Lecture 1 Flashcards
sinus node BPM
60-100
atrial BPM
60-80
AV junction BPM
40-60
Ventricles BMP
20-40
Placement of RA, LA, RL, LL, and V1 electrodes
Placement of Chest Leads (V1-6)
what does the P wave represent
SA node - rapidly spreads through RA to AV node. Also spreads through atrial muscle directly form RA to LA
-Atrial depolarization
what does the Q wave represent
1st area of ventricular muscle to be activated is the interventricular septum, which activates from L to R
what does the R wave represent
L and R ventricular muscle walls get activated, w/ the endocardial surface being activated before epicardial surface
what does the S wave represent
a few small areas of ventricles are activated at late stage
what does the T wave represent
ventricular muscle repolarizes
what does the U wave represent
after-potentials of ventricular muscle and repolarization of purkinje fibers
Causes of left axis deviation
- normal variant (diaphragm elevation)
- left ventricular enlargement
- inferior myocardial infarction
- right sided tension pneumothorax
- ventricular pacemaker
- left anterior hemiblock
right axis deviation causes
- normal variant (children)
- right ventricular enlargement
- lateral myocardial infarction
- left-sided tension pneumothorax
- pulmonary emboism
- left posterior hemiblock
degrees for normal cardiac axis
0-90
left axis deviation degrees
0- -90
right axis deviation degrees
-90 - +90
definition of sinus bradycardia
<60 bpm
definition of sinus tachycardia
>100 bpm
criteria to be sinus rhythm
- P wave before each QRS
- Normal P waves should be upright in leads I, II, and inverted in aVR
- Normal sinus rhythm = impulses originate at SA node at normal rate
sinus arrhythmia
- all complexes normal, rhythm is irregular
- Longest R-R interval exceeds shortest > 0.16s
- normal
- R to R progressively lengthens with expiration and then shortens with inspiration
PR interval
- should be 0.12-0.2 seconds
- 3-5 small boxes
- measured from beginning of P wave to beginning of QRS complex
- represents time taken for stimulus to spread through the atria and pass through the AV junction
QRS complex
- 0.08 - 0.12 seconds
- 2-3 small boxes
- measured from beginning of Q wave to the end of the S wave
- represents time taken for stimulus to spread through the ventricles
QT interval
- ventricular depolarization and repolarization
- normal range: <440 in males, <460ms in females
- >350 ms
- pathologic, fatal arrhythmias
