Effects of the Left Ventricular Mechanics on Left Ventricular-Aortic Interaction: Insights from Ex Vivo Beating Rat Heart Experiments

The interaction between the left ventricle (LV) and aorta is critical for cardiovascular performance, particularly under pathophysiological conditions. However, how changes in LV mechanics, including preload and afterload, affect aortic function via LV–aorta interactions remains poorly understood due to the challenges associated with varying loading conditions in vivo. To overcome these limitations, the effects of varying LV preload or afterload on LV and aortic functions via LV–aorta interactions are quantified using ex vivo beating rat heart experiments in this study. In five healthy rat hearts under retrograde Langendorff and antegrade working heart perfusion, LV pressure, volume, aortic pressure, and aortic blood flow were measured. Key findings include the following: (1) under Langendorff perfusion, aortic flow increased linearly with LV developed pressure (DP), with a slope of 4.04 mmHg·min/mL; under working heart constant-pressure perfusion (2) a 12.4% increase in afterload decreased aortic flow by 58.8%, indicating that elevated aortic pressure significantly impedes aortic flow; (3) a 10.4% increase in preload enhanced aortic flow by 44.2%, driven primarily by an increase in LV DP that promoted forward flow. These results suggest that aortic pressure predominantly influences aortic flow under varying afterload conditions, whereas LV DP plays the dominant role in regulating aortic flow under different preload conditions. These findings demonstrate that the heart’s loading conditions strongly impact aortic blood flow. Specifically, elevated LV afterload can severely limit forward blood flow, while increased LV filling with increased LV preload can enhance blood flow, highlighting the importance of managing both afterload and preload in conditions such as hypertension and heart failure with preserved ejection fraction. This pilot study also established the feasibility of experimental platforms for coronary and ventricular function analysis.