Functional aortic annulus remodelling—revisited

The importance of functional aortic annulus (FAA) stabilization by combining annulus and sinotubular junction (STJ) stabilization has been widely discussed lately. A recently published study from Benhassen and colleagues tackles this topic with an experimental pulsatile in vitro model. The authors compared the geometrical and dynamic properties of single- and double-ring annuloplasties in a porcine aortic root model [1]. The study showed that both single- and double-ring annuloplasties downsized the aortic annulus and STJ. Additionally, the double-ring annuloplasty showed a more significant increase in coaptation height [8.5 (±0.9) vs 9.8 (±0.8) mm, P < 0.01]. The authors observed the greatest force reduction when both annuli—the entire FAA—were addressed. How does it translate into clinical practice? First, these findings align with what has already been observed regarding repair durability, confirming the importance of FAA-directed repair. Shraer et al. [2] from the Lansac group found that simultaneous stabilization of both elements of FAA is more durable than the subvalvular annuloplasty alone. Summarized 17 years of experience bicuspid aortic valve repair study from our group also showed the superiority of addressing both annuli, aortic with external annuloplasty and STJ by its remodelling with graft, in terms of repair durability with freedom from reoperation of 91.8% at 7 years [3]. The second important aspect of the paper is the influence of annular stabilization on radial forces distribution. The authors found that aortic annuloplasty reduces those forces by ameliorating and absorbing the stress, especially when STJ stabilization is also performed. It may further support the idea of solid STJ annuloplasty by either a ring or aortic prosthesis implantation. In a finite elements study using computed tomography angiography, we observed a significant wall tension force increase at the STJ level in the pre-dissection stage [4]. However, stabilizing the aortic root scaffold between both planes may require supporting its vertical axis to ameliorate longitudinal stress distribution. The longitudinal stress might be associated with the outcome of the aortic aneurysm, as recently demonstrated by Zamirpour et al. [5]. Interestingly, the internal annuloplasty HAART ring, due to its 3D structure, has the potential to absorb and minimize the stress forces in a longitudinal direction as well [6]. Therefore, It could be essential to look at longitudinal stress force distribution to get additional insight into the biophysical behaviour of the aortic root after annuloplasty. We congratulate the authors for the excelent study and vital contribution to improving repair longevity. Conflict of interest: Marek J. Jasinski: Corcym and Medtronic.