Lead II ECG Interpretation Flashcards
1
Q
At rest, is potassium concentration greater inside or outside the cell?
A
Inside
2
Q
At rest, is sodium concentration greater inside or outside the cell?
A
outside
3
Q
What is depolarization?
A
A wave of electrical current that causes cardiac cells to become positively charged; should result in cardiac muscle contraction
4
Q
What are admission criteria for cardiac monitoring?
A
- Patients who are/have: 48 hours (about 2 days) post MI, unstable angina or NSTEMI, A fib, new onset arrythmias, syncope when arrythmia is suspected
- Patients who are on: low dose dobutamine, other antiarrhythmic medications
- Pre/Post pacemaker or with suspected pacer malfunction
- Pre/Post cardiac catheterization
- Patients who are experiencing: rhythm disturbances or at risk for life threatening arrythmias
5
Q
Discharge criteria for cardiac monitoring without physician’s order?
A
a) SR with normal rate
b) Intervals normal
c) No coronary symptoms within 24 hours
d) No rise in cardiac markers for 24 hours
e) Controlled A fib
6
Q
Discharge criteria for cardiac monitoring that requires a physician’s order?
A
a) **HR <40 or >100 at rest
b) Antiarrhythmic drug loading
c) Was admitted with diagnosis of dysrhythmia or syncope
d) Is having PVC or new occurrence of PVC with symptoms
7
Q
What is the admission procedure for cardiac monitoring?
A
- Telemetry monitor setup
- Documentation - strip analyzed at beginning of each shift - includes: rate, PR, QRS, QT, and rhythm interpretation
- Review rhythm at the end of each shift for arrythmias
8
Q
What are nursing priorities for a patient with a dysrhythmia?
A
- Assess indicators of cardiac output and oxygenation, especially changes in level of consciousness
- Assessment includes:
Rate and rhythm of apical and peripheral pulses
Heart sounds
Blood pressure and pulse pressure - Signs of fluid retention
- Collaborative problems – Review from N253: decreased cardiac output, heart failure, thromboembolic event (especially with atrial fibrillation), and cardiac arrest
9
Q
What is cardioversion?
A
- “Timed” electrical current to terminate tachydysrhythmia
- Cardiac monitor is set to synchronize with the ECG so the patient receives the shock during the QRS complex
- Sync prevents the discharge from happening on the T wave (the most vulnerable part of the rhythm)
- Patient will be sedated and respiratory support should be present
- Amount of electricity varies from 50J to 360J (normally around 200J)
* If it is successful, patient will convert to SR, have adequate pulses and BP
10
Q
What is a pacemaker?
A
- Device used to generate electrical impulses
- Electricity delivered through electrodes placed in the heart’s chambers – causes contraction
- Usually used when patient has bradycardia but can be used in some tachydysrhythmias
- Can be permanent or temporary
- This is a surgical procedure and can be accompanied by many common post op complications such as pneumothorax, infection, hematoma, dislodgement of device etc.
11
Q
Why is Lead II a preferred lead to interpret?
A
Follows normal path of ventricular depolarization
12
Q
What does the vertical plane of the ECG graph paper show?
A
voltage
13
Q
What does the horizontal plane of the ECG graph paper show?
A
time
14
Q
What is the P-wave?
A
Depolarization of the atria in response to the SA node triggering.
15
Q
What is the PR interval?
A
Delay of AV node to allow filling of ventricles.
16
Q
What is the QRS complex?
A
Depolarization of ventricles, triggers main pumping action
17
Q
What is the T-wave?
A
Ventricular repolarization
18
Q
What it the ST segment?
A
Beginning of ventricle repolarization, should be flat
19
Q
What are the steps invovled in reading a rhythm strip?
A
- Calculate the heart rate
- Determine regularity (R-R interval)
- Identify and examine P waves
- Measure PR interval
- Determine if each P wave is followed by a QRS complex
- Evaluate the QRS complex
- Measure the QT interval
- Diagnose the rhythm
20
Q
What is the range for a normal PR interval?
A
0.12 - 0.20 seconds
21
Q
Identify this rhythm.
A
Sinus rhythm
22
Q
Identify this rhythm.
A
Sinus tachycardia
23
Q
Identify this rhythm.
A
Sinus bradycardia
24
Q
Identify this rhythm.
A
Atrial fibrillation.
25
Identify this rhythm.
Atrial flutter
26
Identify this rhythm.
Coarse V-fib
27
Identify this rhythm.
Fine V-fib
28
Identify this rhythm.
Ventricular tachycardia
29
Identify this rhythm.
Asystole
30
Identify this rhythm.
