When insufficient arterial inflow becomes the Achilles heel of the av-fistula—what are the surgical approaches?

Klaus Konner

Medizinische Klinik I, Krankenhaus Köln-Merheim, Köln, Germany

Correspondence and offprint requests to: K. Konner, Schauins Land 24, D-51429 Bergisch Gladbach, Germany.

Historical notes

Generations of nephrologists and vascular surgeons were taught that the success of vascular access depended on the availability of a suitable vein preferably at the wrist. This was absolutely correct during the first decade after the publication of the ingenious idea by Brescia and Cimino in 1966 to construct an arterio-venous fistula for maintenance haemodialysis. At that time, only patients younger than 40 years were accepted for chronic dialysis programmes. Diabetes was considered a contraindication to dialysis treatment [1]. Thus, the quality of the venous system was indeed the only factor taken into account.

Reality

Time has changed. The number of diabetic and elderly patients has increased dramatically worldwide, especially type II diabetes has become more prevalent with advancing age of the dialysis population. A high risk of cardiovascular death is found in these patients [2]; duration of dialysis therapy and life expectancy is reduced significantly. The impact of age and diabetes on the quality of the arterial vasculature is well documented.

Lessons learned

During the late 1970s, when elderly and diabetic patients with ESRD started to be accepted for chronic haemodialysis therapy, the strategy that had been successful so far was not changed. Priority was given to an anastomosis located at the wrist despite occasional technical problems in suturing the vein to a calcified artery. The result was a high failure rate, especially caused by early thrombosis and by problems with a low arterial blood flow rate as a consequence of reduced arterial inflow. Adequate postoperative dilatation of the veins did not occur in these patients. Two observations helped to overcome this impasse:

In addition, the analysis of haemodynamics of maturing arteriovenous fistulas as published by Wedgwood in 1984 [3] supported the new view on the role of the arterial system: Wedgwood had found a blood flow rate in the radial artery of 20–30 ml/min increasing up to 200–300 ml/min immediately after creation of an av fistula. Flow rates of 600–1200 ml/min were reached after maturation.

Obviously, such high blood flow rates could not be achieved when the feeding artery was atherosclerotic and had lost its compliance because of arteriosclerotic remodelling.

Patho-morphological properties of the arterial vasculature

Atherosclerosis is primarily an intimal disease whereas arteriosclerosis is primarily a medial degenerative condition causing dilatation, diffuse hypertrophy and stiffening of arteries [4].

The genesis of atherosclerosis starts with endothelial dysfunction, progresses to the formation of fatty-streak and ends as advanced, complicated lesions comprising macrophage accumulation, fibrous-cap formation and presence of necrotic core, as impressively documented by Ross [5], who emphasized the inflammatory character of atherosclerosis.

As early as 1974 Lindner had pointed to a potentially more agressive course of atherosclerosis in patients on haemodialysis [6]. Recently, Jungers et al. concluded that the development of atherosclerosis in uraemic patients is not restricted to the stage of dialysed dependence, but is seen in the earliest stages of chronic renal failure and progresses relentlessly on dialysis [7].

Early signs of endothelial dysfunction (endothel-dependent decrease of vasodilatation) along the brachial artery as predictor of coronary artery disease were detected ultrasonographically by Celermayer [8]. Using a multigate-pulsed Doppler system Barenbrock et al. investigated the effect of hypertension on elastic wall properties and found a decrease of arterial distensibility [9].

Amann and Ritz pointed to analogies between ageing and uraemia with regard to cardiovascular remodelling [10].

Factors impacting on remodelling include:

Preoperative evaluation

In order to achieve satisfying arterial inflow selection of the location of the first vascular access, especially in diabetic and elderly patients, should be based on several clinical findings:

Surgical consequences

The aim of the surgeon is to create a well functioning arteriovenous fistula. The artery and the vein have to be `healthy', that means that the structure of the vessel wall will allow dilatation, the prerequisite for sufficient arterial inflow and the high blood flow rates needed for haemodialysis treatment. Arteries with advanced loss of distensibility may be sutured to a vein, but the fistula will not develop adequate flow and function.

