Approximately 30 percent of patients with an aortic aneurysm are considered too high risk for surgery. Yet, due to the anatomical anomalies of the aneurysm, existing endograft devices are not suitable. Left with no treatment options, many of these patients will die. Physicians are turning to “extreme” endovascular aneurysm repair and thoracic endovascular aneurysm repair to create solutions for these otherwise out-of-luck patients.
Endovascular aneurysm repair (EVAR) and thoracic endovascular aneurysm repair (TEVAR) have saved thousands of lives since Juan C. Parodi, MD, first treated an abdominal aortic aneurysm (AAA) using a catheter-based approach in Buenos Aires more than 20 years ago. The very first devices for TEVAR were actually “manufactured” at institutions, such as Baptist Cardiac & Vascular Institute in Miami, and Stanford University in Stanford, Calif., on a customized basis for patients who faced life-threatening aneurysms and no traditional surgical solution.
Despite the ever-growing number of endograft devices and the evolution of designs that address variations in anatomy, gaps remain in the solutions available, particularly in the U.S., due to regulatory issues. This leaves a significant number of patients without alternatives: they are too high risk to undergo surgical AA repair, but their anatomies don’t fall within the purview of acceptable indications for FDA-approved devices. Manufacturers offer custom-made endografts, but these devices require six to eight weeks to make, far more time than many of these patients have.
Many interventionalists and surgeons now go off label to design solutions for “extreme” EVAR/TEVAR. Benefits of clinically driven innovation are two-fold: providing patients with potentially life-saving solutions and driving medical device development.
While manufacturers continue to develop new versions of these devices, in many cases, they are slow to provide solutions due to concerns about low procedural volumes and sales. Consequently, many physicians see “extreme” EVAR/TEVAR as a solution for this population. With the patient’s informed consent, these physicians alter existing endografts or create entirely new devices. The main area of concern is the proximal landing zone, which can be a challenge in people with difficult anatomy, such as short neck, no neck, angulation or problematic aneurysm location. This can lead to difficulties in sealing the graft without affecting blood flow of the branch vessels, particularly the renal arteries.
Among the endograft modifications currently employed are physician-created fenestrations and chimneys. Although manufacturers have designed fenestrated endografts, none are commercially available in the U.S.
An alternative technique is to place peripheral stents in the branch vessels. These stents are then deployed along with the endograft, and the resulting “chimneys” (typically one for each branch vessel) allow an adequate proximal landing zone while enabling blood flow of the branch vessels outside of the endograft. When anatomy requires a downward-facing stent, the approach is known as a periscope chimney. Myriad versions of the chimney technique can be employed as dictated by the anatomy.
Lack of long-term data on the success, durability and stability of physician-created or modified endografts is a concern, but research suggests they provide a reasonable alternative. A prospective study of inoperable patients with juxtarenal aneurysms suggests physician-modified fenestrated endografts were safe and effective.
Interventionalists and surgeons encourage the development and availability of commercially available endografts that address these anatomy issues. However, it is likely there will always be patients who fall through the cracks, whose anatomy precludes the use of existing devices. Innovative physicians should be credited with attempting to find solutions for patients otherwise left with no options.
Dr. Katzen is medical director at Baptist Cardiac & Vascular Institute and course director of the International Symposium on Endovascular Therapy (ISET). The ISET meeting is scheduled Jan. 16 to 20, in Miami.