Percutaneous valve replacement offers options for some patients

Issue: October 2008

Since the delivery of the first catheter-based pulmonary stent valve, developments in techniques and technology have expanded in the area of percutaneous valve replacement to include both pulmonary and aortic valve replacement therapies.

According to some physicians, percutaneous valve replacement presents several potential advantages for the patient populations who are able to receive it. The primary advantage is a potential reduction in the number of surgical procedures in patients who require repeated valve replacements. Percutaneous valve replacement is used primarily in patients with pediatric and adult congenital heart disease, but has also been used in elderly patients with pulmonary valvular insufficiency.

“This will have a huge impact because these patients that we are dealing with have already undergone two or three open heart surgeries at a young age, and if they live to age 70, the number of expected operations they will endure is a minimum of four or five,” Ziyad M. Hijazi, MD, professor of medicine at Rush University in Chicago, told Cardiology Today. “If you can replace a couple of these valves percutaneously, you will cut out at least two major open heart surgeries, so the impact is going to be phenomenal in these patients with bad valves.”

The decision on who should receive pulmonary or aortic valve replacement therapy depends largely on the patient.

“The pulmonary valve implantation was introduced with the idea that you would do this in patients who would be operable and who would have surgical alternatives to this treatment, but to whom one would give a chance of avoiding surgery if possible,” Philipp Bonhoeffer, MD, professor of cardiology at the Great Ormond Street Hospital for Children in London, told Cardiology Today. “The aortic valve arena was introduced only in those patients who had no surgical options, and if things went wrong when there was no surgical backup, we would lose the patient but give them an opportunity they did not otherwise have with surgery.”

According to Bonhoeffer, contact between a valve’s stent apparatus and the surrounding tissue at the differing implant sites is one logistical challenge engineers and designers have to cope with.

“This is not a problem with the aortic valve, because there is a fibrous tissue which holds the aortic valve relatively in place,” Bonhoeffer said. “The right ventricular outflow tract has a dynamic nature, and that puts big challenges on the mechanics of the stent, and one has to find ways to build stents which can cope with that particular situation pathologically.”

Role for imaging

According to Bonhoeffer, cardiac imaging technologies and imaging specialists could play an important role in the development of percutaneous valve replacement therapies, resulting in safer procedures for patients.

“One thing we need to think about is the role of imaging, and we need better support for imaging technologies,” Bonhoeffer said. “We are currently basing our pictures on simple angiography … The technology in imaging has made huge improvements, but imaging is not tightly tied to the intervention, and this link needs to be built in more detail in order to provide more detail for patient safety.” – by Eric Raible

For more information:

Feldman T, Leon B. Prospects for percutaneous valve therapies. Circulation. 2007;116:2866-2877.
Lurz P, Coats L, Khambadkine S, et al. Percutaneous pulmonary valve implantation: The impact of evolving technology and learning curve on clinical outcomes. Circulation. 2008;117:1964-1972

At the present time, patients with degenerative aortic valve stenosis are good candidates for this if they are presently at high risk or not good risk for surgical therapy. It should be emphasized that surgical aortic valve replacement is still the gold standard for care for patients with aortic stenosis, but for the high-risk patient or the patient who truly cannot be operated on because of other comorbidities, the percutaneous valve route offers a very attractive alternative.

In the longer run, the development of second and third generation valves may expand the indications to younger patients and to patients who are potentially also surgical candidates but who would prefer to have percutaneous valve replacement – very similar to the kinds of changes that occurred when angioplasty and stenting developed and we all said that CABG was still the gold standard. Ultimately, angioplasty and stenting took over a lion’s share of what cardiac surgeons had done in the past.

This will likely happen in the future, but a question of the etiology of the aortic stenosis – bicuspid vs. degenerative valves – and how that will impact the success of percutaneous therap will determine ultimately whether or not we will be able to use it in younger patients, particularly because younger patients usually have congenital bicuspid aortic stenosis and not degenerative. This may not be as user-friendly for the percutaneous valve replacement as is degenerative tricuspid valve stenosis.

–Peter C. Block, MD
Cardiology Today Co-Section Editor

It does require thus far a teamwork approach to these patients. The procedure requires not only expert interventional cardiologists, but also surgical expertise and excellent imaging, including transesophageal echocardiography.

Thus, noninvasive cardiologists must be part of the team. Having surgeons and cardiologists work together has been most effective, both in making decisions about patient selection for a standard open-heart procedure vs. a percutaneous procedure, and in collaborating during the actual procedure itself.

–Robert Bonow, MD
Professor of Medicine, Northwestern University, Chicago