The influence of fixation on the cardiac tissue in a 1-year observation of swine hearts.

AIM: The aim of this study was to investigate the influence of formaldehyde-based fixation on dimension, weight and shape of cardiac tissue during a 1-year observation.

MATERIALS AND METHODS: Seven measuring sites were permanently marked in 40 swine hearts prior to fixation. Four study groups (n = 10 each) were assembled that differed only in concentration and the type of fixative. The fixatives were 2%, 4% or 10% formaldehyde phosphate-buffered solution (FPBS) and alcoholic formalin. The samples were measured before fixation and then after fixation at 1 week, 3, 6 and 12 months.

RESULTS: At the 3-month point, the 10% FPBS had caused significant changes in the smallest number of parameters, while the 2% FPBS affected the greatest number of dimensions. The most significant changes included chordae tendineae shrinkage and an increase in muscle thickness. After 6 months, the most significant changes were observed in 2% and 4% FPBSs and were also mainly associated with an increase in muscle thickness and chordae tendineae shrinkage. 1-year preservation compared to the baseline showed the most significant changes in muscle tissue thickness and hearth weight. The artery diameter decreased in long-term fixation in every tested solution. For atrial and angle measurements, 4% FPBS caused most significant changes among investigated fixatives.

CONCLUSIONS: In all tested solutions, long-term fixation significantly changed cardiac tissue dimension compared to the nonpreserved samples. Short-term to 1-year fixation changes are smaller, but they should not be neglected. Different fixatives should be used depending on the character of the planned measurements.