Portal de Periódicos da CAPES

Aortic Valve Repair

2009; Elsevier BV; Volume: 14; Issue: 4 Linguagem: Inglês

10.1053/j.optechstcvs.2009.11.002

1532-8627

Munir Boodhwani, Gébrine El Khoury,

Infective Endocarditis Diagnosis and Management

Aortic valve replacement remains the gold standard for the treatment of severe aortic valve disease. However, valve repair is emerging as a feasible and attractive alternative to valve replacement in selected patients. Valve repair can reduce or eliminate the risks of prosthesis-related complications including thromboembolism, endocarditis, anticoagulant-related hemorrhage, and reoperation due to structural valve deterioration, among others. Analogous to the mitral valve, a reconstructive approach to the aortic valve requires a thorough and detailed understanding of the valve anatomy, valve function, assessment, and classification of pathologic lesions, and treatment of all affected components of the valve. In this illustrative article, we describe key features of aortic valve and root anatomy, our approach to valve assessment and lesion classification, and a demonstration of commonly used reparative techniques for aortic valve repair. Type 1 lesions are most frequently due to dilation of the various components of the functional aortic annulus and may occur in isolation or in association with cusp disease. A type 1a lesion occurs due to a supracoronary ascending aortic aneurysm with concomitant dilation of the sinotubular junction (STJ). This is corrected by replacing the ascending aorta and remodeling the STJ using a Dacron tube graft (Fig. 3). When significant associated aortic insufficiency (AI) is present, subcommissural annuloplasty is also performed as described in Figure 4. Aneurysms of the aortic root (type 1b) are frequently associated with dilation of the STJ and the aorto-ventricular junction (AVJ). These are treated using valve-sparing root replacement, preferentially using the reimplantation technique because it provides better stabilization of the VAJ. The important steps of the valve-sparing procedure are described in Figure 5 and supplemental videos. Subcommissural annuloplasty is typically performed at midcommissural height, except at the noncoronary/right coronary commissure, where it should be performed higher to avoid the membranous septum and conduction tissue. Care should also be taken in this area during tying of the suture to avoid a tear in the septum. At the other two commissures, the subcommissural annuloplasty may be performed at a lower level if greater increase in the coaptation surface is desired. In addition to replacing a diseased aortic root, a valve-sparing root replacement using the reimplantation technique also serves as an annuloplasty of the aortic valve as it stabilizes the VAJ and STJ and protects against further dilation. Our approach to this procedure has been previously described,1Boodhwani M. de Kerchove L. El Khoury G. Aortic root replacement using the reimplantation technique: Tips and tricks.Interact Cardiovasc Thorac Surg. 2009; 8: 584-586Crossref PubMed Scopus (37) Google Scholar but key aspects are highlighted below. The key principle is to externally dissect the aortic root as low as possible, given the natural anatomic limitations, ie, where the root inserts into ventricular muscle (Fig. 1B) (Video 1; supplementary video is available online at http://www.optechtcs.com). The root dissection is started along the noncoronary (NC) sinus and continued toward the left coronary (LC)/NC commissure. In this area, the subannular region of the aortic valve (AV) is fibrous and dissection can therefore be carried to below the level of insertion of the leaflets. Moving toward the right coronary (RC)/NC commissure as well as along the right sinus and the RC/LC commissure, the dissection is limited by nonfibrous portions of the annulus. The sinuses of Valsalva are then resected, leaving approximately 5 mm of aortic wall attached, and the coronary buttons are harvested. See Fig. 5A.Figure 5(A) The three commissural traction sutures are pulled perpendicular to the annular plane with a slight inward motion to ensure good leaflet coaptation. When the leaflets are coapting adequately, a Hagar dilator is used to size the circle that includes the three commissures and a graft 4 mm larger is chosen as this graft will sit outside the commissural posts. (B) To prevent AI, the three commissures must be attached to the prosthesis along the same plane, the new sinotubular junction. Due to external limitations of root dissection, the graft has to be tailored. First, the distance from the base of the interleaflet triangle to top of the commissure is measured at the LC/NC commissure and marked on the graft. Then, at the RC/NC and RC/LC commissures, the distance from the proximal suture to the top of the commissure is measured and used to determine the amount of graft material that needs to be trimmed. Thus, the height of the trimmed portion is the difference between height of the unrestricted LC/NC commissure and the distance from the proximal suture line to the top of the respective commissure. The pledgeted sutures are then passed through the base of the prosthesis, respecting the spaces between sutures and, importantly, the curvilinear contour of the suture line. The commissural traction sutures are pulled up together while tying down the prosthesis to ensure appropriate seating around the aortic annulus. LCC = left coronary commissure; NCC = noncoronary commissure; RCC = right coronary commissure. (Color version of figure is available online at http://www.optechtcs.com.)View Large Image Figure ViewerDownload Hi-res image Download (PPT) 2-0 braided sutures with pledgets are passed from inside to outside the aorta with the pledgets on the inside, starting from the NC/LC commissure and moving clockwise. Along the fibrous portion of the aortic annulus, these sutures are inserted along the horizontal plane formed by the base of the interleaflet