Perspective: valve sparing root repair: tips and tricks

Abstract

The remodeling and the reimplantation procedures were described more than 25 years ago with the aim of sparing otherwise normal aortic valves in the presence of a root aneurysm. Important achievements in this discipline have occurred over the past decade including development and refinement of valve preserving aortic root replacement techniques, development of a classification system for aortic insufficiency, and development of surgical approaches to cusp disease with varying cusp anatomy. The main advantage of the reimplantation is the resulting annular support, and the disadvantages are the unfavorable hemodynamics and relatively longer procedural time. Conversely, the main advantages of remodeling are the physiological hemodynamics and the shorter procedural time, and the disadvantage is the lack of annular support. With technical advances and modifications, however, the differences between these two procedures have narrowed. Today preference for a reimplantation procedure is based on the perception of a better reproducibility of the surgical procedure, an increased procedural safety due to the characteristic hemostatic feature of this surgical approach, the possibility of achieving favorable hemodynamics, and a much larger amount of data present in the literature on long-term results.

In the early 1980s, Yacoub described a valve sparing aortic root remodeling for those cases with non-diseased aortic leaflets. In this technique, the Dacron conduit is tailored to fit the crescent shape of the aortic annulus [1]. Later on, David introduced an alternative approach called the reimplantation technique, where the aortic valve is spared and integrated within a Dacron graft [2]. Despite the concept of aortic valve sparing was introduced several years ago, confusion still exists about the strengths and weaknesses of these two different surgical procedures.

A better understanding of aortic valve function has led to the appreciation of the role of adjacent structures in modulating leaflet movements. Very important steps in this direction were (a) the recognition of the role of the sinuses of Valsalva in smooth leaflet approximation [3–5], (b) the importance of annular stabilization for stable results [6], and (c) the measurement and verification of a satisfactory and sufficient leaflet coaptation [7].

The basic concept of both procedures is to eliminate any pathologic dilatation of the root and thus restoring aortic valve function. Root remodeling recreates the normal configuration of aortic sinuses and the sino-tubular junction while the ventricular-aortic (AV) junction is excluded from root remodeling. The long-term stability of the procedure had been in fact questioned just because the remodeling lacked annular stabilization [8].

On the other side, root reimplantation corrects annular ectasia as well as dilatation of the sino-tubular junction. The reimplantation anchors the aortic graft proximally at the AV junction below the leaflets with the commissures sewn inside the polyester fabric graft. For this reason, a major step of the reimplantation procedure is an accurate dissection of the aortic root as low as possible, given the natural anatomic limitations of the heart structures [9]. However, the major theoretical problem with the classic reimplantation technique is that it eliminates the sinuses of Valsalva that are important in regulating leaflet dynamics and somehow abolishes the 3-D dynamic motion of the normal aortic annulus [3–5]. However, the annuloplasty appears reasonable, just like in the diseases of the mitral valve, in reducing the size of a dilated AV junction that is often part of the problem. It is therefore easy to understand how a stable annuloplasty become even more important whenever there is a clear annular ectasia like in patients with connective tissue diseases [10].

Through the years, thanks to an improved general knowledge, both procedures have been significantly improved, so that is now possible to perform a reimplantation procedure with neo-sinuses reconstruction [11] or a remodeling procedure with annular stabilization [12, 13] both in case of tricuspid or bicuspid aortic valves. In this way, both procedures can now guarantee an anatomical root reconstruction and an increased long-term durability.

