An aortic ring: From physiologic reconstruction of the root to a standardized approach for aortic valve repair

Design Characteristics of a Three-Dimensional Geometric Aortic Valve Annuloplasty Ring

Objective

A full geometric annuloplasty ring could facilitate aortic valve repair. The purpose of this report was to document the design of such a ring using mathematical analyses of normal human aortic valve computed tomographic angiograms.

Methods

One-millimeter axial slices of high-resolution computed tomographic angiograms from 11 normal aortic roots were used to generate high-density x, y, and z coordinates of valve structures in Mathematica. Three-dimensional least squares regression analyses of leaflet-sinus coordinates were used to assess geometry of aortic valve and root structures.

Results

Normal valve geometry could be represented as three leaflet-sinus general ellipsoids nested within an elliptical aortic root. Minor-major diameter ratio of the valve base was 0.60 ± 0.07, and elliptical geometry extended vertically up the commissures. By contrast, leaflet-sinus horizontal circumferences were fairly circular (diameter ratios, 0.82–0.87), and the left coronary/noncoronary commissural post was located at the posterior base minor diameter-circumference junction, with the center of the right coronary leaflet opposite. Post location on the circumference was symmetrical, with a deviation of only ±2% to ±3% from 33.3% symmetry. Commissural posts flared outward by 5 to 10 degrees, and leaflet areas were statistically equivalent ( P > 0.10). From end diastole to midsystole, the aortic root became less elliptical (diameter ratio increased by 0.15), but root area expanded minimally (less than +5%). A one-piece rigid annuloplasty ring was designed with 2:3 base ellipticality, three 10-degree outwardly flaring symmetrical posts, and post height = base circumference/2π.

Conclusions

A three-dimensional aortic annuloplasty ring was designed that could prove useful for enhancing applicability and stability of aortic valve repair.

Aortic valve repair--current status, indications, and outcomes

Aortic valve repair is a new development with old roots. In the past 20 years, marked progress has been made in understanding the normal anatomy of the aortic valve and the interrelation between cusps and root. Aortic dilatation is the single most frequent pathogenetic factor in aortic regurgitation, accompanied by cusp pathology, that is, prolapse or congenital anomaly in most industrialized countries. Frequently, aortic and cusp pathology coexist. Different operative techniques have been established for correction of aortic and cusp pathology. Experience has shown that the combined application of repair procedures will lead to good results if normal valve and cusp configuration is achieved. Some congenital anomalies may require design alteration of the aortic valve. Low-operative mortality rates have been reported consistently. When adequate repair durability is achieved, the incidence of valve-related complications is lower than what has been reported for valve replacement. Aortic valve repair is currently in transition from surgical improvisation to a reproducible operation and an option for many patients with aortic regurgitation. Current research focuses on some special aspects, such as stabilization of the basal ring, ideal material and technique for cusp replacement, and more objective information on ideal valve configuration.

Techniques of Aortic Valve Repair

Similar to mitral repair, newer methods of aortic valve reconstruction are achieving excellent outcomes with an 85% to 90% freedom from valve-related complications at 10 years. The goal of this review is to illustrate these newer and more stable techniques of aortic valve repair. Most patients with aortic insufficiency from either trileaflet or bicuspid aortic valves are candidates for repair, in addition to selected patients with mixed aortic stenosis/insufficiency and aortic root aneurysms. Initially, aggressive commissural annuloplasty is performed to reduce measured valve diameter to 19 to 21 mm. Leaflet prolapse is corrected with plication stitches placed in the free edge of each leaflet adjacent to the Nodulus Arantius. In this regard, the leaflet free edge functions as the chorda tendinea of the aortic valve, and shortening with plication stitches raises the leaflet to a proper “effective height.” Leaflet defects are augmented with gluteraldehyde-fixed autologous pericardium, and mild-to-moderate strategically placed spicules of calcium are removed with the cavitron ultrasonic surgical aspirator. Using these methods, most insufficient aortic valves, and many with mixed lesions, can be satisfactorily repaired. Six cases are illustrated in this review, spanning the spectrum of pathologies from annular dilatation without leaflet defects, to standard congenital bicuspid valve with prolapse, to trileaflet prolapse, to unusual bicuspid pathology with calcification, to a moderately calcified trileaflet valve with mixed lesions, and to aortic root aneurysms with severe aortic insufficiency. All valves were repaired using the techniques described above with trivial residual leak and minimal gradients. All repairs have been followed with yearly echocardiography, and valve reconstruction with these methods is now quite stable with excellent late outcomes. Most insufficient aortic valves now can undergo stable repair with minimal late valve-related complications. Greater application of aortic valve repair seems indicated.

Aortic annuloplasty: towards a standardized approach of conservative aortic valve surgery

Dystrophy represents the most common etiology of aortic insufficiency and aortic root aneurysms in Western countries. Main characteristic lesions of dystrophic aortic roots are the constant dilation of the aortic annular base and sinotubular junction diameters, preventing coaptation of otherwise pliable bicuspid or tricuspid valves. Although these lesions are amenable to conservative aortic valve surgery, mechanical valve replacement remains the surgical standard. The multiplicity of current surgical techniques for conservative aortic valve repair substantiates the need for standardization. Analysis of the literature emphasizes two basic surgical objectives: the treatment of the lesions (dilation of aortic annular base and sinotubular junction) as well as the preservation of aortic root dynamics. From these findings, we suggest a standardized approach for conservative aortic valve surgery meeting both of these principles, based on the implantation of an expansible aortic ring. In the case of aortic root aneurysm, the remodeling technique is combined with a subvalvular external aortic annuloplasty. In the case of isolated aortic insufficiency, a double aortic annuloplasty (sub- and supravalvular) is performed.