triangles. Importantly, however, along the nonfibrous portions of the annulus where the external dissection of the aortic root is limited by muscle, these sutures are inserted along the lowest portion of the freely dissected aortic root, making the proximal suture line slightly higher at the RC/NC and RC/LC commissures compared with the LC/NC commissure (Fig. 1B). See Fig. 5B. The commissures are reimplanted first using 4-0 polypropylene sutures while pulling up on the prosthesis and the native commissure and then tied into place (Video 2; supplementary video is available online at http://www.optechtcs.com). Radial traction is then applied on two adjacent commissural sutures; this clearly delineates the "line of implantation." This running suture line is performed in small regular steps passing the suture from outside the prosthesis to inside and through the aortic wall, staying close to the annulus, and then back out of the prosthesis. After valve reimplantation, it is critical to re-examine the leaflets for any unmasked prolapse and symmetry, and the height and depth of coaptation. Prolapse can be repaired using a variety of techniques including leaflet resection, free margin placation, or free margin resuspension as described below. Cardioplegia is administered through the distal end of the graft with partial clamping to distend the new aortic root and assess root pressure and signs of left ventricle dilation. A limited echocardiographic view may be obtained at this time. The cardioplegia solution is then slowly aspirated out of the prosthesis without distorting the leaflets. This gives another visual assessment of the AV in its physiologic closed state as well as the area and height of coaptation. Prosthesis sizing tends to be somewhat larger for bicuspid than for tricuspid aortic valves to accommodate the typically larger VAJ. During prosthesis preparation, the graft is tailored to be symmetric (ie, 180°) around the two cusps regardless of the native valve anatomy (which may be asymmetric in type 1 valves). During valve reimplantation, the pseudocommissure is reimplanted at the same level as in the native valve. Alteration of the height of the pseudocommissure can cause cusp restriction. Cusp prolapse is associated with excess length of the free margin, which can be corrected using either central free margin plication or free margin resuspension. When a single cusp is prolapsing, the two nonprolapsing cusps serve as the reference and are used to estimate the required reduction in the free margin length. When two cusps are prolapsing, the third nonprolapsing cusp is used as a reference to indicate the desired height of coaptation. In the rare instance that all the cusps are prolapsing, the goal is to achieve a cusp coaptation height at the midlevel of the sinuses of Valsalva. See Fig. 6. See Fig. 7 and Video 3 (supplementary video is available online at http://www.optechtcs.com). Bicuspid aortic valve disease affects not only the valve cusps but also the functional aortic annulus. Bicuspid AV may be divided into two general types. Type 0 bicuspid AVs do not contain a median raphé and have two symmetric aortic sinuses, two commissures, and a symmetric base of leaflet implantation of the two cusps. This configuration is present in a minority of cases. The mechanism of AI in this setting is usually cusp prolapse of one or both cusps due to the presence of excess cusp tissue. Type 1 bicuspid AVs, which are significantly more prevalent, have a median raphé on the conjoint cusp and an asymmetric distribution of the aortic sinuses with a large aortic sinus accompanying a large nonconjoint cusp and two smaller cusps fused together with a median raphé. The raphé often attaches to the cusp base in the form of a "pseudocommissure," which has a height lower than that of the true commissures. The raphé may be restrictive, fibrotic, calcified, or prolapsing. Furthermore, the base of leaflet implantation is typically larger (ie, occupying a greater proportion of valve circumference) and higher on the conjoint cusp compared with the nonconjoint cusp. The mechanisms of AI in type 1 valves can be due to a rigid and restrictive raphé associated with small fused cusps resulting in a triangular coaptation defect. Alternatively, the raphé may be short and nonrestrictive with well-developed cusps and associated prolapse of the conjoint cusp. Bicuspid valve anatomy can be anywhere along a spectrum between type 0 and type 1. Figure 11(A) When a severely restrictive or calcified raphé is present, a parsimonious triangular resection of this tissue is performed. (B) Next, the quantity of remaining cusp tissue is assessed by putting the two arms of a 6-0 polypropylene suture on the free margin of the conjoint cusp, on either side of the resected raphé. At this point, lack of cusp restriction and good valve opening are signs of the presence of adequate cusp tissue. (C) The leaflet edges are reapproximated primarily when adequate cusp tissue is present using running locked or interrupted 6-0 polypropylene sutures. (D) In the absence of adequate tissue, a triangular autologous treated or bovine pericardial patch is used for cusp restoration.Show full captionNext, the free margins of both cusps are compared for the presence of any prolapse, which is corrected using free margin plication or resuspension with PTFE.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Next, the free margins of both cusps are compared for the presence of any prolapse, which is corrected using free margin plication or resuspension with PTFE. Identification and classification of valve pathology is a cornerstone for the successful application of repair techniques to the aortic valve. Like the mitral valve, repair of the aortic valve requires the correction of cusp disease as well as reduction and/or stabilization of the aortic annulus. The overall aim of the repair procedure is to restore a normal surface, length, and height of coaptation, which is associated with improved long-term outcome.