Experimental Analysis of Transseptal Puncture to Investigate the Mechanical Properties of Fossa Ovalis

Abstract

Background/Objective: Optimization of needle characteristics for trans-septal puncture is of paramount importance to reduce the extent of tissue deformation. This was achieved by studying the mechanical behavior of fossa ovalis (FO) in lamb hearts. The fossa ovalis tissue samples obtained after dissection were subjected to experimental indentation and tensile tests to determine tissue deformation. Methods: Lamb hearts (n = 20) were dissected to obtain fossa ovalis tissue samples. These were subjected to indentation and tensile tests to determine the puncture and rupture forces respectively. Indentation tests were performed using two different indenters: A steel indenter with a hemispherical tip and a Brockenbrough (BRK) needle (bevel tip). Tensile tests were formed using Zwick Roell (Z005) tensile machine at 100 N load cell. ImageJ analysis was also performed to determine the diameter and shape of FO. Results: Indentation results demonstrated that the hemispherical indenter requires a greater punch force compared to the puncture force with the BRK needle. The mean punch force of the hemispherical indenter (15.57 N) was nearly 3 times greater than the puncture force of the BRK needle (5.47 N). Variations between the two indenters provide an insight into the importance of device geometry on trans-septal procedures. The tensile test results illustrated a typical failure pattern with a toe region, linear region, and failure region. The mean rupture force determined was 10.51 N. ImageJ analysis confirmed an oval shape of FO and the diameters measured were in the range 9.0–15.3 mm. Conclusions: The mechanical aspects of fossa ovalis in lamb hearts were successfully studied through a series of experimental indentation and tensile tests. This study serves as a guide to dissecting the challenging FO sample. The procedures for indentation and tensile tests are detailed with common experimental challenges encountered addressed. The correlation of the parameters involved in these experimental tests to the collagen fiber orientation in tissues is also discussed, providing an insight into the deformation of tissues and variations in fiber orientation before and after trans-septal procedures.