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Depboylu et al. Vessel Plus 2018;2:26 I http://dx.doi.org/10.20517/2574-1209.2018.39 Page 5 of 11

rence of paravalvular leaks can be explained by 3 mechanisms: (1) prosthetic valve-annulus size mismatch; (2)
inappropriate placement of the prosthetic valve; and (3) incomplete apposition of the stent due to deformed
native structure.

Aortic root calcification, its degree and geometric distribution are the main factors affecting the native
structure. Asymmetric and severe calcifications may deform the prosthesis resulting in paravalvular leaks.
Assessing the aortic root calcification with echocardiographic examination and/or Agatston score, may de-
[18]
crease the risk of paravalvular leak .

The use of self-expandable valves is a major determinant for significant paravalvular leak. The studies have
shown that self-expandable valves were associated with moderate-severe paravalvular leak compared with
[19]
balloon-expandable valves (19.8% vs. 12.2%) .
Central leak
[20]
The incidence of moderate or severe central leak is 4.5%-11.7% and usually occurs due to structural dys-
function of the valve. Central leak can be the result of leaflet restriction or damage, during crimping or im-
[21]
plantation as well as over dilatation of the valve . Post implantation dilatation of the prosthetic valve may
[22]
also cause central leak .
In case of any complication, aortic root angiography is performed for the quantification of central leak. In-
tra-procedural echocardiography may be performed for determining the severity of leak and the location of
the prosthetic valve. Increase of left ventricular end-diastolic pressure and decrease of aortic diastolic blood
pressure also support the diagnosis. If the leak is central, gentle probing of leaflets with a soft wire and/or
catheter or delivery of a second prosthetic valve may solve the problem. The management of paravalvular
leaks is controversial. Mild degrees may be clinically followed as they are thought to be not progressive.
However, more severe degrees of leaks may deserve intervention. Usually, balloon post-dilatation is the first
option, using a slightly oversized balloon.

Repositioning of the implanted prosthetic valve, delivery of a second prosthetic valve and percutaneus vas-
cular occlusion devices may be the other choices for the treatment. However, in large and high volume leaks,
for implanting the appropriate device, large sheaths may be needed. Particularly in self-expanding prosthe-
ses, valve struts and calcification of the annulus may complicate the advancement of delivery systems mainly
[23]
when using large sheaths .

[14]
Otherwise, SAVR should be performed for both types of leaks .

PROSTHETIC VALVE MALPOSITIONING
Valve malpositioning usually occurs during or just after valve implantation. However, rare delayed migra-
[24]
tion cases together with acute heart failure and/or cardiogenic shock have been reported in literature . The
incidence of the prosthetic valve malpositioning is about 1.3% (CoreValve® 2.3% vs. Edwards SAPIEN® valve
[20]
1.0% . The predisposing factors for the prosthetic valve malpositioning can be listed as: (1) incorrect assess-
ment of the aortic annulus; (2) incorrect implantation of the prosthetic valve; (3) insufficient or early termi-
nation of rapid ventricular pacing; (4) presence of prosthetic mitral valve; and (5) presence of severe mitral
annular calcification extending to anterior leaflet and left ventricular outflow tract.

In case of any complication, aortography and trans-esophageal echocardiography are performed for evaluat-
ing the position and confirming the malposition or migration of prosthetic valve [Figure 3A and B].

Hemodynamic status of the patient, final position and the type of prosthetic valve determine the treatment.
For self-expandable ones, if the prosthetic valve is still attached to the delivery system, it may be re-captured