AVG thrombosis-- can any drug prevent it?

AVG can clot and certain patients, they clot frequently.  What is the data on pharmacological interventions to improve AVG outcomes in terms of preventing further clots?

A recent article in CJASN discusses this nicely via a case of a patient who has numerous AVG and most clot within weeks  of creation. The authors discuss patho-physiology of thrombosis of AVG but then discuss the potential pharmacological options.  I encourage all to look at Table 1 as it summarizes the randomized controlled trials on major agents that we consider are useful in preventing clots.

Apparently, warfarin, ASA + clopidogrel showed no difference and were more harmful in causing bleeding. 

Lowering homocysteine levels by folic acid didn’t do much either. Only trials that showed benefit were the ones that used Fish oil.  One is a small single center trial that showed decrease in thrombosis and other was a multicenter trial that showed that fish oil (four 1-g capsules/day) halved the frequency of the AVG thrombosis and angioplasty.

Worth a read for all nephrologists!

Rise of Interventional Nephrology

Interventional Nephrology – Opportunities Ahead

Over the past century, the field of nephrology has evolved with the successful performance of hemodialysis by G. Haas in 1925, cutting needle kidney biopsy in 1951 by Iversen and Brun, and kidney transplant by Murray and Harrison in 1954. Over the last 5 decades, the field of nephrology saw immense improvements in the technology that support these therapies leading to remarkable change in the quality of care. The introduction of Interventional Nephrology in the late 1990’s has invigorated enthusiasm to the field of Nephrology.

The “bread  and butter” of Nephrology practice revolves around providing adequate dialysis therapy. With the technological innovations, dialysis therapy is now mainly provided by the supportive staff and dialysis centers have been converted in to “well-oiled treatment factories”. Interventional Nephrology brings in a new ray of hope and turns a mundane fellowship into a challenging ‘hands-on skill’ oriented field.

The pioneers of the field, Gerald Beathard, Steven Ash and Jack Work were able to form the American Society of Diagnostic and Interventional Nephrology in 2000 (www.asdin.org), with a mission to promote the procedural aspect of the practice of nephrology. ASDIN has developed training and certification guidelines that are vigorous and well respected by most hospital credentialing committees.

Interventional nephrology includes a variety of procedures - renal ultrasonography, placement and removal of tunneled hemodialysis, placement of peritoneal dialysis catheters, angiography and balloon angioplasty for vascular access stenosis (including central veins), endovascular stent and coil placement for dialysis access dysfunction, and thrombectomy procedures for clotted vascular access. The training for these procedures, which began primarily in the private arena has evolved over the past decade and gradually is being adopted by academic centers. The new field has clearly made a positive impact on the care of dialysis access. Further, Interventional Nephrology is being recognized as a potential tool to attract new trainees and eventually improve the dwindling nephrology work force. The critical balance between the intellectual component, procedural skills and lifestyle hopefully will make it attractive for the future generation of trainees to choose nephrology as a career.

Post by

Dr Tushar Vachharajani

Interventional Nephrologist

Nephrology Crosswords: Interventional Nephrology

http://www.nature.com/ki/journal/v81/n3/pdf/ki2011373a.pdf

Access educational Tool

The AV fistula first website has developed some really good teaching resources for fistula and graft management and access care.  The videos that are very educational and helpful are the link below:
have a look:
http://www.fistulafirst.org/HealthcareProfessionals/FFBIChangeConcepts/ChangeConcept9.aspx

ASN2011: Dialysis Mortality

SOME TEACHING POINTS FROM ASN 2011 Pre course on Dialysis Care

We all know that mortality is very high for incident hemodialysis and could reach as high as 50%. 

Hakim et all showed in a retrospective study in looking at Fersenius data. They looked 10 years back and found out that those with the highest mortality had catheters. One conclusion could be that these deaths could be  infectious complications. It behooves us therefore to prevent these kind of deaths. 

Unfortunately people had these catheters and died despite the fact that thery were followed by nephrologists for more than six months.

Bradbury et al, AJKD, 2009 showed that mortality decreased by 36% and 29% when catheter was changed to AVF, and AVG respectively; and mortality increased by 80% when permanent access was changed to a catheter.

What are some reasons to this suboptimal care: 

Late referal to nephrology, priamary avf failure, patient-induced delays and in-decisions, etc. (NDT)

Patients were reluctant bc of fear of needels and fear of surgery and prior failures of fistulas.

Our job as nephrologists is to prevent these deaths and spend the time and energy to convince patients get AVF or AVG.

Post from

Dr.Azzour Hazzan

Hofstra NSLIJ Nephrology

 

ASN2011: Late Breaking Oral Presentation: FISH Trial

Dr Lok from Canada presented the findings of the FISH trial that looked at use of 4gm of fish oil as a primary preventive for AVG stenosis.  The primary outcome was native potency and they did a randomized controlled placebo based trial.  It was a large group of patients and it was a well designed trial.

Unfortunately, the primary outcome was negative and there was no statistical significance of native potency prevention. But the secondary outcomes such as rate to thrombosis, number of interventional procedures, and cardiac events( MI and CHF) were statistically significant in the fish oil group.  

