Simultaneous measurement and modulation of multiple physiological parameters in the isolated heart using optical...

Area of Science:

• Cardiovascular physiology
• Optical imaging techniques
• Biomedical engineering

Background:

• Whole-heart multi-parametric optical mapping offers insights into cardiac electrophysiology.
• Advancements in voltage-sensitive dyes and imaging technology are crucial for progress.

Purpose of the Study:

• To demonstrate the utility of 2nd-generation voltage dyes for improved cardiac mapping.
• To present a simple solution for panoramic multi-parametric mapping of the whole heart.
• To illustrate the application of flash photolysis of caged compounds for localized cardiac studies.

Main Methods:

• Utilized isolated rat whole-heart model for proof-of-principle studies.
• Characterized isosbestic points of novel voltage dyes (di-4-ANBDQBS, di-4-ANBDQPQ).
• Developed dual-wavelength and three-parameter mapping systems using custom optical filters and single-camera setups.
• Implemented panoramic mapping with off-the-shelf optics.
• Demonstrated localized perturbation of calcium dynamics using caged NP-EGTA and UV LED flash photolysis.

Main Results:

• Successfully mapped voltage and calcium dynamics using new dye combinations (di-4-ANBDQBS/fluo-4, di-4-ANBDQPQ/rhod-2).
• Achieved three-parameter mapping (voltage, calcium, NADH) with di-4-ANBDQPQ, rhod-2, and NADH.
• Demonstrated 360° spatiotemporal panoramic mapping of cardiac activity.
• Confirmed successful NP-EGTA loading and localized flash photolysis, altering calcium dynamics.

Conclusions:

• Developed scalable, single-view and panoramic techniques for multi-parametric optical mapping of the whole heart.
• Showcased the effectiveness of 2nd-generation voltage dyes in enhancing cardiac electrophysiological studies.
• Established a method for localized optical perturbation of cardiac electrophysiological parameters using caged compounds and UV LEDs.