Transthoracic echocardiography in healthy Diannan small-ear pigs.

BACKGROUND: Pigs are widely used as large animal models in cardiovascular research. Establishing breed-specific physiological reference values is essential for experimental design and data interpretation. METHOD: Cardiac chamber dimensions, great vessel diameters, and hemodynamic parameters were systematically evaluated by transthoracic echocardiography (TTE) in 31 healthy Diannan small-ear pigs (mean weight: 47.2 ± 17.2 kg; 15 males, 16 females). Key structural indices were compared with human reference values. Animals were divided into three weight groups: 20-39 kg, 40-59 kg, and 60-80 kg. RESULTS: Left and right atrial and ventricular diameters and volumes, as well as aortic and pulmonary artery diameters, increased significantly with body weight (P < 0.05) but remained smaller than human reference ranges (P < 0.05). Left ventricular wall thickness exceeded human values (P < 0.05), indicating a "small-cavity, thick-wall" structural phenotype. Left ventricular ejection fraction (LVEF) did not differ significantly from human values but decreased slightly in higher weight groups. Left ventricular diastolic function (E/e') and right ventricular systolic indices (fractional area change [FAC]) showed distinct weight-dependent patterns. Sex did not significantly affect any echocardiographic parameters. CONCLUSION: Weight-associated variations reflect physiological cardiovascular development in Diannan small-ear pigs. This study provides baseline non-invasive echocardiographic data for this breed under isoflurane anesthesia. These data offer essential reference values for cardiovascular disease modeling, xenotransplant donor screening, and pre-operative assessment of novel cardiovascular technologies.