EKG Flashcards
Analyze on every ECG
- Rate
- Rhythm
- Interval
- Axis
- Ischemia
- Pacemaker
one large box represents…
- 0.2 sec of time
- 5mm of amplitude
one small box represents…
- 0.04 sec of time
- 1 mm of amplitude
high lateral
- I
- aVL
lateral
- V5
- V6
septal
- Vi
- V2
anterior
- V2
- V3
- V4
inferior
- II
- III
- aVF
rate
- Assume standard paper speed 25 mm/sec
- Regular Rhythm
– Count the number of large boxes between P waves, R waves or pacer spikes
– Beats per minute = 300 / # of large boxes
sinus bradycardia
•<60 bpm
sinus tachycardia
- >100 bpm
- Sinus tachycardia
– Regular
– P wave before each QRS
irregular rate
•differences in bpm across the ECG
rhythm
- Most difficult and complex part of ECG interpretation
- Computer interpretation often wrong
- Need to look at:
– P wave morphology
– QRS morphology
– P:QRS relationship
P:QRS = 1
– P wave precedes every QRS
– Sinus rhythm
if P wave FOLLOWS every QRS…
P:QRS = 1
– P wave follows every QRS
– Super ventricular tachycardia (SVT)
if P:QRS < 1 or NO P waves…
P:QRS < 1 or NO P WAVES
– Atrial fibrillation
– Irregular irregular
if P:QRS > 1 or NO P wave…
P:QRS < 1 or NO P WAVES
– Junctional rhythm
– From below the AV node
P:QRS < 1 or NO P wave…
P:QRS < 1 or NO P WAVES
– Ventricular rhythm
– From the ventricle, wide complex
P:QRS
- P wave 0.8 - .10 ms
- PR interval 0.12 - 0.20 ms
- QRS complex 0.06 - 0.10 ms
- QTc <0.44 ms
1st Degree AV Block
- The distance from the beginning of the P wave until the beginning of the QRS complex is > 0.20 sec.
- This is first degree AV block.
RBBB
- prolonged QRS
- Extra deflection in V1 reflects the rapid depolarization of the left ventricle followed by the slower depolarization of the right ventricle. The last electrical activity is thus to the right, or towards lead V1.
LBBB
- prolonged QRS interval
- Normally the septum is activated from left to right.
- In LBBB, the normal direction of septal depolarization is reversed (becomes right to left), as the impulse spreads first to the RV via the right bundle branch and then to the LV via the septum.
- This sequence of activation extends the QRS duration to > 120 ms. The overall direction of depolarization (from right to left) produces tall R waves in the lateral leads (I, V5-6) and deep S waves in the right precordial leads (V1-3), and usually leads to left axis deviation.
- difficult to call ischemia in LBBB
- As the ventricles are activated sequentially (right, then left) rather than simultaneously, this produces a broad or notched (‘M’-shaped) R wave in the lateral leads.
axis
•Represents major vector of ventricular activation
ST interval
•Abnormalities of the ST segment can suggest ischemia
– After depolarization & repolarization period
•Normal is to be “isoelectric”
– ST depression = ischemia
– ST elevation = active infarction
Other causes of ST changes
- LBBB
- RBBB
- LVH
- RVH
- pericarditis
- BER
old infarctions
- Old infarctions are represented as lack of R waves OR presence of Q waves
- No all Q waves are pathologic Q waves can be related to:
– Anatomic and positional effects
– Myocardial injury or loss (duration, extent, size of MI)
– Ventricular enlargement
– Altered conduction (LBBB or pre-excitation pattens)
