Cath Lab Digest

Abdominal aortic aneurysms (AAA) are an important form of cardiovascular disease. In the U.S. alone, more than 1 million individuals between the ages of 50 and 84 may harbor an AAA.¹ One hundred thousand new cases are diagnosed and 50,000+ patients undergo AAA repair each year (Figure 1). As many as 15,000 deaths per year can be attributed to this disease, mostly related to rupture,^1,2 which makes it the 13th leading cause of mortality overall. Men are affected far more frequently than females (5:1), but women are well documented to have worse outcomes after repair and higher rupture mortality.^3,4 Since the 1950s when surgical techniques for resection and graft replacement were developed, definitive treatment has been available. AAA repair became a relatively common operation as early as the 1960s, and evolved to be one of the signature procedures for vascular surgeons everywhere. Amid the good news nature of such developments, it emerged rapidly that the operation was maximally invasive and often caused major morbidity, even death. Worse yet, many patients were excluded from treatment when deemed medically unfit for such major surgery.

Emergence of EVAR

Dr. Juan Parodi, together with Drs. Julio Palmaz and Hector Barone, performed the first endovascular aneurysm repair (EVAR) procedure at the Instituto Cardiovascular de Buenos Aires (Argentina) on Sept 7, 1990.Although unknown at the time, they eventually learned that others had been developing similar less invasive solutions for AAA disease, most notably Volodos in the Ukraine,⁶ Lazarus in the U.S.,⁷ and a few others.⁸ The revolutionary new technique was destined to change everything and signaled the beginning of a whole new era in aortic surgery and vascular surgery overall.⁵

EVAR Devices, Then and Now

Evolving over the last 20 years, FDA approval of the first two stent-graft devices at the end of September 1999 (Medtronic’s AneuRx and Guidant’s Ancure) marked the end of the infancy phase of the emerging new technologies. Major improvements and new iterations were just around the corner. The next logical step was major design improvements and enhanced devices. In all, 7 FDA-approved EVAR endograft devices are currently available in the U.S. market (Figure 2). The latest unlimited approval was Medtronic’s Endurant in December 2010. It is thought of as an advanced-generation technology⁹ and has become quite dominant in many markets worldwide, the U.S. included. More recently yet, TriVascular’s Ovation AAA stent graft received limited Humanitarian Device Exemption (HDE) approval, predicated on its ultra-low profile 14 Fr delivery system that enables treatment of patients with very small and/or diseased access femoral and iliac arteries (Figure 3). It is a promising new technology and outcomes have been favorable so far, but a much larger clinical experience and long-term data will be required before rendering definitive judgment on the Ovation stent graft device.Just recently in April 2012, the FDA approved the premarket approval application for the Zenith Fenestrated AAA stent graft by Cook (Figure 4). This device features fenestrations and/or scallops to allow grafting into and revascularization of the renal and visceral arteries. Each proximal body component is customized for an individual patient. Commercial launch is expected in the summer of 2012.

Device Families

Stent grafts are frequently categorized as first generation, second generation, etc. It is a confusing nomenclature because generations have never officially been defined. It may prove more useful to describe devices according to their origin, or families. EVAR device families can therefore be defined by their manufacturers (Figure 5):

• Aptus: Endostaple, FDA-approved but not the graft;
• Bolton: Treovance, not approved;
• Cook: Zenith; Zenith Flex, FDA-approved; Zenith LP, not approved; and now Zenith Fenestrated, FDA-approved - customized;
• Cordis: Incraft, not approved;
• Endologix: Powerlink, FDA-approved; Nellix, not approved;
• Gore: Excluder; Excluder C3, FDA-approved;
• Lombard: Aorfix, not approved;
• Medtronic: AneuRx; Talent; Endurant, all FDA-approved;
• Trivascular: Ovation, HDE FDA approved;
• Vascutek: Anaconda, not approved.

Current and Future Developments

While the currently available devices perform quite well in general, there are still several unmet needs that have appropriately become the main drivers for ongoing research and new developments, including: