TAVR (Transcatheter Aortic Valve Replacement) is a minimally invasive procedure that treats severe aortic stenosis by implanting a new valve without removing the diseased one. This technique has revolutionized care, particularly for patients who are not good candidates for traditional open-heart surgery. As the population receiving TAVR expands, a common question arises regarding the long-term viability of the implanted device. A TAVR valve can be replaced, often through a repeat, less invasive procedure, providing confidence in long-term heart valve management.
Understanding TAVR Valve Lifespan and Failure
The TAVR device is classified as a bioprosthetic valve, constructed from animal tissue (usually bovine or porcine pericardium) mounted on a metal frame. Unlike mechanical valves, bioprosthetic valves do not require lifelong blood thinners. However, they are subject to natural wear and tear, and these tissue valves will degenerate, with an expected lifespan typically ranging from 10 to 15 years.
The deterioration that necessitates replacement is primarily known as structural valve deterioration (SVD). This process occurs due to fibrotic remodeling and calcification, where calcium deposits accumulate on the delicate valve leaflets, stiffening them. Calcification prevents the leaflets from opening fully (aortic stenosis) or closing tightly (regurgitation). Other failure mechanisms include severe blood clots (thrombosis), infection (endocarditis), or an early technical issue like a severe paravalvular leak (blood flowing around the valve frame). When symptoms of heart failure, such as shortness of breath or fatigue, return, intervention is needed to restore proper blood flow.
The Primary Solution: Valve-in-Valve TAVR
The most common and preferred strategy for a failed TAVR valve is a repeat minimally invasive procedure known as Valve-in-Valve TAVR (ViV). This technique involves delivering a new transcatheter valve directly inside the frame of the previously implanted device. The new valve expands, pushing the old leaflets aside and immediately restoring healthy blood flow dynamics.
The ViV procedure is highly advantageous because it avoids the need for a second open-chest operation, which carries significant risks, especially for older patients or those with multiple health issues. The new valve is delivered via a catheter inserted through the femoral artery in the groin (a transfemoral approach). This often requires only local anesthesia and conscious sedation, allowing for a much quicker recovery, often measured in days rather than months.
Technical Challenges of ViV
Despite its benefits, the ViV procedure presents unique technical challenges compared to the first TAVR. A primary concern is the risk of coronary obstruction, where the frame of the new valve could block blood flow to the heart’s own arteries. Careful pre-procedural planning using CT scans is necessary to ensure adequate clearance. Another consideration is the potential for an elevated pressure gradient across the new valve, particularly if the initial implanted TAVR valve was small. Placing a second valve inside the first reduces the overall opening size, creating higher resistance to blood flow that can impair heart function. Specialized techniques and valve selection are utilized to mitigate these anatomical constraints.
When Redo Open Heart Surgery is Necessary
While Valve-in-Valve TAVR is the first-line solution, a redo open-heart surgery is sometimes necessary when a less invasive approach is not feasible. This procedure, known as surgical aortic valve replacement (SAVR) after TAVR, involves carefully removing the failed transcatheter valve and implanting a traditional surgical heart valve.
The complexity and risk of a redo SAVR are considerably higher than the initial TAVR or a ViV procedure. Previous procedures leave scar tissue, making the operation longer and technically more demanding. The operative mortality rate for this complex surgery can be significantly elevated compared to initial valve replacement procedures. This higher risk is why the multidisciplinary Heart Team carefully weighs all options before recommending this path.
Redo SAVR is typically reserved for cases involving severe infection of the valve (endocarditis), which necessitates complete removal of the infected device and surrounding tissue. It may also be required for severe anatomical complications that cannot be resolved with a catheter, such as a large paravalvular leak or an anatomical structure that makes ViV deployment unsafe. The decision to proceed with open surgery is only made when the patient’s anatomy or the nature of the valve failure prevents a safe and effective outcome from a repeat transcatheter procedure.