IVUS

[drsclafani]

In this case, we had an excellent venographic and IVUS outcomes but ended up with an occluded vein.

So, was the residual stenosis with 10mm ok? Should this have been the end point? Or with the 12mm balloon should we have stopped at a lower pressure? When limiting balloon pressure to 10 ATM or less I have not seen any occlusions like this. Yet, I have also dilated many veins with > 20 ATM and had good outcome but more occlusions as well.

mike, i dont think it is the pressure that is the problem. it is using high pressures with a balloon too large. I average 13 ATM in the last 150 cases.

yes, this was a combination of too much pressure and too large of a balloon.

i typically have been limiting pressure to less than 6 atm. this case was the first time in probably 3 months of going over 15 atm.

mike
for the sake of uniformity, i describe the dilatation based upon the diameter of the balloon. But, you know this, I use CSA measurements to select the balloon. Generally i have found that a balloon with a 50% increase in CSA compared to the vein is not a problem as the vein is compliant as flow increases and decreases the vein enlarges and shrinks.

I think that when you eliminating the waist of a valve problem with only 5 Atmospheres of pressure, you are using a balloon was too small.

my balloon selection is all high pressure balloons, so i have atlas and conquest balloons. I use 40 mm length because the shorter balloon often slips beyond the stenosis. My average pressure is over 13 atmospheres. When i first started, following the suggestions of Sinan to use large balloons, I had thromboses like everyone. I dont think it was the pressure, it was in mis-sizing the balloons. Sinan suggested using 18 mm for women and 22 mm for men, but once i started using this formula of 25-75% over CSA to select the balloon, The complications rate really dropped quite low. the only thromboses have been two patients who stopped their month of thrombin inhibitor and anti-platelet inhibition without discussing with me and two minor dissections that remained patent. That is in the last 100 patients. I find that acceptable.

I do not seem to be getting those two month recurrent symptoms now. Followup venography has shown most veins remain widely patent.

So to summarize my opinions
1. Large balloons are necessary because opening the valve requires it
2. high pressure is necessary because opening the valves requires it
3. Too large a balloon with high pressure results in excess injury to the vein wall, and may result in thrombosis
4. Too small a balloon will NOT open the valve completely and result in higher restenosis rates.
5. too low pressure will not open many of these stenoses. The choice is not a larger balloon but higher pressure with the proper sized balloon.
6. multiple inflation sometimes leads to opening the stenosis when one or two do not.
7. If you have to exceed burst pressure of the balloon, it is often better to concede and accept less than optimal results and bring patient back in three months or so. Often a second angioplasty succeeds at lower pressure
8. short term anticoagulation with antithrombin agent and antiplatelet agent is essential to avoid thromboses


I have always been disturbed by the illustrations shown by zamboni in his papers that show small balloon angioplasty and valves that never were completely opened. It just does not make sense to me to not open the valve. I really dont think that you can open the valves with low pressure. Effacing the waist in the balloon requires high pressure most of the time

[MarkW]

Dr S,
Many thanks for your post. I would be delighted if I read your thoughts in a short communication/letter in a journal. Then you would be quotable in 'evidence based medicine' terms, which with your academic record would send a powerful message.
Using small balloons and low pressure was good practise two years ago but your evidence base has developed leading practise to using:
- IVUS to correctly size the balloon
- sufficient pressure, duration and repeats to open the valve
- anticoagulation with both antithrombin and antiplatelet agents

I hope that your leading practise spreads around the globe. This will really benefit pwMS who are currently spending their scarce finances on sub-optimal clinics.

