months. • However:

– Why was PTA 8% so much lower than other studies– Surgical revision is technically creating a new access– No length of follow-up provided or standard error limiting

interpretation of data– What about damage to axillary and basilic veins in the future?

• Kian, Sem Dialysis 2008: 21(1): 93-6.

AVF Stent GraftsAVF Stent Grafts

• 17 patients

• Thromboses, stenoses, pseudoaneurysms

• Access circuit patency: 88% at 6 and 12 months

• Lesion patency: 94% at 6 and 12 months

Bent CL, JVIR April 2010

Why Does Most Stuff Not Work?Why Does Most Stuff Not Work?

• Intimal injury leading to intimal hyperplasia– Have to inhibit or prevent injury, exclude injured

area

• Most devices repeat or create injury cycle• Surgery itself associated with injury cycle• Poor reporting/study design

– Mixing of grafts/fistulas/lesion types– Type of follow-up– definitions

SummarySummary

• No evidence to date to suggest any new devices / methods improve overall access patency compared to angioplasty for venous stenosis in hemodialysis patients

• Stents should be used for salvage only, not primary intervention

• Stent grafts have improved patency in graft patients – does this translate to fistulas?