Analyzing a Rhythm Strip Sinus Arrhythmias Flashcards
What does the horizontal and vertical axis represent on EKG paper?
H: Time seconds
V: Voltage (mV) mm
How fast does the EKG paper move?
25mm/sec
What does 1 “small box” represent
0.04 seconds
What does 1 “Large box” represent?
0.20 seconds
What do 5 “Large boxes” represent?
1 second
What do 30 large boxes represent
6 seconds
Where does the cardiac rate normally come from?
The SA node (60-100bpm)
Do cardiac cells have the ability to pace the heart?
Yes, if needed they can
What are automaticity Foci?
- Potential pacemarkers that are capable of pacing the heart in emergency situations (ectopic Foci)
- Atria, AV junction, and the ventricles
If the SA node fails what is the next likely automaticity center to assume cardiac pacemaker activity?
Atria
If there was an EKG with a rate of 35 BPM where is the rate originating from?
Ectopic Pacemaker (ventricles)
What are the 5 steps to analyzing an EKG?
- Rate
- Rhythm
- Axis
- Hypertrophy
- Infarction
*Only 1 and 2 can be analyzed on a rhythm strip
What does the rate of a rhythm strip represent?
- Heart rate will always refer to ventricular rate unless atrial and ventricular rate differ
What are the methods for determining rate?
- “6 second method”
- 300, 150, 100, 75, 60, 50
- Precise calculations
When would the 300, 150,100,75,60,50 method be used?
- For normal and fast rates
*not accurate if the rate is irregular
When would the 6 second method be used?
- For bradycardia or irregular rhythms
When would you NOT use precise calculation?
- For irregular rhythms
How to do the “precise calculation” method?
- Count the number of small squares between the peaks of the R-R
- 1500/# of small squares
What are the 10 points to consider when analyzing a rhythm strip?
- Is the rhythm fast or slow?
- Is the rhythm regular or irregular
- Do you see any P waves?
- Are all the P waves the same?
- Does each QRS complex have a P wave
- Is the PR interval constant?
- Are the P waves and QRS complexes associated with one another?
- Are the QRS complexes narrow or wide?
- Are the QRS complexes grouped or not grouped
- Are there any dropped beats?
What are dropped beats?
P wave with no QRS
What is an irregular rhythm?
R-R greater than 3 boxes
>0.12 seconds
What does the wave of depolarization represent?
The movement of conduction from the SA node down to the heart
What is the normal size of a P-wave?
Width: <0.12 seconds
Height: <2.5mm
When are P waves considered “sinus”
- 1:1 P to QRS ratio
- All P waves are identical in size, shape and position
How to measure the PR interval?
- Measure from the beginning of P wave as it leaves baseline to beginning of the QRS complex
What is the normal size of the PR interval?
0.12 to 0.20 seconds (3-5 small blocks)
How to measure the QRS duration
- Measure from the beginning QRS complex until the ST segment begins
What is the normal QRS duration
0.06 to 0.11 seconds (greater than 3 small boxes is abnormal)
What is the J-point?
Place where QRS ends and ST segment begins
Where would J-Point elevation be shown?
In patient with early REPOLE, LVHH with strain and pericarditis
When would a Q wave be abnormal?
- > (or equal to) 0.03 seconds or wider (1 small box or larger)
- Its height is > (or equal to) 1/3 height of the R wave
What happens during the ST segment?
- Electrically silent period between ventricular depolarization and repolarization
Why is the T-wave an upward deflection?
Bc it is a negative wave traveling away from the electrode
What can symmetric T waves be a sign of?
Ischemia
What does the QT interval represent?
Ventricular systole (waiting to repolarize)
What is an abnormal QT duration?
> 10 small boxes (0.4 seconds)
What are Sinus Arrhythmias?
- Originate from the sinus node
Can be
*sinus tachycardia
*sinus bradycardia
*sinus arrest or block
What are P-Mitrale?
- When the P waves are greater than 0.12 seconds in leads (I and II) and notched (m-shaped)
- Seen in left atrial enlargement
What causes the notching in P-mitrale?
- Caused by the prolonged conduction times required to transmit the impulse through the enlarged left atrium
What does the notching represent?
The right then left atria depolarization
What is the most common cause of P-mitrale?
Severe mitral valve disease
*mitral stenosis leads to left atrial hypertrophy to overpower stenotic valve
What is a sinus pause?
An umbrella term of disorders in which there is a sudden failure of the SA node to initiate or conduct impulse
1. Sinus exit block
2. Sinus arrest
Are premature beats included in the calculation of heart rate?
No
What are the rules for diagnosing multiple rhythms?
- Describe the basic underlying rhythm first
- Then describe the additional information
