Reply to Anderson and Mori

Aortic annulus and the importance of annuloplasty

Dystrophic aortic insufficiency accounts for the majority of Western cases of aortic insufficiency and can be divided into the three phenotypes of isolated aortic insufficiency, dilated aortic root, and dilated ascending aorta. Each of these phenotypes is associated with a dilated annulus and/or sinotubular junction. Recent international guidelines recommend reimplantation or remodeling with aortic annuloplasty for valve-sparing root replacement, as well as consideration of aortic valve repair in cases of aortic insufficiency. A dilated aortic annulus is a major risk factor for failure of aortic valve repair procedures, indicating the need to address the annulus at the time of aortic valve or root repair. Calibrated annuloplasty should be performed at sub- and supravalular levels in order to restore the ratio of the sinotubular junction and annulus and be adapted according to the phenotype of the root and ascending aorta. Standardization of aortic valve repair techniques with use of a calibrated annuloplasty will improve dissemination of techniques and rate of aortic valve repair. Current medical evidence shows that aortic valve repair is safe, produces better quality of life, and reduces valve-related mortality compared to prosthetic valve replacement.

Surgical anatomy of the aortic valve and root-implications for valve repair

The aortic root is an important anatomical structure positioned at the center of the heart, making it critical to the functioning of the major cardiac chambers. Deep knowledge of the anatomical "surroundings" of the aortic root is crucial for surgeon attempting to spare or repair a leaking aortic valve. In fact, root dissection is a necessary step to "skeletonize" the aortic valve, allowing the surgeon to work on the critical components of its structure, namely the aorto-ventricular junction, the virtual basal ring (VBR) and the sino-tubular junction (STJ). These three components, along with the insertion of the leaflet to the aortic wall, form the skeleton of the aortic valve that is essential in guaranteeing valve competence. A good anatomical proportion between the various component of the skeleton of the aortic valve need to be verified, or re-established in order to set the basis for an optimal aortic valve repair. Once the skeleton of the heart has been correctly addressed, the condition of the valve leaflets need to be considered. Excess of leaflet tissue is treated by leaflet plication or resection and lack of leaflet tissue is addressed by tissue extension with autologous or heterologous materials. In the present manuscript, we highlight the principal structure of the aortic root and describe in detail each anatomical component. This basic anatomical knowledge is also important for a through understanding of the normal function of the valve and root structure during the cardiac cycle. The close boundaries existing between the left ventricular cavity and the aorta are important in explaining the sophisticated function of opening and closing of the aortic valve. Similarly, the role played by the sinuses of Valsalva in regulating the blood flow exiting the ventricle underline the concept that "form follows function" and emphasizes the importance of a good anatomical reconstruction for an optimal and long-lasting valve function.

Rationale for aortic annuloplasty to standardise aortic valve repair

Available evidence shows that aortic valve repair reduces valve-related mortality and improves quality of life compared to prosthetic aortic valve replacement. One of the most important predictors of bicuspid and tricuspid aortic valve repair failure is the absence of treating a dilated aortic annulus greater than 25-28 mm. Competency of the aortic valve depends on multiple factors including the diameter of the annulus, sinotubular junction, valve cusps and commissures. Dystrophic aortic insufficiency (AI) is the commonest cause of AI in the Western world and is characterised by dilatation of the aortic annulus (≥25 mm), sinuses and/or sinotubular junction (≥30 mm). Depending on whether the sinuses of Valsalva and/or tubular ascending aorta are dilated, three phenotypes can be identified: dilated aortic root, dilated ascending aorta and isolated AI. All three phenotypes are associated with a dilated aortic annulus. Aortic annuloplasty reduces the dilated aortic annulus and improves the surface of coaptation, as in the case of mitral valve repair. In treating AI, it is also important to restore the physiological sinotubular junction/annulus ratio, which can be carried out with remodeling root repair + subvalvular annuloplasty (for dilated aortic root), tubular ascending aorta replacement + subvalvular annuloplasty (for dilated ascending aorta) and double sub- and supra-valvular annuloplasty (for isolated AI). Aortic annuloplasty is now considered an essential component of aortic valve repair and valve-sparing root surgery.