Author + information
- Received March 4, 2013
- Revision received May 17, 2013
- Accepted May 21, 2013
- Published online November 1, 2013.
- Vinnie N. Bapat, MD∗ (, )
- Rizwan Q. Attia, MRCS,
- Fortunata Condemi, MD,
- Ravi Visagan, MBBS,
- Maya Guthrie, BSc,
- Shelina Sunni, BSc and
- Martyn Thomas, MD
- ↵∗Reprint requests and correspondence:
Dr. Vinnie Bapat, 6th Floor East Wing, Department of Cardiothoracic Surgery, St. Thomas’ Hospital, Westminster Bridge Road, London SE1 7EH, United Kingdom.
Objectives This study sought to provide a guide to the fluoroscopic appearances of various valve-in-valve (VIV) combinations by deploying a transcatheter heart valve (THV) within a degenerated surgical heart valve (SHV) in an ideal position.
Background VIV procedures are being increasingly performed with substantial experience acquired in treating degenerated SHV in the aortic position with Sapien/Sapien XT (Edwards Lifesciences Ltd., Irvine, California) and CoreValve/Evolute (Medtronic Inc., Minneapolis, Minnesota) valves. Although less invasive than conventional surgery, securing the THV in an optimal position within the SHV determines the success of this novel treatment.
Methods For VIV implantation, we selected appropriate Sapien XT and CoreValve/Evolute sizes depending on the internal diameter of the SHV. Implantation was performed in vitro. In case of the Sapien XT valve, it was deployed 4 to 5 mm below the sewing ring of the SHV, whereas the CoreValve/Evolute was deployed 5 mm below the level of the sewing ring. Photographs and fluoroscopic images of the various VIV combinations were obtained in side profile to study the ideal position and end-on profile to study the circularity of the THV.
Results Fluoroscopic images obtained in side profile highlighted the differences in various VIV combinations, as all SHV are unique in their fluoroscopic appearances. Also, all THV implants in various VIV combinations achieved a nearly circular shape.
Conclusions To achieve an optimal result when considering VIV, it is important to be familiar with the structure and fluoroscopic appearances of the failed SHV, the THV used, and their combination.
- transcatheter aortic valve implantation
- transcatheter valve
- valve replacement
Transcatheter aortic valve implantation has established itself as an accepted therapy for inoperable and high-risk patients with calcific aortic stenosis (1). Clinical need has led to the use of this technology in a variety of indications, such as in the treatment of a degenerated bioprosthetic surgical heart valve (SHV) (2). Multiple reports of valve-in-valve (VIV) procedures have appeared in the literature during the last 2 years with substantial experience acquired in treating a degenerated SHV in the aortic position with 2 transcatheter heart valve (THV) devices currently available on the market—Sapien/Sapien XT (Edwards Lifesciences Ltd., Irvine, California) and CoreValve/Evolute (Medtronic Inc., Minneapolis, Minnesota) (2–8). Initial experience, although small, of VIV procedures for degenerated SHV in mitral, tricuspid, and pulmonary positions has also been reported (9–11).
This novel treatment appears promising as it is less invasive and provides a secure and nearly circular landing zone for the THV. Securing the THV in an optimal position within the SHV and choosing the right size of the THV determines the immediate and long-term success of this novel treatment. A suboptimal position can be fraught with complications such as embolization, suboptimal function, or regurgitation (12). Understanding the structure and fluoroscopic appearances of various SHV and both THV helps achieve an optimal result during a VIV procedure. In this paper, we discuss the fluoroscopic relationship between various VIV combinations and provide a fluoroscopic guide to an optimal positioning of the THV within various commercially available SHV. We also examine whether supra-annular position of the CoreValve can be maintained when implanted within a bioprosthetic SHV and whether circularity of the THV is maintained after a VIV implantation.
Various SHV were obtained from the different manufacturers (Table 1). Most SHV are manufactured and marketed as a single model across the globe, but the Perimount SHV (Edwards Lifesciences Ltd.) is available in 2 models that are different in their fluoroscopic appearance; model 2700 is used in the United States, and model 2725 is used in the rest of the world (Fig. 1).
Three sizes—23, 26, and 29—are commercially available in Europe. In addition, size 20 is available in Canada and Japan. Details of the stent height and diameter are provided in Table 2. The stent material is cobalt chromium alloy. Sizes 20 to 26 have 2 rows of metal “cells” of which the bottom row is covered with cloth (Fig. 2A), and the size 29 has 3 rows of which the lower 2 are covered with cloth (Fig. 2B). The bovine pericardial leaflets are sutured to the stent frame. This is visible externally by a green suture line (Figs. 2A and 2B), the level of which can be identified fluoroscopically (Fig. 2C).
