Anatomy of the heart and EKG interpretation Flashcards
Left main artery
Has more branches
Heart is more muscular and requires more blood
Coronary artery
Supply bld to heart muscle
systemic
Body
Systole
Contracts creating pressure that opens the valves
- right ventricle flows to lungs
- left ventricle to aorta to body
4 unique qualities of the heart
Automaticity, conductivity, contractivity, excitability
Diastole
Relax
blood returns from vena cava
right atrium to right ventricle
pulmonary veins from left atrium to left ventricle
Automaticity
Initiate electric pulse
Conductivity
Ability of myocardial cells to receive conduct electrical pulses
Contractivity
Shorten in response to an electrical impulses
Excitability
Respond to an impulse or stimulus
Sinoatrial Noade (sa)
Pacemaker Normal conduction of the heart
Atrioventricular Node (av)
Regulates blood flow
Bundle of His (av bundle)
Transfer electrical impulses from atria to the ventricles via bundle branches
Bundle branches
Split electrical impulse down the right and left side
Purkinje fibers
Electrical pathway for each cardiac cell
Impulse activates ventricles simultaneously
Produce an electrical wave
P wave
First positive deflection Occurs when atria depolarize
atrial contraction
Q wave
- Represent conduction of impulse down the inter ventricular septum
- First negative deflection before R wave
- Not always visualized on the ECG
R wave
- First positive wave of the QRS complex
- Rep. Conduction of electrical impulse to the left ventricle
S wave
First negative deflection after R wave
QRS complex
Complete ventricle depolarization
atrial repolarization occurs (not seen)
0.06 - 0.1 seconds
ST segment
End of the S wave to the beginning of T wave
Myocardial damage
Elevated ST segment
Isoelectric line
Baseline
Ischemia
Reduced oxygen to the heart
T wave
Ventricular repolarization Positive
TWI
Inverted T wave
U wave
Not on all EKGs
sympathetic branch
increase heart rate in response to norepinephrine
parasympathetic
decrease heart rate via vagus nerve
Depolarization
stimulation, that
causes the heart to contract
Repolarization
cellular recovery following contraction
heart relaxes allowing for chamber to refill
PR interval
measured beginning of P wave (atrial depol) to beginning of QRS (ventr. depol)
.12-.20 seconds
how long it takes the ventricles to contract
QT interval
Time required for ventricular depolarization and repolarization
starts at the beginning of QRS complex and ends at the end of T
J point
end of QRS complex
1 square on the paper is equilvelent to ______ seconds
.04
calculating heart rate
6 second method
300 method
1500 method
6 second method
best for irregular
not as accurate
300 method
300, 150, 100, 75, 60, 50
start on the next bold line after the R wave
subtract the two numbers the next R wave falls between and divide by 5
the number you get is the equivelent to one box
Describe the 1500 method.
- Ccount the number of small boxes between two R
- divide 1500 by that number
What is Sinus Bradycardia?
Where does it originate from?
Originating from the SA node with a heart rate of less than 60 BPM.
This rate may or not affect cardiac output.
What is sinus tachycardia?
Where does it originate from?
Sinus tachycardia originates from the SA node with a heart rate above 100 BPM.
Define
Informed consent
A process for getting permission before conducting a healthcare intervention on a person, or for disclosing personal information.
Define
troubleshooting
handle problems
Which electrode is considered the ground in an EKG?
right leg
Which electrodes are considered the precordial leads?
chest leads
Describe Lead I on an EKG and which limbs it consist of.
positive
records tracing from right arm (-) to left arm (+)
Describe Lead II on an EKG and which limbs it consist of
Positive
records tracing from right arm (-) to left leg (+)
most favourable
Describe Lead III on an EKG and which limbs it consist of
Positive
records electrical activity from left arm (-) to left leg (+)
Which leads are considered augmented leads and unipolar?
Why are they called augmented?
aVR
aVL
aVF
tracings are increased in size
Describe the aVR lead and the direction of its vector.
Negative deflection
only limb lead on right side
in direction of right arm
records activity from heart to right arm
Describe aVL lead and its vector.
Positive deflection
smallest deflection
heart to left arm
Describe the aVF lead and its vector.
Positive deflection
measures in the direction of left foot
Name 3 EKG machine function.
Input
signal processing (delay)
output display
What is the normal speed for an ECG
25mm/sec
What is the normal artifact filter for an EKG?
normal setting between 40 - 150 Hz
How many electrodes in a 12 lead ECG ?
10
What is being measured on the horizontal axis of an EKG reading?
time (seconds)
What is being measure on the vertical axis?
Myocardial Voltage (millivolts)
What is the measurement of one large box?
5mm x 5mm
