Single camera system for multi-wavelength fluorescent imaging in the heart.

Area of Science:

• Cardiovascular Physiology
• Biomedical Optics
• Fluorescence Imaging

Background:

• Optical mapping is crucial for studying cardiac electrophysiology, measuring parameters like membrane potential and calcium dynamics.
• Current dual-camera systems are limited to measuring only two parameters simultaneously.
• A need exists for advanced optical mapping capable of measuring more than three parameters.

Purpose of the Study:

• To develop and validate a novel optical mapping system for simultaneous measurement of multiple cardiac electrophysiological parameters using a single camera.
• To overcome the limitations of existing dual-camera systems in multi-parameter measurements.
• To enhance the capabilities of fluorescence imaging in cardiac research.

Main Methods:

• A custom optical system with specialized lens units and a filter wheel was designed for a single camera.
• The system synchronizes camera exposure and filter switching using a phase-locked loop for frame-by-frame alternate recording.
• High-quality optical signals were ensured through careful design, achieving specific numerical apertures (NA 0.1 object space, NA 0.23 image space).

Main Results:

• The system successfully recorded membrane potential (V(m)) and intracellular calcium (Ca(2+)) dynamics simultaneously at 125fps in a Langendorff-perfused rabbit heart.
• Observed planar waves and synchronized V(m) and Ca(2+) upstrokes with basic pacing.
• Demonstrated efficacy in recording V(m) and Ca(2+) signals during induced ventricular fibrillation.

Conclusions:

• The developed single-camera optical mapping system enables simultaneous measurement of multiple cardiac electrophysiological parameters.
• This innovative method significantly advances the potential of fluorescence imaging for comprehensive cardiac research.
• The system's efficacy and availability are validated for studying complex electrophysiological phenomena.