CoreValve and Evolute
CoreValve sizes 26, 29, and 31 and Evolute size 23 are available commercially (Fig. 3). The stent height and diameter for all sizes is provided in Table 2. Each stent has 3 parts: inflow; waist; and outflow. The inflow of these valves is covered with porcine pericardium and is the part that essentially stays in the left ventricular outflow tract. The waist is where the porcine pericardial leaflets are sutured to the stent. CoreValve and Evolute metal frames have joints referred to as “nodes,” which help in identifying the actual valve structure under fluoroscopy (Fig. 3A and 3B). The nadir of the leaflets corresponds to the third node from the base of the valve (Fig. 3C). The outflow remains in the ascending aorta and helps stabilize the device.
For VIV implantation, we selected the appropriate Sapien XT and CoreValve/Evolute sizes depending on the internal diameter of the SHV. Implantation was performed in vitro. The Sapien XT valve was crimped using a dedicated crimper and delivery system and deployed inside a SHV to achieve a secure fixation. A secure implant was achieved uniformly across various SHV types by implanting the Sapien XT valve 4 to 5 mm below the sewing ring of the SHV, unlike a 50-50 placement of Sapien XT needed in the native calcified aortic valve.
For a CoreValve/Evolute, the recommended implant depth in the treatment of native aortic stenosis is 5 mm below the annular plane; this was maintained for VIV implants in vitro also. A suitable size CoreValve/Evolute was crimped in cold saline and then deployed 5 mm below the level of the sewing ring in a hot water bath with temperature >37°C.
Photographs and fluoroscopic images of the various VIV combinations were obtained in side profile, which provided the basis of an ideal implant position for various VIV combinations and end on, which provided an idea about the circularity of the THV after implantation (Fig. 4).
Fluoroscopic images obtained in side profile highlighted the differences in various VIV combinations. This is because all SHV are unique in their fluoroscopic appearances, and the relationship between the radio-opaque markers in a given SHV and the level of its sewing ring also varies. This difference was particularly obvious when a particular SHV model was available in intra-annular and supra-annular designs (Figs. 4A and 4C to 4E).
Importance of an ideal position
As in the treatment of a native calcified aortic valve, an ideal placement of a THV is important when performing a VIV procedure. Due to differences in their design, both THV will present with unique problems when implanted in a suboptimal position. If implanted too high, both can result in embolization and/or coronary obstruction (12,13). A low implantation in the case of the Sapien XT valve can result in aortic regurgitation from a leak through the open cells due to its relatively shorter covered portion; in addition, it may not cover the degenerated SHV leaflets fully, which may then interfere with its function (12). In the case of CoreValve/Evolute, a low implantation can lead to loss of the supra-annular function of its leaflets and incomplete expansion of the waist, which may result in suboptimal valve function. It can also interfere with mitral valve function (14).
Thus, an ideal placement of a THV in SHV can be defined as a placement where it is securely fixed to prevent an embolization but has its uncovered portion above the sewing ring of the bioprosthetic valve and has covered the degenerated bioprosthetic leaflets without causing coronary obstruction. As the VIV procedure is predominantly performed under fluoroscopic guidance, understanding the relationship between the actual structure of the THV and the SHV and their radio-opaque components is important.
Bioprostheses design and its relevance to ideal positioning
SHV have 3 components: the 3 leaflets; the stent frame; and a sewing ring that is outside the stent frame (15). During open-heart surgery, the sewing ring of a SHV is sutured to the aortic valve annulus after excision of the leaflets. This provides the narrowest and most secure plane. During a VIV procedure, a correct size THV should be deployed at least 4 to 5 mm below this plane to achieve a secure fixation.
A few SHV are manufactured as intra-annular and supra-annular designs, which look very similar under fluoroscopy; for example, CE Porcine and CE SAV Porcine (Edwards Lifesciences), Perimount and Perimount Magna, and Epic and Epic Supra (St. Jude Medical, St. Paul, Minnesota) (15). To identify the level of the sewing ring under fluoroscopy, it is important to understand the difference between intra-annular and supra-annular designs of a SHV. Essentially, an intra-annular design has the sewing ring 3 to 5 mm above the bottom of the stent frame, whereas in the supra-annular design, the sewing ring and the bottom of the stent frame are at the same level (Figs. 5A and 5B). This is not important when the sewing ring itself is radio-opaque as in the Epic and Epic Supra (Figs. 4H and 4I) but assumes importance when the stent rather than sewing ring is visible under fluoroscopy as in CE Porcine and CE SAV Porcine (Figs. 4D and 4E).