Kind regards,
MarkW

[Cece]

So to summarize my opinions
1. Large balloons are necessary because opening the valve requires it
2. high pressure is necessary because opening the valves requires it
3. Too large a balloon with high pressure results in excess injury to the vein wall, and may result in thrombosis
4. Too small a balloon will NOT open the valve completely and result in higher restenosis rates.
5. too low pressure will not open many of these stenoses. The choice is not a larger balloon but higher pressure with the proper sized balloon.
6. multiple inflation sometimes leads to opening the stenosis when one or two do not.
7. If you have to exceed burst pressure of the balloon, it is often better to concede and accept less than optimal results and bring patient back in three months or so. Often a second angioplasty succeeds at lower pressure
8. short term anticoagulation with antithrombin agent and antiplatelet agent is essential to avoid thromboses

the question is what to do after the 10mm balloon with ivus still showing poorly opening leaflets. i can see a few options.

1. do nothing
2. repeat dilation with 10mm balloon
3. dilate with a cutting balloon
4. go bigger (we do not have an 11 mm balloon, so 12 was our next option).

since the waist in the balloon resolved at 5 atm, i don't think 2 or 3 would have offered anything.

so that leaves us with 1 or 4.

this will be great discussion for the workshop

Assuming that the 10 mm is the properly sized balloon, then option #4 is eliminated. I don't think either of you use cutting balloons? That would take option #3 off. Option #1 is not the best because of the residual narrowing, but in hindsight it might have preserved the vein, so it remains on the list. Option #2, as I understand it, is repeating the dilation with the regular 10 mm balloon. From what Dr. Sclafani is saying, I believe there is an option #5, repeating the dilation with a 10 mm balloon at high pressure.

Would another waist show up on a high pressure balloon of the same size, even after one waist was eliminated on the normal pressure 10 mm balloon?

I am very interested in the "routine second angioplasty" idea, in which a second angioplasty is expected as part of the procedure, if it does turn out that the vein is more amenable to staying patent when done twice. (#7 on Dr. Sclafani's list)

[DrCumming]

Hi Cece,

In this case, there was no residual waist with the 10mm balloon - so changing balloons would not matter. Typically we only use high pressure non compliant balloons.

Yes, I do sometimes use cutting balloons - will post a case of this shortly.

And, sometimes, coming back and dilating again later works. We used to do this before cutting balloons when we had a stenosis that would not open up. It seems like the first inflation "softens up" the area (I am guessing by inducing inflammation). We used to do this in dialysis patients.

[1eye]

This diatribe may contain information that is obvious and second nature to vein doctors. However critics may need reminding.

Because we are dealing with curves, on veins, not square corners, things are modified by pi. But remember pi * the radius squared is around three times the radius squared. Ballooning a straight length you get about six times the cube of the new radius, in volume, for every diameter's worth of ballooned length. What I am getting at is there is a very big change, going from 1 dimension to two (squaring), and an even bigger change when calculating volume changes, since you also have the length of the new channel, not just its radius (cubing).

If a vein has a wide spot, increasing the length of that wide spot will still decrease the total resistance significantly, especially when it is a collateral vein that is not stenosed, but appears in parallel. In fact, if surgeons could construct a new collateral vein, a parallel bypass of the same diameter as the stenosed vein should be, the total flow would be greater than or equal to what it should be.

Another thing that needs to be remembered is that a dilation decreases fluid resistance by a factor which depends not on the square, or even the cube of the radius, but the fourth power of the diameter, which is twice the radius. In a ballooning, it is the diameter that is changed.

The result of all this is that a little dilation goes a long, long, long, long way. For this reason perhaps the precision of balloon and stent sizing, as well as dilation measurements, is too coarsely-grained. Treatment might be more effective than we think it is. But it might also be more destructive than we think it is. When once a waist is broken, it might be very easy to overdo dilation. Maybe we should be specifying tenths of millimeters, in radii and lengths, and balloon volumes in cubic millimeters at some standard pressure, assuming outside pressure is negligible when not dilating.

