The Scope E-Newsletter March 2010 Cassada Introduces Non-Invasive Technique to Diagnose Venous Obstruction

David Cassada, MD Leg swelling can be a common cause for vascular surgical evaluation, and iliocaval obstruction due to May-Thurner Syndrome (MTS) can be difficult to diagnose.

David Cassada, MD, Associate Professor, Surgery's Division of Vascular/Transplant Surgery, in collaboration with Mitchell Goldman, MD, Chairman, and faculty and staff in the Department of Surgery and the Vascular Research Laboratory, developed a novel, non-invasive technique for the diagnosis of MTS, a compression of the left iliac vein by the right iliac artery. Using a simple blood pressure cuff and a duplex scanner, the velocity of outflow from the leg upon blood pressure cuff release was measured and compared to normal controls in the contralateral side. A decrease in outflow velocity correlated well with the diagnosis of MTS.

Traditionally, the condition has been indicated by exercise induced swelling, pain and fluid retention, most often in young females, and has been diagnosed using invasive procedures including CT and MRI scans, followed by a venogram to duplicate the results. The radiographic scans provided positive results less than 50 percent of the time, causing MTS to be under-diagnosed.

Once MTS is diagnosed, a stent is placed in the blockage. Dr. Cassada and his team have also found that measuring maximum venous outflow velocity through the tourniquet approach post-treatment is effective in determining its success.

This technique, previously described in an article by Michael Lebow, MD, Vascular Surgery Fellow Alumnus, has received significant professional acknowledgement. Dr. Cassada recently presented his abstract for this method, co-authored by Surgery Resident Matt Jones, to the Southern Association for Vascular Surgery, and his abstract for a similar technique to be used on the arm for the planning and treatment of conditions such as central venous stenosis and thoracic outlet syndrome has been accepted for poster competition at the Society for Vascular Surgery 2010 Vascular Annual Meeting in June.

"We have proven this technique works for the leg," said Dr. Cassada. "We are still in the process of proving it works for the arm. However, using this approach on the arm will affect more people worldwide because of dialysis. Veins are destroyed over time, and this will help us plan for treatment. Measuring venous outflow velocity, if we think the central vein is obstructed, can stop us from going into the operating room and doing something that won't work."