Optical System for Assessment of Atrial and Ventricular Mechanics in Langendorff-perfused Mouse Hearts

The mouse heart serves as a widely used model in cardiovascular research, facilitated by advances in engineering technologies. However, assessment of atrial and ventricular contractility remains challenging due to the small size of the mouse heart. This study introduces a novel methodology for evaluating contractility and heart rate in an intact, isolated heart. Using a Langendorff-perfused mouse heart in combination with a high-resolution optical system enables evaluation of atrial and ventricular contractility. The experimental setup addresses challenges associated with small heart size and rapid contraction rates while acquiring high-resolution signals. Synchronization between stimulus frequency and heart contraction frequency in the range of 420 to 660 beats per minute (bpm) was consistent with results from the auxotonic method. Additionally, measurements of ventricular shortening and atrial dynamic signals allow for the determination of atrioventricular contraction. This method is suitable for assessing contractility and heart rate in an intact, isolated heart without pharmacological or systemic influences. These results demonstrate that the optical system enables measurement of ventricular and atrial shortening responses.