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Transcatheter Aortic-Valve Implantation (TAVI)

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Updated October 04, 2011

Question: Transcatheter Aortic-Valve Implantation (TAVI)
My 85-year-old mother has terrible shortness of breath from aortic stenosis, but her doctor says the surgery to fix her valve would be too much for her to survive. I have read about a new kind of operation to replace this valve through a catheter. Is this new operation something my mother could tolerate?
Answer: You're referring to a procedure known as transcatheter aortic-valve implantation (TAVI), a currently experimental method of treating aortic stenosis.

In aortic stenosis, the aortic valve becomes partially obstructed, which means the heart has to work very hard to pump blood through the circulation. Eventually, the heart fails unless the obstruction can be removed. Until recently, the only way to accomplish this is by the surgical replacement of the aortic valve. Valve surgery is indeed a major, open-heart procedure, which carries significant risk an anyone, but especially in frail, elderly patients.

Doctors have been working with the biomedical industry for decades to invent a less invasive, easier-to-tolerate method of replacing a damaged aortic valve, and in recent years have been testing several new devices for performing TAVI - a method of replacing the aortic valve by means of a catheter.

While results with TAVI so far have been quite promising, problems remain. It seems clear that the TAVI procedures can indeed successfully replace aortic valves, and that after the procedure is finished, the obstruction is markedly improved - but the procedural risk is still significant.

For instance, in a study known as the PARTNER trial, 358 patients with aortic stenosis who were deemed too sick for usual aortic valve replacement surgery were randomized to either TAVI valve replacement or standard medical care. At one year, patients receiving TAVI had a significantly reduced mortality rate, and those who survived that year had significantly improved symptoms.

However, TAVI still caused significant complications. Here is what UpToDate, an electronic reference for doctors and patients, has to say about the complications of TAVI, as reported from the early studies:

  • "Major complications at 30 days included death (6.3 percent), stroke (2.4 percent), renal failure requiring dialysis (1.3 percent), and heart block resulting in permanent pacemaker implantation (6.7 percent). Vascular complications included access-related complications (17.9 percent), aortic dissection (1.9 percent), and non-access-related complications (1.1 percent)."
Further,
  • "A diffusion-weighted magnetic resonance imaging (MRI) study that compared 32 patients who underwent TAVI to 21 historical controls treated with surgical aortic valve replacement [21]. New clinically silent cerebral foci of restricted diffusion were significantly more frequent in patients who had undergone retrograde aortic valve implantation than in those who had undergone surgical aortic valve replacement (84 versus 48 percent)."
What this means is that there are a lot of complications that can occur with TAVI, including death, stroke, kidney failure, heart rhythm problems, and serious damage to major blood vessels. Furthermore, there is evidence of "subclinical brain injury," that is, small areas of brain damage that may not cause obvious problems, probably caused by embolism (blood clots) related to the TAVI procedure. This sort of brain damage has been associated with subtle or "soft" symptoms, such as more forgetfulness, slowness, or reduction in mental "sharpness."

Despite these complications, patients with severe aortic stenosis who were treated with TAVI, on average, did significantly better than patients treated with standard, non-surgical care. This is at least partially due to the fact that medical treatments simply cannot overcome the mechanical obstruction created by the aortic stenosis.

So, while open heart surgery remains the treatment of choice for severe aortic stenosis, TAVI appears to offer a very viable alternative to patients who are deemed to be too sick for the standard surgical procedure.

While TAVI has been available in Europe for some time now, the FDA is only now seriously considering it for approval, at least on a restricted basis, in the United States. You might ask your mother's cardiologist to refer her to a center which has been performing TAVI to see whether she might be a candidate.

Want to learn more? See UpToDate's topic, "Valve Replacement In Aortic Stenosis In Adults," for additional in-depth medical information.

Sources:

Leon MB, Smith CR, Mack M, et al. Transcatheter aortic-valve implantation for aortic stenosis in patients who cannot undergo surgery. N Engl J Med 2010; 363:1597.

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