Biogenic polymer-based patches for congenital cardiac surgery: a feasibility study

Emma Richert; Andrea Nienhaus; Silje Ekroll Jahren; Amiq Gazdhar; Maximilian Grab; Jürgen Hörer; Thierry Carrel; Dominik Obrist; Paul Philipp Heinisch

doi:10.3389/fcvm.2023.1164285

Biogenic polymer-based patches for congenital cardiac surgery: a feasibility study

Front Cardiovasc Med. 2023 Jun 22:10:1164285. doi: 10.3389/fcvm.2023.1164285. eCollection 2023.

Authors

Emma Richert^#^{1

2}, Andrea Nienhaus^#³, Silje Ekroll Jahren³, Amiq Gazdhar⁴, Maximilian Grab⁵, Jürgen Hörer^{1

2}, Thierry Carrel⁶, Dominik Obrist³, Paul Philipp Heinisch^{1

2}

Affiliations

¹ Department of Congenital and Paediatric Heart Surgery, German Heart Centre Munich, Technische Universität München, Munich, Germany.
² Division of Congenital and Pediatric Heart Surgery, University Hospital of Munich, Ludwig-Maximilians-Universität, Munich, Germany.
³ ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland.
⁴ Department of Biomedical Research, University of Bern, Bern, Switzerland.
⁵ Department of Cardiac Surgery, Ludwig-Maximilian University, Munich, Germany.
⁶ Department of Cardiac Surgery, University Hospital, Zürich, Switzerland.

^# Contributed equally.

Abstract

Objective: Currently used patch materials in congenital cardiac surgery do not grow, renew, or remodel. Patch calcification occurs more rapidly in pediatric patients eventually leading to reoperations. Bacterial cellulose (BC) as a biogenic polymer offers high tensile strength, biocompatibility, and hemocompatibility. Thus, we further investigated the biomechanical properties of BC for use as patch material.

Methods: The BC-producing bacteria Acetobacter xylinum were cultured in different environments to investigate optimal culturing conditions. For mechanical characterization, an established method of inflation for biaxial testing was used. The applied static pressure and deflection height of the BC patch were measured. Furthermore, a displacement and strain distribution analysis was performed and compared to a standard xenograft pericardial patch.

Results: The examination of the culturing conditions revealed that the BC became homogenous and stable when cultivated at 29°C, 60% oxygen concentration, and culturing medium exchange every third day for a total culturing period of 12 days. The estimated elastic modulus of the BC patches ranged from 200 to 530 MPa compared to 230 MPa for the pericardial patch. The strain distributions, calculated from preloaded (2 mmHg) to 80 mmHg inflation, show BC patch strains ranging between 0.6% and 4%, which was comparable to the pericardial patch. However, the pressure at rupture and peak deflection height varied greatly, ranging from 67 to around 200 mmHg and 0.96 to 5.28 mm, respectively. The same patch thickness does not automatically result in the same material properties indicating that the manufacturing conditions have a significant impact on durability.

Conclusions: BC patches can achieve comparable results to pericardial patches in terms of strain behavior as well as in the maximum applied pressure that can be withstood without rupture. Bacterial cellulose patches could be a promising material worth further research.

Keywords: biogenic polymers; biomedical engineering; congenital; innovation; patch.