Arteriovenous Fistulas Types, Trends, Physical Examination & Treatment B. Karenko, DO January 25, 2014

I have no disclosures

Objectives Identify types of vascular access Evaluate trends of vascular access Physical examination of AV Fistulas Normal When to refer Treatment

Type of Hemodialysis Access Synthetic AV Graft Central Venous Catheter AV Fistula

Radiocephalic Fistula Radial Artery to Cephalic Vein Forearm Preferential

Brachiocephalic Fistula Brachial Artery to Cephalic Vein Antecubital Fossa

Brachiobasilic Fistula Brachial Artery to Basilic Vein Upper Arm +/- transposition

AV Fistula Advantages Disadvantages Long Maturation Time Smaller Surgery Decreased Infection Decreased Thrombosis Longer Lifespan 68% AVF 49% AVG Long Maturation Time More Difficult Cannulation High Primary Failure with Difficult Vasculature Infections: 4.4-12 times less infections than AV Graft Thrombosis: 2.4-7.1 times less procedures for thrombus clearing than AV Grafts Lifespan: 1 year patency 68% AVF 49% AVG Allon & Robbin, Kidney Int. 62:1109-1124, 2002. Nassar & Ayus. Kidney Int. 60:1-13, 2001 Pisoni RL, et al., Kidney Int. 61:305-306, 2002

Best to Worst AVF AVG CVC

Prospective Observational Study >300 Hemodialysis Sites Vascular Access Use & Outcomes; An International Perspective from the Dialysis Outcomes & Practice Patterns Study Prospective Observational Study >300 Hemodialysis Sites 12 Countries >35,000 patients Nephrol Dial Transplant. 2008 Oct; 23(10);3219-26.

AV Fistula Use 1996-2007 Since 2005; there has been >65% AVF use in Japan, Italy, Germany, France, Spain, UK, Australia and New Zeeland, From 1996-2007, the use of AVF doubled from 24 to 47% in the USA Concomitantly, graft use fell by 50% from 58% in 1996 to 28% in 2007 Nephrol Dial Transplant. 2008 Oct; 23(10);3219-26.

Referral Timeframe Nephrol Dial Transplant. 2008 Oct; 23(10);3219-26. Patient’s were significantly less likely to start HD with an AVF in a country that had a longer duration of time from the initiation of the referral to vascular evaluation, and from evaluation to the creation of an AVF Nephrol Dial Transplant. 2008 Oct; 23(10);3219-26.

Creation to Cannulation Patients were less likely to start HD with an AVF in countries with a longer time from access creation to first cannulation Nephrol Dial Transplant. 2008 Oct; 23(10);3219-26.

Successful Fistula Adequate Vessels Good Pump >0.4 cm If the blood vessels are >0.4cm in diameter, 89% will be adequate for hemodialysis >0.4 cm Robbins Radiology 225; 59-64, 2002

Monitoring/Surveillance New AVF Established AVF Identify 1° Failures Plan for Early Interventions Plan for Surgical Revision Early Detection Thrombosis Inadequate Flow

Physical Examination Look Listen Feel

Look Radiocephalic Brachiobasilic (transposed) Brachiocephalic

Look Early diagnosis of infection (rash, buttonhole erythema/edema, drainage) can prevent bacteremia and sepsis

Aneurysm & Hematoma As aneurysm's increase in size, the risk of rupture increases. Thinning of the skin over the aneurysm (shiny) suggests the aneurysm is unstable and may need to be resected.

Steal Syndrome With steal syndrome (where to much arterial blood is diverted to the av fistula causing ischemia distal to the site), you can experience muscle wasting,

Central Vein Stenosis Extremity Swelling Collateral Veins

Arm Elevation Test Elevate the arm above the head. If the fistula collapses, it means there is good venous outflow. If only a portion collapses, the portion that remains distended is distal to the stenosis (portion that collapses is proximal to the stenosis)

Auscultation Normal Bruit High Pitched (stenosis)

Feel (Palpation) Inflow Assessment Outflow Assessment Augmentation Test Absence of Thrill Pulsitile Use the Augmentation test to assess inflow. Normally a fistula is soft and is not pulsitile; easily compressible. If you artificially create a stenosis by occluding outflow with your fingers, the strength of the inflow is directly proportional to the arterial inflow pressure; weak inflow = weak pulse

Outflow Obstruction

Treatment of Stenosis Venous Anastomosis/Outlet Significant Lesions <600 ml/min flow >50% stenosis on angiogram A majority of lesions are located at the venous anastomosis or venous outlet (80%)

Endovascular Angioplasty First Line Treatment 7-8mm peripheral 12-14mm central Poor long term patency 50% require repeat treatment within 6-12 months 7-8 mm balloon in the peripheral veins 12-14 mm balloon in the central veins 35-70% patency at 6 months with balloon angioplasty alone Am. J Kidney Disease 2001; 37 (5); 1029

Stents Three Indications Angioplasty Failure Rapid Recurrence of Lesion Vessel Rupture Failure of angioplasty to resolve the lesion to <50% stenosis Rapid recurrence of the lesion (within 3 months of prior angioplasty Vessel rupture with angioplasty J. Am Coll Cardiol Interv. 2010; 3(1); 1-11

Patency 92% 80% 69% 35% 24% Retrospective single center study examining the SMART SES nitinol stent 211 pts (112 AV fistula, 99 AV Graft) Patency was higher in those who received stents; 30 days 92% vs 80% 90 days 69% vs 24% 180 days 25% vs 3% 3% 30 90 180 Clin J Am Soc Nephrol. 2008, 3(3);699

Surgical Revision of Stenosis Advantage Elimination of the lesion Disadvantage Frequent new lesion development Loss of venous access sites Post surgical pain/recovery time

Thrombosis Percutaneous/Surgical Thrombectomy Thrombolytic Agents

Percutaneous Thrombectomy A sheath is placed at both the arterial inflow and venous anastamosis Angiojet (most common) thrombectomy is performed in both directions to remove the thrombus Balloon angioplasty is performed at the venous stenosis site * Failure to correct the underlying outflow stenosis leads to rapid re-thrombosis J. Am Coll Cardiol Interv. 2010; 3(1); 1-11

Surgical Thrombectomy Small incision in the fistula is made The clot/stenosis is removed via expansion of the balloon at the tip of the fogarty catheter and retraction of the catheter to the incision site J. Am Coll Cardiol Interv. 2010; 3(1); 1-11

Thrombectomy Percutaneous/Surgical Thrombectomy Primary Patency 3 months: 30-60% 6 months: 10-40% Elective Angioplasty vs Thrombectomy Percutaneous and surgical thrombectomy are comparable in terms of primary patency Primary patency following thrombectomy and angioplasty is 30-60% at 3 months, and 10-40% at 6 months Patency following thrombectomy and angioplasty is worse than elective angioplasty of a patent but stenosed graft J. Vasc. Interv. Radio. 1999; 10 (2pt1):129

Thrombolysis (local) Agents Contraindications Pulse Spray Mechanical Clot Disruption 50% patent at 1 yr Agents: Alteplase (t-PA), Urokinase most common Contraindications: recent CVA, bleeding disorders, recent major bleeding/surgery, severe hypertension Pulse Spray: Angiojet Ultrasound assisted: Ekos Catheter Mechanical Clot Disruption: Trellis Catheter

Major Concern Development of Clinically Significant PE 650 Thrombectomy Cases 1 Clinically Significant PE Study out of Georgia examined 650 cases thrombectomy cases performed, only 1 clinically significant PE was noted and symptoms (hypoxia, pain) resolved within 24 hours Kidney Int. 1994; 45(5) 1401

Questions?