Thus, in Perimount and Magna (Figs. 4A and 4C) or CE Porcine and CE SAV Porcine (Figs. 4D and 4E), the level at which the THV is deployed for secure fixation varies as the sewing ring is at different levels. Therefore, in a degenerated CE Porcine and Perimount (intra-annular designs), the sewing ring is already 5 mm above the inflow, hence the bottom of the THV should be deployed in line with the bottom of the radio-opaque markers of these valves (Figs. 5C and 5E). However, if these were CE SAV Porcine or Magna (supra-annular designs), where the sewing ring is in line with the bottom of the inflow, the THV should be deployed 5 mm below the radio-opaque markers of these valves for secure fixation (Figs. 5D and 5F).
A few SHV such as Mosaic (Medtronic) present a unique challenge as they do not have a marker to identify the level of the sewing ring. Although a balloon aortic valvuloplasty can be performed to define the waist, which corresponds to the level of the sewing ring, it is not desirable and is unnecessary as it may lead to leaflet tear or particulate embolization. The best way to ensure an ideal placement of the transcatheter device 4 to 5 mm below the sewing ring is to deploy the Sapien XT valve in such a manner that the top of the valve lies just below the radio-opaque eyelets (Fig. 4L) and the CoreValve/Evolute such that the fourth node is level with the eyelets (Fig. 4L). We have quantified this in all suitable combinations of Mosaic and Sapien XT/CoreValve/Evolute.
Majority of the SHV when implanted surgically are nearly circular. If the leaflets are thickened and calcified irregularly, it can influence the final circularity of the THV. We obtained end-on fluoroscopic views of both Sapien and CoreValve combinations to check the degree of circularity. In all cases, near-circularity was achievable for both the valves across all types of VIV combinations. Examples of various combinations are demonstrated in Figures 4E and 4F.
Supra-annular position of CoreValve/Evolute
When ideally placed, the supra-annular position of CoreValve/Evolute was maintained across all VIV combinations. This was confirmed by identifying the position of the third node from the base (which corresponds to the nadir of leaflets) in relation to the sewing ring of SHV (Fig. 4B).
It also becomes clear that if the CoreValve/Evolute is implanted deeper, then it may lose its supra-annular position. When implanted in an ideal position, whether a supra-annular position translates into supra-annular function needs to be quantified with flow studies, as it might depend on the degree of splaying of the stent posts of the SHV. This, in turn, depends on the radial strength of the CoreValve/Evolute and the resistance offered by stent posts, which varies in all SHV.
We, therefore, conclude that an understanding of the fluoroscopic appearances of SHV, THV, and their combinations provides an excellent guide for a VIV procedure. This is essential to avoid embolization due to high placement and suboptimal function due to low placement of the THV. Circularity of the THV is also maintained across all VIV combinations. Supra-annular position of a CoreValve/Evolute is also achieved when placed in an ideal position but needs further testing to evaluate actual benefit.
Dr. Bapat has received speaking fees from Edwards Lifesciences; and consulting fees from Medtronic Inc., St. Jude Medical, and Symetic. Dr. Thomas has received consulting fees from Edwards Lifesciences and St. Jude Medical; and research support from Edwards Lifesciences. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Abbreviations and Acronyms
- surgical heart valve
- transcatheter heart valve
- Received March 4, 2013.
- Revision received May 17, 2013.
- Accepted May 21, 2013.
- American College of Cardiology Foundation
- Généreux P.,
- Head S.J.,
- Wood D.A.,
- et al.
- Gurvitch R.,
- Cheung A.,
- Ye J.,
- et al.
- Khawaja M.Z.,
- Haworth P.,
- Ghuran A.,
- et al.
- Piazza N.,
- Bleiziffer S.,
- Brockmann G.,
- et al.
- Gotzmann M.,
- Mugge A.,
- Bojara W.
- Faza N.,
- Kenny D.,
- Kavinsky C.,
- Amin Z.,
- Heitschmidt M.,
- Hijazi Z.
- Dvir D.,
- Webb J.,
- Brecker S.,
- et al.