Percutaneous aortic valve replacement
|Percutaneous aortic valve replacement|
Percutaneous aortic valve replacement (PAVR), often transcatheter aortic valve implantation (TAVI) or transcatheter aortic valve replacement (TAVR), is the replacement of the aortic valve of the heart through the blood vessels (as opposed to valve replacement by open heart surgery). The replacement valve is delivered via one of several access methods: transfemoral (in the upper leg), transapical (through the wall of the heart), subclavian (beneath the collar bone) and direct aortic (through a minimally invasive surgical incision into the aorta).
Severe symptomatic aortic stenosis carries a poor prognosis. Until recently, surgical aortic valve replacement has been the standard of care in adults with severe symptomatic aortic stenosis. However, the risks associated with surgical aortic valve replacement are increased in elderly patients and those with concomitant severe systolic heart failure or coronary artery disease, as well as in patients with comorbidities such as cerebrovascular and peripheral arterial disease, chronic kidney disease, and chronic respiratory dysfunction.
Transcatheter aortic valve replacement (TAVR) has been developed as an alternative to the surgical approach in this high-risk population.
The catheter procedure was developed in France, initially performed in 2002 on April 16 by Prof Alain Cribier in Hopital Charles Nicolle, in Rouen. It is now approved in more than 50 countries. It is effective in improving functioning in the patients with severe aortic stenosis. In the US, it received FDA approval in November 2011 for use in inoperable patients and in October 2012 for use in patients at high surgical risk.
Transcatheter aortic-valve replacement (TAVR) using a self-expanding transcatheter aortic-valve bioprosthesis (CoreValve) was associated with a significantly higher survival rate at 1 year follow-up than surgical aortic-valve replacement in a recent randomized study of 795 patients with severe aortic stenosis who were at increased surgical risk.
There are two current market leaders whose devices have earned CE Mark approval in Europe and are available to physicians for implantation in appropriate patients; the Medtronic CoreValve device and the Edwards SAPIEN device by Edwards Lifesciences. The Medtronic CoreValve received FDA approval on January 17, 2014.
The current, third-generation 18Fr (for a description of catheter sizing reference theFrench catheter scale) CoreValve System has 3 components, as follows:
- A self-expanding nitinol support frame with cells configured in a diamond cell design, which anchors a trileaflet porcine pericardial tissue valve.
- An 18Fr delivery catheter.
- A disposable loading system.
The Edwards SAPIEN valve is a trileaflet bioprosthesis made of bovine pericardium mounted on a balloon-expandable stainless-steel stent. This system is currently available in two sizes: (1) a 23-mm valve with a stent height of 14.3 mm and (2) a 26-mm valve with a stent height of 16.1 mm.
The second-generation device, Edwards SAPIEN XT, is made of a cobalt-chromium alloy, which provides the same radial strength with a reduced valve profile. This valve is currently commercially available in Europe and is approved for the TF approach. It is under investigation for the TA approach. The system will be available in 21-mm and 29-mm sizes in the future.
The Edwards SAPIEN valve may be implanted via a transfemoral (TF) or transapical (TA) approach, and the Medtronic CoreValve system can be delivered through a femoral, subclavian, or direct aortic approach.
- "Transcatheter Aortic Valve Replacement". November 6, 2013.
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- "Transcatheter Aortic-Valve Replacement with a Self-Expanding Prosthesis". May 8, 2014.
- "CoreValve Beats High-Risk Surgery for AV Stenosis in Pivotal Trial". March 29, 2014.
- FDA Approves Medtronic's CoreValve Heart Device
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- "2012 ACCF/AATS/SCAI/STS Expert Consensus Document on Transcatheter Aortic Valve Replacement".
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