GRAFT THROMBOSIS: RECENT TRENDS IN MANAGEMENT

Introduction

Most patients with end-stage renal disease undergo hemodialysis thrice weekly to Optimize their survival Minimize medical complications and Enhance their quality of life

A reliable vascular access is a Critical requirement for providing adequate

hemodialysis

Introduction

The ideal vascular access would be Easy to place Ready to use as soon as it is placed, Deliver high blood flows indefinitely, and Free of complications

None of the existing types of vascular access achieves this ideal

Among the three types of vascular access currently available, Native arteriovenous (AV) fistulas are superior to AV

grafts, which, in turn, are superior to dialysis catheters

Introduction

Recognizing the relative merits of the vascular access types, the Kidney Disease Outcomes Quality Initiative (K/DOQI) guidelines recommend placement of AV fistulas in at least 50% of hemodialysis

patients, AV grafts in 40%, and Dialysis catheters in no more than 10%

Loop Forearm Graft, Venous Preparation

SPECIFIC CRITERIA

PTFE A-V Graft

Autologous options have been considered / excluded / exhausted

(Exception : graft first may preserve future options)

Absence of Collagen Vascular Disease (Lupus Nephritis)

Generally, forearm before upper arm

(Exception : secondary upper arm graft on non-dominant side)

Superficial vein target preferable to deep vein

Min diam of venous target >4.5 mm, min length > 16 mm

Success upper arm graft limited if diam < 5 mm

Arterial target diam > 3.5 mm (4.0 mm upper arm)

Consider 5 mm graft

Consider crossing joint

Introduction

Vascular access procedures and their subsequent complications represent a major cause of Morbidity, Hospitalization, and Cost for chronic hemodialysis patients

AV grafts

AV grafts are prone to Recurrent stenosis and thrombosis and Require multiple radiologic or surgical

interventions to ensure their long-term patency for dialysis

AV graft thrombosis

About 80% of graft failures are due to thrombosis Thus, improving graft longevity requires

implementing measures to reduce the frequency of graft thrombosis When grafts are referred for thrombectomy, a

significant underlying stenosis is observed, most commonly at the venous anastomosis, the draining vein, or the central veins

This observation suggests that Prophylactic angioplasty of hemodynamically significant

graft stenosis may reduce the frequency of graft thrombosis, and thereby increase cumulative graft survival

AV graft thrombosis

Thrombosed grafts usually have an underlying stenosis, most commonly at the venous anastomosis

or in the draining vein Salvage of clotted grafts requires

Thrombectomy as well as Angioplasty or surgical revision of the

underlying stenosis

AV graft thrombosis

However, the primary patency (intervention free survival) is considerably worse after treatment of clotted grafts, as compared with Elective angioplasty of patent grafts with stenosis

After elective angioplasty, the primary graft patency is 70 to 85% at 3 mo and 47 to 63% at 6 mo

In contrast, after thrombectomy and angioplasty of clotted grafts, the primary patency is only 33 to 63% at 3mo and 11 to 39% at 6 mo

AV graft thrombosis

Comparison of outcomes of 656 radiologic graft interventions performed at a single dialysis center found a 3-mo primary patency of 71% after elective angioplasty, as

compared with 30% after treatment of clotted grafts

Am J Kidney Dis 2001;37: 945–953

AV graft thrombosis

Given the dismal outcomes of clotted grafts, it would be desirable to Identify prospectively grafts that are at risk for

thrombosis and intervene prophylactically to prevent the graft from clotting

Because graft thrombosis is usually superimposed on hemodynamically significant stenosis, it is a plausible hypothesis that timely detection and correction of the stenosis will prevent graft thrombosis

Clin J Am Soc Nephrol 2007;2: 786–800

AV graft thrombosis

Achieving this goal requires having a Simple Cheap Reproducible, and Sensitive method to

Monitor for graft stenosis

Clin J Am Soc Nephrol 2007;2: 786–800

Mechanical Interventions to Reduce Graft Thrombosis

Approaches for detection of graft stenosis Clinical monitoring consists of physical

examination (absent thrill, abnormal bruit, or distal edema),

Abnormalities identified during dialysis sessions Prolonged bleeding from needle sites or Difficulty in cannulation), or

An unexplained decrease in Kt/V on a constant dialysis prescription

Clin J Am Soc Nephrol 2007;2: 786–800

NKF KDOQI GUIDELINES 2006 Updates Vascular Access

AVGs have the following advantages: A large surface area and vessel available for

cannulation initially They are technically easy to cannulate The lag-time from insertion to maturation is

short For PTFE-derived grafts, it is recommended that not

less than 14 days should elapse before cannulation to allow healing and incorporation of the graft into local tissues, although ideally, 3 to 6 weeks are recommended

