James J. Wynn, M.D. Medical College of Georgia

Transcription

1 James J. Wynn, M.D. Medical College of Georgia

2 Early patency Long durability (decades?) Resistance to infection Aesthetically acceptable

3 Early referral to nephrologist Early evaluation to vascular surgeon Fistula First! Ultimate goal: Successfully initiate dialysis with a native AV fistula

4 Autogenous AV fistulas widely recognized to be superior to synthetic AV graft access Improved patency Less infectious and other complications Grafts continue to be used commonly especially in the US Dramatic increase in the use of catheters for dialysis

5 Published in AJKD October 1997 Updated in 2000 and again in 2006 Two primary objectives: 1) Increasing the placement of native AV fistulae 2) Detecting access dysfunction prior to access thrombosis and intervening to correct problems Goals 1) Primary AV fistulae in 50% of new patients; 40% of prevalent patients should have AVF; new stretch goal is 66% 2) Reevaluate for AV fistula at each access failure 3) Center access and complication databases

6 Previous goals and objectives re affirmed Re emphasizes the need to place functional access (not fistula at all costs) Late referral for access identified as primary barrier to fistula placement

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8 2006 ADR

9 2006 ADR

10 2006 ADR

11 Dialysis Outcomes and Practice Patterns Study Longitudinal study of over 6000 patients in US and Europe AVF use associated with younger age, male sex, and absence of PAD, angina, obesity Patients in Europe were 21 times more likely to have AVF Using AVF at initiation of dialysis: Europe 66% US 15% (60% used catheter) Pisoni et al, 2002

12 Pisoni et al, 2002 Incident Patients Initiating HD With an AVF

13 Greater resistance to infection Lower rate of revision 77% of grafts required revision within 12 months at UAB Clearly reduced risk of infection related death (83% increase with catheter use) (USRDS)

14 Stage 1 with normal or high GFR (GFR > 90 ml/min) Stage 2 Mild CKD (GFR = ml/min) Stage 3 Moderate CKD (GFR = ml/min) Stage 4 Severe CKD (GFR = ml/min) Stage 5 End Stage CKD (GFR <15 ml/min)

15 Patients with stage 4 CKD: Should undergo kidney replacement therapy education Avoid using upper extremity veins suitable for dialysis access for blood draws, IVs, PICCs Obtain preoperative (? pre referral) UE vein mapping Evaluate central vein patency in patients with h/o previous catheter, pacemaker, AICD Fistula should be placed at least 6 months prior to anticipated need AV grafts should be placed 3 6 weeks prior to anticipated need

16 Early referral to nephrologist Protect all veins Early referral to access surgeon Fistula only No later than Stage IV CKD Liberal use of vein mapping Secondary AVF placement when possible AVF placement in patients presenting at end stage Surgical expertise

17 Cannulation training Early access evaluation Address failure to mature Access monitoring and intervention Facility and patient education Monitor outcomes

18 Diameter > 0.6 cm Depth of 0.6 cm ( ) Blood flow > 600mL/min Segment straight enough to cannulate

19 Early: surgical technique, vessel suitability, poor selection Failure of maturation Late complications

20 Cephalic system Begins laterally Passes to antecubital fossa and subsequently to anterior shoulder Superficial throughout Basilic system Intern s vein in forearm medial and posterior and superficial Relatively deep above elbow Brachial vein Accompanies brachial artery Part of deep venous system of the arm

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22 Goal: good function without threatening the hand History Hand dominance Previous access (fistulas, grafts, lines, pacemakers, AICD) Thrombotic history Anti platelet therapy Physical examination Brachial pressure bilaterally Allen test Vein examination High tourniquet Ballotment Presence of collateral veins

23 Superior to physical exam, especially in patients w/o obvious veins Good veins discovered in 48/62 patients w/o clinically evident veins (Malovrh, 2002) Effective in increasing fistula creation Increase in fistula creation from 34% to 64% at UAB (Allon, 2001) AVF constituted 77% of access in new patients Criteria Vein diameter > 2.5 mm with no stenoses and patent outflow

