Transcatheter aortic valve-in-valve (VIV) is an established treatment of degenerative surgical bioprostheses in patients at high operative risk and was approved by the US Food and Drug Administration in 2015. The aortic VIV procedure is not currently approved to treat para-prosthetic valve regurgitation or failed/degenerated transcatheter heart valves (THVs), and it is contraindicated in patients with infective endocarditis.
Indications
Although there are no randomized clinical trials specifically addressing this treatment and the long-term durability of this treatment remains to be determined, the American Heart Association/American College of Cardiologists (AHA/ACC) guidelines for the management of patients with valvular heart disease give it a class IIa indication (level of evidence B) based on nonrandomized data, including registries and case series. Data from two large registries (Valve-in-Valve International Data and PARTNER II valve-in-valve registry) show that the most common indication for the procedure was valve stenosis in 30% to 50% of patients followed by pure valve regurgitation in 20% to 30%, and combined valve failure in the remaining patients. Reported 30-day mortality is up to 8%, stroke rate is up to 3%, and the 1-year survival rate is similar in both registries at 83% to 88%, respectively. ,
AHA recommendations
| IIa | B – NR | For severely symptomatic patients with bioprosthetic aortic valve stenosis judged by the heart team to be at high/prohibitive risk of reoperation and in whom improvement in hemodynamics is anticipated, a transcatheter valve-in-valve procedure is reasonable. |
| I | C | For patients in whom TAVR is being considered, a heart valve team, including experts in valvular heart disease, cardiac imaging, interventional cardiology, cardiac anesthesia, and cardiac surgery, should collaborate to provide optimal patient care. |
Contraindications
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Active endocarditis
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Native prosthesis too small or too large for VIV transcatheter aortic valve replacement (TAVR)
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Patient with poor life expectancy/comorbidities that would preclude likely benefit from VIV TAVR procedure
Specific considerations for valve-in-valve TAVR
When approaching transcatheter aortic VIV implantation, all the concepts that were described earlier in this book hold. This includes the building blocks of structural interventions, TAVR patient selection, and procedural planning. However, when planning an aortic VIV procedure, two major pitfalls that are unique for this procedure must be considered. First, therapy of small surgical valves should be approached with caution, as patient prosthesis mismatch (PPM) and significant residual gradients remain a major challenge, with 28% of patients having a residual aortic gradient of 20 mmHg or more. Second, when the indication for the procedure is valvular regurgitation, every effort should be taken to rule out aortic paravalvular leak because VIV implantation is not expected to improve hemodynamics in this case.
In addition to careful patient selection and procedural planning, the VIV procedure itself has particular operator-associated aspects that are different compared with standard TAVR. On the one hand, the surgical heart valve provides a perfect circular annulus to allow even expansion of the transcatheter valve. It is also a suitable anchor for fixation and can partially protect from complications such as annular rupture or complete atrioventricular (AV) block. On the other hand, operators must be aware of the critical importance of precise valve positioning and the risk of coronary obstruction.
Procedural planning
Mechanism of bioprosthesis failure
Transcatheter aortic VIV is less likely to improve patient outcome in cases of PPM or paravalvular regurgitation. These entities are not uncommon, and every effort should be made to rule them out early during procedural planning. Transthoracic echocardiography (TTE) is the primary imaging modality for the assessment of bioprosthetic valves. Comprehensive imaging should include valve prosthesis components, antegrade velocity, mean gradient, aortic valve effective orifice area, and evaluation of any transvalvular or paravalvular regurgitation. Transesophageal echocardiography (TEE) should be strongly considered when paravalvular leak is suspected or when transthoracic imaging is suboptimal.
Bioprostheses are prone to structural valve degeneration, which can present as either leaflet calcification, resulting in stenosis, or leaflet flail or tear, resulting in regurgitation. Early degeneration is associated with several risk factors, including young patient age, renal disease, and PPM of the originally implanted valve. When valve degeneration is suspected, careful echocardiography is mandatory, and four-dimensional computed tomography (4DCT) should also be considered to understand the mechanism of valve degeneration and to confirm the need for reintervention. Although not used routinely in clinical practice, 4DCT is particularly helpful for the detection of valve thrombosis and pannus formation.
Every effort should be made to distinguish PPM from valve degeneration. PPM is likely when, despite a relatively small valve area and elevated gradients, leaflet morphology is normal. When available, careful evaluation of echocardiographic studies at the time of original valve implantation is necessary, because PPM is associated with abnormal valve hemodynamics at the time of prosthesis implantation. , Valve degeneration is likely, and transcatheter aortic VIV implantation should be considered when there is an increase in transvalvular gradients over time with concomitant decrease in valve area.
True internal diameter of the surgical valve
The next step after confirming the need for VIV implantation is to understand the true internal diameter (ID) of the aortic bioprosthesis. Valve size labeling is not standardized and varies between different manufacturers. Valve labeling may refer to ID, outer diameter, or external diameter ( Fig. 12.1 ). Different bioprostheses with the same label size can have different IDs and external sewing ring diameters. The stent labeled ID is a measurement of the stent frame without leaflets. Leaflet type and mounting inside or outside the stent frame influence the true ID. The exact ID of the bioprosthesis is the critical information needed for VIV implantation and can easily be obtained from the VIV application. The application is free and includes design and sizing information for multiple types of surgical valves, as well as fluoroscopic images of all surgical valves. Examples of several commonly used surgical valves are shown in Figs. 12.2 and 12.5 .
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