Action Potential & Automaticity – The Premier EKG Resource for Medical Professionals

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LECTURES:
1. Action Potential & Automaticity
2. Complete ECG Course
3. The EKG Guy Videos

Action Potential = depolarization (activation) + repolarization (recovery)

Occurs in all cardiomyocytes, but varies in cell type
Flow of electrically charged ions => electrical current + electrical conductors (ie, surrounding fluids & tissues) => electrodes => ECG
Note: Electrical potential of conducting system is too small to be detected; therefore, only atrial & ventricular activity recorded

Sinoatrial node:

Automaticity = ability of specialized cardiac cells to achieve spontaneous depolarization & function as “pacemakers” to form new cardiac-activating impulses
Pacemaker potential (4) = Na+ influx at resting state
…Na+ influx (4) => AP near -40 mV + Ca2+ influx + depolarization (0) => K+ efflux => repolarization (3)…
AP propagates via gap junctions

Contractile myocyte:

True resting potential (4) & thus must be stimulated
…K+ efflux (resting state, -90 mV) => cell stimulated => rapid Na+ influx => depolarization (0) => K+ efflux => early repolarization (1) => Ca2+ influx => plateau phase (2) => Ca2+ channels close + K+ efflux => repolarization (3)…
Total AP duration: atria ~200 ms; ventricles ~300 ms
Absolute refractory period: no stimulus can trigger new action potential
Relative refractory period: strong stimulus can trigger new action potential

Categories:

EKG A To Z EKG Middle1 Left

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DID YOU KNOW?

Dr. Anthony Kashou (The EKG Guy) is a physician resident at the Mayo Clinic in Rochester, Minnesota. He is on a mission to transform ECG education and filling the gap exists around the world. Dr. Kashou has taught and developed curriculum for medical students, including 500+ lectures and 100+ hours of adult and pediatric ECG lessons.

At the Mayo Clinic, he pursues innovative ECG research and was awarded first place for his research at the Minnesota American College of Cardiology Conference 2018. His passion for medical education and innovation led to the development of EKG.MD, which provides a convenient and accessible forum to learn the fundamentals and foundations of ECG interpretation. He has also authored dozens of peer-reviewed articles for medical journals and textbooks, along with multiple ECG books for learners at all levels.

Dr. Kashou continues to lead and teach weekly ECG sessions and weekend seminars for residents, nurses, ECG interpreting technicians, and physician assistants at the Mayo Clinic. He has been asked and is currently developing an ECG board review course for cardiology fellows. He has an online following of over 275,000 individuals and is the founder of the largest, fastest growing ECG community in the world. His clinical research focuses on developing innovative ECG algorithms that can be integrated and implemented into clinical practice.

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