Constructing Adult Zebrafish Einthoven's Triangle to Define Electrical Heart Axes

Area of Science:

• Cardiovascular Physiology
• Comparative Electrophysiology
• Zebrafish as a Model Organism

Background:

• Zebrafish are widely used for studying human cardiac electrophysiology, arrhythmias, and myopathies.
• Similarities between zebrafish and human electrocardiograms (ECGs) support their use as a model.
• However, zebrafish electrical heart axes remained undetermined, limiting comparative analysis.

Purpose of the Study:

• To systematically construct the first zebrafish Einthoven's triangle.
• To determine the frontal electrical heart axes of adult zebrafish using the Cabrera system.
• To compare zebrafish and human cardiac electrical axes and underlying mechanisms.

Main Methods:

• Simultaneous bipolar dual-lead ECG recording in live adult zebrafish.
• Construction of the Einthoven's triangle using recorded ECG leads.
• Application of the hexaxial reference system (Cabrera system) to determine frontal electrical axes.

Main Results:

• The first zebrafish Einthoven's triangle was successfully constructed.
• Zebrafish and human normal frontal electrical axes were found to be reflections across 0° in the Cabrera system.
• Differences in axes are attributed to opposite propagation directions along the heart's longitudinal axis during activation and repolarization.

Conclusions:

• This study provides the first determination of zebrafish frontal electrical heart axes.
• Established differences and similarities offer critical context for using zebrafish as a model for human cardiac electrophysiology.
• Findings enhance the understanding of zebrafish cardiac axis mechanisms and their relevance to human studies.