Transcript EKG

ELECTROCARDIOGRAM
An electrocardiogram (EKG or
ECG) is a graphic
representation of the heart’s
electrical activity.
Endocardium
Myocardium
Epicardium
Cells of the Heart
Muscle
• Cardio Myocytes
• Polarized: inside is negative at rest;
outside is positive
• Depolarized: voltage channels open
and allow sodium in which reverses
polarity due to shift in electrolyte
concentration.
• Repolarized: Cell returns to initial
polarized state
Action Potential
• Nervous system (neurons) and
muscle cells carry action
potential
• When administering an EKG, the
action potential measured is
some skeletal and mainly
cardiac.
Properties of Cardiac
Cells
•
•
•
•
•
Automaticity
Excitability
Conductivity
Contractility
The heart can initiate its own
impulse (automaticity), respond to
the impulse(excitability), and
transmit this impulse (conductivity).
• Contractility-mechanical property
• Purkinje Fibers
COMPONENTS
• Isoelectric Line
• Cardiac Cycle
• EKG paper
CARDIAC CYCLE
• One complete heart beat
• Depolarization – Cells
stimulated & polarity changes
• Repolarization – Cells return to
their normal state.
SINE WAVE
•
•
•
•
•
•
•
P Wave
QRS Complex
T Wave
U Wave
PR Interval
QT Segment
ST Segment
Normal Parameters
• P-R Interval: .12-.20
• QRS Complex: .08-.12
• Q-T Interval: .42-.46
EKG PAPER
• Paper is heat
and pressure
sensitive
• Horizontal – rate
• Vertical voltage
1m
m
.2se
c
5m
m
.o4
sec
Lead Placement
• Lead I: Ventricular
Depolarization toward positive
electrode. QRS positively
deflected
• Lead II: Same as Lead I
• Lead III: Ventricular
Depolarization between + and so deflection + and -.
SINUS HEART RHYTHMS
• Normal Sinus
• Sinus Bradycardia
• Sinus Tachycardia
VENTRICULAR ARRYTHMIAS
• Premature Ventricular Contraction
(PVC)
• Ventricular Tachycardia (V-Tach)
• Ventricular Fibrillation (V-Fib)
• Asystole