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May Thurner Syndrome -Dr. Daugherty responds to Dr. Mueller
Last Updated: 8/7/2012
|Rich, Nicos Labropoulos, et al., (JVS 2007 46:101-107) reported ratios of peak venous velocity at venous stenoses. Only a quarter of the lesions they studied were iliac vein lesions, but they found that a PVV ratio of 2.5 predicted a greater than 50% stenosis. We are collecting data on iliac vein lesions comparing PVV ratios with diameters by IVUS. The value of 2.5 may be good, but I am even more comfortable that a PVV ratio of 3.5 or greater is indicative of a hemodynamically significant iliac vein stenosis the treatment of which usually dramatically improves symptoms. We look also for reversal of flow in the internal iliac vein or other cross-pelvic collateral flow with color and Doppler. If we are unsure whether an iliac vein lesion is hemodynamically significant, we are walking some of our patients on a treadmill and repeating the US looking for elevated velocities across the lesion and for reversal of internal iliac vein flow after exercise to confirm our suspicion of hemodynamic significance. |
We look for narrowing of the vessel by gray scale and color flow and we measure diameters of the vein at the lesion and at a reference location such as the more normal-appearing vein peripheral to the lesion. We look for wall thickening in the vein, endolumenal echos, webs with flow distrurbances.
Usuallly, the cause of the lesion is fairly obvious. The iliac vein compressions usually are associated with an artery compressing the vein. The artery usually is a normal iliac artery, but it could also be a tortuous or calcified artery or an aneurysm. I have not seen, but I wonder if we cause iliac vein compression from aorto-femoral grafting. Another group of patients will have endolumenal echos from old organized thrombus, webs,or synechiae. A third group of patients are those with iliac vein strictures, most commonly from phlebosclerotic changes, but we have seen post-surgical strictures of iliac veins as well. The strictures usually are fairly easy to see becasue of the elevated velocities across the lesions.
Earlier in the blog, I listed the patients that we evaluate for iliac vein lesions. Since we evaluate only those who have moderately severe symptoms, we do not know the true incidence of iliac vein lesions or the relative incidence of mild, moderate, or severe stenoses. We commonly see compression of iliac and left renal veins which we believe is not hemodynamically significant and which we view as a variation of normal. We also know that 80% of iliofemoral DVTs have an underlying iliac vein compresssion. What we do not know is the risk of a hemodynamically-significant iliac vein stenosis to cause an iliofemoral DVT over time.
Best Regards, Stephen
Submitted by Stephen F. Daugherty - 8/7/2012
|re my last blog post to dr. daugherty, would also love to hear what specific iliac vein gray scale / color / PW CDU criteria the Stony Brook lab uses for both types of iliac venous disease: May-Thurner / compression, and occlusion/thrombosis/stenosis|
Submitted by rich mueller - 8/5/2012
for M-T iliac CDU, do you typically visualize a gray scale or color flow narrowing of the vessel due to extrinsic compression or a focal color flow disturbance in addition to the PW velocity stepup?
also, how about iliac CDU findings for thrombotic/occlusive/stenotic diseases? same criteria of 2.5x velocity step up and internal iliac retrograde flow? same questions there as well do you see a gray scale or color flow lumen narrowing or focal color turbulence?
many thanks !
Submitted by rich mueller - 8/5/2012
|Consensus documents of the Union of International Phlebologie/International Union of Phlebologie(y) are silent regarding definition of terms such as iliac vein obstruction/non-thrombotic iliac vein obstruction/may-thurner syndrome and so on. Until there is some consensus that the lesions even exist it will be difficult to draft a manuscript that will be accepted given that the natural history currently is not known.|
It is important to remember that these are PERMISSIVE lesions. I have patients with complete iliac or i v c occlusion whom develop venous collaterals and are essentially a symptomatic, while others have significant symptoms with morphological obstruction of only about 50%
Dr Daugherty will tell you that he can generally tell which patients have non-thrombotic venous obstruction based upon history.
If the reader can not confidently tell which patients likely have proximal venous obstruction by history when presenting to the outpatient clinic my strong recommendation would be to spend at least a week in the rane center clinic in Jackson/flowood miss
John W. Hovorka, MD, FACS, APBM/UHM, RVT, CLT
909 N. Jackson Road
McAllen, TX 78501
Submitted by John Hovorka, MD - 8/5/2012
|Dr. John Havorka has performed IVUS for evaluation of iliac veins in the office in South Texas. He reported his initial experience last year either at the AVF or ACP annual meeting.|
Currently, reimbursement is a problem for office IVUS. The reimbursement issue will resolve eventually if clinical diagnostic value and cost effectiveness is proven.
