The prerequisite of development of pulmonary barotrauma [PB] is retention of the breathing mix in the lungs during a sudden decrease in external pressure or its administration into the airways under increased pressure or in a volume exceeding the maximum lung capacity. In such cases, the pulmonary parenchyma ruptures and air enters both the pleural cavity and/or the lumen of ruptured blood vessels located in the alveolar septa. The result is permanent disruption of the pulmonary parenchyma. The aim of the study was to assess the influence of post-PB lesions on the heart muscle and the importance of hyperbaric treatment on the exacerbation of such lesions in the heart. The hearts of 35 rabbits were used in the study. In animals of the experimental group, PB was induced in the pressure chamber using the proprietary method described in previous publications. Part of the animals in this group were treated with air hyperbaria. The comparison group consisted of animals, which did not undergo PB during a simulated dive. All animals were weighed, observed for four weeks and then put to death following the experiment. In autopsy, among others, whole hearts were collected and weighed after fixation. Subsequently, the C/S ratio, i.e. the body to heart weight ratio, was calculated. The measurement results were subject to statistical analysis. A statistically significant increase in the C/S ratio was found, indicating an increase in the share of heart weight in the total body weight in the group of animals with PB not treated with air hyperbaria as compared to the control group.