INTRODUCTION
For patients with isolated aortic valve insufficiency and aortic annulus dilatation, aortic valve repair has proven superior to conventional valve replacement [1, 2]. A risk factor for recurrent aortic insufficiency after aortic valve repair is a dilated aortic annulus >25 mm that is not stabilized with a subvalvular annuloplasty ring [3–5]. When a subvalvular annuloplasty ring is used in aortic valve repair, it reduces annulus diameter, increases coaptation height and enhances freedom from recurrent aortic insufficiency [6–8]. The severity of aortic insufficiency has been related to the degree of dilatation at the level of the aortic annulus but also the sinotubular junction (STJ) [4]. When a dilatation occurs at the aortic annulus or STJ, the normal STJ/annulus ratio is distorted and entails reduced cusp coaptation and subsequently aortic insufficiency. Lansac et al. [3] have shown that a double annuloplasty ring procedure with an annuloplasty ring at both the aortic annulus and STJ tends to reduce the degree of recurrent aortic insufficiency compared with a single annuloplasty ring at the aortic annulus. This approach supports the concept of considering the aortic root as a functional aortic unit, referred to as the functional aortic annulus [9], where all structural components must be addressed to achieve optimal results after aortic valve repair.
Several aortic annuloplasty rings exist for aortic valve repair. The 2 most commonly used are the polytetrafluoroethylene suture annuloplasty and the Dacron ring obtained from a Dacron tube graft (Vascutek, Terumo, Japan). Both the Dacron ring and the suture annuloplasty have shown good results with and without the remodelling procedure [3, 10–12]. Some concerns exist regarding the expansibility of the Dacron ring, because the Dacron tube graft material is thought to have a limited capacity of radial expansion. The suture annuloplasty is considered to be more compliant than the Dacron ring, but the placement of the suture annuloplasty is less standardized.
To enhance the understanding of the mechanisms behind a potentially more durable aortic root repair, a systematic, reproducible and controllable investigation must be performed to compare the biomechanical properties of the single-ring versus the double-ring repair procedure.
We hypothesized that the double annuloplasty ring procedure stabilizes the entire aortic root more than the single annuloplasty procedure with preserved expansibility, and reduced stresses in all segments of the STJ.
Hence, the aim of this porcine in vivo study was to compare:
The segmental force distribution in the aortic annulus and STJ after the single-ring and double-ring procedures.
The overall dimensions, shape and segmental expansion of the aortic annulus and STJ after the single-ring and double-ring procedures.