ECG's Flashcards
cardiac electrical conduction cycle
SA node causes contraction –> AV node –> bundle of HIS –> bundle branches –> purkinje fibers
cardiac mechanical conduction cycle
atrial depolarization/systole (P wave) –> ventricular depolarization/systole (QRS) –> ventricular re-filling (T wave)
SA node
the pacemaker
- located in right atrium
- 60 to 100 bpm
AV node
gatekeeper/delivers down bundle of HIS
- can take over if SA node fails
40-60 bpm
5 lead ECG placement
- snow above grass (left)
- smoke over fire (right)
- brown in the middle (4th intercostal)
small box
0.04 seconds
big box
5 small boxes
0.20 seconds
6 seconds
30 box chunks
- count QRS complex to determine rate
steps to interpretation
- regularity
- P:QRS ratio (determines sinus)
- morphology (determines consistency)
- rate
- measure intervals
- interpret
determiming rate
atrial vs ventricular
atrial= # of P waves x10
ventricular= # of QRS complex x10
if there is P wave for every QRS complex you only need to determine one
arrhythmias
occur from abnormal pacemaker due to
- disturbance in impulse formation, disturbance in impulse conduction, or both
artifact
abnormal readings on waveform that may not coordinate with an arrhythmia
Atrial fibrilation
AV node still working but too many impulses which leads to blood pooling in atria and can cause clotting which leads to stroke or PE
treat with anticoagulant; will not be able to determine P or T wave
Atrial flutter
“saw tooth” P wave
- proceeds A-fib
treat with anticoagulant and electrode procedure
SVT
unable to visualize P wave and no P:QRS ratio, very narrow QRS complex
- rhythm originates from above ventricles
can treat with cardioversion
ventricular tachycardia
no T wave or PR interval just up and down lines but wavy; very wide QRS complex
- can have pulse or pulseless
- check for S+S (will show as low BP, diaphoretic)
- can treat with cardioversion and medications
fast rate, morphology of QRS complex
ventricular fibrilation
squiggly lines
- no pulse; must call code
ventricles quivering
asystole
no cardiac conduction
- first thing to do is check patient just in case leads are just misplaced
- call code
first degree AV block
AV node taking time sending from atria to ventricles
- will see long PR measurement
- may be due to ischemia
second degree AV block type 1
PR interval changes in each segment
second degree AV block type 2
random drops in QRS complex
third degree AV block
irregular P:QRS ratio
- loss of synchronicity between atria and ventricles
- will see 30 bpm in ventricular
- atrial rate would be 60-80 bpm
PR interval
beginning of P to beginning of Q
- 0.12-0.20 seconds (3-5 small boxes)
QT interval
beginning of Q to end of T
- 0.36-0.44 seconds (9-11 small boxes)
ST segment
no time
end of S to beginning of T
- tells us about MI
QRS complex
0.06-0.12 seconds (1-3 small boxes)
lethal arrythmias
4
- pulseless ventricular tachycardia
- ventricular fibrilation
- asystole
- pulseless electrical activities