Although it is useful to be confident with both techniques of valve sparing procedures, it is better to choose one of the two techniques and get acquainted with all the details that are necessary to achieve good and stable reproducibility of the results. It is not advisable to keep switching from one technique to the other before having mastered one of the two approaches. The remodeling technique requires a careful suturing between the Dacron conduit and the valve remnants. To this extent, it is of paramount importance to suture exactly at the interface between the crown-shaped cusp insertion where there is a fibrous and strong tissue that somehow limits the risk of bleeding. It needs to be emphasized that this suture is exposed for the whole length to the open pericardium and small discrepancies between the Dacron and the patients’ tissue might result in small bleeders that are difficult to reach once the aorta has been closed and pressurized. Furthermore, the suture line will be under considerable tension and a waterproof suture is of paramount importance. Attention to detail in suturing is especially critical also because an excess of Dacron along the suture is necessary to obtain a proper shape of the sinuses of Valsalva. When suturing the tongues of Dacron to the valve remnant, it is also important to pay attention to the possibility of slightly modifying the natural and proper commissural distance (two or three depending on the valve phenotype whether bi- or tricuspid). This in fact might be the cause of an induced leaflet prolapse that will need to be addressed to avoid any residual valve regurgitation. For these reasons, after the root remodeling is completed, it is advisable to properly measure each leaflet effective height (the height from the leaflet basal insertion to the leaflet free margin at the level of the nodules Arantii) and verify a good and satisfactory leaflet coaptation [7].

As for the associated annuloplasty, that is advisable in most cases if we want achieve a long-term stability of the spared or repaired valve; there are mostly two different options. One, as introduced by Schaefers [14], is mainly based on the use of a strong Goretex suture passed from the external wall of the aorta, below the coronaries and around the annulus in a circumferential fashion and tighten around a Hegar dilator of an appropriate size (usually 22–23 mm). This suture is fixed to the fibrous portion of the annulus in four well-defined and localized points, paying attention not to interfere with the surrounding structure (coronaries, AV node, etc.). The intrinsic advantage of this type of annuloplasty technique is in the limited need for a deep root dissection as well as in the very limited time required to execute it. The second option requires the use of a ring as advocated by Lansac [15], or a strip of Dacron, Teflon, or similar material that need to be fixed to the annulus by a series (5 or 6) pledgeted sutures passed below the aortic valve, from inside out in a circumferential fashion, in a way that resembles the technique commonly used for the reimplantation technique [16]. Soft tissue like Dacron or Teflon, differently from a less flexible ring, allows a better conformability of the annuloplasty with heart tissues especially at the level of the right coronary cusp where the presence of right ventricular muscle usually acts as a barrier to properly reach the level of the ventricular-aortic junction.

The reimplantation technique requires, as a first and very important step, an accurate root dissection in order to be able to literally pull the valve out of the heart and reach the level of the aorto-ventricular junction from the external wall of the root. This can be particularly cumbersome in two specific points. The first one is at the level of the commissure between the right and left cusps facing the pulmonary artery trunk where there is the presence of strong fibrous tissues that need to be open. Once open, it gives way to a loose fat tissue that allows going deeper at the level of the interleaflet triangle. The second point is along the right cusp, where the presence of the right ventricular muscle and its adhesion to the root wall might interfere with a through and complete dissection. This anatomy can be highly variable and ease of dissection might vary among patients. Once the dissection is complete, a series of pledgeted U stitches are passed below the aortic valve from inside out. The number of suture might vary from 6 to 12 depending on the preference but without any major impact on the efficacy of the resulting annuloplasty. Sutures are to be passed 1–2 mm below the hinge point of the leaflet base taking care not to interfere in any manner with the leaflet movements. At this point, a proper Dacron graft needs to be chosen. There is the possibility of using a standard straight Dacron graft as described in the original technique with the understanding that the sinuses of Valsalva are being abolished; an oversized straight graft (as a David V procedure) [17] needed to provide pseudo-sinuses; or specifically designed grafts that incorporate sinuses of Valsalva and guarantee a proper reconstruction of the root anatomy. The theoretic arguments favoring polyester fabric pseudo-sinuses include, among other reasons, slower aortic cusp closing velocities, which reduce the diastolic stresses on the cusps and thus potentially enhance valve durability. To this extent, a Dacron conduit designed specifically for aortic root operation was introduced by us in the early 2000 [18]. This graft, called the “Valsalva” graft, has been our choice since the beginning of our experience and the following tips and trick refer to the proper use of this graft. It should be stated from the beginning that the steps of the operation follow those originally described by David with the exception of few details necessary to adapt the graft to each patients’ aortic valve in order to achieve a perfect anatomical reconstruction.

