Izzat MB and Alkhayat MM. Templates of flat pericardial patterns for precise aortic cusp extension. Asian Cardiovascular & Thoracic Annals 2018; 26: 361–366. DOI: 10.1177/0218492318780482

Abstract

Optimization of complex aortic valve repair procedures calls for simplification and standardization to make the technique reproducible. Considerable effort has already been dedicated towards this goal. For example, we reported recently in The Asian Cardiovascular & Thoracic Annals how the conception of a theoretical geometric model of the intact aortic valve was used to develop new templates for exact cusp extension patches. This geometric model was also used to conceive other original ideas in the aortic valve repair domain, including the design of new cusp sizers and molds to create precise pericardial cusps. The geometric model was founded on the classical descriptions of natural aortic valve geometry by Swanson, Mercer and Thubrikar. Lately, de Korchove and colleagues re-explored natural cusp dimensions in aortic valve homografts, so we were logically keen to validate our theoretical geometric model against this recent anatomical description. At first, we compared basic cusp dimensions in the geometric model (Mod.) with those in the anatomical description (Anat.), and this comparison did not reveal any statistically significant difference in any of four studied dimensions (Mod. vs. Anat. in parentheses): free-margin length (29.5 5.1 vs. 34.3 3.1mm), insertion length (50.0 8.6 vs. 51.0 4.9mm), geometric height (18.1 3.1 vs. 18.9 1.5mm), or coaptation surface (203 68 vs. 184 32mm) (all p1⁄4 ns). Next, in view of the limited number of specimens and the wide spectrum of aortic root diameters in the anatomical description, we proceeded to compare the geometric model with the anatomical description using the “dimensionless” ratios between cusp and root dimensions. Once more, compared ratios were virtually identical in the geometric model and the anatomical description (Math. vs. Anat. in parentheses): ratio of free-margin length to root diameter (1.28 vs. 1.29), ratio of geometric height to root diameter (0.72 vs. 0.71), ratio of commissural height of geometric height (0.97 vs. 1.1), ratio of insertion length to geometric height (2.70 vs. 2.69), and ratio of effective height to geometric height (0.48 vs. 0.45) (all p1⁄4ns). These findings serve to reinforce the validity of the theoretical geometric model in representing the complex geometry of aortic valve components. It is already clear that the sensible approach to advance aortic valve repair techniques is to develop objective reference tools and instruments to clarify the mechanisms of valve malfunction, to facilitate case-specific operative planning, and to guide accurate implementation of selected repair technique. The present findings further support the validity of using our theoretical geometric model as a basis for developing such new approaches to aortic valve repair.