Page 12 - Journal of Structural Heart Disease Volume 4, Issue 1

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Original Scienti c Article
reduce paravalvar leak. The proximal and distal flare diameters are 10 mm larger than the diameter of the straight segment. There are two small “ears” at the proximal part of the valve for attachment to the deliv- ery system. The frame is made of a single Nitinol tube by laser-cutting. This design improves frame integ- rity; however, manufacturing of di erent sizes to fit patient anatomy is more time-consuming and costly. There are ve (previously six) open cells in the distal ared part to allow easy access to the branch PA, with a wire across to decrease the chance of fracture of the distal stent. Figure 1 depicts the current design of the valve. The delivery system (Figure 2) consists of a 20– 22-F capsule and a 16-F, 100-cm-long shaft with a ro- tating handle for deployment of the valve. The valve prosthesis is loaded into the capsule by submerging the Nitinol frame in sterilized cold saline solution and crimping the frame with a crimper provided by the manufacturer.
Pre-Procedural Evaluation
Due to the wide variety of post-operative anatomi- cal variants existing within this group of patients, the most crucial step for Venus P-valve implantation is the initial detailed anatomical assessment of the RVOT. Schievano et al. [21] evaluated variations in postop- erative RVOT morphology in 83 patients using CMR, assessing implications for tPVR. Five di erent mor- phological subtypes were identi ed, and although type I morphology (i.e., pyramid-shape) was most commonly seen in those undergoing transannular patch, type II–V morphologies were also seen within this subgroup.
CMR is important for understanding anatomy and initial device size selection. It is advisable to perform cardiac catheterization before valve implantation for better valve selection, especially as di erent valve sizes may not be available on the shelf. This should be done for complete hemodynamic assessment and measurement of RVOT and PA dimensions. Angio- grams in the main PA and RVOT can be done in the antero-posterior or right anterior oblique with crani- al angulation and lateral projections. Measurements of the maximum systolic diameter of the RVOT, the main PA at the mid-part and its bifurcation, the max- imum systolic diameter of the proximal and distal PA branches, and the length from the RVOT to PA bifur-
Figure 1. The Venus P-valve Nitinol frame. Panel A. Note the new design of the valve with ve open cells (black arrow). Panel B. The valve viewed from below (from the right ventricle out ow portion), with Panel C being the straight segment of the valve.
Figure 2. Delivery system with its components. Panel A. Carrot at the tip (arrow). Panel B. Shaft and handle with rotating knob (arrow) to allow slow valve deployment.
cation can be obtained. Simultaneous selective left coronary angiography (or ascending aorta angiogra- phy) and inflation of a sizing balloon in the main PA should be routinely performed to assess expansibility and diameters as well as proximity of the left coro- nary artery system to the RVOT. Important di erences of up to 4.7 mm between CMR and angiographic bal- loon measurements have been noticed. Undersizing may lead to possible migration of the valve. To pre- vent valve migration, the implanted valve diameter should be 2–4 mm larger than the maximum diame- ter of the main PA on balloon interrogation.
Alkashkari W. et al.
Transcatheter Pulmonary Valve Replacement