Abdominal Aortic Aneurysm

In the past 30 years, the occurrence of abdominal aortic aneurysm (AAA) has increased threefold.3-5 AAA is caused by a weakened area in the main vessel that supplies blood from the heart to the rest of the body. When blood flows through the aorta, the pressure of the blood beats against the weakened wall, which then bulges, balloon-like, into an aneurysm. If the aneurysm grows large enough, there is a danger that it will burst. Most commonly, AAAs occur in the portion of the vessel below the renal artery origins. The aneurysm may extend into the vessels supplying the hips and pelvis.

Once an aneurysm reaches 5 cm in diameter, it is usually considered necessary to treat to prevent rupture. Below 5 cm, the risk of the aneurysm rupturing is lower than the risk of conventional surgery in patients with normal surgical risks. The goal of therapy for aneurysms is to prevent them from rupturing. Once an abdominal aortic aneurysm has ruptured, the chances of survival are low, with 80 to 90 percent of all ruptured aneurysms resulting in death. These deaths can be avoided if an aneurysm is detected and treated before it ruptures.

Through its national screening program, Legs For Life®, the Society of Interventional Radiology (SIR) Foundation has offered free screening for early detection and monitoring of AAA. Of those screened, 25 percent have been found to be at risk for AAA.

Prevalence
  • Approximately one in every 250 people over the age of 50 will die of a ruptured AAA
  • AAA affects as many as eight percent of people over the age of 605
  • Males are four times more likely to have AAA than females9
  • AAA is the 17th leading cause of death in the United States, accounting for more than 15,000 deaths each year.10
  • Those at highest risk are males over the age of 60 who have ever smoked and/or who have a history of atherosclerosis, commonly known as “hardening of the arteries”)
  • Those with a family history of AAA are at a higher risk (particularly if the relative with AAA was female)
  • Smokers die four times more often from ruptured aneurysms than nonsmokers
  • 50 percent of patients with AAA who do not undergo treatment die of a rupture5
Symptoms

AAA is often called a “silent killer” because there are usually no obvious symptoms of the disease. Three out of four aneurysms show no symptoms at the time they are diagnosed. When symptoms are present, they may include:

  • Abdominal pain (that may be constant or come and go)
  • Pain in the lower back that may radiate to the buttocks, groin or legs
  • The feeling of a “heartbeat” or pulse in the abdomen

Once the aneurysm bursts, symptoms include:

  • Severe back or abdominal pain that begins suddenly
  • Paleness
  • Dry mouth and skin and excessive thirst
  • Nausea and vomiting
  • Signs of shock, such as shaking, dizziness, fainting, sweating, rapid heartbeat and sudden weakness
Diagnosis

In some, but not all cases, AAA can be diagnosed by a physical examination in which the doctor feels the aneurysm as a soft mass in the abdomen (about the level of the belly button) that pulses with each heartbeat.

The most common test to diagnose AAA is ultrasound, a painless examination in which a device (a transducer) about the size of a computer mouse is passed over the abdomen. Sound waves are computerized to create “pictures” of the aorta and detect the presence of AAA. Other methods for determining the aneurysm’s size are CT scan (computerized tomography), MRI (magnetic resonance imaging), and arteriogram (real time X-rays).

Treatment

Currently, there are three treatment options for AAA:

Watchful waiting – Small AAAs (less than 5 centimeters or about 2 inches), which are not rapidly growing or causing symptoms, have a low incidence of rupture and often require no treatment other than “watchful waiting” under the guidance of a vascular disease specialist. This typically includes follow-up ultrasound exams at regular intervals to determine whether the aneurysm has grown.

Surgical Repair – The most common treatment for a large, unruptured aneurysm is open surgical repair by a vascular surgeon. This procedure involves an incision from just below the breastbone to the top of the pubic bone. The surgeon then clamps off the aorta, cuts open the aneurysm and sews in a graft to act as a bridge for the blood flow. The blood flow then goes through the plastic graft and no longer allows the direct pulsation pressure of the blood to further expand the weak aortic wall.

Interventional Repair – This minimally invasive technique is performed by an interventional radiologist using imaging to guide the catheter and graft inside the patient’s artery, rather than making a large incision. For the procedure, an incision is made in the skin at the groin through which a catheter is passed into the femoral artery and directed to the aortic aneurysm. Through the catheter, the physician passes a stent graft that is compressed into a small diameter within the catheter. The stent graft is advanced to the aneurysm, then opened, creating new walls in the blood vessel through which blood flows.

This is a less invasive method of placing a graft within the aneurysm to redirect blood flow and stop direct pressure from being exerted on the weak aortic wall. This relatively new method eliminates the need for a large abdominal incision. It also eliminates the need to clamp the aorta during the procedure. Clamping the aorta creates significant stress on the heart, and people with severe heart disease may not be able to tolerate this major surgery. Stent grafts are most commonly considered for patients at increased surgical risk due to age or other medical conditions.

The stent graft procedure is not for everyone, though. It is still a new technology and data are not yet available to show that this will be a durable repair for many years. Thus, people with a life expectancy of 20 or more years may be counseled against this therapy. This technology is also limited by size. The stent grafts are made in certain sizes, and the patient’s anatomy must fit the graft, since grafts are not custom-built for each patient’s anatomy.

