Mapping the ECG in the live rabbit heart using Ultrasound Current Source Density Imaging with coded excitation

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Electrophysiology

Background:

• Conventional electrical mapping has limitations in treating cardiac arrhythmia and epilepsy.
• Ultrasound current source density imaging (UCSDI) offers noninvasive 4D electrical field mapping but struggles with weak signals at physiological currents.

Purpose of the Study:

• To evaluate coded ultrasound excitation (chirps) for enhancing UCSDI sensitivity.
• To demonstrate the feasibility of mapping electrocardiogram (ECG) signals in a live rabbit heart using improved UCSDI.

Main Methods:

• Utilized coded ultrasound excitation (chirps) instead of square pulses to improve acoustoelectric (AE) signal detection.
• Applied UCSDI with a clinical intracardiac catheter and 1 MHz ultrasound transducer on a live rabbit heart preparation.
• Performed B-mode pulse echo imaging alongside UCSDI.

Main Results:

• Coded chirps improved AE signal detection by up to 6.1 dB compared to square pulses.
• Successfully mapped the ECG in a live rabbit heart preparation.
• Identified regions of high current flow in the heart wall during ECG peaks using UCSDI.

Conclusions:

• Coded ultrasound excitation significantly enhances the sensitivity of UCSDI.
• This improved technique allows for better visualization of cardiac electrical activity.
• These advancements represent crucial steps toward clinical translation for cardiac activation wave mapping.