Submitted by Stephen Daugherty - 8/4/2012
|We have been working to perfect our use of iliac ultrasound as a measure of being a center for Venous excellence|
We have diagnosed several patients with May Thurner syndrome as well as with iliac chronic thrombosis
Would appreciate if Nicos has any PowerPoint slide sets or papers on the topic that he could share with blog readers
Also Dr Daugherty raises some interesting questions. Has to date really anyone used IVUS in an outpatient setting and if so is anyone reimbursing for that and are there regulatory issues? Seems like output use would be unlikely
Submitted by Rich mueller - 8/4/2012
|I cannot imagine a better teacher for abdominal/pelvic venous color duplex studies than Nicos Labropoulos.|
We perform abdominal/pelvic venous color duplex ultrasound (CDU) for:
1. Nearly all C5, C6 patients,
2. C3, C4 patients with disabling pain or severe edema out of proportion to LE venous findings,
3. Abnormal common femoral vein flow such as aphasic or asymmetrical flow if the patient has disabling pain or severe edema,
4.Continuous flow in the CFV,
5.All patients with post-thrombotic syndrome,
6.Pelvic pain, dyspareunia, labial or perineal varicosities,
7.LE varicosities arising from the internal pudendal or obturator region or the lower buttock.
We work our patients up with abdominal/pelvic venous CDU as described in my earlier entry in this blog. For those who do not have good abdominal/pelvic venous CDU, I urge you to work on this so you can evaluate these patients hemodynamically. I believe that office-based IVUS with transabdominal US guidance needs to be evaluated as a quick and accurate diagnostic tool, but it will not evaluate hemodynamics as will transabdominal venous CDU.
We have been very casutious and selective in who we treat, but we have placed iliac vein stents in 140 patients over the past ten years. We have seen four thromboses of stents placed for post-phlebitic obstructions and we rarely observe a restenosis requiring treatment. We have seen no stent fractures. I believe iliac vein stenting for obstructive/compressive lesions is an excellent and durable procedure with proper patient selection and when performed well.
Submitted by Stephen F. Daugherty - 7/31/2012
|Re: ultrasound training for pelvic veins there are not too many places that offer such exposure. You can always consider visiting Nicos Labropoulos at our institution for a few days. Feel free to contact us if you wish to go that route (firstname.lastname@example.org)|
Re: when to intervene Patients with C3 disease who have disabling symptoms despite stockings and a significant lesion we offer them treatment with stenting. We also look for obstruction and offer treatment in patients with C4-6 routinely. Obviously discussion with the patient on the risks and benefits also plays a significant role in decision making.
Submitted by Antonios Gasparis, MD, FACS - 7/31/2012
|Over the last six months I have seen six people with unilateral leg swelling. One had right leg involvement only. Only one had any abnormality I could identify and that was an obstructive flow pattern at the left groin. I would me more than willing to learn the ultrasound techniques needed to make the diagnosis of MT, but where can I get that training?
One other consideration-after more than thiry years doing vascular surgery, I have been impressed that while acute vein problems can be addressed, chronic problems do not lend themselves well to intervention. Long term results of venous stents remains in some doubt. When are symptoms bad enough to warrant intervention, and when should we stay conservative in the care of MT?
Submitted by michael raborn - 7/26/2012
We also use duplex imaging routinely to identify underlying iliac vein compression.
If you do not have a trained vascular lab to image the iliac veins - CTV is very good
to look for compression.
In patients who there is high clinical suspicion (C4-6, previous DVT)
even if the non-invasive imaging is not positive, we will proceed with diagnositc venogram
Submitted by Antonios Gasparis, MD, FACS - 7/26/2012
|I believe digital venographaphy with portable fluoro ( of fixed) utilizing subtraction imagery is perfect for this (for those of us less skilled in pelvis sonography) and it is a great find in our specialty as probably MTS represents an under diagnosed condition with straight forward treatment and results using endovascular stenting
Submitted by richard gitter MD/ Gitter Vein Institute - 7/26/2012
|Thank you very much for your response. I think there are few people in the US that have the expertise that you do in performing these pelvic USs. I have referred patients to you for this very reason. |
We have to decide on what is a good test to screen for these patients, if we do not have access to good pelvic sonography. Our choices are CTV, MRV, or Venogram.
I would like to hear more discussion on this topic, since this is a question I ask myself when evaluating patients for possible compressive lesions of the iliac vein.
Submitted by Ronald Bush, MD, FACS - 7/25/2012
|We find that properly performed abdominal/pelvic venous color duplex US is far better than CT venograpms at identifying iliac vein lesions and it is very helpful in evaluating the hemodynamic significance of a lesion. We look for a velocity ratio greater than 2.5 across the lesion and retrograde flow in the internal iliac or other collateral veins. Sometimes we see a stenosis by CDU and it takes treadmill exercise to cause retrograde flow in the internal iliac vein. We use a CTV for supplemental anatomic information before making a definitive decision to proceed with venogram/IVUS/venoplasty and stenting.
Stephen F. Daugherty, MD, FACS, RVT, RPhS
Medical Director, VeinCare Centers of Tennessee
Tennessee Vascular Center
Clarksville Surgical Associates, PLC
647 Dunlop Lane, Suite 100
Clarksville, Tennessee 37040
Submitted by Stephen F. Daugherty, MD - 7/25/2012
|So a venous CT would be a a reliable way to R/O any iliac vein stenosis? Only do invasive pressure measurements (IVUS?) if CT is positive?
Submitted by Michael Raborn - 7/25/2012
|Venous CT may show stenosis, but you do not know if it hemodynamically significant, only pressure measurements can.
Submitted by Ron Bush, MD, FACS - 7/24/2012
what do you do when you suspect May
Thurner, but when symptoms warrant IVUS/venography and is a venous CT enough to
RO significant MT?
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