Sharon Wargo remembers how difficult it once was to just get around.
“I was limited as to how far I could walk without becoming short of breath,” the 73-year-old Genoa, Cayuga County, resident says.
Wargo was experiencing the effects of severe aortic stenosis, a serious blockage of the aortic valve of her heart. Transcatheter aortic valve replacement, or TAVR, a medical procedure that received FDA approval just a few years ago, has given her the ability to breathe more easily.
The aortic valve is located between the left ventricle of the heart and the aorta, the body’s largest artery. When it functions properly, its leaflets either open to allow blood to flow from the left ventricle to the rest of the body or close to prevent it from flowing backwards into the ventricle. The valve can undergo what’s called stenosis, a progressive narrowing, which can be age-related. Eventually, the condition can become severe.
“Something that would be maybe the size of a dime hole to a quarter hole or even larger would be incredibly smaller,” says Dr. Jeremiah Depta M.D., an interventional cardiologist at Rochester Regional Health’s Sands-Constellation Heart Institute, who has performed many TAVRs.
Severe aortic stenosis, which afflicts one in seven over the age of 75, can cause fatigue with exertion, dizziness or other alarming symptoms.
“When you become symptomatic, it’s associated with a fairly high risk of mortality,” Depta says. “Within one to two years, half of those patients will be dead.”
Many who acquire this condition also have other ailments; chronic obstructive pulmonary disease forces Wargo to use an oxygen tank. By the time she was diagnosed with severe aortic stenosis last April, she already had had one heart attack.
“If I hadn’t had the procedure, the chances of having another one were pretty doggone high,” she says.
Traditionally, patients with severe aortic stenosis underwent surgical aortic valve replacement, or SAVR.
“The breastbone gets cut open, the person gets placed on a heart-lung machine, and the surgeon goes in and actually removes the old valve and puts in a new one,” says Dr. Frederick Ling M.D., director of the University of Rochester Medical Center’s Cardiac Catheterization Laboratory.
Though SAVR is very effective, the highly invasive surgery carries its own dangers.
“For older patients in the population that may develop this condition, it can be higher risk for them to go with open heart surgery,” Depta says.
TAVR can offer the benefits of SAVR while being less invasive—and less risky—for patients.
The procedure was first successfully used in 2002, when a French team implanted a prototype artificial aortic valve in a patient who was unable to undergo SAVR. In 2011, after lengthy, in-depth studies of TAVR had been performed, the FDA approved Edwards Lifesciences Corp.’s Sapien transcatheter heart valve for use with patients who suffer from severe inoperable aortic stenosis.
The following year, Ling led the team that performed the first TAVRs in the Rochester area. The team, which consisted of URMC physicians and specialists and one physician from the Rochester Cardiopulmonary Group, (which was part of RRHS at that time) implanted Sapien THVs in a 77-year-old Greece woman and a 91-year-old Genesee County man. Both patients eventually died—not as a result of TAVR, but due to other medical conditions.
“In both patients, the valves were functioning well,” Ling says.
The FDA went on to approve the Sapien THV for a larger group of patients with severe aortic stenosis: those who are eligible for SAVR but are at high risk for complications or death from open heart surgery.
Since then, two main types of replacement aortic valves have come to be used to treat such patients: the Sapien 3 THV and the CoreValve Evolut R, which is made by Medtronic. Both are the latest additions to their lines.
The artificial valves consist of tubes of flexible metal mesh into which leaflets, or “doors,” have been sewn. The leaflets are made of pig or cow tissue, depending upon the device.
“They use the pericardial tissue, which is the tissue that comes from the sack that surrounds the heart,” Depta explains.
During TAVR, a catheter—a long, thin, flexible tube—is used to implant the artificial valve. The catheter is inserted into the body with a needle.
“With the current technology, in 90 percent of the people we can go through the groin or through the common femoral artery,” Depta says.
If the patient’s condition warranted, the valve could also be implanted through a small incision that would be made in the patient’s chest, underneath the left breastbone or in another location, according to Depta. As part of the procedure, a temporary pacemaker is also implanted.
Once the new valve has been placed inside the malfunctioning one, the pacemaker radically speeds up the heart, reducing the flow of blood through that organ to near zero. The artificial valve is then expanded, pushing the leaflets of the natural valve out of the way. At the same time, the new valve’s walls are forced against those of the old one, making a seal.
If the TAVR is successful, the artificial valve’s leaflets begin working with the normal functioning of the heart and the pacemaker is removed.
Today’s aortic valves incorporate elements that were not found in some of the devices that came before them. Tests of the Sapien THV found that the new valve did not always make a complete seal with the walls of the existing one, reducing the device’s benefits to the patient.
“Up to 20 percent of the people would have more than a mild leak around the valve,” Depta says.
The latest version of the Sapien has a kind of skirt at the bottom that improves its ability to create that seal.
“You will be able to get a mild or less leak in 97.5 percent of the patients,” Depta says. “You get close to a surgical (SAVR) result.”
Early artificial aortic valves were also quite large—as big as “your pinky or bigger,” Ling says. As a result, up to 15 percent of patients suffered vascular complications as a result of TAVR, including injuries to their femoral arteries. The larger devices were also more prone to scrape plaque from the walls of blood vessels, which might increase the risk of a stroke.
“Initially, when the trials were first done, it looked like the risk of stroke from the TAVR procedure was slightly higher than surgery,” Ling says.
The newest versions of the artificial valves are smaller.
“The technology has changed to the size of a robust pencil,” Ling says. “The vascular complication rates have gone down to five percent or less.”
Such improvements in TAVR also have decreased the time needed for recovery.
“Our current length of stay is between two to three days, instead of nine to 10 days when we started,” Ling says.
Changes of this kind appear to have reduced the procedure’s risks. At URMC, where about 240 TAVRs have been performed, the procedure’s mortality rate has declined.
“Our mortality rate is now 3 to 4 percent,” Ling says.
By contrast, studies have found that SAVR has a predicted mortality rate of 8 percent or more, according to Ling. Large-scale TAVR trials conducted over the past five years have shown that the long-term mortality rates of the two are comparable.
“There is no difference if you got surgery (SAVR) or if you get TAVR, in terms of the two main endpoints, which are dying and stroke,” Depta says.
By the time Wargo was diagnosed with severe aortic stenosis, her condition was very serious.
“If you think in terms of a 10-lane highway, I only had one lane available—that’s how bad my valve was,” she says.
Wargo underwent TAVR at Rochester General Hospital, where she remained for just a few days before returning home. Though she felt better right after the procedure, Wargo really noticed its effects upon returning to the hospital for a follow-up visit.
“I walked the full length of the parking garage, which was something I could not have done prior to the TAVR,” she says.
According to Depta, research into TAVR has already indicated that the procedure could be used with other patients who suffer from severe aortic stenosis. That group could continue to grow in the coming years.
“You’re going to find that TAVR will eventually be utilized as the procedure of choice for everyone,” Depta says.
Mike Costanza is a Rochester-area freelance writer.
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