Endovascular aortoiliac aneurysm repair: surgical progress through new treatment paradigms and innovative endograft design.

Effective treatment for patients with an abdominal aortic aneurysm (AAA) began more than 50 years ago through the development of prosthetic grafts, which were used to replace aneurysmal segments of diseased arteries. Open surgical repair of AAAs became the gold standard for treating this disease. In 1999, two device manufacturers received US Food and Drug Administration approval for their endovascular aneurysm repair (EVAR) devices to treat selected patients with AAA. During the next 10 years, multiple other EVAR devices received US Food and Drug Administration approval, and, now, EVAR rivals open surgical repair as the standard for treating aortoiliac aneurysm disease. The purpose of this article is to outline advances in the device technology used for EVAR procedures, identify historical progress of treatment options, recognize complications after EVAR, describe improvements in device design, and specify related nursing implications.

Limitations of current EVAR endografts and potential solutions for their deficiencies.

All current endovascular aneurysm repair (EVAR) devices have defined limitations that prevent the endovascular therapist from using them to treat all forms of aortoiliac aneurysm disease. Short, angulated infrarenal aortic neck pathology, occlusive disease in iliac access arteries, need for preservation of important branch vessel arterial flow, endograft migration, and endoleak all represent major impediments for successful EVAR. Need for secondary intervention after EVAR in a significant number of patients has detracted from universal acceptance for this therapy. New devices in manufacturers' pipelines may provide solutions for many of the current EVAR device deficiencies. As these new devices become more complex, meticulous patient follow-up to verify anticipated outcomes and new training paradigms for the future endovascular therapist will be required.

Influence and critique of the PIVOTAL and the EVAR 2 Trials.

Management of a condition that has potentially life-threatening consequences may not lend itself effectively to the scrutiny of a randomized clinical trial when an observation or no treatment option is offered as part of the trial. This type of trial often experiences a significant rate of crossover of subjects from no treatment to treatment, and when results are analyzed on an intent-to-treat basis, they may fail to resolve the issue under study. These trials are frequently used as Level 1 medical evidence and the potential impact on clinical decision-making and reimbursement can be quite significant and long-lasting. The authors observed this phenomenon during participation in the Positive Impact of Endovascular Options for Treating Aneurysms Early (PIVOTAL) trial and have observed it in an analysis of the Endovascular Aneurysm Repair 2 (EVAR 2) trial. Possible solutions to mitigate the high crossover effect are offered for consideration. Some clinical conditions dealing with potentially life-threatening problems probably do not lend themselves to be studied in randomized prospective clinical trials containing an observation or no treatment arm.

Inherent problems with randomized clinical trials with observational/no treatment arms.

Randomized clinical trials (RCTs) offering an observation/no treatment (OBS/NoRx) arm as control and which are focused on the management of a condition with potentially life-threatening consequences, however small the risk, often experience a significant rate of crossover to treatment by those randomized to the OBS/NoRx arm. Results of these trials when analyzed on intent-to-treat basis often fail to resolve the issue at which they were directed. The authors have observed this in trials of abdominal aortic aneurysms with this design and use these to exemplify the dilemmas RCTs of such design create, with crossovers ranging from 27% to over 60% (EVAR II, UKSAT, ADAM, PIVOTAL). Results of these trials are frequently used as level I medical evidence and their potential impact on clinical decision making and reimbursement can be quite significant and long-lasting. Recommendations regarding trial end points and suggestions to mitigate the high crossover effect are offered. It may be that some clinical conditions dealing with potentially life-threatening problems should not be studied in randomized prospective clinical trials containing an OBS/NoRx arm.

Technical tips for endovascular repair of common iliac artery aneurysms.

Isolated common iliac artery aneurysms are rare, comprising <2% of all aneurysm disease. These aneurysms present as either isolated disease, .03% of the population, or, in conjunction with abdominal aortic aneurysm, in approximately 20% to 25% of such cases. Common iliac artery aneurysms are defined as any localized dilatation of the common iliac artery >1.5 cm in diameter. Elective repair for isolated common iliac artery aneurysms is generally not undertaken for aneurysms <3 cm in diameter unless they are part of an abdominal aortic aneurysm repair. Most common iliac artery aneurysms are found incidentally during abdominal/pelvic diagnostic imaging studies or at the time of pelvic or abdominal surgery. As with abdominal aortic aneurysms, endovascular repair of common iliac artery aneurysms follows techniques similar to those used for endovascular repair of abdominal aortic aneurysm. Management includes aneurysm exclusion with an endograft, which seals at sites within the proximal and distal common iliac artery and may involve coil occlusion of the hypogastric artery with extension of the reconstruction into the proximal external iliac artery, or use a "bell-bottom" endograft limb placed at the common iliac bifurcation. Technical tips for successful outcome are described here, and all US Food and Drug Administration approved endografts have been used for repair. There were no statistically significant differences in outcomes that correlated with device or repair techniques used for management of common iliac artery aneurysms. Mid-term 54-month outcome has been excellent, with no common iliac artery ruptures or aneurysm-related deaths and the need for secondary interventions was gratifyingly small.