24 Duplex exam of radial and ulnar arteries in 211 patients prior to AV access Radial artery dominant in 57% 50% had both arteries > 2mm diameter and peak RA flow > 125mL/min 45% had cephalic vein > 2.5mm diameter My opinion: 2 mm seems a reasonable threshold diameter Goldstein/Gupta, Arch Surg, 2003

25 Isometric forearm exercises prior to AVF placement in 5 patients over 6 months (Leaf et al, 2003) Increased grip strength Doubling in size of forearm veins w/ and w/o tourniquet

26 Begin peripherally with radial cephalic fistula Consider forearm basilic transposition Move proximally to upper arm fistula Cephalic Basilic Move to the dominant hand if veins clearly superior Prosthetic graft only when other options exhausted Place fistulas 6 months prior to dialysis delay graft placement until near end stage

27 Frequently limited by vessel size, calcification or previous use Requires magnification, good exposure, practice, attention to artery/vein orientation Avoid acute vein angulation by adequate mobilization Still suffer high failure rates

28 Full mobilization of basilic vein from medial epicondyle of humerous to wrist Tunnel to radial artery at wrist or loop to antecubital artery Frequently large diameter

29 Cephalic preferred over basilic Superficialization may be required in patients with large arms

30 Normal Anatomy Brachiocephalic AVF Brachiobasilic AVF Brachial-median antecubital vein AVF Fitzgerald, J. T. et al. Arch Surg 2004;139:

31 Transverse antecubital incision Generous mobilization of the cephalic vein Avoid tension

32 Transposition versus one or two stage elevation Requires full mobilization of the basilic vein Upper arm to axilla for elevation Below the elbow to the axilla for transposition Clearly a bigger operation Wound complications

33 Humphries et al, Am J Surg, % 1 year patency Hossny, J Vasc Surg, transpositions, 40 elevations in one (20) or two (20) stages 66/70 used successfully No difference in patency among the three groups Rao, J Vasc Surg, 2004 Failure to mature in 38%, especially older patients Murphy, Br J Surg, 2000 Only 68% used successfully for dialysis Segal et al, AJKD % primary failure

34 Oliver et al, KI, basilic and 56 cephalic AVF, 80 AVG Primary failure more common with AVF Infection much more common with AVG

35 Saphenous elevations reported sporadically Femoral (deep) vein fistula

36 Scattered reports in last 3 4 years with limited experience Use of femoral vein in peripheral bypass associated with limited morbidity

37 Huber et al, J Vasc Surg, 8/ patients / > 600 total access volume

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40 Large study intended to identify clinical characteristics associated with primary failure and failure to mature Scoring system developed and validated prospectively Variable Points Age >= PAD +3 CAD +2.5 White race 3 Baseline +3 Awarded to all patients Lok et al, JASN, 2006

41 Score Risk Category Failure Rate PossibleClinical Application <2.0 Low 24% PE ± duplex ultrasound; create AVF 2.0 to 3.0 Moderate 34% PE, duplex ultrasound ± venogram; create AVF 3.1 to 6.9 High 50% Arteriogram + venogram; create AVF with very close postoperative monitoring (e.g., weekly or biweekly), and anticipate the need for aggressive intervention to facilitate maturation 7.0 Very high 69% Consider another form of permanent access (e.g., graft); continue to avoid Lok et al, JASN, 2006 catheter use

42 Excess sepsis More expensive Higher mortality Mortality improves with conversion to permanent access

43 Aslam, N. et al. Clin J Am Soc Nephrol 2006;1: Copyright 2006 American Society of Nephrology

44 Figure 1. Kaplan-Meier cumulative mortality curve, by type of vascular access in use among 616 participants in the Choices for Healthy Outcomes in Caring for End-Stage Renal Disease (CHOICE) Study Astor, B. C. et al. J Am Soc Nephrol 2005;16: Copyright 2005 American Society of Nephrology

