Layer-specific strain analysis by speckle tracking echocardiography reveals differences in left ventricular function...

Area of Science:

• Cardiology
• Translational Medicine
• Echocardiography

Background:

• The rat heart is a widely used experimental model for human cardiac function.
• Echocardiography in rats typically involves sedation, unlike in humans, raising questions about the direct comparability of cardiac function data.
• Differences in left ventricular (LV) function between sedated rats and alert humans may exist due to anesthetic effects.

Purpose of the Study:

• To investigate potential differences in LV function between healthy sedated rats and healthy alert humans using echocardiography.
• To determine which echocardiographic parameters of cardiac function are comparable between these two groups, despite sedation in rats.

Main Methods:

• Echocardiography was performed on 110 healthy sedated rats (ketamine-xylazine) and 120 healthy alert humans.
• Layer-specific speckle tracking echocardiography was used to calculate strain parameters.
• Analysis included layer and segmental strain, LV twist, and torsion-to-shortening ratio.

Main Results:

• Layer longitudinal strain and LV twist were found to be equal between sedated rats and alert humans.
• Segmental strain and radial strain showed significant heterogeneity in rats compared to humans.
• Layer circumferential strain was greater in humans, and LV rotation differed at the apex and base in rats.
• The torsion-to-shortening ratio was equal in both groups.

Conclusions:

• Global longitudinal strain, LV twist, and torsion-to-shortening ratio are comparable between sedated rats and alert humans.
• These specific parameters can be reliably inferred from sedated rat models to humans without scaling adjustments.
• Findings support the use of these parameters in translational studies using ketamine-xylazine sedated rats as a model for human cardiac function.