E1: Dysrhythmia Flashcards
What do each of the following represent
P wave
QRS complex
T wave
P: Atrial contraction
QRS: Ventricular contraction
T: Ventricular relaxation
Order of electrical impulse for normal heart beat
- SA Node
- Atrial Tissues
- AV Node
- Bundle of His
- Ventricular tissues
Some patients w/arrhythmias are asymptomatic, however, many present with _______ or ______
In more severe, life threatening cases there is a ↓ cardiac output which causes _____ and _____
tachycardia or hemodynamic instability
dizziness and syncope
Bradycardia
Define
Symptoms
Etiology/Pathogenesis
Cardiac rhythms that are too SLOW
Heart rate < 60 beats per minute (BPM)
Symptoms
Asymptomatic typically
Lightheadedness, syncope (fainting)
Etiology/Pathogenesis
Autonomic causes ( ↓ SNS or ↑ PNS)
Endocrine causes (e.g. hypothyroid)
SA node dysfunction (young patients and athletes)
e.g. sick sinus syndrome: sinus bradycardia due to lack of O2 delivery to the sinus node
AV conductance disturbances, e.g. heart block
First degree AV Block
constant and predictable conduction delay; PR interval extended
Second degree AV block
Type I second degree AV block
periodic impulse interruptions
Type I second degree AV block (Mobitz I or Wenckebach block)
progressive delay in AV conduction with successive atrial impulses until an impulse fails to conduct
Third degree AV block
complete heart block
All atrial impulses fail to conduct to the ventricles
Cardiac arrhythmia etiology/pathogenesis
Ectopic focus (Ectopic pacemaker)/Automaticity
Triggers
Re-entry current
Ectopic focus (Ectopic pacemaker)/Automaticity
1. new, functional pacemaker outside of normal pacemaker (SA node)
2. Results in premature contraction faster than the normal rate
3. Can occur anywhere in the heart
4. Causes: Ischemia, scarring, electrolyte disturbances, drugs (e.g. caffeine, stimulants), advancing age
Triggers
Spontaneous, multiple depolarizations
Re-Entry Current
An electrical impulse recurrently travels in a circular circuit within the heart
Tachycardia
Define
Symptoms
Etiology/Pathogenesis
Atrial tachycardia AKA sinus tachycardia
Cardiac rhythms that are too FAST
Heart rate > 100 beats per minute
Symptoms
Asymptomatic often
Lightheadedness, syncope (fainting), and palpitations
Etiology/Pathogenesis
Autonomic causes ( ↑ SNS or ↓ PNS)
Endocrine causes (e.g. hyperthyroid)
Atrial tachycardia AKA Sinus tachycardia
SA node-originated
100-200 BPM
Atrial Flutter
Atrial rate:
Current?
Rhythm?
How does it compare to ventricular rates?
How does it appear on ECG?
atrial rate: 240-300 BPM
Re-entry current
“regularly irregular” rhythm
Fixed ratio of P:QRS
2:1 or 3:1; sometimes 4:1
Ventricular rates
80-150 BPM
Saw tooth pattern
Atrial Fibrillation
Atrial rate:
Rhythm?
Symptoms?
Associated w/ ______
How does it appear on ECG
Atrial rate: (“A fib”) 300-600 BPM
“irregularly irregular” rhythm
May be asymptomatic
-AV nodes filter most of impulses from reaching the ventricles
-Ventricular rates (80-150 BPM)
Associated with valvular thrombus
-stagnation of blood, emboli
-Ischemic stroke
Rapid-firing of multiple atrial automaticity foci, rapid ventricular rate, continuous chaotic atrial spikes and NO P waves
Atrioventricular Nodal Re-Entry Tachycardia (AVNRT) Pathophysiology
Where do re-entry circuits most commonly occur?
Why do they occur?
What is the end result?
Where:
Re-entry circuits most commonly occur at the bundle of His @
Why:
Re-entry circuit
-areas of partial block (shaded) may cause the original impulse in one branch to slow
-retrograde impulse travels back up the branch (b to a)
End result:
establishes a new circuit for a new heart rate
Ventricular Tachycardia
Define
BPM
Differentiate sustainable vs non-sustainable
What may it progress to…
What does it appear like on ECG
abnormal firing of electrical signals in the ventricles
100-250 BPM
Sustainable vs. non-sustainable
Depends on whether the fast rhythm self-terminates within 30 seconds
May progress to ventricular fibrillation (pulselessness and sudden death)
On ECG:
Atrial waves hidden by large ventricular complexes (wide QRS complex)
Ventricular fibrillation
Define
BPM
Symptoms
Pulseless??
Death?
What does it appear like on ECG
abnormal firing of electrical signals in the ventricles
300-600 BPM
Patients may collapse suddenly or become unconscious
pulseless- No blood flow (no cardiac output)
death w/in minutes
ECG: “bag of worms”, non-perfusing rhythm
Torsades de pointes (TdP)
Tachy or bradycardia
Associated w/patients w/__________
Life-threatening?? Why?
ADR of _____
Appearance on ECG
tachycardia
Associated with patients with Long QT syndrome (prolonged QTc interval on ECG)
*** Low potassium
life-threatening (non-perfusing rhythm)
-May progress to v. fib
may present as sudden cardiac death, pulselessness, low blood pressure
ADR of drugs i.e. Azithromycin-Zithromax®, moxifloxacin-Avelox®
ECG: twisted ribbon
