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| Journal of Vascular Access 2003; 4: 81 - 82 |
| Vasculorama |
G. Dunea1
1Cook County Hospital, Chicago, Illinois, USA
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ABSTRACT
None
Drugs and fistula survival
A prospective study of 900 fistulae and 1944 grafts in 133 hemodialysis facilities in the United States attempted to correlate outcome with the drugs prescribed for indications unrelated to vascular access preservation. Calcium blockers were associated with improved primary graft potency, aspirin with secondary graft patency, angiotensin-converting enzyme inhibitors with better fistula patency, and warfarin with worse primary graft patency. The complexity of the clinical situations, however, would suggest that such associations do not prove causality (Am J Kidney Dis 40: 1255).
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Adherence of hemodialysis catheter to venous stent
A patient who had previously undergone dilatation of superior vena cava stenosis and stent insertion experienced discomfort and a choking sensation at each attempt to remove his tunneled silastic temporary catheter. A chest radiograph showed that one part of the split catheter had become stuck to the stent, seemingly tethered down by fibrous adhesions. The catheter was removed by accessing the circulation through the femoral vessels, then snaring the catheter with a wire and pulling it out through a femoral sheath (Nephrol Dial Transplant 18: 432).
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Dangers of temporary catheters questioned
Many studies have shown that patients with temporary dialysis catheters fare poorly compared to those with a permanent access. Yet these differences may be due at least in part to such patients being at high risk to begin with. According to an Italian group, excellent results can be obtained if venous catheters are treated with the same care and asepsis as is required for handling peritoneal dialysis catheters. In one unit of 88 patients the yearly mortality was 5% and no death was due to infection. Reduced flow through some of these catheters was compensated for by lengthening dialysis time (Kidney Int 63: 767).
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Brachial artery dilatations after arteriovenous creation
Swiss investigators have followed a small group of dialysis patients for over ten years and found that the brachial arteries used for fistula creation have a tendency to gradually dilate. Mean diameter, originally 6.4 mm, increased to 6.6 mm after three years and to 7.4 mm after ten years (normal brachial artery diameters are 3.5 to 4.3 mm for women and 4.1 to 4.8 mm for men). It appears that a high blood flow is the main factor causing the arterial dilatation (J Vasc Surg 37: 564).
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Fibrin sheaths block hemodialysis catheters
The formation of fibrin sheaths around tunneled hemodialysis catheters is a complication that has recently attracted much attention. These sheaths tend to cover the catheter ports and interfere with the blood flow. They may be disrupted by thrombolytic infusions (urokinase or rTPA) or by physically stripping with a snare introduced through a second venipuncture and passed over the line (Nephrol Dial Transplant 18: 1026).
Desperate diseases require desperate remedies
Two patients with occluded superior vena cava and iliac veins underwent major thoracic surgery, including resection of the fifth costal cartilage and part of the rib, and had a shunt established between the left axillary artery and the right atrium. A graft was placed in a tunnel across the sternum and connected at both ends by means of polytetrafluorethylene grafts to the axillary artery and the right atrium. The grafts remained patent and usable for six to eight months (Dial Transplant 32: 333).
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Catheter fracture after blunt trauma
An echymotic swelling in the right supraclavicular area developed in an 83-year old dialysis patient two days after he fell and bumped his chest against a doorknob. After an angiogram showed that blood was leaking out through a small hole in the venous port, the catheter was replaced over a guidewire. Such tears in catheters, which can also occur spontaneously, are more likely to happen if the catheter is placed in a medial location and becomes pinched off by the first rib. The leaks are frequently complicated by sepsis, hence the advisability of administering prophylactic antibiotics (Nephrol Dial Transplant 18: 618).
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Cutting through high-grade stenosis
Tight graft stenosis resistant to high-pressure balloon dilatation may be salvaged by using a cutting balloon. This is a device consisting of three or four blades arranged longitudinally around a balloon that is inserted over a guidewire and manipulated through the stenotic segment. The balloon, also used to dilate stenosed coronary arteries, is appropriate for lesions 10-20 mm in length in vessels with diameters ranging from 2 to 4 mm. Larger diameter balloons may become available in the future. The balloons cause a controlled incision in the intima that makes further successful angioplasty possible. (AJR 180: 1072).
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Pulse spray injection of t-PA
Another approach to dealing with occluded arterio-venous grafts is to insert a catheter with side slits in an antegrade fashion and inject boluses of tissue plasminogen activator (t-PA) solution with a pulse spray injector. After angioplasty the venous access is accessed and a balloon thrombectomy catheter inserted, then digital subtraction angiography performed to evaluate the rest of the vessels and carry out further dilatation if indicated (AJR 180: 1063).
George Dunea, MD FRCP, FACP
Associate Editor
Address for correspondence:
Cook County Hospital
1825 West Harrion Street
Chicago, Illinois 60612, USA
geodunea@aol.com
REFERENCES
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G. Dunea
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