Heart and EKG Overview

  • Introduction to the Heart

    • Focusing on the heart after discussing the brain, as both are vital for living organisms.

  • Electrocardiogram (EKG/ECG)

    • EKG is a key diagnostic tool used to examine heart activity through electrical leads placed on the body.
    • Leads:
    • Commonly used leads:
      • Lead I: between the right arm and left arm.
      • Lead II: from the right arm to the left leg.
      • Lead III: between left leg and left arm.
    • These leads are bipolar, meaning they measure the electrical potential between two points.
    • EKGs can have up to 12 leads for comprehensive heart monitoring.

  • Heart's Electrical Activity

    • The heart acts as a volume conductor due to the presence of water and ions, facilitating electrical conduction.
    • Depolarization and repolarization of heart tissue are crucial for heart function.

  • Electrical Pathway of the Heart

    • Depolarization normally initiates at the Sinoatrial (SA) node, followed by the Atrioventricular (AV) node, and then spreading to the Purkinje fibers.
    • Direction of electrical activity: from right to left and downwards.
    • Electrical Axis: An arrow representation indicating heart activity direction.

  • Phases of Cardiac Cycle on EKG

    • Phases represented include:
    • P Wave: Atrial depolarization.
    • QRS Complex: Ventricular depolarization; significantly larger due to larger muscle mass.
    • T Wave: Ventricular repolarization.
    • Atrial repolarization occurs simultaneously during the QRS complex but is not visible due to lesser mass and activity.

  • Cardiac Events

    • The sound of the heart can be related to electrical events and blood flow.
    • Heart Sounds:
      • Sound 1 corresponds to closing of AV valves after ventricles contract.
      • Sound 2 occurs when semilunar valves close as ventricles relax, preventing blood backflow.

  • Heart Rhythm Issues

    • Heart problems can include:
    • Atrioventricular (AV) Block: Missed P wave signals or abnormal electric conduction.
    • Ventricular Fibrillation: Erratic electrical activity throughout the ventricles leading to inefficient pumping and necessitating defibrillation for restoring normal rhythm.

  • Conclusion

    • Understanding these concepts helps in diagnosing and treating cardiovascular issues.
    • Upcoming learning will progress to new topics in cardiac physiology or similar areas.