Recovery Time
  • Patients are often discharged the day after interventional repair
  • Once discharged, most return to normal activity within two weeks, compared to six to eight weeks after surgical repair
Efficacy

Interventional repair is an effective treatment that can be performed safely, resulting in lower morbidity and lower mortality rates than those of reported for open surgical repair.1,6-8

Benefits of Interventional Repair
  • No abdominal surgical incision
  • No sutures, or sutures only at the groins
  • Faster recovery, shorter time in the hospital6-8
  • No general anesthesia in some cases
  • Less pain6-8
  • Reduced complications6-8
Disadvantages of Interventional Repair
  • Possible movement of the graft after treatment, with blood flow into the aneurysm and resumption of risk of growth/rupture of the aneurysm
  • Probable lifetime requirement for follow-up studies to be sure the stent graft is continuing to function

Public Lacks Awareness of Vascular Damage from Smoking

In the United States, nearly one in five deaths, or an estimated 440,000 deaths per year, are related to tobacco use.1 Approximately half of all Americans who continue to smoke will die due to smoking-related complications.1 Second-hand smoke alone causes 150,000 to 300,000 lower respiratory tract infections, such as bronchitis and pneumonia, in young children each year.1 Of these, between 7,500 and 15,000 result in hospitalization.1 Plus, a pregnant woman can harm or kill her unborn child by smoking.

Of the more than 4,000 chemicals that are emitted by a lit cigarette, 43 are known to cause cancer. Tar that can cause cancer in the tissues it reaches, highly addictive nicotine which affects the nervous system and carbon monoxide that reduces the ability of blood to carry oxygen throughout the body are the most dangerous chemicals. When the chemicals come into direct contact with tissues or organs, such as the mouth, throat, or lung, the rate for cancer is from twice to 14 times as high as that for non-smokers. Although most people are well aware of the risk of cancer from smoking, few people realize the damage smoking causes throughout the body’s vascular system.

Smoking and Vascular Disease

Smoking damages the blood vessels and smokers are at risk for all vascular diseases including peripheral arterial disease, stroke, heart attack, abdominal aortic aneurysm and subsequent death.

In a healthy blood vessel, the inner lining of the arteries, known as the endothelium, constricts and dilates with blood flow. Smoking damages the endothelium, making arteries prone to spasms and deposits of diffuse plaque that diminish their ability to dilate properly.  This condition is known as atherosclerosis, often called “hardening of the arteries.” Atherosclerosis is a gradual process in which cholesterol and scar tissue build up, forming a substance called plaque that clogs the blood vessels and makes them less elastic.

Smokers are at increased risk for peripheral arterial disease, clogged arteries in the legs, that cause insufficient blood flow to get to the leg muscles. This causes pain, especially when walking and, left untreated, this insufficient blood flow can lead to limb amputation. While this may require angioplasty and stenting to improve blood flow, many people can avoid these procedures and alleviate their symptoms just by quitting smoking and beginning a specific exercise regimen. Smoking makes that big a difference in vascular disease.

Treatments

Interventional radiologists provide treatment for many smoking-related diseases. Since they are first trained in diagnostic radiology, they use imaging to understand, visualize, and diagnose the full scope of the disease’s pathology and to map out the procedure tailored to the individual patient. Then during the procedure, they image as they go, literally watching and guiding their catheter through the vascular system or through the skin to the site of the problem. Following are some of the conditions that can be treated by interventional radiologists:

Aortic Abdominal Aneurysm – A weak area in the aorta, the main blood vessel that carries blood from the heart to the rest of the body. As blood flows through the aorta, the weak area bulges like a balloon and can burst resulting in death if it gets too big. An interventional radiologist can perform a stent graft to reinforce the weak artery wall and avoid major abdominal surgery.

Peripheral Arterial Disease – Hardening of the arteries (atherosclerosis) in the legs that can cause intermittent claudication—pain that occurs when a person walks and subsides when s/he stops. Atherosclerosis causes the arteries that carry blood to the arms or legs to become narrowed or clogged. Interventional radiologists can treat this by performing a balloon angioplasty to open a blocked artery and placing a stent to hold the artery open, if needed. However, many people are treated just with smoking cessation and a medically supervised exercise program.

Carotid Artery Disease and Stroke – In some patients, atherosclerosis in the carotid artery in the neck can lead to ischemic stroke. Plaque build-up in the carotid artery may result in a stroke by either decreasing blood flow to the brain or by breaking loose and floating into a smaller vessel, depriving a portion of the brain of blood flow. In patients at high risk of having a stroke, the narrowed section of artery may be reopened by an interventional radiologist through angioplasty and reinforced with a stent, thereby preventing the stroke from occurring.

Stroke – Most commonly caused by a blood clot in the brain that starves the brain from receiving oxygen, which can cause the affected sections of the brain to die. If caught in time, within six hours of the symptoms, an interventional radiologist can deliver a clot-busting drug directly into the brain to the site of the clot to dissolve it and restore blood flow to the brain. This treatment can often prevent the disabling effects of a stroke.

Lung Cancer – Cigarette smoking is the most common cause of lung cancer.2 Interventional radiologists can treat lung cancer patients nonsurgically by “freezing” tumors with cryotherapy or “cooking” them with radiofrequency heat.

Kidney Cancer – 32,000 Americans are diagnosed with kidney cancer each year.2 Although surgical removal of the kidney offers the best chance for a cure, some patients are not surgical candidates. Interventional radiologists offer nonsurgical treatment using radiofrequency heat that “cooks” and kills the tumor.

Osteoporosis – Because smokers have lower levels of estrogen, smoking is bad for their bones and is a risk factor for osteoporosis, which can result in spinal fractures.3 By injecting bone cement through a needle into fractured vertebrae, interventional radiologists can shore up the vertebra and relieve pain. This procedure, known as vertebroplasty, is a pain treatment for people with spinal fractures that have not responded to medical management.

Benefits of IR Treatments
  • Often no general anesthesia is required
  • Procedures are often outpatient
  • Less risk
  • Less pain
  • Less risk for infection
  • Shorter hospital stay