the ekg. animation – listen carefully es/hhw/hhw_electrical.html
TRANSCRIPT
The EKG
Animation – Listen Carefully
• http://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_electrical.html
ELECTROCARDIOGRAMEKG (ECG)
Remember: The heart has its own electrical
system.
Do you the know the 4 parts involved?
What is an EKG?
• What is an Electrocardiogram?– A measurement of the electrical activity in the
heart.
• What 4 parts of the heart are used in electrical signal?– Sinoatrial node, atrioventricular node, Bundle
of His, Purkinje Fibers
1. SA - Sinoatrial Node
1.initiates an electrical sequence
2. AV - Atrioventricular Node
3.Purkinje Fibers
4.Bundle of His
ECG• ECG = measurement of electrical activity over time• Measured using electrodes
– Electrical contacts on the skin– Electrodes measure voltage between the electrodes
over time• Can be used to measure abnormal heart rhythms of the
heart– Such as damaged muscle tissue during a myocardial
infraction– Can diagnose irregular heart beat, irregular speed of
contractions, angina (tissue damage), or even tissue death (myocardial infarction).
Electrodes
• Can be placed in different areas to achieve different results/measurements
• Detect the electrical impulse being produced by the heart – detecting the difference between the charges in the
areas where the electrodes are attached– The greater the intensity of the impulse, the greater
the difference in the charges, and the larger the upward or downward peak will appear on the EKG
Can You Label All of the EKG Parts?
What Does an EKG Look Like?
R
Q
P = P Wave- Just before atrial contraction
QRS Complex- Impulse causing ventricle
contraction
T= T Wave – Ventricles relax
p
S
T
P Through T = Systolic Pressure
T Through P = Diastolic
Direction of impulse
Table 2
Standard Resting Electrocardiogram Interval Times
P–R interval 0.12 to 0.20 s
QRS interval less than 0.12 s
Q–T interval 0.30 to 0.40 s
How is it Measured?
• Heart generates electrical current• At rest…
– Heart muscle is polarized (more positively charged ions on the outside of the heart cells
– More negatively charged ions are inside• Then the positive ions move to the inside of cells and negatively
charged ions move to the outside– The flow of electrons into the cells cause an electrical current– This is called depolarization
• Then the positive ions move back to the outside of the cells and negatively charged ions move back to inside– This is called repolzarization
Current passes through body to skin.
Current can be measured with an electrocardiogram. (EKG,ECG)
Vernier.com
Depolarization and Repolarization
• At rest…– Heart muscle is polarized (more positively charged ions on the
outside of the heart cells– More negatively charged ions are inside
• Then the positive ions move to the inside of cells and negatively charged ions move to the outside– The flow of electrons out of the cells cause an electrical current– This is called depolarization
• Then the positive ions move back to the outside of the cells and negatively charged ions move back to inside– This is called repolarization
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Depolarization
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Heart Cells Cause Muscle Contraction
Repolarization
Common Issues
• P Wave Absent– Lack of normal depolarization of the atria
• QRS Complex Absent– indicates the electrical impulse was blocked
before it reached the ventricles• Abnormally shaped complexes
– abnormal spread of the impulse through the muscle tissue, such as in myocardial infarction• pulse cannot follow its normal pathway because
of tissue death or injury
What does all of this mean?• P wave
– Atrium contract/depolarize– Blood flows through atrium into ventricles– SA node sends signal to AV node
• Q– Atrium relax/repolarize
• R– Left Ventricle contract/depolarize– AV node sends signal to Purkinje fibers
• S– Right Ventricle contract/depolarize– AV nodes sends signal to Purkinje fibers
• T wave– Ventricles relax/repolarize
Excel Results for EKG
Time (seconds)
Test Subject P Wave (start) Q R S T Wave (end) P-R Interval QRS Complex Q-T Complex Heart Rate (BPM)
Walters 1
Walters 2
Walters 3
Myocardial Infarction
EKG in LabView
Quiz Question 1
• What is the main item that neutrophils attack in the body?a) Bacteria
b) Viruses
c) Allergies
d) Cancer
Quiz Question 2
• The white blood cell count in the body is normally _____.a) 1,000 to 2,000
b) 4,000 to 10,000
c) 15,000 to 20,000
d) 95,000 to 100,000
Quiz Question 3
• The systolic phase of an EKG begins at _____.a) P
b) Q
c) R
d) S
e) T
Quiz Question 4
• The R point corresponds with ______.a) Atrium contraction
b) Left Ventricle contraction
c) Right Ventricle contraction
d) Ventricular relaxation
Quiz Question 5
• The T wave corresponds with ______.a) Atrium contraction
b) Left Ventricle contraction
c) Right Ventricle contraction
d) Ventricular relaxation