EKG Flashcards
The EKG is
graphic representation of electrical conduction through the heart
Conduction system
SA node-AV node-Bundle of His-Purkinje fibers-myocardium
The isoelectric line is
the baseline-straight line from which the components of an EKG wave are defined
P wave
Indicates atrial depolarization, or contraction of the atrium
- amplitude (height) is no more than 3 mm
- no peaking
PR interval
Indicates AV conduction time
- measures from the beginning of the P wave to the beginning of the QRS
- normal duration time is 0.12 to 0.20 seconds
QRS complex
indicates ventricular depolarization or contraction of the ventricles
- normally not longer than .10 in duration
- R waves are deflected positively and the Q and S waver are negative
T wave
indicates ventricular repolarization
-rounded and asymmetrical
ST segment
represents the time between the end of the contraction and repolarization
- normally not depressed
- may be elevated slightly in some leads (no more than 1 mm)
Each small square on the EKG graft is
0.04 seconds
One large square on EKG graft is
0.020 seconds (contains 5 small squares)
30 squares equals
6 seconds
1500 squares equals
1 minute
Determine regular rhythm
measure from R to R
- if the rhythm varies by 0.12 seconds or more the rhythm is irregular.
- if the rhythm doesn’t vary or vaires <0.12 sec then it is considered regular
Determine HR Ventricular
count the number of squares R to R -divide by 1500 (for regular) or 6 sec method (for irregular) -count number of R to R and multiply by 10 for irregular beat
Measure PR interval
-measure from the beginning of the P wave as it leaves baseline to the beginning of the QRS complex. Count the squares and multiply by 0.04 seconds
Measure the QRS complex
-measure from the beginning of the QRS complex as it leaves the baseline until the end of the QRS complex when the ST segment begins. Count the squares and multiply by 0.04 seconds
Sinus Rhythm
- impulse originates in the SA node
- normal sinus rhythm
- Components
- PQRST are all present
- P waves have the same appearance in front of each QRS
- rhythm-regular
- rate- atrial and ventricular rate are the same 60-100
- conduction- PRI 0.12-0.20 sec
- QRS <0.12
Sinus Bradycardia
- components PQRST are all present
- P waves have the same appearance, in from of each QRS
- rhythm- regular
- rate- <60 beats/min
- conduction: normal
- patient response: normal for athletes, decreased CO for others
- TX: atropine if symptomatic
Sinus Tachycardia
- components PQRST are all present
- p waves have the same appearance in from of each QRS
- rhythm- regular
- rate->100 beats/min
- conduction- normal
- patient response decrease CO
- TX- treat cause
Atrial rhythms/premature atrial contraction
- components-PQRST present, same appearance in baseline rhythm, P wave abnormal or lost in PAC
- rhythm- irregular, R-R are not the same
- PAC occurs early, causing a short T-QRS length
- conduction-QRS <.12 sec, PRI measured on baseline rhythm
Atrial Tachycardia
- components- QRST present, same appearance, P lost in the preceeding T, T may invert due to ischemia
- rhythm- regular
- Rate- 150-250
- conduction- unable to measure PRI, QRS normal
- patient response decrease CO
- Tx- beta-blockers, calcium channel blockers, digonxin
