ECG Basics And Interpretation Flashcards
Name and locate the normal placement of a 12 lead ECG.
- Lead on right arm, left arm, and one leg
- 6 Precoridal leads around heart (V1 most medial and V6 most lateral)
Define Mean Electrical Axis.
Where does it commonly point?
Vector that shows where most depolarization occurs - where there is the most muscle mass. Most commonly left ventricle
Identify Normal rhythm and its conduction pattern
Rhythm: small/positive P waves, large/positive/narrow QRS, 1:1 ratio b/t P waves and QRS, consistent HR
Identify sinus bradycardia rhythm and its conduction pattern
Heart rate under 60 BPM - everything else is normal (waves, complexes, and intervals)
Identify sinus tachycardia rhythm and its conduction pattern
Heart rate over 100 BPM - everything else is normal (waves, complexes, and intervals)
Identify atrial flutter rhythm and its conduction pattern
- Rapid, regular atrial depolarizations
- Multiple P waves, not a QRS Complex for every P wave
- QRS is normal
Identify ventricular tachycardia rhythm and its conduction pattern
- Missing P waves
- Wide QRS Complex (that’s all you see on ECG)
Identify ventricular fibrillation rhythm and its conduction pattern
- Tiny up and down wave across ECG
- Uncoordinated depolarization…not ejecting any blood at all
Identify 1st degree block rhythm and its conduction pattern
- Prolonged PR Interval
- Normal Heart rate
- Decreased AV Nodal Delay
- Common in highly trained athletes
- SA Node still fires properly, it just takes longer to cross AV node
Identify atrial fibrillation rhythm and its conduction pattern
- Irregular QRS Complex
- P waves present?
- No coordination of atrial depolarization
Explain how to find the rate and rhythm with a given ECG.
- Count number of “big squares” between successive R waves (in QRS complex)
- Divide 300 by that number.
* If the wave is between two big squares, like 3 and 4, then the rate would be between 75 and 100.
Which leads do you look at to calculate MEA?
Lead I and aVF
Predict the effect of myocardial damage on impulse conduction
-
What changes will be seen in an ECG for hyperkalemia?
- Progressive changes…
1. Peaked T-waves
2. Prolonged PR Interval
3. Widened QRS—merges with T wave
What is positive and what is negative in Lead I?
Positive: Left Arm
Negative: Right Arm
What is positive and what is negative in Lead II?
Positive: Legs
Negative: Right Arm
What is positive and what is negative in Lead III?
Positive: Legs
Negative: Left Arm
What is positive and what is negative in Lead aVL?
Positive: Left Arm
Negative: Right Arm and Legs
What is positive and what is negative in Lead aVR?
Positive: Right Arm
Negative: Left Arm and Legs
What is positive and what is negative in Lead aVF?
Positive: Legs
Negative: Arms
Which type of leads are used to localize infarcts?
Precordial
Identify 2nd degree block rhythm and its conduction pattern
- The P wave to QRS ratio is greater than 1:1
- Type I: PR interval gets progressively longer and then eventually a beat is dropped (missing QRS)
- Type II: PR Interval is set and there is eventually a beat dropped
Identify 3rd degree block rhythm and its conduction pattern
- P waves and QRS have regular rhythm but are not in sync with each other
- QRS can be widened
What is R-Wave Progression?
As you move from V1 to V6 (precordial leads) the R wave gets progressively taller and more positive.
This is a good way to determine if someone is having a heart attack or ischemic event (R wave breaks down in these patient’s)
