CP LEC 3: ECG Flashcards
What are the 4 questions to ask when interpreting an ECG
Speed?
QRS Width?
P Wave?
Regular or Irregular?
What are the ECG red flags?
- ventricular rate > 120 or < 45 bpm
- A fib
- complete heart block
- ST elevation or depression
- abnormal T wave inversion
- Wide QRS width
How long is a normal ECG strip?
6 seconds
What are two ways to find the HR from a 6 second strip?
- count R waves, x 10
- count big boxes between R waves (2=150, 3=100, 4=75, 5=60)
What is atrial kick?
Normal contraction of atria to increase pressure gradient and send blood to ventricals through mitral valve
note: if HR is too fast, there is not enough time for atrial kick = decreased CO
What does the P wave represent?
Depolarization of atria
What does the PR interval represent? What does it mean if the PR interval is lengthened?
Duration of time for electricity to go from SA to AV node (Atria to ventricals)
lengenthed PR = decreased HR
What does short PR interval mean?
hyperkalemia
What does long PR interval mean?
normal delay in AV node or 1st HB, beta blockers, Calcium channel blockers, digoxin, hypokalemia, magnesium
What does the QRS complex represent
R and L ventricular depolarization
What does the T wave represent?
Ventricular repolarization
What does the QT interval represent
Time between ventricular start of depolarization and end of repolarization
If an ECG is reading with an abnormally low voltage, does this mean a problem is likely?
Yes
What is the isoelectric line?
The x=(0) in an ECG; no electrical activity in the heart.
Monitoring a Q wave is important because it can tell you….
If there was a recent MI
Q wave with MI?
Q wave will drop lower;stays depressd for long time;scar tissue -> neg defections –> do not work with pt post acute MI until ST wave goes back to normal.
The normal rythmicity of the SA node is…
60-100bpm
The normal rythmicity of the AV node, the AV junction, and the Bundle of His is…
40-60bpm
What is the normal rhythmicity of the purkinje networks?
20-40
ST elevation vs depression
ST elevation : full thickness heart muscle damage: MI
ST depression: partial ischemia, can be non stemi MI
The rate of an arythmia can tell you what?
Where its coming from based on the autorythmicity of the different heart cells
An inverted T wave could potentially indicate what 2 problems?
Myocardial ischemia or infarction
An ST segment depressed by 2 boxes could mean what
Myocardial ischemia
angia symptoms
An ST segment elevated by 2 boxes could mean what
Myocardial infarction