161 Evaluation and Intervention for Hemodialysis Vascular Access 7 Fig. 7.2. Two types of tunneled dialysis catheters: A) Double tip or split catheter, as typified by the Ash split catheter (polyurethane) and B) the single catheter double lumen catheter shown here as a Hickman catheter (silicone rubber). Fig. 7.3. Catheter size has a direct effect on flow. This explains the greater dialysis effi- ciency with a cuffed catheter 14.5F, and a temporary catheter 12F. 162 Access for Dialysis: Surgical and Radiologic Procedures 7 and optimal catheter tip length and positioning. Knowledge of central venous anatomy is imperative when placing central catheters (Fig. 7.4). I find the best func- tion is achieved when (Fig. 7.5): • the catheter is low in the neck in the internal or external jugular vein, with the tips extending inferior to the cavo-atrial junction in the right atrium, • the exit site is just lateral to the mid-clavicle, and • the tissue in-growth cuff is 1-2 cm deep to the skin. These criteria necessitate measurement of the distance to the right atrium to correctly choose a catheter of appropriate length. Also breasts should be retracted caudally when choosing the catheter exit site to prevent displacement of the catheter by gravity. Split catheters are not position dependent, but single dual-lumen cath- eters should have the arterial port facing centrally toward the major pool or right atrial blood. Remember that the catheter is placed when the patient is recumbent and will foreshorten when the patient sits or stands erect. Catheter dysfunction is often related to the catheter tip design employing mul- tiple side holes in the catheter tip to improve flow during dialysis, but allowing thrombus to form between dialysis treatments because of hemostasis within the catheter tip (Fig. 7.6). The routine practice of explosive catheter irrigation before Fig. 7.4. Anatomy of the superior vena cava and right atrium and ventricle. 163 Evaluation and Intervention for Hemodialysis Vascular Access 7 connection to the dialysis machine will greatly improve long-term catheter func- tion. Nursing manuals, however, prohibit most dialysis nurses from performing this simple preventive maneuver. Access physicians should give specific orders to have this maneuver performed. The other common cause of catheter dysfunction is the development of a fibrin “biofilm” sheath that often acts as a valve to prevent aspira- tion through the arterial port (Fig. 7.7). In 100 consecutive catheter exchanges with angiography to evaluate for the presence of a sheath, we found a significant sheath in 42%. The recent availability of t-PA in 2 mg doses has provided dialysis centers a means to treat access catheters with thrombolytic enzymes as part of delivery of dialysis. Whether or not payers will fund catheter thrombolysis remains to be seen. When catheter clearing fails, we have chosen to exchange catheters demonstrat- ing poor function. Even though thrombolytic enzymes can effectively be utilized to clear a tunneled catheter, 10,12 we have often observed only a short-term improve- ment usually resulting in a rapid return for additional treatment. Fibrin sheath strip- ping has not been specifically effective, 11,12 even though the technique itself can be relatively easily mastered. Placing a through-and-through guide wire down the cath- eter to be stripped and out a femoral venotomy sheath can greatly facilitate the ease of snaring and stripping the catheter by placing the snare around the guide wire. Because of the lack of efficiency and relatively high cost in both time and material, we have found it more effective to remove a non-functioning catheter, destroy the fibrin sheath, if present, by PTA, 13 and replace the catheter with one of more optimal size and position (Fig. 7.8). Our current preferred catheters are 14.5 polyurethane Fig. 7.5. Ideal position for a catheter. Right IJ vein access. Extends with tip inferior to cavo atrial junction. 164 Access for Dialysis: Surgical and Radiologic Procedures 7 Fig. 7.6. A) Dual lumen catheter showing soft thrombus occluding arterial port from side holes to tip. B) Split tip catheter showing thrombus plug occluding from most proximal side hole to tip. There is also some thin fibrin “biofilm” on the catheter. C) Fibrin sheath causing poor flow (arterial) seen on face. D) Arterial lumen plug of thrombus and fibrin biofilm removed by “explosive irrigation”. 