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

Figure 1. Factors related to coronary obstruction.

and a higher surgical risk score predict the likelihood of PPM, suggesting that PPM may be a surrogate
marker for adverse outcomes . Surgical 19 mm biological valves have a “physiological” mean gradient of
[22]
approximately 25 mmHg if the leaflets of the valve are sutured inside the posts of the stent (e.g., Carpentier-
Edwards Pericardial) and around 10 mmHg if the leaflets are sutured outside the stent frame (e.g.,
[41]
Mitroflow) .
A TAVR ViV is associated with a higher risk of high residual severe gradients and one-year mortality. In the
STS/ACC TVT and VIVID registries, more than 30% of ViV procedures were associated with severe
residual gradients after surgery [2,42] . ViV TAVR was associated with hemodynamic deterioration with
gradient increase of more than 10 mmHg between discharge and 30-day follow-up in the TVT registry .
[43]
Patients at even greater risk are those who have undergone SAVR, with PPM, and then arrive with SVD [2,44] .
Severe PPM before the ViV procedure was associated with higher 30-day and 1-year mortality and a post-
[45]
procedure gradient greater than 20 mmHg . To try to reduce the risk of having a high post-procedure
gradient, some measures can be taken, such as the choice of a supra-annular valve and a high THV implant.
Self-expandable (SE) valves, compared with balloon-expandable (BE) valves, are associated with lower post-
ViV gradients, especially in severe preexisting PPM . In TAVR, deep implantation of a SE valve is a
[46]
stronger predictor of PPM than age, annulus size, left ventricular outflow tract, and valve size . The
[47]
recommended cut-offs for high positioning for CoreValve/Evolut and SAPIEN 3 are 5 mm and 20%,
respectively . However, the optimal height and deployment dimensions for ViV prostheses are still
[48]
unclear. In vitro testing, lower gradients, and larger orifice areas are achieved with taller implants that
[49]
provide more freedom to the leaflets . Higher implantation, however, is associated with an increased risk
[18]
of residual regurgitation and valve embolization, which varies between prosthesis types [50,51] . Seiffert et al.
[52]
and Dvir et al. recommended an optimal depth of 3 mm for the Medtronic SE valve and 80% aortic/20%
ventricular for the Edwards valve. Increased THV size is not always associated with increased EOA. In
vitro, a higher EOA was observed for the Trifecta and Epic Supra valves but a lower EOA for the Mitroflow.