Ekg Interpretation Contract - PowerPoint

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					Basic EKG Interpretation
History

Mid 1880’s - Ludwig & Waller discovered
 that the heart’s rhythm could be
 monitored from a person’s skin
1901 - Dr. William Einthoven invented the
 EKG machine
EKG - Electrocardiogram - Electrical
 activity of the heart (contraction of the
 myocardium)
Electrical Conduction

Heart muscle cells - “myocytes”
“Depolarization” moves as a wave through
 the myocardium
“Depolarization” stimulates the heart’s
 myocytes, they become + and contract
Cell-to-cell depolarization through the
 myocardium is carried with Na+ ions
EKG
Myocardial contraction is caused by
 depolarization. The recovery phase
 that follows depolarization is known as
 repolarization.
The SA Node (“Sinus Node) is the
 heart’s dominant pacemaker. - Sinus
 Rhythm
Each depolarization wave emitted
 through the SA Node spreads through
 the atria producing a P Wave.
P Wave = Atrial Depolarization

AV Node - Conducting pathway b/t the
 atria and the ventricles
When a wave of atrial depolarization
 enters the AV Node, depolarization
 slows, producing a brief pause, thus
 allowing blood to enter the ventricles.
 Ca++ ions
Ventricular Conduction
Depolarization shoots rapidly through
 the HIS Bundle, and the Left & Right
 Bundle Branches
The HIS Bundle and both Bundle
 Branches are made up of rapidly
 conducting Purkinje fibers.
Depolarization of the entire ventricular
 myocardium produces a QRS complex.
QRS represents ventricular contraction.
Ventricular Conduction

The Q Wave, when present, always
 occurs at the beginning of the QRS
 complex and is the first downward
 deflection.
The next upward deflection represents
 the R Wave.
The next downward wave is the S
 Wave.
The horizontal segment of baseline that
 follows the QRS is known as the ST
Continued.
If the ST Segment is elevated or
 depressed beyond baseline level, this is
 usually a sign of problems.
The ST Segment represents the initial
 phase of Ventricular Repolarization.
The T Wave represents the final,
 “rapid” phase of ventricular
 repolarization.
The T Wave is usually a low, broad
 hump.
Repolarization is accomplished by K+
 ions leaving the myocites.
Ventricular systole (contraction) begins
 with the QRS and persists until the end
 of the T Wave.
Physiologically, a cardiac cycle
 represents atrial contraction, and
 ventricular contraction followed by a
 resting stage. Page 29
Recording the EKG

Page 31
Smallest divisions are 1 mm high X 1 mm
 wide.
5 small squares make up one large square
The height or depth of waves is voltage.
The upward or downward deflection is
 called amplitude.
EKG Recordings
The amount of time represented by the
 distance b/t two heavy lines is .2 of a
 second.
Each small division represents .04
 seconds.
A standard EKG has 6 limb leads and
 six chest leads.
Bipolar limb leads - Page 38.
Limb Leads

AVR, AVL, & AVF are unipolar limb leads.
Page 42.
Page 43.
Page 44.
6 Chest Leads
V1 - V6
Rate

R to R intervals
300, 150, 100, 75, 60, 50
6 second strip
Count cycles and add a zero to the end

				
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