**11. Dialysis Interventions**

Dialysis fistulas grafts are increasing in number, as renal failure becomes an epidemic. Failure of these grafts is frequent and accounts for most of the morbidity associated with these grafts. Immediate graft malfunction due to surgical causes is quickly identified during placement. Acute thrombosis within these grafts can occur at any time following placement. This is a constant problem for nephrologists due to the nature of hemodialysis itself. Chronic needle punctures within the graft 3-4 times a week results in numerous chances for thrombus formation. Also, heparinization during hemodialysis and then reversing the

Balloon venoplasty can be performed after the bulky thrombus has been removed uncovering an underlying venous stenosis. This can be treated with venoplasty to improve the diameter of the vessel thus improving its flow. It is the gold standard for venous stenosis in various distributions including subclavian, iliac or venacava corresponding to the various syndromes described previously. Typically, these interventions treat the underlying venous stenosis resulting in venous patency. The more central the venous stenosis, the better the result following venoplasty. Recurrent or residual venous stenosis following balloon venoplasty occurs frequently especially in those patients with chronic central venous catheters. Despite venoplasty, these venous lesions are very difficult to treat and recurrent

Stents can be used in any venous distribution from peripheral to central veins. Covered and uncovered metal stents can be used for recurrent stenosis. Central venous stenosis as in the SVC and IVC require the largest available stents. Covered stents and the newest Flair covered stent (CR Bard, Tempe, AZ) are now available for dialysis fistula anastomoses where by a smaller fistula graft enters into the larger native venous outflow resulting in a smooth transition and improve flow dynamics. Venous stenting can also be performed following suboptimal balloon venoplasty result. Venous stenting is not performed on thrombus alone but is used as an adjunct to suboptimal venoplasty and venous

Activase (TPA) (Genenetech, South San Francisco, CA) and Tenecteplase (TNK) (Genenetech, South San Francisco, CA) are the most common thrombolytic agents currently available. These drugs are fibrinolytic agents which break down fibrin into split products thus allowing clot to lyse within the vascular system. In the veins, both work similarly but TNK seems to lyse clot faster with less bleeding complications due to its exquisite fibrin specificity. Tenecteplase is the newer of the two agents. It has a 14 fold higher fibrin binding specificity than TPA. Due to the larger volume of clot within veins, a larger dose of drug is necessary to lyse the clot burden. This is one of the reasons for combining mechanical with thrombolytic agents. With combination therapy, less drug can be used in these larger capacitance vessels if combined with one of the above-mentioned mechanical devices.

Dialysis fistulas grafts are increasing in number, as renal failure becomes an epidemic. Failure of these grafts is frequent and accounts for most of the morbidity associated with these grafts. Immediate graft malfunction due to surgical causes is quickly identified during placement. Acute thrombosis within these grafts can occur at any time following placement. This is a constant problem for nephrologists due to the nature of hemodialysis itself. Chronic needle punctures within the graft 3-4 times a week results in numerous chances for thrombus formation. Also, heparinization during hemodialysis and then reversing the

**8. Balloon venoplasty** 

venous stenosis may require stenting

**9. Venous stenting** 

thrombolysis.

**10. Thrombolytic agents** 

**11. Dialysis Interventions** 

coagulation during and after dialysis catheter removal results in thrombosis of the graft. If unable to open the graft within a reasonable time, then other means of vascular access are required. Typically, another central venous dialysis catheter is needed until a new graft is created or the present one is cleaned out.

Interventional doctors are well adapted to lysis of dialysis graft using both pure pharmacological and mechanical thrombectomy. These grafts can be cleared of their thrombus burden in the interventional lab without requiring further surgery. Pure thrombolysis catheters like Speed Lyser delivers drug directly to the clot through multi-side holes via one micro catheter system. The drug is allowed to sit within the graft and dwell for a period of time called "lyse and wait" technique. Over this period of time, the clot is lysed and the graft is cleared of thrombus. TPA is used for this purpose. It can be injected directly into a graft. TPA can be given as a 6mg bolus within the dialysis grafts for this treatment. Following lysis, other interventions may be necessary to alleviate the source of the underlying graft malfunction.

### **12. Inferior venacava filter placement**

Caval thrombosis can be acute or chronic. Filters can be used for the treatment of acute caval thrombosis, prophylaxis of pulmonary embolism and also be the source of caval thrombosis. Both treatment and cause of caval thrombosis makes interruption filters a double-edged sword. Either way, endovenous means are used exclusively for caval thrombosis.

Furthermore, most of the patients undergoing venous thrombolysis receive retrieval Inferior Vena Cava filter before the intervention. This is usually placed at the same setting. This idea is to reduce the risk of an iatrogenic fatal pulmonary embolism during the procedure. This filter can then be removed if indicated up to six months following implantation. Prior to removing the filter, a duplex venous ultrasound of the lower extremities is obtained to document clot resolution.

#### **13. References**


**6** 

Daniel Link

*USA* 

**Late Complications of Deep Venous** 

**and Non Healing Ulcers** 

*Davis School of Medicine University of California,* 

**Thrombosis: Painful Swollen Extremities** 

Patients with complications of deep vein thrombosis (DVT) experience a "life changing event" stemming from their DVT. Constant swelling, pain and discoloration of the involved lower extremity are common. These symptoms result from "venous hypertension secondary to reflux, obstruction, or insufficiency of muscle pumps" (Kearon 2003; Labropoulos 2004). Although the symptoms are well described, patients often have no plan for long term follow up after the acute DVT event. The venous system adjusts to impaired valvular function and obstructed outflow venous channels in the first year following the DVT. A life long commitment to compression hose therapy (Franks, Moffatt et al. 1995) with ambulation and extremity elevation at rest will minimize swelling and pain. Unfortunately, in the acute phase patients often cannot tolerate compression hose but they should be "coached" into compression hose as soon as possible. "60% of patients post DVT develop post thrombotic syndrome (Ashrani, Silverstein et al. 2009); fitted, graded compression hose reduce the rate in half" (Kahn ; Brandjes, Buller et al. 1997; Pirard, Bellens et al. 2008). Following a course of anticoagulation and advice for compression hose therapy, DVT patients usually are followed by their primary care provider. Recently there has been increasing interest in more closely following DVT patients. A duplex supervised by a vascular/vein specialist should be performed to assess the "pumping" capacity, available venous channels and valvular competence a few weeks to months after a DVT event (van Ramshorst, van Bemmelen et al. 1994; Caps, Manzo et al. 1995; Salcuni, Fiorentino et al. 1996; Nicolaides 2000). This is especially indicated if patients experience persistent pain and swelling, or if a change occurs in the status of the limb swelling and pain after a long stable period, or if there is continued increase in pigmentation in the pressurized area. Chronic complications, post thrombotic syndrome (PTS), can present clinically depending on the initial severity of the deep venous abnormality, but may also develop abnormalities in the years following a DVT (Bradbury 2010). The overwhelming goal of the treatment of complicated post DVT patients is to preserve skin integrity and to prevent or heal ulceration (Kearon 2004; Bradbury 2010). Pain, infection, and loss of function result in a significant cost to the patient and the community as a whole.

Veins are substantially different from arteries and exist as a network of thin channels with little intrinsic muscular wall. Large intramuscular veins like the gastrocnemius vein can

**1. Introducton** 

**2. Anatomy** 

