AAAs: It's All in the Family

The aorta is the main artery, or blood vessel, that extends from the heart to the lower abdomen and carries blood to the internal organs and all lower parts of the body. The lining of the aorta has three layers that form the walls of a hollow tube. Sometimes, these walls become weak and bulge. When that happens, the bulging part of the artery is called an aneurysm. While an aneurysm can occur anywhere along an artery, this article focuses on those that occur in the lower abdomen, below the kidneys.

Ruptured abdominal aortic aneurysms (AAA) account for more than 15,000 deaths a year and are the 13th leading cause of death in the United States. This condition occurs in one to two percent of the general population. Due to increased awareness about the disease, the number of abdominal aortic aneurysms diagnosed in this country has increased by three-fold.

Most people with aneurysms do not have any symptoms or complaints. Aneurysms can continue to grow and can become so weak that they can tear or rupture, allowing blood to leak out of the artery. If the bleeding is not immediately stopped, permanent damage or death results. A ruptured aneurysm is fatal in 75 to 90 percent of cases, so this is one of the most dangerous diseases in medicine. The incidence of AAA increases at about age 55 for men and at about age 70 for women. Early detection and timely repair can save lives and also achieve an annual saving in healthcare costs of more than $14,000 per patient per year.

Factors Which Identify Risk for AAA
The risk factors for AAAs include:

• smoking
• elevated blood pressure
• family history

Smoking is the leading cause of continued growth of aneurysms. As the aneurysm size exceeds five centimeters (cm) in diameter, the risk of rupture increases. AAAs larger than five cm have approximately a 10 percent risk of rupture per year. The risk increases as the aneurysm size increases. AAAs over seven cm have a 32 percent risk of rupture for one year. An aneurysm will increase in size on average about 0.4 centimeters per year. Stopping smoking, therefore, is very important.

Genes May Provide Information
Genetic risk factors contribute to the development of AAAs. Recent studies suggest a specific defect on one or more chromosomes. Close male relatives of individuals with aneurysms appear to be at greatest risk, but other relatives may also be at risk. Identification of the genes that predispose a person to develop an aortic aneurysm may someday help identify the disease at an early stage.

Diagnosis and Prevention
Early diagnosis and management of AAAs can prolong life. Hence, non-invasive screening to identify the size of the aneurysm is beneficial if focused on persons at highest risk. High-risk individuals include those between the ages of 50 years and 80 years, with a history of smoking, and those with hypertension and a personal history or family history of aneurysms.

If a close member of your family has been diagnosed with abdominal aortic aneurysmal disease, you should consider having a screening, especially if you are older than 50 years. An abdominal ultrasound is a safe and cost-effective first step for diagnosing aneurysms. This test is an outpatient procedure that takes only about 20 minutes. Other tests to determine if aneurysms are present include a CT scan or MRI.

Treatment
Small aneurysms should be monitored periodically depending on the size of the aneurysm. Although elective surgical repair by most surgeons is indicated when the AAA is 5.5 cms or larger, in a healthy patient an elective repair may be indicated when the AAA size exceeds 5.0 cms.

Traditional treatment has involved surgical repair by opening the bulging section and sewing a graft made of cloth-like synthetic material to the sections of the artery above and below the aneurysm, so that the blood can no longer put pressure on the bulge. More recently, an innovative approach using a minimally invasive procedure called endovascular repair has been developed. In this procedure, a small surgical cut or opening is made in the groin and a stent graft (a metal stent covered by fabric graft material) is guided to the aneurysm from inside the artery. Not all patients are candidates for the endovascular repair. The type of procedure best suited for each individual should be discussed with the vascular specialist.

About the Authors: Aravinda Nanjundappa, MD, is an interventional cardiologist and registered vascular technologist (RVT) with additional training in vascular medicine and peripheral interventions. He is the Assistant Professor of Medicine in the Division of Cardiology, East Carolina University, Greenville, NC.

C. Steven Powell, MD, is the Chief of Vascular Surgery and Professor of Surgery, East Carolina University, Greenville, NC