A May-Thurner Syndrome Review by Al-Nouri and Milner

May-Thurner syndrome is a challenging condition for medical practitioners. It can have debilitating sequelae resulting from post-thrombotic syndrome. Al-Nouri and Milner presented an expert review of May-Thurner syndrome in volume 8, issue 3 of Vascular Disease Management. They describe the evolution of endovascular management of the syndrome.  Below, we excerpt the article.

May-Thurner syndrome — also called iliocaval compression syndrome, Cockett syndrome or iliac vein compression syndrome — occurs secondary to compression of the left iliac vein by the overriding right iliac artery. Virchow was the first author to be credited with describing iliac vein compression. It was not until 1957 that May and Thurner brought much attention to the anatomic variant thought responsible for Virchow’s observation. They found that the right iliac artery compressed the left iliac vein against the fifth lumbar vertebra in 22–32% of 430 cadavers.1 These terms may be used interchangeably, but they all describe the phenomenon of left-sided vein compression by the right iliac artery causing left iliofemoral deep venous thrombosis (DVT).

Etiology and Incidence

The incidence of May-Thurner syndrome is unknown and ranges from 18–49% among patients with left-sided lower extremity DVT.2 Close to 600,000 hospitalizations occur in the United States each year due to DVT. DVT is more common in the left lower extremity than the right, and May-Thurner syndrome is considered to be a risk factor for patients with left-sided iliofemoral DVT. May and Thurner postulated that the chronic pulsations of the overriding right iliac artery led to the development of a “spur” in the vein wall, and that this spur would result in partial venous obstruction (Figure 1). Chronic trauma to the inner side of the vein wall due to adjacent arterial pulsations leads to the accumulation of elastin and collagen, contributing to spur formation.3 In addition to the chronic arterial pulsations, mechanic compression of the iliac vein by the thick-walled overriding iliac artery leads to extensive local intimal proliferation, impaired venous return and venous thrombosis.4 In addition to the mechanical alterations to the vessel wall, hypercoaguable states, when tested, are found in the majority of patients. Kolbel et al5 found underlying hypercoaguable disorders in 67% of patients screened prior to treatment of chronic iliac vein occlusion. Left iliac vein compression is the most common variant seen in May-Thurner syndrome; however, several other variants have been described in the literature. Compression of the left common iliac vein by the left internal iliac artery,6compression of the right common iliac vein by the right internal iliac artery,7 compression of the inferior vena cava by the right common iliac artery8 and right-sided May-Thurner syndrome in a patient with a left-sided inferior vena cava9 have all been described.

In February, VDM published video of an interview with Christopher Kwolek, MD, about the Vortex suction catheter, in which he described a challenging case of a patient who developed thrombosis of the inferior vena cava and who also had May-Thurner syndrome. Dr. Kwolek’s treatment plan changed due to discovery of the symptoms of May-Thurner. The patient underwent surgical removal of clot in the groin, when without the May-Thurner symdrome symptoms, surgery may not have been necessary.

“We tried to go in with the standard catheter, but she had a critical stenosis at the origin of the left common iliac vein due to extrinsic compression from the artery — May-Thurner syndrome — so we ended up taking her to the operating room, and with a small incision we cleaned out the clot in the groin. Then using the Vortex suction thrombectomy catheter, we removed the clot all the way up to the inferior vena cava,” said Dr. Kwolek.

Read more about this case in “Large-Diameter Catheter for Pulmonary Embolism: An Interview with Christopher Kwolek, MD.”



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