Flowband Applications

Current banding methods used to address ischemic steal such as MILLER banding have minimal control over the final flow.

However, Flowband provides fine, atraumatic flow control.

Utilizing flow monitoring, Flowband can be used to optimize distal flow for each patient while ensuring adequate AV flow.

Without flow monitoring, Flowband allows one to perform incremental flow reductions while observing distal perfusion and heart function. 

There is no physiologic need or rationale to operate a fistula wide open. Placing a midpoint band creates high- and low-pressure segments. This configuration reduces overall AV flow and the pressure returning to the right heart. This technique was first reported as a solution to a low-flow steal scenario.(12)  Central banding may also reduce the ischemic stunning experienced with dialysis.(13)  

It has been known for over 150 years that opening a large fistula will enlarge the heart. AV flow reduction is very effective in relieving heart failure by increasing peripheral resistance and reducing central pressure (14). Flows from 500-900 ml/min have been shown to lead to reduced overall structural heart changes (8-10). Controlled flow reductions are possible with Flowband. 

Reducing AV flow by only 300ml/min provides an additional 110 gallons of blood per day to the systemic circulation. While access ligation has been shown to result in regression of LV hypertrophy (15,16), controlled flow reduction is also expected to reverse some cardiac changes. 

The presence of a patent access robs blood from transplanted kidneys. At the same time, approximately 20% of kidney allografts fail within 5 years requiring dialysis to reinitiated. Current clinical practice is an all-or-nothing approach to ligation. Flowband provides an intermediate solution that attempts to save the access, while increasing graft perfusion and helping the heart. 

The perfusion of kidney grafts, as measured by the resistive index (RI), is increased by access closure and even temporary manual occlusion. (1,2)  The increased perfusion is proportional to the access flow. An increase in RI ≥10% over the first year was found to be an independent risk factor for graft loss with a hazard ratio of 6.2. (3)
 

Closure of a patent access improves both kidney graft and cardiac function, reduced NT-proBNP levels, reduced LV and atrial dimensions, and stability of the eGFR slope. (4)  The presence of a fistula is also a predictor of HF in KT patients. (11)

Five-year eGFR data shows the detrimental effect of an open access on kidney graft function. (5) A 5-year graft survival study of open vs. closed accesses confirmed this: 60% with patent access, and 75% with closed accesses.(6)  Also, the 5-year impact of ligation on cardiac structure shows a persistent regression of the LVM and LVM index. (17)

The work of Gkotsis and Jennings (7) demonstrated the benefit of reducing AV flow for KT patients. Twelve fistulas were banded to a flow of about 600 ml/min. All were patent at 19mo., and 2 of 12 were successfully reused after graft failure. The Flowband allows targeted flow reductions to be performed to maintain access patency after KT. 

Reducing AV Flow following KT results in:

- Increased kidney graft perfusion

- Improved heart function

- Preservation of the access