[munchkin]

[/quote]The result of all this is that a little dilation goes a long, long, long, long way. For this reason perhaps the precision of balloon and stent sizing, as well as dilation measurements, is too coarsely-grained. Treatment might be more effective than we think it is. But it might also be more destructive than we think it is. When once a waist is broken, it might be very easy to overdo dilation.[quote]

This is a perfect statement 1eye. Some of us really know about the more destructive side of treatment.

Do the Dr's discuss this issue with the patient when they are presented with this type of problem? Allowing the patient to participate in a decision that may result in the lose of a vein.
Many of the IR's keep their patients alert enough to communicate.

[DrCumming]

This case is another good example on the complexities of size the balloon and determining an endpoint to the procedure.



This is the left IJ.

Just above the level of the valve, we have an area of 94 mm2.

At the valve, the underlying vein measures 175 mm2.

Valve opens to a maximum area of 57 mm2.

What size balloon to start with?

What are the criteria for deciding a satisfactory result?

[Cece]

This is a perfect statement 1eye. Some of us really know about the more destructive side of treatment.

Do the Dr's discuss this issue with the patient when they are presented with this type of problem? Allowing the patient to participate in a decision that may result in the lose of a vein.
Many of the IR's keep their patients alert enough to communicate.

Alert, but on narcotics.... (Fentanyl)
As involved as I am in understanding every last detail of CCSVI, I made sure I picked an IR whose decisions I trusted, and then I had to let go.

[DrCumming]

To avoid thread rot, lets keep the discussion related to the technical aspects of IVUS and the procedure.

[Cece]

This is the left IJ.

Just above the level of the valve, we have an area of 94 mm2.

At the valve, the underlying vein measures 175 mm2.

Valve opens to a maximum area of 57 mm2.

What size balloon to start with?

What are the criteria for deciding a satisfactory result?

Position the shoulder of the balloon just above the stenosis, so that the area that is 94 mm2 gets ballooned by the shoulder and not the main portion of the balloon.

Consult Dr. Sclafani's chart... http://www.thisisms.com/forum/chronic-c ... ml#p178072 using the measurement 175 mm2. This is a nice large vein. It falls between a 14 and a 16 balloon in size. Start with a 16 mm balloon, with a willingness to go up to an 18 mm balloon if needed but not to a 20. Maybe 8 - 10 atms. I have to read up more on high pressure balloons but I think, if the balloon is sized so that the vein itself is not being too stretched, then the high pressure is mostly acting against the valve and not the vein.

I don't know enough about how to determine the endpoint, other than setting the parameters of not going higher than an 18 mm balloon and not going too high with the atms. (Define "too high"? Not sure. Maybe 18 atm.) You are looking for good flow and no residual narrowing. I think a cutting balloon is not needed if high pressure is used instead.

Still not an IR, and still just an educated guess....

I am wondering about the blue lines of the vein, and then the green bump, does that indicate dilatation at the area of the valve? Is the vein below the valve also approximately 94 mm2?

[drsclafani]

Dr S,
Many thanks for your post. I would be delighted if I read your thoughts in a short communication/letter in a journal. Then you would be quotable in 'evidence based medicine' terms, which with your academic record would send a powerful message.
Using small balloons and low pressure was good practise two years ago but your evidence base has developed leading practise to using:
- IVUS to correctly size the balloon
- sufficient pressure, duration and repeats to open the valve
- anticoagulation with both antithrombin and antiplatelet agents

I hope that your leading practise spreads around the globe. This will really benefit pwMS who are currently spending their scarce finances on sub-optimal clinics.

Kind regards,
MarkW

mark
hopefully my reviews of pressures and balloon size will be accepted for reading at the SIR meeting in SF in March. Some of the results are quite surprising

[drsclafani]

This case is another good example on the complexities of size the balloon and determining an endpoint to the procedure.



This is the left IJ.

Just above the level of the valve, we have an area of 94 mm2.

At the valve, the underlying vein measures 175 mm2.

Valve opens to a maximum area of 57 mm2.

What size balloon to start with?

