Discussion
Valve-in-valve (ViV) procedures have become a viable alternative to
treat high risk redo surgical patients either in the aortic and mitral
position. There are sparse reports of staged or concomitant transfemoral
or transfemoral and transeptal replacements. [2,3]
Several technical aspects must be considered. On the aortic side it is
mandatory an accurate valve sizing to reduce the risk of
patient-prosthesis mismatch (PPM) and to guarantee a maximal valvular
sealing; for a balloon-expandable device it is generally recommended a 1
mm minimum oversizing respect the internal stent diameter of the failed
bioprosthesis.
Regarding the mitral replacement, the key aspects for a successful
implantation are the correct sizing (similar to the aortic one) and the
correct height of implantation to reduce the risk of atrial valve
migration or left ventricular outflow tract (LVOT) obstruction. On this
regard, an acute mitro-aortic angle < 115 degrees and a
neo-LVOT area less than 250 mm2 are commonly
considered as pre-procedural risk factors for LVOT obstruction. [4]
In this case we decided to perform the staged two-steps approach
following these considerations.
We have firstly replaced the aortic bioprosthesis to relief the
afterload, improve cardiac output and diastolic coronary perfusion (CT
evidence of moderate proximal left anterior descending stenosis).
Secondly, the patient presented with a severely depressed LVEF thus we
preferred to postpone the transapical approach to let some degree of
ventricular improvement In fact, the first postoperative echocardiogram
showed an increased left ventricular ejection fraction (EF 35%). Due to
the persistence of small left atrial dimensions although permanent
atrial fibrillation we chose to not pursuit the transseptal approach and
we planned a standard transapical route.
Finally, the delayed second procedure allowed us to re-assess the
geometrical relationships between the mitro-aortic struts and choose the
optimal site of transapical approach for better mitral co-axiality.
In conclusion, patients with previous history of mitro-aortic surgery
can be very challenging in case of either redo surgery or transcatheter
replacement, due to the biological prosthesis’s relationships, although
there is still a lack of a specific risk score [5] for this
particular cohort of patients.
An in-depth geometrical preoperative and postoperative investigation has
proven to be a useful and reproducible tool leading to optimal technical
and at the end clinical outcomes. We strongly believe that in the
structural heart interventions field a close patient-to-patient approach
in a qualified heart team is the only way to perform high quality
procedure with low grade of risk, in a high-level healthcare service.