Chapter 5-Rhythm Strip Interpretation and Sinus Rhythm Flashcards
Identify the components of the rhythm
1-rhythm (regularity)
2-rate
3-P wave morphology
4-PR interval
5-QRS duration and morphology
What is evaluated and classified when determining dysrhythmias?
Waves, segments, and intervals.
P waves represent:
Atrial depolarization
QRS complex represents:
Ventricular depolarization
How do you calculate a regular rate
Either the 300 or 1500 method
How do you calculate an irregular rate
With the 6-second method
Explain the 6 second method
Multiply the number of P waves and QRS complexes in a 6 second strip by 10
When identifying the P wave morphology what two questions need to be answered
- Are the shapes and waveforms all the same?
- Does each P wave have a QRS complex following it?
How do you measure the PR interval
Measure from beginning of P wave to beginning of QRS complex
What is a normal PR interval
0.12-0.20
What is the normal limits for a QRS complex
0.06-0.10 seconds
How do you measure the QRS complex
Measure from where QRS complex starts to the J joint
Describe the J joint
Point where S wave stops and ST segment begins
What are the several questions that need to be answered when determine the QRS measurement and morphology
- Are all QRS complexes equal duration (width)
- What is the actual measurement, and is it within normal limits
- Do all QRS complexes look alike? If no are the unusual complexes associated with premature or ectopic complex?
- Do all QRS complexes follow a P wave
Describe the pathway of sinus node
Starts in SA node, travels to AV node, continues through Bundle of His and bundle branches to ventricles
Describe the classification for Normal Sinus Rhythm
Rhythm - regular
Rate - 60-100
P wave morphology - P waves are same shape, upright deflection, appears in front of QRS complex
PR Interval - between 0.12-0.20 second, same appearance, no variations
QRS duration & morphology - between 0.06-0.10 second, same with no deflections
What is this ECG strip representing
Normal Sinus Rhythm
Describe low cardiac output
Patient experiences symptoms due to the heart not pumping adequately
What are the symptoms of low cardiac output that are considered neurological
-change in mental state
-light headedness
-dizziness
-confusion
-loss of consciousness
What are the symptoms of low cardiac output that are considered cardiac
-chest pain
-palpitations
-chest discomfort
-enlarged cardiac size
-congestive heart failure
What are the symptoms of low cardiac output that are considered respiratory
-difficulty breathing
-shortness of breath
-frothy sputum
-fluid present in lungs
-lung congestion
What are the symptoms of low cardiac output that are considered urinary
-decreased urinary output of less then 30ml in one hour
What are the symptoms of low cardiac output that are considered peripheral
-hypotension
-pale skin
-skin cool and clammy to the touch
Describe the key difference in criteria for Sinus Bradycardia
All criteria are same as normal sinus rhythm except the rate is less than 60 bpm
What is this ECG strip representing
Sinus Bradycardia
How might the patient be affected by Sinus Bradycardia
May or may not experience or display symptoms
What is the main difference in criteria for Sinus Tachycardia
All criteria same as Normal Sinus Rhythm except the rate is between 100-150 bpm
How might the patient be affected by Sinus Tachycardia
Depends on the rate of tachycardia above patients normal resting rate, may experience symptoms of low cardiac output, and complaints such as heart racing
What is this ECG strip representing
Sinus Tachycardia
Describe the key difference in criteria for Sinus Dysrhythmia
All criteria same as Normal Sinus Rhythm except the rhythm interval between the P-P and R-R waves occurs at irregular periods.
Describe vagal tone
Constant tension on vagus nerve that causes heart to beat more slowly
Describe Sinus Dysrhythmia
Condition in which heart rate remains within normal limits but is influence by the respiratory cycle and variations of vagal tone
How might the patient be affected by Sinus Disrhythmia
Usually shows no signs or symptoms, but if serious enough and the heart rate decreases to 40-50 bpm patient may complain of palpitations or dizziness
What is this ECG strip representing
Sinus Dysrhythmia
Describe Sinus Arrest
Occurs when SA node stops firing causing a pause in electrical activity
What is the key difference in criteria for Sinus Arrest
All criteria same as Normal Sinus Rhythm but the rhythm is regular before and after the sinus arrest period (pause), rhythm is considered irregular due to absence in electrical activity during pause
What is this ECG strip representing
Sinus Arrest
When classifying Sinus Arrest what is the 6th criteria you need to calculate, and what is the calculation
Length of pause - must be determined to see how long heart had no rhythm
Measure the R-R interval around the pause and multiple number of boxes by 0.04
How may the patient be affected by Sinus Arrest
Will experience signs and symptoms of decreased cardiac output if pause is longer than 2 seconds and occurs on frequent basis.
May also experience periods of ischemia, hypotension, dizziness and syncope
Define ischemia
Sudden loss or reduction in blood supply (oxygen) to region of heart tissue
Define syncope
Loss of consciousness
Define hypotension
Lower than normal blood pressure that can cause reduction of blood flow to vital organs
Describe Sinus Exit Block
Occurs when SA node initiates electrical impulse that is blocked and not conducted to atria, atria and ventricles do no depolarize, P wave will not be seen until next conducted complex
What other Rhythm is similar to Sinus Exit Block
Sinus arrest
What is the key difference in criteria when classifying a Sinus Exit Block
All criteria is same as Normal Sinus Rhythm except the rhythm is irregular due to pauses and the rate will vary depending on electrical activity
*measure the length of pause
What is this ECG strip representing
Sinus Exit Block
How may the patient be affected by Sinus Exit Block
Seriousness depends on length and frequency of the pause, if pauses are accompanied by low heart rate the patient may expedience signs and symptoms of low cardiac output including hypotension, chest pain, shortness of breath or changes in mental status
Which rhythm shows an irregularity during inspiration and expiration
Sinus Dysrhythmia
A QRS complex measuring 0.12 second or wider indicates what?
Delayed ventricular conduction
What might cause Sinus Exit Block
Acute myocardial infarction, ischemia, or drugs such as digitalis or quinidine