45 Figure 1. Kaplan-Meier survival curves for all-cause mortality for the whole cohort (A) (n = 3381) and the propensity score-matched cohort (B) (n = 1479) for patients with arteriovenous fistula (AVF) versus catheters Polkinghorne, K. R. et al. J Am Soc Nephrol 2004;15: Copyright 2004 American Society of Nephrology

46 Early evaluation at 2 months Detect failure to mature Early intervention Multiple interventions may be required Causes of failure to mature (Beathard) Inadequate arterial inflow Juxta anastomotic venous stenoses (? ischemic vs clamp injury) Outflow stenosis Accessory veins

47 AVF should be soft with maximal thrill at the arterial anastomosis Occlusion should cause pulsatility Pulsatile near arterial anastomosis Suspect juxta anastomotic stenosis Pulsatile futher upstream, sometimes with central thrill More central stenosis Persistent thrill despite occulsion Accessory veins are present US imaging and AV angiogram very helpful

48 Asif, A. et al. Clin J Am Soc Nephrol 2006;1: Copyright 2006 American Society of Nephrology

49 Beathard, KI, 2003 Juxta-anastomotic Stenosis

50 Surgeons are NOT the experts Experienced nurses and techs are Early cannulation is an important cause of fistula failure Fistula flow reaches peak surprisingly early

51 Robbin, 2002

52 Robbin, 2002

53 Lower patency, increased infection rate Tertiary access Thigh grafts Lower primary patency and 2x infection rate (11%) (Miller et al, 2003) Chest wall grafts Intraabdominal grafts

54 Neointimal hyperplasia Response to injury Shear stress High flow rates Evaluation and monitoring Evidence unclear at this point Is early intervention warranted? In 90 s, early intervention to treat stenosis clearly associated with improved patency compared to thrombectomy Logistically favored

55 Acquired stenosis not uncommon Evaluate when Transition from thrill to pulse Decreased efficiency High venous pressures Prolonged bleeding (due to high intragraft pressure) Monitoring techniques: access flow, static pressures, dialysis efficiency, recirculation

56 Traditionally not addressed Combination of pharmacologic and mechanical thrombectomy and angioplasty clearly effective Success in > 90% with 80% long term patency (Schon and Misler, 2000) Subsequently confirmed by multiple groups

57 Metaanalysis of 4 trials from the mid 90 s favored open thrombectomy (Green et al, 2002) Surgical and percutaneous approaches have changed subsequently Must treat underlying stenoses (anastomotic, central) irrespective of approach Logistics again important

58 O Shea et al, patients evaluated in thrombosis clinic due to repeated access thrombosis Elevated anti heparin platelet factor 4: 18% Elevated IgG ACL Ab: 18% Elevated factor VIII: 92% Elevated fibrinogen: 63% Homocysteine Elevated in renal failure Contribution to graft thrombosis unclear Efficacy of folate unclear in CKD

59 Knoll, G. A. et al. J Am Soc Nephrol 2005;16: Copyright 2005 American Society of Nephrology

60 Prevention of neointimal hyperplasia at venous anastomosis Graft modifications Brachytherapy

61 ACE inibition Data varies Aspirin Detrimental in one randomized trial from 90 s Coumadin Only in patients with defined hypercoagulable state and possibly in the chronically hypotensive Aspirin plus Plavix Trial terminated due to excessive bleeding Fish oil 76 vs 15% primary patency at 1 year in small randomized trial Decreased venous outflow resistance

62 4 g daily studied in small randomized trial 76 vs 15% primary patency at 1 year Also decreased venous outflow resistance Mechanisms Inhibits cyclooxygenase Inhibits smooth muscle cell proliferation Reduce PDGF, TNF, IL 1 release from platelets, reduces platelet aggregation

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64 Steal may be a misnomer retrograde flow occurs in many asymptomatic patients Underlying small vessel disease and larger arterial stenoses are important considerations More common in diabetics Occlusion of the access should restore normal flow to the hand and pressure at the wrist suspect arterial stenosis or occlusion otherwise

65 Determine the physiology and anatomy Fistulogram/UE angiogram Address underlying arterial stenoses Distal revascularization/interval ligation Banding Open or hybrid Ligation