Monophasic action potential recordings: which is the recording electrode?

Area of Science:

• Electrophysiology
• Cardiac Electrophysiology
• Biophysics

Background:

• The monophasic action potential (MAP) recording technique is widely used in cardiac electrophysiology.
• There is ongoing debate regarding which electrode (depolarizing or reference) is responsible for recording the MAP waveform.

Purpose of the Study:

• To provide an overview of the current debate surrounding the MAP recording technique.
• To clarify the electrophysiological basis and electrode contributions to the MAP waveform.

Main Methods:

• Literature search using keywords: monophasic action potential, MAP, electrophysiological basis, recording electrode, depolarizing electrode, contact electrode, indifferent electrode, and reference electrode.
• Screening of references from relevant articles for additional papers.

Main Results:

• Conflicting claims exist, with some groups asserting the depolarizing electrode records MAPs, while others emphasize the reference electrode's role.
• Biophysical theory indicates MAPs are bipolar signals, influenced by both the depolarizing and reference electrodes.
• A single electrode cannot record a potential; measurement requires two points.

Conclusions:

• The MAP technique remains valuable for assessing local myocardial electrical activity near the depolarizing electrode.
• Minimizing distance between recording and reference electrodes is crucial to reduce far-field signal contamination.
• Understanding MAPs as bipolar signals enhances interpretation of cardiac electrophysiological data.