Coronary Circulation + EKG Flashcards
P wave corresponds to
Atrial depolarization
QRS complex corresponds to
Ventricular depolarization
T wave corresponds to
Ventricular repolarization
Depolarization causes
Muscle contraction
Repolarization causes
Muscle relaxation
Where does atrial repolarization (muscle relaxation) occur
QRS complex
What are Purkinje fibers
Modified myocardial cells
What is measured in the EKG
Muscle depolarization (muscle contraction)
What cation causes contraction of myocytes
Calcium
An increase in cytoplasmic calcium will cause
Higher contractility of myocytes
Does potassium and sodium cause a physiological increase in myocyte contraction?
No, only intracytoplasmic Ca++
Is [Na+] greater inside or outside the cell
Outside
Is [K+] greater inside or outside the cell
Inside
Myocyte cells are + or - charged inside
Negatively due to K+
Definition of polarized cell
- resting potential inside the cell
+ resting potential outside the cell
V1 and V2 leads observe
Ventricular septum
V2 and V3 observe
Anterior wall of left ventricle
V4 and V5 observe
The anterolateral wall of left ventricle
Cara lateral seen at
I and aVL
Cara anterior seen at
C1, C2, C3, C4
Cara inferior seen at
II, III, aVF
Acute heart attack seen at where in EKG
ST elevation at cara inferior: I, II, aVF
Strategy to count the heart beat
QRS aligned with the lines and count square to square (300-150-100-75-60-59) until the next QRS
Normal heart rate
60-100 beats per minute
Normal P wave parameters
Positive and 3 small squares
A negative P wave suggests
Dysrrythmia
Replace leads
Normal PR parameters
Less than 1/2 big square
If PR interval > half of a big square
Blockage dysrythmia
Normal P - P interval
Same length between P peaks
Normal QRS parameters
< 1/2 big square
Checking axis deviation
Check the leads to see the most uniform (I, II, III, aVL, aVR, aVF)
Go to the circle and turn 90º either left or right to where there is another lead mark
