Anticoagulation with AV Accesses

(1)

Department of Vascular Surgery, Evangelisches Krankenhaus Königin Elisabeth Herzberge, Berlin, Germany

In our experience, the following course of action has proved useful:

(a)

With physiological circulatory conditions and normal coagulation, neither AV fistulas nor AV shunts require drugs that influence coagulation.

(b)

We start primary anticoagulation (INR around 3) only in patients with:

Confirmed hypercoagulability
Arterioarterial grafts
Hypotension (systolic RR < 80 mmHg) with prosthetic grafts

(c)

After thrombosis we proceed according to intraoperative findings at thrombectomy. Criteria comprise:

Arterial inflow and venous outflow resistance
Vascular morphology as shown by intraoperative angiography (which we recommend)
Kind of thrombus material (white, mixed, or red)
Anamnestic suspicion of possible expressed temporary hypotension (e.g., severe diarrhea with pre-existing hypotension, shock, general anesthesia)
Long-lasting compression of the vascular access (bandage, joint position)

Typical aspects of a coagulation disorder are white or mixed thrombi.

Without suspicion of a persistent

Hemodynamic,
Morphological, or
Coagulation-related

cause, we do not order extra tests or introduce additional drug therapy after thrombectomy, but observe the clinical course.

With suspicion of

A morphological cause (arterial or venous stenoses or occlusions)

we complete imaging studies and repair pathologic findings if possible.

With suspicion of

Hypercoagulability

we initiate further coagulation tests.

If they prove positive, we start with (oral) anticoagulants.
If they prove negative, we observe the clinical course. Should there be repeat thrombosis in the absence of other evident causes, we start with anticoagulants despite negative standard test results.

(d)

An increased hematocrite also means a higher blood viscosity. Nonetheless if erythropoietin therapy or transfusions are indicated, they should not be cancelled for fear of AV access occlusion. Their effect should only be risky as to access occlusion under already unstable conditions.

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