Complications in Acute Type B Aortic Dissections Compared

Newswise — Type B aortic dissection is produced by an acute tear in the aortic wall and usually originates at or just beyond the take-off of the left subclavian artery. When this occurs, blood flow propagates this tear between the layers of the aortic wall, resulting in the formation of a false passage (lumen) for blood flow. The majority of patients (70 to 80 percent) present with uncomplicated Type B dissections and are successfully managed medically. In a much more ominous situation, complicated Type B dissections, the process may divert blood from and compress the true lumen, compromising blood flow to the kidneys, intestines, and/or lower extremities, resulting in malperfusion of these organs. Conversely, the thin wall of the false lumen may rupture, a potentially catastrophic and often fatal event for a patient.

The incidence of aortic dissection increases with age and the highest number of cases occur between the ages of 50 and 70 years; it is twice as common in men. Poorly controlled high blood pressure is almost universally present in patients with Type B dissection. Smoking can systematically weaken layers of the aortic wall. Patients typically have an abrupt onset of severe chest or back pain. This presentation requires an expeditious workup, usually involving a CT scan, and prompt initiation of treatment.

Traditionally, complicated Type B aortic dissections have been treated with an invasive open surgical procedure associated with significant morbidity and mortality. However, during the last 15 years endovascular technology, designed to treat vascular disease in a minimally invasive manner using wires, catheters, and stents has evolved and is being used more often. During thoracic endovascular aortic repair (TEVAR) a vascular graft is placed into the diseased aorta, effectively re-lining the aorta. The procedure is performed through a small groin incision under radiographic imaging. This technology has been applied to patients with complicated Type B dissection with improved morbidity and mortality.

A study from the Hospital of the University of Pennsylvania in Philadelphia that compares the technical aspects and outcomes of 47 patients who had Type B aortic dissection with complications from malperfusion and ruptures, was presented today at the 63rd Annual Meeting of the Society for Vascular Surgery®. From 2004 to 2008 patients were followed for a mean of 27 (1-67) months. Indications for treatment were malperfusion, 62 percent; rupture, 51 percent; and 13 percent of patients presented with both conditions.

"At our institution we enjoy a collaborative effort between vascular and cardiac surgery in the treatment of type B aortic dissections. Our group has previously published and presented our results on treatment of patients with Type B dissections using TEVAR. In the last year and a half our group has treated 35 percent more patients for a total of 47 patients. This also allowed for a significantly longer follow-up. Most importantly, the greater number of patients allowed us to closely study and compare the two complications of Type B dissection, malperfusion, and rupture," said Elena Rakhlin, a vascular and endovascular surgery fellow at the hospital.

Researchers noted that TEVAR continued to demonstrate excellent results as well as durability in short- and intermediate-term follow-up for both disease processes. However, each process clearly required unique treatment strategies. TEVAR alone was sufficient to successfully treat a ruptured dissection and stop the bleeding On the other hand, additional stenting was required in nearly half of the patients to rectify end-organ malperfusion, particularly in patients with lower extremity malperfusion. With this approach, no patient suffered limb loss or bowel resection, and renal function recovered in 94 percent of patients with malperfusion. The incidence of stroke and permanent paralysis was low in both groups. Patients with malperfusion required more intensive post-operative care and had longer hospital stays.

"Both groups demonstrated excellent technical and clinical results with 94 percent dissection-related survival at one-year and minimal patient morbidity. In short, TEVAR continued to demonstrate superior results as compared to historic open surgical treatment options," explained Rakhlin.

"Although both conditions can be successfully managed with thoracic endovascular repair (TEVAR), endovascular strategy must be customized to each presentation to achieve these results," said Dr. Rakhlin. "While TEVAR alone is sufficient to address aortic disruption in patients with rupture, adjunctive procedures are often necessary in malperfusion cases."

About the Society for Vascular Surgery®The Society for Vascular Surgery (SVS) is a not-for-profit society that seeks to advance excellence and innovation in vascular health through education, advocacy, research and public awareness. SVS is the national advocate for 2,800 vascular surgeons dedicated to the prevention and cure of vascular disease. Visit the web site at www.VascularWeb.org or you can follow SVS on Twitter by searching for VascularHealth or at http://twitter.com/VascularHealth.