eComment. Are autologous pericardial valves ideal for valve tissue construction?

We congratulate Liu and colleagues for their admirable efforts in treating patients with autologous pericardial aortic valve (APAV) replacement [1]. The subject is not new, however, there is not enough research in the field of constructing or identifying an ideal tissue for valve reconstruction. Anticoagulant-related complications of the mechanical prosthesis is still a major problem adversely affecting long-term patient outcomes. Patient-prosthesis mismatch is another concern in the paediatric population. In addition, although bioprosthetic solutions for valve disease achieve superior initial haemodynamic results, reoperations are observed as an inevitable result of bioprosthesis degeneration due to self and non-self interactions between the host immune system and implanted tissue. Therefore, as authors mentioned, it is necessary to find a way to identify or construct self or non-antigenic tissue to solve the problem, especially in the paediatric population [1]. We think that the results are good enough when compared to current solutions, including mechanical or bioprosthetic valve replacement therapies. However, to our knowledge, the most important result of this study is the 'endothelization' of APAVs demonstrated with immunohistochemistry staining in 4 patients and 'band of elastic tissue' demonstrated in APAVs in group 2 with Van Gieson's stainings. We should focus on endothelization of the surface of the APAV, which is 89% in patient 5, and 22 and 26% in patients 3 and 4, respectively. The factors related to a high percentage of endothelization in patient 5 such as medications, lifestyle etc. and factors preventing further endothelization in patients 3 and 4 should be studied in detail. Formation of elastic tissue bands, which normally does not occur in pericardial tissue but in native aortic valve is worth attention, and is another subject demanding further investigation. The authors mentioned that Gross et al. [2] reported disappointing results in a series of 87 patients, however the 'material and methods' is not the same as in this report. Gross et al. used 0.625% glutaraldehyde to fix the autologous pericardium before mounting the fixed pericardium on a stent whereas Liu et al. [1] used a 0.2% glutaraldehyde solution to fix the autologous pericardium without mounting on a stent. This point is quite important because stents cause additional transvalvular gradients, which may result in early degeneration of the stented autologous pericardium. We can speculate that these disappointing results were a result of this major difference between the studies. The number of current studies providing encouraging results outweigh studies with poor outcomes [3–5]. For the further development in the field of autologous pericardial valve reconstruction, it is necessary to conduct new studies and make up for the shortcomings of autologous pericardial valve construction techniques, first described by Duran [4]. In conclusion, it is a valuable study. We, the readers, thank the authors for sharing knowledge and experience gained from their research. Conflict of interest: none declared