The importance of arterial dilatation and remodelling is nicely illustrated by the observation that in children who have small vessels, i.e. small arterial and various diameters, arteriovenous fistulae can usually be created successfully.

So in a given individual, for the location of the first av fistula one has to select a segment where artery and vein are found to be `healthy'. Keeping in mind the fact that arterial calcification normally is progressively decreasing from the wrist to the axilla, any appropriate segment of the radial, ulnar and brachial artery can be anastomosed to a suitable vein.

An increasing proportion of patients is seen nowadays in whom a first av fistula has been successfully created in the middle or the upper aspect of the forearm, even in the elbow region. These patients rather than suffering from the complications of a peripheral anastomosis achieved with an atherosclerotic artery will profit from a successful, more cephalad primary av fistula.

Elbow and upper arm arteriovenous fistulas are indicated in all patients with an exhausted peripheral venous network. A superficialized basilic vein can provide an excellent long-term vascular access as well as the cephalic vein.

The access surgeon is obliged to always have an arrow in the quiver whenever an individual problem of a patient has to be solved.

Perspectives

Access surgery will have to take into account the quality of the arterial vasculature to obtain an adequate arterial inflow. Nevertheless, in many of the elderly and diabetic patients, the risk of peripheral ischaemia is increased with a wrist fistula as well as with a more cephalad located anastomosis; this may happen early after creation or later after maturation. Prevention of arterial pathology will become more important in the future.

Elderly and diabetic patients with high comorbidity should be referred early to a nephrologist/diabetologist for better control of hypertension, diabetes, calcium, phosphorus and lipid disorders. Presently access surgery has to make the best of modified arterial and venous vasculature as often observed today. It is necessary to forget old rules and to demonstrate intellectual flexibility.

References

  1. Ghavamian M, Gutch CF, Kopp KF, Kolff WJ. The sad truth about hemodialysis in diabetic nephropathy. JAMA 1972; 222: 1386–1389[Medline]
  2. Levey AS, Eknoyan G. Cardiovascular disease in chronic renal disease. Nephrol Dial Transplant 1999; 14: 828–833[Free Full Text]
  3. Wedgwood KR, Wiggins PA, Guillou PJ. A prospective study of end-to-side vs. side-to-side arteriovenous fistulas for haemodialysis. Brit J Surg 1984; 71: 640–642[ISI][Medline]
  4. London GM, Drüeke TB. Atherosclerosis and arteriosclerosis in chronic renal failure. Kidney Int 1997; 51: 1678–1695[ISI][Medline]
  5. Ross R. Atherosclerosis—An inflammatory disease. N Engl J Med 1999; 340: 115–126[Free Full Text]
  6. Lindner A, Charra B, Sherrard DJ, Scribner BH. Accelerated atherosclerosis in prolonged maintenance hemodialysis. N Engl J Med 1974; 290: 697–701[ISI][Medline]
  7. Jungers P, Nguyen Khoa T, Massy ZA, Zingraff J, Labrunie M, Descamps-Latscha B, Man NK. Incidence of atherosclerotic arterial occlusive accidents in predialysis and dialysis patients: a multicentric study in the Ile de France district. Nephrol Dial Transplant 1999; 14: 898–902[Abstract]
  8. Celermayer DS. Testing endothelial function using ultrasound. J Cardiovasc Pharmacol 1998; 32 [suppl 3]: S29–S32[ISI][Medline]
  9. Barenbrock M, Spieker C, Laske V, Baumgart P, Hoeks APG, Zidek W, Rahn KH. Effect of long-term hemodialysis on arterial compliance in end-stage renal failure. Nephron 1993; 65: 249–253[ISI][Medline]
  10. Amann K, Ritz E. Cardiovascular abnormalities in ageing and in uraemia—only analogy or shared pathomechanisms? Nephrol Dial Transplant 1998; 13 [suppl 7]: S6–S11




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