Dysrhythmias Flashcards
(78 cards)
SA node functions
Electrical impulses stimulates and paces heart at a rate of 60-100bpm, impulse travels into atria. Also known as the pacemaker of the heart.
AV node functions
Muscle cells of the atria contract is known as conduction. AV node has a rate of 40-60; AV node slows impulse allowing time for atria to contract and the ventricles time to feel. backup mechanism of the heart.
Bundle of HIS functions
next place the electrical impulse occurs, from bundle of his; impulse travels to the R and L bundle branches of the Perkinje fibers in the ventricles, this allows the ventricles to contract.
What is systole?
electrical stiulation of the muscle cells of the ventricles in turn cause muscle contraction
What is diastole?
once cells repolarize and ventricles relax, this is diastole.
What does the P wave represent?
conduction through the atrium (depolarization)
What does the PR Interval represent?
Impulse time from SA node through AV node
What does the QRS complex represent?
conduction through the ventricles. (ventricular depolarization)
What does the T wave represent?
ventricular repolarization
What does the QT interval represent?
time from ventricular depolarization through repolarization
what does the ST segment represent?
Early repolarization
what does an elevated ST segment show?
evidence of an acute MI
what does a small box represent?
0.04 seconds
what does a large box represent?
0.20 seconds
how many boxes equal one full second?
5 large boxes
how long should an effective strip be?
6 seconds
How many boxes in 6 seconds?
30 large boxes
What is positive deflection?
waveforms that move up the paper
what should you ask yourself when you look at a strip?
- What is the rate? (Fast or slow) (atrial or ventricular) (Relationship between them)
- Is the rhythm regular? (P to P interval equal time? )
- Is the R to R interval the same?
- Is there a P wave present? (are they upright?) (Is there one or more for each QRS) (Do they have the same appearance?)
- Is the PR interval normal?
- Is the QRS normal or wide?
- ST Segment location? (Isoelectric, Depressed, Elevated?)
- What else? (Symptomatic? Life threatening? New onset or chronic?)
What should a normal P wave look like?
should not exceed 1 box in length
What should a normal QRS look like?
0.08 - 0.12 seconds OR 2-3 horizontal boxes
What should a normal ST segment look like?
should be at the ISOELECTRIC line
Should begin at the end of the S wave and end at the beginning of the T wave.
what should a normal PR interval look Like?
0.12-2.0 Seconds or 3-5 horizontal boxes
What is the 1500 method?
a method of counting the HR on a strip
Count the number of small boxes between two R waves, then divide by 1500
BETTER FOR FAST HR