Also, the rate of corrective interventions was more in the placebo arm. Interestingly, there was no difference in cholesterol, TG and LDL in both groups. But HTN mean SBP was less in the fish oil group post intervention.  

A nice trial, but negative results. But there is some suggestion here that fish oil might be helpful in preventing cardiac events. This is the largest cause of death in ESRD patients. Something to follow up on as the research gets published

Ref:

http://www.ncbi.nlm.nih.gov/pubmed/17848497

In the News: Initial access type in dialysis patients and inflammation?

Fistula, graft or catheter placement, which causes more inflammatory response?? No one knows.

The authors conducted a prospective observational study in an incident HD population. C-reactive protein (CRP), interleukin-6 (IL-6), and interferon-γ-induced protein (IP-10) were measured before and at 6-time points after access placement for 1 year. 40 patients were studied with no differences in baseline characteristics. The study found that patients who initiate hemodialysis with a perm cath or an AVG have a heightened state of inflammation, which may contribute to the excess 90-day mortality after HD initiation.

This study is unique in that baseline cytokine values were obtained before first access placement and prior to HD initiation, so some comparison could have been done.  The prospective study design allowed for recording all intercurrent events, which were included in the adjusted analysis. 


Interestingly, this is showing us that any "foreign" object in our body is going to raise the inflammatory markers. AVF doesn't really involve an foreign body and perhaps these results reflect that more than the procedure. The numbers are small and larger studies are needed to clearly clarify this point


The full study is at
http://www.hindawi.com/journals/ijn/2012/917465/

TOPIC DISCUSSION: The Distal Hypoperfusion Ischemic Syndrome-NKF 2011 recap

Hand ischemia: Often we encounter patients who complains of numbness and pain during dialysis in the ipsilateral side of the access; and often diagnose it as steal syndrome; well not entirley true all the time.(70-% of patient have a steal on angiograms without symptoms)

We should all do a detailed history and exam and then think of other common differential before we reach the steal syndrome diagnosis because the steal syndrome indicates a specific management such as ligation of the access.

What is a better term to use is DHIS; distal hypoperfusion ischemia syndrome. important differential diagnosis list below:

CTS, carpal tunnel syndrome; DA, destructive arthropathy; DHIS, distal hypoperfusion ischemic syndrome; IMN, ischemic monomelic neuropathy.

DHIS has multiple causes: Arterial stenosis, vascular steal, and distal arteriopathy as well as combinations of these three; so it is important to visulize the whole access with angiogram including the central vessels to diagnose an arterial stenosis which usally improves after angioplasty and does not need ligation. now important clues are cold extremities on exam and lack of distal pulse. high risk patients are DM, smokers.

The nephrologist should be very involved in the diagnosis phase as well as the management and our role should NOT be just a referral to the vascular suergon.

http://cjasn.asnjournals.org/content/2/1/175.full

IN THE NEWS- TPA vs Heparin- NEJM Study

A recent randomized trial published in NEJM Jan 2011 compares tpa(1mg in each lumen) weekly as catheter lock in dialysis catheters to heparin three times a week( 5000units each week) and 6 month follow up.

The main points indicate:
20% malfunction of catheter in tpa group, 34% malfunction in heparin group
4.5% bacteremia in tpa group, 13% in heparin group
Bleeding was similar in both groups
In conclusion, the authors suggest that tpa is a safer bet: in terms of infection and malfunction risk. Bleeding risk no difference.

Take a look at the article and commentary below:
Ref:
http://www.ncbi.nlm.nih.gov/pubmed/16608513
http://www.nejm.org/doi/full/10.1056/NEJMoa1011376
http://www.nejm.org/doi/full/10.1056/NEJMe1013952

HISTORY LESSON- Scribner Shunt

This month in CJASN, there is a 3 page tribute to the great Scrib : Belding Scribner who discovered one of the first access devices in dialysis and changed the face of Nephrology as a field.
Before his discovery, dialysis was not done for all patients and when done, was a fresh cutdown of artery and vein and that led to lot of bleeding and people ran out of sites to do it. Scribner's idea of connecting the artery to the vein by a short shunt to preserve dialysis access allowed more dialysis for patients.
On March 9, 1960: David Dillard, cardiac surgeon implanted the first shunt made at the bedside by Quinton. The first shunt used allowed that patient to live 11 years!!
History in the making!
http://www.ncbi.nlm.nih.gov/pubmed/21051747
http://www.ncbi.nlm.nih.gov/pubmed/16874726

Dialysis Access Atlas from Fistula First. Check it out!

A nice treat from Dr. Tushar Vachharajani, An Interventional Nephrologist from Wake Forest University Medical Center.

Dialysis Access Atlas

View more presentations from Nephrology, NSLIJ.

Access Educational Tool

Listening to the right sound in AVF and AVG can get your ear trained. Just like a cardiologist. The Fistula First Has a nice tool on the page listed below. Towards the bottom of the page, listen to the bruits!
The link for this tool:

http://www.fistulafirst.org/HealthcareProfessionals/FFBIChangeConcepts/ChangeConcept9.aspx