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Techniques used for arteries cannot simply be transferred to veins. Flow rate and pressure in arteries are much higher. Furthermore, artery walls have a completely different structure than vein walls. Experiences with dialysis patients - where a vein is connected directly to an artery in a small surgical procedure - show that classic balloons used in arteries cannot apply the pressure required to open stenoses that develop in these veins (so-called dialysis fistulas). These veins are too stiff due to connective tissue bands. The use of balloons with a larger diameter than the vessel or the use of two balloons also does not offer a solution. This only results in stretching the healthy wall to either end of the stenosis, which is obviously not the objective.

To solve this conundrum, two different techniques were chosen, the previously mentioned cutting balloon being the first. By inflating this balloon multiple times, turning it a little each time, the desired effect is achieved. The disadvantage of this technique is that local bleeding may occur, as the blades can cut through the thinner vein wall. The other solution is to use high-pressure balloons. The effects are the same as for arteriosclerosis, however high-pressure balloons can be inflated to 16 bars without the risk of the balloon tearing. This allows far more force to be applied to the stenosis, and sufficiently stretches out the connective tissue that causes the narrowing. Tests have shown that the use of stents in dialysis fistulas affect the inner lining of the vein in the long term, resulting in new stenosis and even complete occlusions.

For over a year now, I have been using high-pressure balloons to dilate the parts of veins where stuck valves, membranes and band-shaped thickenings are causing problems. Using high-pressure balloons, I have treated hundreds of patients with good and lasting results. It is important to note I see practically no re-stenoses (new narrowing) in patients in the long term. My conclusion is that the connective tissue strands in the band-shaped stenosis are sufficiently broken up, and no damage has been done to the wall of the treated vein.

The bar is a unit of pressure equal to 100 kilopascals, and roughly equal to the atmospheric pressure on Earth at sea level. Other units derived from the bar are the megabar (symbol: Mbar), kilobar (symbol: kbar), decibar (symbol: dbar), centibar (symbol: cbar), and millibar (symbol: mbar or mb). They are not SI units, nor are they cgs units, but they are accepted for use with the SI.[1] The bar is widely used in descriptions of pressure because it is only about 1% smaller than the atmosphere (symbol: atm), which now is defined to be 1.01325 bar exactly. The bar is legally recognized in countries of the European Union.[2]

1eye wrote:From Wikipedia:

The bar is a unit of pressure equal to 100 kilopascals, and roughly equal to the atmospheric pressure on Earth at sea level. Other units derived from the bar are the megabar (symbol: Mbar), kilobar (symbol: kbar), decibar (symbol: dbar), centibar (symbol: cbar), and millibar (symbol: mbar or mb). They are not SI units, nor are they cgs units, but they are accepted for use with the SI.[1] The bar is widely used in descriptions of pressure because it is only about 1% smaller than the atmosphere (symbol: atm), which now is defined to be 1.01325 bar exactly. The bar is legally recognized in countries of the European Union.[2]

Couldn't you use a balloon that had a bump, a wider (diameter-wise) channel in the middle, sized for the valve, with thicker rubber? The smaller outside part of the balloon might damage the healthy endothelium less, with a weaker wall strength?