165 Evaluation and Intervention for Hemodialysis Vascular Access 7 catheters of the split type (example: Medcomp Ash Split-catheter) or the dual-lu- men catheter (example: the Bard Optiflow) because of their high flow volumes. These catheters are relatively large bore, are inserted through a single needle punc- ture site, and tend to have longer patency with fewer catheter infections than sili- cone rubber tubes in our experience. It must be noted that silicone rubber catheters are sensitive to degradation by iodine and polyurethane catheters are sensitive to degradation by alcohol and glycol (Fig. 7.9). Thus iodine solution is the preferred antiseptic for polyurethane catheters and antibiotic ointment is preferred for sili- cone rubber catheters. Many other polyurethane catheters are now appearing and should also give flow in the range of 400 cc per minute. Even though catheters now have a lumen size that a small balloon catheter or brush type catheter could be utilized for clearing the lumen of thrombus, the time and cost efficacy of such maneuvers limit their usefulness both in the dialysis unit and the interventional suite. From both a functional and cost perspective, catheter exchange has proven most effective in my practice. If there is no evidence of tract or Fig. 7.7B. Thick biofilm on a split tip catheter. Fig. 7.7A. Thin biofilm on a split tip catheter. 166 Access for Dialysis: Surgical and Radiologic Procedures 7 Fig. 7.8. A) Contrast injection shows fibrin sheath after the split tip catheter has been removed. It must be destroyed to achieve adequate function of a new catheter. B) Contrast injection shows fi- brin sheath remaining after removal of a dual lu- men catheter. C) 8 mm PTA of the entire sheath up to the venotomy site destroys sheath. D) Post fibrin sheath PTA angio shows normal anatomy. 167 Evaluation and Intervention for Hemodialysis Vascular Access 7 Fig. 7.9. Chronic antibiotic ointment use at the exit site of a polyurethane catheter has caused wall weakness and “catheter aneurysm”. exit site infection, exchange of a catheter over a guide wire with appropriate angiographic evaluation for a fibrin sheath is acceptable. If a sheath is visualized, I use an 8 mm PTA balloon to destroy it. Other methods such as twirling a pigtail catheter have not been particularly effective for me. The placement site of tunneled catheters is extremely important in preventing central venous stenoses. The natural history of catheter access, however, is that cen- tral venous stenosis can well occur within one year (Fig. 7.10). Subclavian stenoses associated with dialysis access catheters of any type have been noted in my practice to occur in as little as 2 weeks (Fig. 7.11). This stenosis develops primarily due to trauma to the venous wall by the crushing action of the clavicle in apposition with the first rib during motion. Based on my experience, I strongly feel that the place- ment of a subclavian catheter in a dialysis patient whose extremity may eventually be used for a permanent access (or at the same time a new access is placed in the ipsilateral extremity) is a manifestation of lack of knowledge, inadequate technique or equipment, or patient neglect, and constitutes malpractice. The subclavian ap- proach should be used only if there is no plan for further permanent access place- ment in that extremity and only as a last resort (Fig. 7.12). I again stress that it is imperative to place tunneled catheters under ultrasonic localization and fluoroscopic guidance, not only to select the proper vein and avoid complications associated with the puncture, but also to avoid malposition second- ary to inadequate catheter length or position of the catheter tip ports into aberrant veins or in apposition with the right atrial wall (Fig. 7.13). I now almost always exchange dysfunctional catheters through a new tunnel because of six procedure-related infections (sepsis) that occurred after exchange over a guide wire through the same tunnel where the exit site and tunnel showed no clinical suggestion of infection. Even though this number is well below the accepted 168 Access for Dialysis: Surgical and Radiologic Procedures 7 Fig. 7.10A-C. Natural history of catheter related stenosis. A) Exter- nal jugular catheter on the same side as a new forearm graft present for 3-4 weeks. B) Veins are still patent. C) Occlusion present 1 year post placement. 169 Evaluation and Intervention for Hemodialysis Vascular Access 7 Fig. 7.10D-F. D) Central oc- clusion treated with 12 mm PTA. E) Angio post 12 mm PTA. F) Recurrent occlusion in 1 month required stent for prolonged patency. 170 Access for Dialysis: Surgical and Radiologic Procedures 7 Fig. 7.11A-C. A) Central venous oc- clusion related to 2 weeks presence of a left subclavian catheter placed at initial creation of a left forearm graft. B,C) Central venous 10 mm PTA. [...]