Endovascular repair of abdominal aortic aneurysms - Home Study Program

AORN Journal, March, 2003 by Susan W. Hall

ENDOVASCULAR REPAIR OF ABDOMINAL AORTIC ANEURYSMS

The article "Endovascular repair of abdominal aortic aneurysms," is the basis for this AORN Journal independent study. The behavioral objectives and examination for this program were prepared by Rebecca Holm, RN, MSN, CNOR, clinical editor, with consultation from Susan Bakewell, RN, MS, education program professional, Center for Perioperative Education.

A minimum score of 70% on the multiple-choice examination is necessary to earn 3.2 contact hours for this independent study. Participants receive feedback on incorrect answers. Each applicant who successfully completes this study will receive a certificate of completion. The deadline for submitting this study is March 31, 2006.

Send the completed application form, multiple-choice examination, learner evaluation, and appropriate fee to

AORN Customer Service c/o Home Study Program 2170 S Parker Rd, Suite 300 Denver, CO 80231-5711

or fax the information with a credit card number to (303) 750-3212.

BEHAVIORAL OBJECTIVES

After reading and studying the article on endovascular repair of abdominal aortic aneurysms (AAA), the nurse will be able to

(1) discuss the anatomy of the normal abdominal vascular system in regard to the development of an AAA,

(2) describe the diagnostic tests used to diagnose an AAA,

(3) explain how the anatomic measurements of an AAA allow care providers to identify candidates for the endovascular approach to AAA repair,

(4) describe the preoperative preparation of a patient scheduled for endovascular AAA repair,

(5) identify the circulating nurse's role in endovascular AAA repair,

(6) explain the steps of an endovascular AAA repair procedure, and

(7) describe the postoperative phase of the patient undergoing endovascular AAA repair.

This program meets criteria for CNOR and CRNFA recertification, as well as other continuing education requirements.

An abdominal aortic aneurysm (AAA) is dilatation of an artery with an increase in the diameter of the vessel wall when compared to normal vessel size (Figure 1). An AAA is located between the renal arteries and the iliac arteries. Arteries are composed of three layers

[FIGURE 1 OMITTED]

* tunica intima (ie, inner layer),

* tunica media (ie, middle layer), and

* tunica adventitia (ie, outer layer).

Aneurysmal development is caused by weakness in the muscular tunica media and stretching of the tunica intima and adventitial layers. Additionally, progressive enlargement of the vessel is caused by blood pressure within the aneurysm. (1) The standard treatment for AAA has been open surgical repair of the aneurysm. A relatively new procedure called endovascular stent graft repair has been evolving during the last decade and is being used for treatment of AAA with increasing frequency. Endovascular repair of AAA involves deploying a graft into the vessel to seal the aneurysm via a transfemoral approach to the aorta. This approach is less invasive than open procedures, resulting in decreased hospital length of stay, reduced cost, and increased quality of life. An additional benefit of this procedure is the inclusion of patients who have comorbid conditions and otherwise would not be candidates for traditional open repair of their aneurysm.

The primary factors that determine a successful outcome for a patient undergoing endovascular repair of an AAA are

* patient selection focused on anatomy,

* medical comorbid conditions,

* clinician skill,

* hospital experience, and

* access to various endovascular devices. (2)

It is important for perioperative nurses and other perioperative personnel to understand the procedure and be prepared for possible complications that can arise to ensure that optimal care is delivered to the patient. The purpose of this article is to provide an overview of AAAs and to familiarize perioperative nurses with the procedure, possible complications, and language specific to endovascular repair of AAAs.

EPIDEMIOLOGY

As the population ages, AAAs are an increasing health care concern in the United States today because the incidence and prevalence increases with age. (3) The incidence of AAAs has risen from 12.2 to 36.2 per 100,000 procedures in the last five decades. (4) The prevalence of AAAs in adults 65 to 80 years of age is 4% to 7%, and the ratio of men to women affected with an AAA is 5:1. (5) Rupture of an AAA is the 10th leading cause of death in men 55 years of age and older. That accounts for 15,000 deaths per year in the United States. (6)

Aneurysmal diameter size indicates the risk of rupture. Rupture risk is measured as a five-year risk factor. An aneurysm that measures less than 5 cm in diameter has a rupture risk of 1% to 2%. The risk increases to 20% to 49% for aneurysmal sizes greater than 5 cm in diameter. (7) Of the patients who survive the immediate event, the mortality rate after rupture of an AAA is between 78% and 94%. (8) People who undergo elective repair only have a 5% mortality rate. (9)

ETIOLOGY

The etiology of AAA formation is not understood completely. Theories suggest that atherosclerosis and destruction of elastin and collagen fibers in the vessel walls contribute to development. Atherosclerosis is defined as changes to the intimal wall of the artery as a result of lipid deposition and smooth muscle migration and proliferation. (10) It has been postulated that familial genetics or some unknown environmental exposure may have an effect on the decrease of elastin fibers in the vessel walls with resultant collagen weakening that leads to aneurysm growth. (11) Research has identified an association between defects in structural collagen genes and the development of an AAA, but it has not been proven yet. (12)