Page 39 - Journal of Structural Heart Disease Volume 3, Issue 1

Case Report 32
Figure 7. Panel A. Six-month follow-up transesophageal echocardiogram shows adequate positioning of the CoreValve in a paraster- nal long axis view. Panel B. Transesophageal echocardiogram short axis view of aortic valve showing turbulent ow suggestive of perivalvular leak.
gration of the valve in treating a NAVR patient with TAVR. We believe that this should be considered as a possible approach to treatment in this challenging subset of patients.
The CoreValve system consists of a self-expand- able, tri-level frame made of nitinol attached to a tri-lea et porcine pericardium heart valve. Most re- ports of TAVR for NAVR have utilized the CoreValve for its unique self-expanding properties. The upper third/out ow portion of the frame exerts low radial force and sits within the ascending aorta, functioning to orient the prosthesis in the direction of the aortic root and blood ow. The middle third of the frame is constrained to avoid jailing of the coronary arteries and hosts the valve lea ets. It has high hoop force to resist deformation and thus maintain normal lea et function. The lower third/in ow portion of the frame sits within the left ventricular out ow tract/annulus of the native aortic valve and exerts high radial force. Thus, the prosthesis is anchored within the annulus, and its function is supra-annular [3, 4]. In our case, we required additional stabilization at the upper third/ out ow portion of the valve, which was adequately provided by the Palmaz stent.
Palmaz stents are balloon-expandable stainless steel prostheses. All Palmaz stents have a closed cell design, which gives them high radial strength and makes them useful for treating coarctation of the aor-
ta. Most Palmaz stents must be hand-crimped onto a balloon (for example, the 3010 is available mounted on a 12-mm delivery balloon). In the Palmaz stent no- menclature, rst two digits indicate the unexpanded stent length, and the last one or two digits indicate the minimum recommended expansion diameter. Large Palmaz stents (P308) have a recommended expansion diameter between 8–12 mm, with report- ed overdilation to 18–20 mm. Overdilation of these stents leads to signi cant foreshortening <33% at 12 mm and up to 50% at 18 mm and decreases radial strength. Palmaz XL transhepatic stents are designed for an expansion range of 10–25 mm while maintain- ing a radial strength of 12 psi (comparative radial strength of the large Palmaz P308 stent is 6 psi). Their foreshortening ranges between 2.5% at 10 mm and 23% at 25 mm 10–13. In our situation, based on mea- surements of the ascending aorta and the root, both on CT prior to the procedure and aortogram during the procedure, we required a stent expanded to 23 mm. This required the use of a Palmaz XL transhep- atic stent and a 1:1-sized balloon. The foreshorten- ing of the Palmaz stent must be taken into account when determining the length of the stent to ensure adequate overlap with the CoreValve and to prevent jailing of the origin of the innominate and left carotid and subclavian arteries. We used a P4010 stent, ac- counting for foreshortening and the distance from
Journal of Structural Heart Disease, February 2017
Volume 3, Issue 1:28-34