Left Ventricle Velocity Patterns and Energy Changes During Controlled External Impact: A Quantitative Experimental Insight.

PURPOSE: While motor vehicle crashes are a leading cause of death, blunt chest injuries represent a major component of these fatalities. In-vitro experiments provide a reproducible and ethically acceptable approach to replicating blunt chest trauma scenarios. This paper quantifies the effect of low-velocity impacts at different timings of the cardiac cycle on the acute hemodynamic response and energy levels inside models of the left ventricle (LV) and the aorta.

METHODS

A left heart simulator incorporating a transparent silicone LV was used in this study. The LV was submerged in a water-glycerol mixture, which also served as the circulating working fluid, flowing through the left atrium, into the LV and the aorta. Bioprosthetic valves were used in both the mitral and aortic positions. Two linear motors were employed to simulate LV contraction and externally imposed impact at five different timings within the cardiac cycle. Particle Image Velocimetry (PIV) was used to track seeded particles in the fluid, enabling reconstruction of the velocity field and quantification of energy dissipation in the LV and aorta.

RESULTS

The LV velocity field was altered in all cases except during early systolic impact. We observed that vorticity decreased most prominently during late systolic impact, while viscous energy dissipation (VED) increased in all cases at the moment of impact. In the aorta, we observed that flow velocity, flow rate, kinetic energy (KE), and VED increased primarily during systolic impact conditions.

CONCLUSION

These findings demonstrate that the biomechanical response of the heart is phase-dependent, and that even short, sub-physiological impacts can induce flow disturbances.