Basics of EKG and Heart Anatomy

EKG (Electrocardiogram)

Reflects electrical activity of the heart, not mechanical.

Polarization

Heart cells are at rest ('ready' state).

Depolarization

Heart cells discharge electricity ('discharge' state).

Repolarization

Heart cells recover ('recovery' state).

Sinus Node

60-100 bpm (primary pacemaker).

AV Junction

40-60 bpm (backup pacemaker).

Ventricles

20-40 bpm (last resort pacemaker).

Pacemaker Rules

The site with the fastest rate usually controls the heart.

Endocardium

Contains parts of the heart's electrical conduction system.

Myocardium

Made of cardiac muscle fibers; responsible for contraction.

Epicardium

Outer layer; contains nerves and coronary vessels.

A-V Valves

Tricuspid and Mitral (Bicuspid).

Semilunar Valves

Pulmonic and Aortic.

Systole

Contraction phase.

Diastole

Relaxation phase.

Electricity toward a positive electrode

Upright pattern.

Electricity toward a negative electrode

Inverted pattern.

Correct placement of electrodes

Crucial for accurate monitoring (e.g., Lead II).

Regularity in Rhythm Analysis

Check if rhythm is regular or irregular.

Types of Arrhythmias

Include Sinus, Atrial, AV Blocks, Junctional, and Ventricular Rhythms.

Large Square Method for Heart Rate Calculation

Count large squares between R waves, divide by 300.

Small Square Method for Heart Rate Calculation

Count small squares between R waves, divide by 1,500.

6-Second Strip Method for Heart Rate Calculation

Count R waves in 6 seconds (30 large squares) and multiply by 10.

Memorization Scale for Heart Rate Calculation

1 large square = 300 bpm, 2 = 150 bpm, 3 = 100 bpm, 4 = 75 bpm, etc.