What are the criteria for deciding a satisfactory result?

I would increase cross sectional area by about 50%. 175 mm2 would require a 18 mm balloon to start. (254 mm2)

My experiences are disappointing with a smaller balloon in such situations. I always end up going larger.

[1eye]

I'm glad to see measurements with three digits of accuracy. Though I don't know what constrains them from the computer's viewpoint, it looks reasonable. Are those circumferences drawn by hand? I would feel safe knowing they were, I think, even with the clock ticking on the live procedure. The end point could be accurately determined in terms of inflated diameter if there were a predictable correspondence between inflation diameter and pressure. What isn't known is how hard the vein or valve is pushing back. I guess the person blowing up the balloon has to have a keen eye and a good hand on the throttle. There's no feedback, except the fluoroscope. Do you revisit the area with IVUS immediately, to get a measurement of the result? Or does it hurt your chance of success any to re-insert the catheter more times? If these questions are naive, forgive me, this is all new to me. I think a lot of info appears on here when I'm not paying enough attention.

It seems to be a balancing act between adequate dilation and damage to the tissue pushing back. Whether you need to go bigger than the diameter of the rest of the vein, and if you do, by how much, I have no idea. Maybe that is "to be determined", even now? When you say 50-75% bigger than the CSA, I assume you mean the normal part of the vein. I would think how damaging or not that is, is partly determined by what amount you have had to increase the diameter already to get to 0%.

After, say a year, how much different does a ballooned area look, on IVUS, from an unballooned vein? Do the areas show any injury/scars? Is IVUS useful at looking for that, after it's all healed?

[drsclafani]

I'm glad to see measurements with three digits of accuracy. Though I don't know what constrains them from the computer's viewpoint, it looks reasonable. Are those circumferences drawn by hand? I would feel safe knowing they were, I think, even with the clock ticking on the live procedure. The end point could be accurately determined in terms of inflated diameter if there were a predictable correspondence between inflation diameter and pressure. What isn't known is how hard the vein or valve is pushing back. I guess the person blowing up the balloon has to have a keen eye and a good hand on the throttle. There's no feedback, except the fluoroscope. Do you revisit the area with IVUS immediately, to get a measurement of the result? Or does it hurt your chance of success any to re-insert the catheter more times? If these questions are naive, forgive me, this is all new to me. I think a lot of info appears on here when I'm not paying enough attention.

It seems to be a balancing act between adequate dilation and damage to the tissue pushing back. Whether you need to go bigger than the diameter of the rest of the vein, and if you do, by how much, I have no idea. Maybe that is "to be determined", even now? When you say 50-75% bigger than the CSA, I assume you mean the normal part of the vein. I would think how damaging or not that is, is partly determined by what amount you have had to increase the diameter already to get to 0%.

After, say a year, how much different does a ballooned area look, on IVUS, from an unballooned vein? Do the areas show any injury/scars? Is IVUS useful at looking for that, after it's all healed?

I have only one patient that I have managed for 20 months who recently had a venogram just to check. Her veins looked pretty good, without stenoses. I have seen about a dozen patients who had restenosis after treatmentby others a year or more ago. Mostly the valves have restenosed

but this is an IVUS site.

[DrCumming]

1eye, we always check with IVUS and venography after the procedure.

Sal, in this case, do you avoid ballooning the "normal" segment of vein just above the valve? Even with careful balloon positioning how do you avoid having the shoulders of the balloon impacting the normal vein? I am not sure we need to open the valves more than the size of the inflow from the IJ above. My experience has been that most restenosis is from scarring not recurrent valves.

I treated with a 14mm balloon, inflation to 7 ATM. Resolution of the waists in the balloon at 7 ATM. IVUS and venography looked great. US at 1 month showed moderate proximal stenosis at the venoplasty site with a residual lumen of 6 mm. Valves were not visible. Preprocedure US showed proximal IJ diameter of 9-10mm.