EKG Flashcards
AUTOMATICITY
creation of impulse
EXCITABILITY
response to impulse
CONDUCTIVITY
passing of impulse
CONTRACTILITY
contraction + work of heart
CONDUCTION PATHWAY
SA (sinoatrial) NODE > INTERNODAL TRACT > RT/LT ATRIA > AV (atrioventricular) NODE > BUNDLE OF HIS > BUNDLE BRANCHES > PURKINJE FIBERS > VENTRICLE
how many BPM if SA node is controlling it?
60-100 BPM; normal sinus rhythm
how many BPM if AV node is controlling it?
40-60 BMP
how many BPM if BOH is controlling it?
20-40 BMP
what is the P WAVE responsible for?
atrial contraction/depolarization ; the electrical impulse into atria
what is the PR INTERVAL?
time from atrial depolarization to ventricular contraction (goes from start of P to start of R)
what is the QRS complex?
ventricular contraction/depolarization
what is the ST segment?
beginning of ventricular depolarization (from end of S to beginning of T)
what is the T WAVE?
ventricular repolarization (ending wave); heart is in diastole > rest
what is the QT INTERVAL?
entire depolarization and repolarization of the ventricles
EKG measurements: PR INTERVAL
0.12-.20 seconds - normal
EKG measurements: QRS COMPLEX
0.04-0.12 seconds - normal
EKG measurements: ST SEGMENT
0.12 seconds - normal (ensure there isn’t a 1mm+ height = MI)
EKG measurements: QT INTERVAL
0.34-0.43 seconds - normal
how many seconds is obtained to read an EKG?
SIX SECONDS; 6 SECONDS
how many small squares is a 6 second interval?
150 small squares = 6 seconds
how many large squares is a 6 second interval?
30 large squares = 6 seconds
how many small squares is equal to ONE MINUTE on EKG?
1500 small squares = 1 minute
how many large squares is equal to ONE MINUTE on EKG?
300 large squares = 1 minute
how do you figure out the heartrate on the EKG strip?
#1: obtain 6 second sample: 30 large squares OR 150 small squares #2: count the R intervals (intervals between QRS complex) #3: multiply this number by 10 (7 R intervals x10 = 70 BPM)
what is the size of one of the squares; in height?
1 small square = 1 mm
what is the time length of one small square vs large square?
1 small square = 0.04 seconds
1 large square = 0.20 seconds
how many small blocks vs big blocks = 1 minute
1 minute = 1500 small blocks
and
1 minute = 300 large blocks
what is the most accurate way to determine the HR in normal sinus rhythm?
count the small blocks between each R wave; divide that number into 1500 small blocks (number in 1 minute) = accurate heartrate!
***this cannot necessarily be used to determine the HR on an irregular rate
SYSTEMATIC APPROACH TO RHYTHM ASSESSMENT:
1) Determine the rate
2) What is the atrial activity
3) What is the ventricular activity
systematic approach to rhythm assessment - DETERMINE THE RATE
-is the rhythm regular or irregular?
» measure the distance between two R WAVES (R to R intervals)
**how many R intervals x10 = BPM
systematic approach to rhythm assessment - WHAT IS THE ATRIAL ACTIVITY
- is there a P WAVE, and do all P WAVES all look the same
- is there a P WAVE for every single QRS COMPLEX?
- is atrial activity rapid, irregular, or difficult to identify?
- what is the PR INTERVAL; is it normal or prolonged? **NORMAL = 0.12-0.20
systematic approach to rhythm assessment - WHAT IS THE VENTRICULAR ACTIVITY?
- what is the QRS INTERVAL; is it normal or prolonged?
- what is the QRS duration?
- what is the ST SEGMENT; is it normal or prolonged? is it elevated, or depressed?
- is the T WAVE upright or inverted?
- what is the QT INTERVAL; is it normal or prolonged?
what is NORMAL SINUS RHYTHM?
NSR = 60-100 BPM
- P>Ps are normal + consistent
- there is a P wave for every QRS complex
- R>Rs normal + consistent
- PR interval = 0.16 seconds
- QR complex = 0.04 seconds
- QT interval = 0.40 seconds
what is SINUS BRADYCARDIA?
**less than 60 BPM; normal rhythm LESS than 60 BPM; all other aspects of the EKG would be normal except for the lower HR
What interventions are needed for SINUS BRADYCARDIA?
- administer oxygen
- administer atropine and/or epinephrine
- external pacing
what is a common cause of this? (movie theatre example)
too much digoxin leads to hypokalemia;
too much potassium leads to increased digoxin levels
what is SINUS TACHYCARDIA?
***BPM GREATER THAN 100; heart is working harder, pushing blood faster
-this can be normal if exercising, or other high demands on body
what to do with tachycardia?
TREAT THE UNDERLYING CAUSE/ISSUE:
-decreased B/P; treat HYPOtension
-decreased oxygen sat; administer oxygen
etc.