Supraventricular Tachycardia
31
What happens during repolarization?
recovery of the cell to its resting state; normally results in myocardial relaxation
32
What are the action potential phases?
Phase 0: depolarization: sodium moves into the cell
Phase 1: early repolarization: sodium channels close
Phase 2: plateau phase: calcium channels open
Phase 3: repolarization: potassium shifts back into the cell
Phase 4: resting membrane potential: original electrochemical gradient is in place
33
What is the absolute refractory period?
Period where the cell absolutely cannot respond to another stimulus regardless of the strength of the stimulus
34
What is the relative refractory period?
Cell is relatively, but not completely, unresponsive
35
What is a supranormal period?
A time in which weaker than normal stimulus can produce depolarization.
36
What is the primary pacemaker in the heart?
SA node
37
What impulse does the SA node generate?
60-100 bpm
38
What impulse does the AV junction generate?
40 to 60 bpm
39
What impulse does the ventricular purkinje fibers generate?
20 to 40 bpm
40
What is an ECG?
A graphic representation of the electrical, not mechanical, activity of the heart
41
What nursing actions are required when you see a change in the ECG?
* Check patient and assessment
* Check leads
* Determine what preceded the change
* Could get a 15 lead ordered if symptomatic
* If significant, SBAR a physician
42
What is the order of conduction through the heart?
1. SA node initiates
2. Travels via the internodal pathways to the AV node
3. Atria depolarize and AV node slows electrical impulse. Atrial contraction begins.
4. Electrical impulse travels rapidly to the heart apex via the bundle of His and bundle branches.
5. Electrical impulse travels through Purkinje fibers and through ventricular myocardium. Ventricular contraction.
43
What does it mean if the PR interval in > 20 seconds?
May indicate a heart block
44
What might it indicate if the PR interval is < 0.12 seconds?
may indicate a junctional rhythm or a pre-excitation syndrome
45
What is the normal duration of the QRS interval?
0.06 - 0.12 seconds
46
What might it indicate if the QRS complex is greater than 0.12 seconds?
If > 0.12 seconds – indicates abnormal depolarization of the ventricles
47
How long is a normal QT interval?
Normal is around .40 seconds
48
Why is a QT interval over .50 seconds dangerous?
If QT is over 0.50 seconds, it becomes dangerous and risks an R on T phenomenon (the heart does not have time to naturally recover in the T wave)
49
What order in the heart will pacemaking go if the prior cells fail?
SA node: 60 - 100
AV node: 40 - 60
Bundle of His: 40 - 60
Left and right bundle branches: 20 - 40
Pukinje fibers: 20 - 40
50
What is sinus tachycardia?
* Abnormally rapid heart rate that ranges from 100 to 150 bpm and originates in the SA node
* Results from sympathetic nervous system stimulation
* Can also be compensatory response to decreased cardiac output
51
What is sinus bradycardia?
* heart rate of less than 60 bom
* Originates in the SA node
* May be seen in athletes; a slower rate can still maintain an efficient cardiac output
* Can result from stimulation of the parasympathetic nervous system
* Also side effect of drugs such as digitalis, beta andrenergic agonists and CCBs
52
What is atrial flutter?
* Fast atrial rate of between 250 and 350 bpm
* atria firing so rapidly that the AV node is unable to respond to every impulse
* ventricular rate depends on how many impulses get through
* ECG has sawtooth appearance
* Goal is to control the ventricular rate and restore the patient to sinus rhythm
* Anticoagulation should be considered
53
What is atrial fibrillation?
* Atria contract at a rate greater than 350 bpm; they are unable to have adequate filling or contraction
* multiple foci fire in disorganized fashion
* the atria quiver rather than contract
* stroke volume diminished
* prone to forming clots; greatest risk is when the rate returns to sinus rhythm and expels clots
* most common in older adults
* puse deficit present
54
What is ventricular tachycardia?
* Classified as three or more consecutive premature ventricular contractions (PVCs) occurring at a rapid rate, usually greater than 100 bpm
* QRS complex is wide
* Loss of consciousness occurs as cardiac output diminishes
* Synchronized cardioversion may be used to convert VT, however pulseless VT requires CPR
55
What is ventricular fibrillation?
* A fatal rhythm, most common cause of sudden cardiac arrest
* ECG chaotic due to weak, disorganized ectopic pulses from multiple locations in the ventricles
* rhythm grossly irregular and impossible to identify any PQRST waves
* Defribrillation is the treatment of choice
56
What is asystole?
* Represents complete cessation of electrical impulses
* Patient is unconscious and pulseless
* Must check rhythm is verified in two seperate leads as fine ventricular fibrillation can mimc asystole
* Chest compressions started immediately and continuously
