When doctors hear people talk about abdominal aortic aneurysms as “ticking time bombs,” they tend to grow a bit weary. In reality, they say, many patients diagnosed with a small, slow-growing AAA can be safely monitored for years. And if repair is needed, elective surgery is available.
The aorta is the large, central artery that carries blood from the heart to your body. The upper section within the chest is the thoracic aorta, and the lower section is the abdominal aorta. Because the aorta receives pressure with each heartbeat, parts of the aorta's wall can gradually weaken in people at risk.
Aortic dissection involves a tear in the aorta’s wall, causing the layers to separate. Aneurysm, a bulge or ballooning in the artery wall, is more common in the abdominal aorta. A ruptured abdominal aortic aneurysm is a medical emergency.
Grafts are used to fix a weakened aorta.
By diagnosing an AAA early, while it’s still small, doctors can carefully monitor patients while treating their risk factors – known as watchful waiting.
Cecil Merritt, 81, a retired engineer in Leighton, Alabama, learned he had an abdominal aortic aneurysm in 2008. The previous year he’d been operated on for melanoma on his shoulder, and he needed a follow-up CT scan. It was his oncologist who told him he had an AAA. “Never felt it,” Merritt recalls. “Didn’t have any symptoms.”
“Most aneurysms are diagnosed with imaging studies that are done for some other reason,” says Benjamin Starnes, a professor and chief of the vascular surgery division at the University of Washington.
In terms of discovering an early AAA, unfortunately, most patients are “completely asymptomatic,” Starnes says. “They don’t come with any abdominal or back pain. The patient will typically come in because they’ve had an X-ray or they’ve had an ultrasound study for some other completely unrelated condition, and oh by the way, they found out that they have this aneurysm.”
In Merritt’s case, although he never smoked, he had almost every other risk factor include several relatives who’d had aortic aneurysms.
How Do You Know?
CT scans, ultrasounds and MRIs can all be used to diagnose and measure aneurysms. A single screening is recommended for all men ages 65 to 75 who’ve ever smoked. Older men who’ve never smoked should check with their doctors. Women aren’t routinely screened for AAA because their risk is much lower.
James Black, chief of the division of vascular surgery at Johns Hopkins Hospital, says women’s risks are closer to men’s at younger ages. However, at 65 and beyond, AAA risk “clearly predominates” for men, affecting three to five men for every woman affected. But “the problem is while aneurysms are more infrequent in women, they have a higher risk for rupture,” Black says. “So we sometimes get more nervous about aneurysms in women than we do in men.”
As for Merritt, six years after diagnosis his aneurysm hasn’t changed, and he’s still in watch-and-wait mode.
When you talk to your doctor about AAA, Black says, “The first question really should be – what’s the size of the aneurysm?”
“Most aneurysms when they’re small have a very low risk for rupture – perhaps at best it might only be 0.5 percent or 1 percent per year,” Black says. An aneurysm less than 4.5 centimeters (under 2 inches) across is considered small. These patients come in every six to 12 months for follow-up imaging tests.
The medical focus is on reducing their risk factors. “Things that are associated with a rapid growth trajectory of the [AAA] are blood pressure and smoking,” Black says. “So to that end we ask patients to wind down their smoking habit as soon as they can.”
Beta blockers, a specific type of blood pressure medicine, have been shown to slow aneurysm growth in the aorta, Black says, and “there’s some experimental evidence that statin medications help keep the blood vessel wall healthy.”
Exercise restrictions aren’t needed with a small aneurysm, Black says. However, when an aneurysm reaches a “moderate” level of about 4.5 to 5 centimeters, he advises sticking with “steady-state” exercise – such as swimming, or jogging or biking on a relatively level surface.
Catastrophe of Rupture
For patients with an unsuspected aneurysm, unchecked growth can turn into a dire emergency. “A ruptured aneurysm is a model of pure catastrophic hemorrhage,” Starnes says. It’s as if someone stuck a knife into the aorta and pulled it back out, he says.
Pain – sudden, intense and continuous – often starts in the patient’s back or abdomen, and can wrap around into the groins. Black describes “a real severe, double-over sort of pain where you want to turn off the lights and crawl into a ball. Not, ‘I feel a little sore from raking leaves or shoveling a little too much snow.’”
Starnes says a drop in patients’ blood pressure is the next phase, and they’ll need to lie down or even faint. The body then releases hormones to raise the blood pressure. Other signs of rupture include dizziness, sweating, clamminess, nausea or vomiting, fast pulse, shortness of breath and loss of consciousness.
If you or a loved one is having these symptoms, call 911 – timing is critical. “Typically,” Starnes says, “on average, patients will survive after a ruptured aneurysm about two hours.”
Starnes practices at the Harborview Medical Center in Seattle. The Level 1 trauma center covers patients in a five-state area, and as a result he sees more ruptured aneurysm emergencies than any hospital in the country.
“It used to be that the mortality rate once the patient got to the hospital – their risk of death was 50 percent,” Starnes says. “Flip of a coin. We implemented a program seven years ago to treat those patients without putting them to sleep with minimally invasive procedures. And we lowered the mortality rate to 16 percent.”
Elective surgery is far preferable to emergency surgery, and most patients do well afterward. The question is: when to have it. With very small aneurysms, it’s likely the risks of surgical complications outweigh the risks of just leaving the aneurysm alone, Black says.
But “when the aneurysm crosses 5 to 5.5 cm in size, that is the tipping point where intervention should be very heavily considered,” he says. The threshold may differ for women and people with chronic obstructive pulmonary disease, he adds.
Surgical options for aneurysm include traditional open surgery and less-invasive endovascular repair. A CT or MRI scan, along with other factors, will help determine the right option for you.
Endovascular repair is performed under either general or local anesthesia. A stent – a thin metal tube that makes up the core of a “stent graft” – is guided through the femoral artery toward the area of the aneurysm. Patients can usually leave the hospital in the next one or two days. A vascular surgeon, general surgeon or cardiac surgeon can perform the procedure.
Black notes that correct fit can be an issue with stents, and not all patients are good candidates. Patients must be willing to come back regularly, usually yearly, for a CT scan to make sure the device is working well.
Open surgery is always done under general anesthesia. A large incision is made straight down the middle of the abdomen, across the abdomen or to the side. The aneurysm is isolated between surgical clamps and opened, and a synthetic graft is sewn into place to replace the weakened part of the aorta. Surgical risks include bleeding, graft or wound infection, and blood clots.
Recovery takes longer with open surgery than endovascular repair. Patients spend a week or more in the hospital and about one to three months recovering fully at home.
An abdominal aortic aneurysm “didn’t grow overnight,” Starnes says. “It’s been something that developed over time and if it’s thankfully recognized at a small size, it can be monitored over time until it gets to a size where it can be electively repaired very, very safely.”