CHICAGO – Mesenteric stenting has replaced open surgery as first-line treatment for chronic mesenteric ischemia, but it is still a therapy in flux.
Controversy exists over single- versus multivessel revascularization when both the celiac artery (CA) and superior mesenteric artery (SMA) are diseased and symptoms are consistent with chronic mesenteric ischemia (CMI), Dr. Jean Panneton said at a symposium on vascular surgery sponsored by Northwestern University.
Some vascular specialists argue that complete revascularization provides better protection when one vessel occludes, while those favoring single-vessel revascularization contend that bypassing only the most problematic vessel avoids a longer, more complex operation in these typically fragile patients.
The data on single- versus multivessel mesenteric bypass is mixed, he said. Some studies have found that two-vessel bypass results in less symptom recurrence, improved patency, and fewer reinterventions than single-vessel bypass. Other studies, however, have found no difference in 1-year patency or freedom from symptom recurrence between the two treatments.
Regardless of the number of vessels treated, no consensus exists as to which artery responds best to stenting, Dr. Panneton, from Eastern Virginia Medical School in Norfolk, said. In their own review of 121 consecutive patients over a 7-year period, there was a major discrepancy between SMA and CA stenting in 1-year primary patency (55% vs. 18%) and 6-month clinical patency (86% vs. 67%).
“In our experience, celiac stenting had much worse ISR [in-stent restenosis] and clinical patency rates than SMA stenting, which questions its utility,” he said.
In the celiac group, stents with a diameter < 6 mm were significantly more likely than larger-caliber stents to lose primary patency, defined as peak systolic velocity < 350 cm/sec.
Interestingly, a subset analysis of patients undergoing two-vessel stenting of the CA and SMA revealed no significant differences in ISR rates or survival free from symptom recurrence, compared with single SMA stenting (J. Vasc. Surg. 2013;57:1062-6).
Surveillance after mesenteric stenting is another area in flux. Duplex ultrasound (DUS) has been validated as an accurate modality for determining native mesenteric artery stenosis, but no firm DUS criteria exist for diagnosing ISR, Dr. Panneton said. Several studies have reported that DUS velocity criteria for native mesenteric stenosis overestimates the percentage of stenosis of stented arteries.
A receiver operator curve (ROC) analysis by Dr. Panneton and his colleagues demonstrated that an SMA peak systolic velocity (PSV) of 445 cm/sec had the highest sensitivity (96%), but only 43% specificity for predicting ISR.
Further prospective validation is needed, although a similar ROC analysis reported 100% sensitivity and 95% sensitivity using a PSV of 412 cm/sec to identify SMA > 70% ISR (J. Vasc. Surg. 2012;55:730-8), he noted.
Intravascular ultrasound (IVUS) is useful as an adjunct to DUS and angiography for the detection of ISR of mesenteric arteries, but isn’t practical for routine surveillance. There is also a dearth of data on outcomes when IVUS is used with other imaging modalities, Dr. Panneton added.
What is clear is that a paradigm shift has occurred in the treatment of CMI, reflected in a threefold increase in the number of mesenteric revascularizations performed in the U.S. during the last 10 years. Still, 5-year survival rates are nearly identical between open surgery and mesenteric stenting, despite primary, secondary, and clinical patency rates seeming to favor open mesenteric bypass.
“Future technology will address the higher ISR and reintervention rates associated with mesenteric stenting and likely improve outcomes,” Dr. Panneton said.
Mesenteric stenting can still be useful, even after bypass, he said, highlighting a 78-year-old woman with a history of aortobifemoral bypass who required endovascular rescue of an SMA graft thrombosis after presenting with acute mesenteric ischemia.
“We were able with a guidewire, to get through the reversed C-loop graft that came from the iliac to the SMA and get into the distal SMA vessel,” he said. “We also used pharmacomechanical thrombectomy to really declot the graft and place a stent at the proximal anastomosis of the iliac-SMA Dacron graft.”
The team has also done mesenteric stenting using a retrograde open mesenteric stenting technique.
“It’s quite useful in acute mesenteric ischemia, but we’ve also used it more recently even in chronic mesenteric ischemia for patients who did not tolerate aortic cross-clamping or did not have any good aorta,” he said. “An example of that would be a porcelain aorta where we don’t want to clamp anything.”
Dr. Panneton is a consultant and serves on the speaker’s bureau for Medtronic.