ECG Flashcards
What do the following represent?
What does small square on a ECG represent in time?
What does large square on a ECG represent in time?
Small Square
- 0.04ms
Large Square
- 0.2ms
5 Large Squares
- 1 Second
How do parts of ECG correspond to what’s occurring in the heart e.g. (Depolarization/ Repolarization phases).
What’s the normal ranges for a PR interval
0.12ms - 0.2ms
What’s the normal range of a QRS complex
< 0.12ms
How do you calculate the 300 method using R-R complex.
How to Use the 300 Method:
Find two successive R waves: These are the peaks of the QRS complexes. Measure the number of large squares between them.
Divide 300 by the number of large squares between the R waves.
Example
1 large Square = 300
2 Large square= 150
3 Large squares= 100
4 Large Squares= 75
5 Large Squares= 60
6 Large Squares = 50
What is the process you follow when assessing P waves
P Waves
- Are the upright?
- Are they Preceding each QRS?
- Are they regular?
- Are they < 0.12
- Are they <2.5mm in Limb leads and 1.5 in precordial.
What are some conditions that affect P waves?
> Peaky P waves
- Right atrial enlargement
- Hypokalemia.
> Flattered P waves
- Hyperkalemia
> Dropped P waves
- Sinoatrial block
- AV blocks (Mobitz type I)
> Regularity
- AV blocks can affect P wave regularity
> P wave disassociation
Third degree block
- Complete dissociation between atrial and ventricular activity. The atria and ventricles beat independently, as the electrical impulse is blocked at the AV node or His-Purkinje system.
What is the process you follow when assessing PR intervals
- ## Is it between 0.12-0.2 (3-5 small squares)
What is the normal timeframe for QRS Complexes
< 0.12ms
What are some conditions that can affect a QRS complex
Represents the electrical activity associated with the contraction of the heart’s ventricles.
Key Characteristics:
- Duration: Normally lasts 0.06 to 0.12 seconds (60–120 milliseconds).
What can cause a Widen or Narrow QRS complex?
Widened QRS Complex
A QRS duration >120 ms (0.12 seconds) is considered wide and can be caused by:
- Bundle Branch Blocks:
Right Bundle Branch Block (RBBB) - Left Bundle Branch Block (LBBB):
- Ventricular Tachycardia:
- Hyperkalemia:
Ventricular Pacing:
- Narrow QRS Complex
A QRS duration <120 ms is considered narrow and usually indicates normal conduction through the atrioventricular node into the ventricles.
- SVT or Tachycardia
What are some conditions that affect the P-R interval
> Prolonged
- First Degree AV block (Generally >300)
- Second degree AV block (Mobitz I): Progressively lengthening until dropping a P wave.
- Hyperkalemia
- Hypothyroidism
- Beta Blockers
> Note: Relevant condition
- Second degree (type II block) -Intermittent failure of the AV node to conduct a P wave to the ventricles without prior PR interval prolongation.
What does Biphasic and Monomorphic mean?
In the context of an ECG (electrocardiogram), the term “monomorphic” refers to a pattern where the morphology (shape or appearance) of a particular waveform, such as a QRS complex, is uniform or consistent across all beats. This means that the electrical activity causing the waveforms follows the same pathway, resulting in identical-looking waves each time the event occurs.
Biphasic (pictured)
The term “biphasic” in the context of an ECG refers to a waveform that has two distinct phases or deflections: one positive (upward) and one negative (downward)
What is Normal Sinus Rhythm
Normal health Rhythm originiating from the SA node.
Rate:
- 60–100 beats per minute (bpm).
Regularity
- Regular
P Wave:
-Present before each QRS complex.
PR Interval:
-Normal duration: 0.12–0.20 seconds (120–200 milliseconds
QRS
- Narrow: <0.12 seconds (<120 milliseconds), showing normal conduction through the ventricles.
T Wave:
- Follows each QRS complex.
Positive in most leads and follows normal repolarization patterns.
What is sinus Tachycardia and Sinus Bradycardia
> Sinus Tachycardia
- refers to a faster-than-normal heart rate, usually >100 beats per minute (bpm), while maintaining normal sinus rhythm characteristics.
Key Features on ECG:
- Heart Rate: >100 bpm.
- P Waves: Present, precede each QRS complex, and have a consistent morphology.
- QRS Complex: Narrow (<0.12 seconds) unless a conduction abnormality is present.
Rhythm: Regular
- Twaves: Present
> Sinus Bradycardia
- refers to a slower-than-normal heart rate, usually <60 bpm, while maintaining normal sinus rhythm characteristics.
Key Features on ECG:
- Heart Rate: <60 bpm.
- P Waves: Present, precede each QRS complex, and have a consistent morphology.
- QRS Complex: Narrow (<0.12 seconds) unless a conduction abnormality is present.
- Twaves: Present
- Rhythm: Regular.
