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Annibali et al. Mini-invasive Surg 2022;6:12 https://dx.doi.org/10.20517/2574-1225.2021.101 Page 3 of 16

[7]
paravalvular leak, but no difference in 30-day and 1-year outcome . Stented valves, especially those with
externally mounted leaflets (e.g., Mitroflow, Livanova PLC/Sorin Group, Saluggia, Italy), have frequently
been used in the past, mainly in small anatomies, because they guarantee a lower final gradient, but these
are the valves at the highest risk for coronary obstruction in ViV procedures [15,16] .

The type of transcatheter heart valve (THV) must also be carefully selected. There are supra-annular valves
(i.e., functional leaflets placed over the aortic annulus), such as the CoreValve/Evolut (Medtronic,
Minneapolis, Minnesota, USA) and the ACURATE (Boston Scientific, Marlborough, MA, USA), whereas
others are intra-annular, such as the SAPIEN (Edwards Lifesciences, Irvine, California, USA) and the
Portico (Abbott, Lake Bluff, Illinois, USA). There are no randomized comparison studies between TAVR
ViV and SAVR or between different transcatheter devices in ViV procedures. From two propensity-
matched comparisons between transcatheter valves, the CoreValve family showed greater effective orifice
area (EOA), lower mean gradients, lower incidence of moderate-to-severe aortic regurgitation and lower
mortality compared with the Portico, whereas a comparison between SAPIEN XT and SAPIEN 3 patients
documented lower 30-day mortality in the latter. There were no differences in elevated postprocedural
gradients between devices, and SAPIEN 3 patients, because of the different valve profile, were more likely to
undergo pacemaker implantation after ViV TAVR (6% vs. 2.5%, P = 0.07) [17,18] .

Computed tomography scan (CT) remains, in the presence or even more in the absence of data regarding
the procedure performed or the implanted prosthesis, a fundamental tool for planning a ViV TAVR.
Thanks to the CT study, it is therefore possible to have precious information regarding the type of
prosthesis, the correct size of the valve and the confirmation of the true internal lumen (ID), which is the
true reference measurement for our THV. The ID corresponds to the internal diameter in the case of a valve
with externally mounted leaflets, while, in the case of internally mounted leaflets, the internal diameter of
the prosthesis will be reduced .
[19]
Finally, regarding the correct study of the bioprostheses, the “Valve-in-Valve” app developed in
collaboration between the technology company UBQO and Dr. Vinayak Bapat is certainly one of the must-
[20]
have tools for optimal planning of the ViV TAVR procedure .
CORONARY OBSTRUCTION
Compared to TAVR on native valve, ViV TAVR has a higher risk of coronary occlusion (0.1% vs. 3.1%).
Although rare, this complication is one of the most worrisome events and is associated with a higher 30-day
[14]
mortality compared to an uneventful procedure (48.6% vs. 3.7%) . Obstruction of the left coronary artery is
more frequent (72%) than obstruction of both ostia (20%) or the right coronary artery alone (8%). The
primary mechanism underlying this event is the displacement of the surgical valve leaflets toward the
coronary ostia after valve implantation (58%), but it can also occur after initial valvuloplasty (3%), after
post-dilatation (3%), within the first 24 h after TAVR (22%), or even afterward (14%). The obstruction may
be partial (57%) or complete (43%); the patient presents severely hypotensive (58%) and with ischemic ECG
changes. Percutaneous coronary intervention (PCI) was attempted in 77.8% of patients, with only 64.3%
successful. Mortality was 22% in successful PCI and 50% when patient was referred for emergency coronary
artery bypass grafting. Eighty percent of patients with unsuccessful PCI died. In 36% of cases, coronary
obstruction had delayed onset and most of these complications (77%) occurred in patients with self-
expanding devices because of their ability to continue to expand after the procedure. The incidence of
coronary obstruction in TAVR from failed surgical prostheses is much higher in externally mounted valves
(6.4%) and stentless valves (3.7%), compared with those with internally mounted leaflets (0.7%). Stentless
and stented valves with externally mounted leaflets, such as Mitroflow (Livanova PLC/Sorin Group,