... stenosis F) Swing site dilated to 8 mm 7 Access for Dialysis: Surgical and Radiologic Procedures Evaluation and Intervention for Hemodialysis Vascular Access G 177 Fig 7.15G,H Three week follow up shows a normal AVF-now in use for 6 months H Problems occur even after maturity has progressed and cannulation begun If the vein has been harvested from a deeper location and superficialized after ligation of...Evaluation and Intervention for Hemodialysis Vascular Access 171 Fig 7.11D-F D) Persistent central occlusion after PTA E) Stent placement and 12 mm PTA F) Unrestricted flow post stenting 7 172 Access for Dialysis: Surgical and Radiologic Procedures 7 Fig 7.12 Subclavian catheter should only be placed after extremity is abandoned Note relationship of catheter to 1st rib and clavicle accentuating... Surgical and Radiologic Procedures Fig 7.16A-C PTA and side vein occlusion to promote maturation A,B) Angio of immature AVF—note beaded juxta-anastomotic (J-A) segment, tiny primary vein and large diverting side vein C) 6 mm PTA of J-A segment and entire draining primary vein 7 Evaluation and Intervention for Hemodialysis Vascular Access 179 Fig 7.16D-F D) 6 mm PTA of J-A segment and entire draining primary... mm caliber and has had uninterrupted use for 18 months 7 180 Access for Dialysis: Surgical and Radiologic Procedures Fig 7.17A-C AVF failure to mature: PTA and side vein occlusion A,B) Angio of immature AVF with clinically large side vein compressed C,D) Entire primary vein was dilated to 6 mm E) Persistent side vein diversion of flow 7 Evaluation and Intervention for Hemodialysis Vascular Access 181... also justify intervention and are findings usually alleviated by prospective interventions Thus, these objective clinical findings indicate a need for angiographic evaluation and PTA to be performed to promote improved flow and prevent thrombosis (Fig 7.26) 196 Access for Dialysis: Surgical and Radiologic Procedures Fig 7. 25 Pseudoaneurysm with mural thrombus can compress an access to cause thrombosis... insertion C) Long segment thrombosis (up to and including the stent) eight months after initial stenting-thrombosis was 1 week old 7 192 Access for Dialysis: Surgical and Radiologic Procedures Fig 7.24D-F D) Long segment thrombosis (up to and including the stent) eight months after initial stenting-thrombosis was 1 week old E) AVF contained two aneurysms and multiple stenoses which were dilated post... consider minimal adequate size to be 6 mm, and ideal size for dialysis 7-8 mm Evaluation and Intervention for Hemodialysis Vascular Access 1 75 Fig 7.15A-C PTA for immature brachio-basilic transposition AVF A,B) Angio shows 6 mm brachial artery with a 17 cm long segment 2 mm caliber firm scarred vein C) 6 mm PTA of entire long segment of small caliber vein 7 176 Fig 7.15D-F D) Central veins are normal above... recirculation measurement 194 Access for Dialysis: Surgical and Radiologic Procedures Fig 7.24J-L J) Thrombectomy device to fragment adherent thrombus K) Vessel wall looks terrible at the end of procedure-use access for dialysis L) Two weeks later angio shows smooth wall with good flow 7 Evaluation and Intervention for Hemodialysis Vascular Access 1 95 7 Fig 7.24M,N Two weeks later angio shows smooth... fistulae We Evaluation and Intervention for Hemodialysis Vascular Access 189 Fig 7.23 Short segment AVF recanalization A) Angio after passage of a catheter through the clot showing a short segment thrombosis B) Balloon deformity showing an anastomotic stenosis as the underlying etiology of thrombosis C) Full 6 mm PTA of lesion and thrombus 7 190 Access for Dialysis: Surgical and Radiologic Procedures Fig 7.23D,E... treat exit-site infections Again the technique described above for exchange through a new tunnel is utilized Tunnel infection, the equivalent of an abscess, must be aggressively dealt 174 7 Access for Dialysis: Surgical and Radiologic Procedures Fig 7.14 Tissue cuff separation at catheter removal requires foreign body retrieval from the tunnel with through IV antibiotic therapy, catheter removal, and placement . a longer Fig. 7.15G,H. Three week fol- low up shows a normal AVF-now in use for 6 months. G H 178 Access for Dialysis: Surgical and Radiologic Procedures 7 Fig. 7.16A-C. PTA and side vein occlusion. greater dialysis effi- ciency with a cuffed catheter 14.5F, and a temporary catheter 12F. 162 Access for Dialysis: Surgical and Radiologic Procedures 7 and optimal catheter tip length and positioning fistula is now 8 mm caliber and has had uninterrupted use for 18 months. 180 Access for Dialysis: Surgical and Radiologic Procedures 7 Fig. 7.17A-C. AVF failure to mature: PTA and side vein occlusion.