Multiple insertion sites are available

NKF KDOQI GUIDELINES 2006 Updates Vascular Access

AVGs have the following advantages: A variety of shapes and configurations is

available to facilitate placement It is easy for the surgeon to handle,

implant, and construct the vascular anastomosis

The graft is comparatively easy to repair either surgically or endovascularly

NKF KDOQI GUIDELINES 2006 Updates Vascular Access

The sum of the available data, until recently, supported PTFE grafts over other biological and other synthetic materials, based on lower risk for disintegration with infection,

longer patency, better availability, and improved surgical handling Biological grafts (bovine heterografts) have

greater reported rates of complications compared with synthetic grafts

NKF KDOQI GUIDELINES 2006 Updates Vascular Access

For nearly 2 decades, PTFE has been the material of choice for bridge

grafts. However, during the past decade, modifications

and the use of other materials, such as PU,

cryopreserved femoral vein, bovine mesenteric vein, and hybrids with self-sealing composite material, have been developed and used

None of these has shown any “survival” patency over plain PTFE, except for the composite/PU graft

NKF KDOQI GUIDELINES 2006 Updates Vascular Access

Composite/PU graft Has an advantage because of its self-

sealing property to be cannulated within hours, if needed, for dialysis

As a result, it can be placed without having to use a catheter for initiation of dialysis therapy, in some cases Direct comparisons between PTFE and human

umbilical cord vein grafts and other synthetic polymers have not been made

NKF KDOQI GUIDELINES 2006 Updates Vascular Access

Treatment of thrombosis and associated stenosis:Each institution should determine which procedure, percutaneous thrombectomy with angioplasty or surgical thrombectomy with AVG revision, is preferable based upon expediency and physician expertise at that center.

6.7.1 Treatment of AVG thrombosis should be performed urgently to minimize the need for a temporary HD catheter. (B)

6.7.2 Treatment of AVG thrombosis can be performed by using either percutaneous or surgical techniques. Local or regional anesthesia should be used for the majority of patients. (B)

6.7.3 The thrombectomy procedure can be performed in either an outpatient or inpatient environment. (B)

NKF KDOQI GUIDELINES 2006 Updates Vascular Access

6.7.4 Ideally, the AVG and native veins should be evaluated by using intraprocedural imaging. (B)

6.7.5 Stenoses should be corrected by using angioplasty or surgical revision. (B)

6.7.6 Methods for monitoring or surveillance of AVG abnormalities that are used to screen for venous stenosis should return to normal after intervention. (B)

NKF KDOQI GUIDELINES 2006 Updates Vascular Access

Outcomes after treatment of AVG thrombosis:After percutaneous or surgical thrombectomy, each institution should monitor the outcome of treatment on the basis of AVG patency. Reasonable goals are as follows:

6.8.1 A clinical success rate of 85%; clinical success is defined as the ability to use the AVG for at least 1 HD treatment. (B)

6.8.2 After percutaneous thrombectomy, primary patency should be 40% at 3 months. (B)

6.8.3 After surgical thrombectomy, primary patency should be 50% at 6 months and 40% at 1 year. (B)

Clin J Am Soc Nephrol 2007;2: 786–800

Clin J Am Soc Nephrol 2007;2: 786–800

Options for treating steal DRIL procedure distal

revascularization-interval ligation

excision of a portion of the vein

plication w/ mattress or continuous sutures

crossed PTFE band interposition of a 4 mm

PTFE

Treatment of venous access complications.

Venous angioplasty Graft thrombolysis

Contraindications to Thrombolytic Therapy

Absolute  

  Recent major bleeding  Recent stroke  Recent major surgery or trauma  Irreversible ischemia of end organ  Intracranial pathology  Recent ophthalmologic procedure

Relative   

History of gastrointestinal bleeding or active peptic ulcer disease  Underlying coagulation abnormalities  Uncontrolled hypertension  Pregnancy  Hemorrhagic retinopathy

Recent articles

Patency rate and complications of polytetrafluoroethylene grafts compared with polyurethane grafts for hemodialysis access. RESULTS:

One-year patency rate was reported to be 64% and 52% in the PTFE and PVAG groups, respectively. There was no significant difference in 1-year (64% versus 52%) and 2-year (49% versus 41%) patency rate of the PTFE and PVAG grafts used as vascular access. There was also no difference between the numbers of complications reported in the two groups.

CONCLUSION: It could be concluded that either PTFE or PVAG grafts can be used

with the same expected outcomes

Ups J Med Sci. 2010 Nov;115(4):245-8

Long-term Outcome of a Cuffed Expanded PTFE Graft for Hemodialysis Vascular Access Compared to the standard ePTFE, the

cuffed ePTFE graft provided better long-term outcome, especially in terms of secondary patency rates after radiological intervention

World Journal of Surgery Volume 32, Number 8, 1827-1831

Balloon Angioplasty Versus Surgical Revision for Thrombosed Dialysis Graft Outlet Stenosis After Graft Thrombectomy The result of dialysis graft outlet balloon

angioplasty was comparable to that of surgical revision. Considering the invasiveness, balloon angioplasty should be considered when treating thrombosed dialysis grafts.

ANGIOLOGY August 2010; 61 (6):580-583

12 F. Catheter

Multi-side-hole tip

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