Imaging electrical excitation inside the myocardial wall

Area of Science:

• Biomedical optics
• Cardiovascular research
• Electrophysiology

Background:

• Cardiac arrhythmias can originate from ectopic electrical activity deep within the myocardium.
• Accurate localization of these deep sources is challenging with current methods.
• Voltage-sensitive dyes offer potential for mapping cardiac electrical activity.

Purpose of the Study:

• To develop and validate a novel method for determining the 3D coordinates of deep myocardial depolarization sources.
• To utilize a new near-infrared voltage-sensitive fluorescent dye, DI-4-ANBDQBS, for this purpose.
• To assess the accuracy and depth-independence of the method in myocardial tissue.

Main Methods:

• An alternating transillumination approach was employed, comparing epifluorescence and transillumination images.
• Two CCD cameras recorded simultaneous images from endocardial and epicardial surfaces at high frame rates (up to 3 KHz).
• The method was tested on live pig ventricular myocardium (8-18 mm thickness) and optical phantoms.

Main Results:

• The 3D coordinates of depolarization sources were localized with a precision of ±1.3 mm (transmural) and 3 mm (in-plane).
• The accuracy of source detection was independent of its depth within the ventricular wall.
• Successful localization was demonstrated in thick myocardial preparations.

Conclusions:

• The developed near-infrared voltage-sensitive dye and imaging method can accurately localize deep ectopic depolarization sources in the 3D myocardium.
• This technique holds promise for improving the understanding and diagnosis of cardiac arrhythmias.
• The depth-independent accuracy makes it suitable for thick cardiac tissue applications.