The choice of graft size has always been considered a crucial step and several fancy formulae have been described. However, after several years of experience, a 30- or 32-mm graft has always been used in more than 95% of the cases. In our practice, we use the intraoperative measurement of the aortic annulus (using a Hegar dilator) as the sole criterion determining the choice of prosthetic tube graft. Five millimeters is added to the annulus to choose the proper conduit size. As a rule of the thumb for a 25-mm annulus, we take a 30-mm conduit and for a 27 mm or larger annulus, we take a 32-mm conduit. Once the conduit size has been chosen, it needs to be adapted to the patient’s natural valve. Often the length of the skirt of the graft (the portion devoted to root reconstruction) is greater than the commissural length. For this reason, the commissural length is measured from the base of the interleaflet triangle (at the point of the previously placed U pledgeted suture) up to the top of the commissure. This distance is marked upon the graft in a way that the top of the commissure will be placed exactly at the level of the new sino-tubular junction (Fig. 1). Furthermore, to facilitate the subsequent step of valve suturing, the line of the sinuses is also marked upon the graft (small arrow). Once the sub-valvular sutures are placed at the proper (and marked) level, the graft is parachuted down and the sutures are tied. When tying the suture, the introduction of a Hegar dilator across the valve might help to obtain the desired annular reduction (usually 22–23 mm) and avoid any overcorrection. At this point, working inside the conduit, the commissures are retrieved and positioned at the level of the sino-tubular junction. In case of tricuspid morphology, the commissures are usually placed 120° apart (at the cross of the reference black line and the sino-tubular junction); if the valve is bicuspid, most of the time the commissures are placed 180° apart. In doing so, care should be paid to obtain a nice leaflet coaptation and to avoid any distortion or undue tension on the commissure. It should be also noted that quite often once the valve, whether bicuspid or tricuspid, is reimplanted in a conduit (by definition smaller than the dilated aorta), one of the leaflets might show a prolapse that will need to be addressed in order to achieve a perfect valve competence. In fact, cusp prolapse is frequently seen in the presence of aortic dilatation and visible only after surgical correction of root dilatation. If the free margin of one or two leaflets is prolapsing inside the ventricle, methods of leaflet repair should be added to the valve sparing procedure. In any case, this evaluation is best done after the valve has been reimplanted inside the tube.

Fig. 1.

The length of the commissure is marked onto the skirt of the graft from the sino-tubular junction down toward the base of the graft (arrow). The corresponding signs indicated the level and the line where to place the sub-annular sutures. This is important in order to be sure that the top of the commissure, once stretched up, will reach exactly the level of the sino-tubular junction. Another curved line (small arrow) is made to outline the shape of the sinuses and is useful as a suturing path for fixing the valve remnant to the Dacron graft

It should be underlined that, irrespective of the technique used, remodeling or reimplantation, it is of primary importance to normalize cusp configuration and the measurement of effective cusp height has been helpful in the assessment. In order to have an easy and reproducible indicator of prolapse or adequate cusp configuration, the effective height of each cusp should be measured. An effective height of 9 mm measured with a caliper intra-operatively corresponds to a similar height on postoperative echocardiograms and will result in an almost normal configuration of the aortic cusps [7]. Simple shortening of the free margin and the adjacent tissue can eliminate the tissue redundancy and normalize cusp geometry. The use of central plicating sutures appears easier to apply and more reproducible. The alternative method of using a fine polytetrafluoroethylene suture along the free margin has been promulgated to normalize the length of the free margin but from our point of view, it is more difficult, less reproducible, and slightly less accurate.

In conclusion both procedures can now provide excellent root reconstruction and adequate clinical results in terms of late valve durability. Attention to details is of paramount importance for long-term stability of the results. The type of technique chosen to reconstruct the root, whether remodeling or reimplantation, cannot be blamed for an incorrect geometry of the spared valve or for an untreated cusp prolapse. A perfect leaflet coaptation should always be the most important target of the operation. In such case, we can probably consider it a life-long lasting procedure.

Compliance with ethical standards

Conflict of interest

Ruggero De Paulis receives royalties from Vascutek Terumo. Raffaele Scaffa declares that he has no conflicts of interest.

Ethical approval

This article does not contain any studies with animals performed by any of the authors.

Informed consent

Informed consent was obtained from all individual participants included in the study.