Addressing Key Limitations of Diastolic Function Assessment in Mouse Echocardiography by Enabling Robust...

Area of Science:

• Cardiovascular Research
• Echocardiography
• Murine Models

Background:

• Echocardiographic assessment of diastolic function in mice is challenging due to physiological constraints.
• Early (E) and late (A) transmitral filling velocities are often compromised by wave fusion at high heart rates.

Purpose of the Study:

• To quantify limitations of standard echocardiographic parameters in murine diastolic function.
• To evaluate a novel non-A4C-view-dependent echocardiographic measurement (NAEM) approach for assessing isovolumetric relaxation time (IVRT).

Main Methods:

• Developed a NAEM approach using speckle-tracking analysis of B-mode cine loops from the parasternal long-axis view (PSLAX).
• Assessed E/A ratio and IVRT in mice with normal function, HFpEF, and HFrEF (n=8 each) using both standard Doppler and NAEM methods.

Main Results:

• Wave fusion occurred around 460 bpm in normal and HFpEF mice; HFrEF showed fusion independent of heart rate.
• NAEM-derived IVRT strongly agreed with Doppler reference (r²=0.9339, p<0.0001) with minimal bias.
• NAEM-derived E/A ratio did not perform adequately.

Conclusions:

• The NAEM approach validates IVRT measurement in murine echocardiography without Doppler.
• This method simplifies diastolic function assessment, reducing technical barriers for future studies.
• Enables robust retrospective analysis of existing echocardiographic datasets.