ECG Laboratory Flashcards
EKG Reading Format
- Rate
- Rhythm
- Axis
- Intervals (PR, QRS, QT)
- ST segments (Ischemia, injury, infarction)
Sinus bradycardia
Under 60 BPM
Sinus tachycardia
Over 100 BPM
Rate interpretation on EKG
1 box = 300 BPM 2 boxes = 150 BPM 3 boxes = 100 BPM 4 boxes = 75 BPM 5 boxes = 60 BPM 6 boxes = 50 BPM
Rhythm is assess by comparing which intervals on the EKG?
R-R intervals
Lead and axis pairs (3)
- Lead I and AVF
- Lead II and AVL
- Lead III and AVR
Positive Lead I and Positive AVF would put the heart in which axis?
Normal axis
Positive Lead I and Negative AVF would put the heart in which axis?
Left axis
Negative Lead I and Positive AVF would put the heart in which axis?
Right axis
Negative Lead I and Negative AVF would put the heart in which axis?
Indeterminate/Extreme axis
The PR interval represents what part of the cardiac cycle?
Atrial depolarization
Conduction velocity between the SA node and AV node.
This is the best marker to asses AV node conduction velocity as it takes up the majority of the PR interval.
Normal PR interval range
120-200ms
Why is the P wave followed by a pause?
The pause represents the slowing of depolarization through the AV node, which allows for filling of the ventricles from the atria.
The AV node should be the only conducting pathway between the atria and ventricles. Other pathways are ________.
Pathologic.
Short PR intervals (below 120ms) may be indicative of what?
The presence of a bypass tract, accessory pathway, bundle of Kent, and pre-excitation.
Short PR intervals often characteristically show what on EKGs?
Delta waves.
No pause between the P wave and the QRS complex.
A prolonged PR interval greater than 200ms is indicative of what?
First degree AV block: prolonged AV node conduction.
The QRS complex represents which part of the cardiac cycle?
Ventricular depolarization
QRS complex labeling conventions
The first negative wave is Q
The first positive wave is R
The second negative wave is S
It is possible to have more than one R and S wave.
Normal QRS interval
Below 120ms
A wide QRS (greater than 120ms) may be indicative of what?
Bundle branch block, impaired conduction in the right/left bundle, or possibly a beat of ventricular origin.
The QT interval represents which part of the cardiac cycle?
Ventricular depolarization to ventricular repolarization.
Normal QT interval
Generally under 440ms
ST elevations are commonly seen in patients with a history of ________
MI
Prolonged QT intervals can lead to ________ and ________ ________.
Arrhythmias; sudden death
Factors that can affect the QT interval include ________ and ________ ________.
Medications; electrolyte abnormalities
