Chapter 8 PowerPoint Flashcards
Normal conduction: ____ Node sends signal to ____ node?
SA Node sends signal to AV node
Two types of heart blocks?
Partial
Complete
Types of partial heart blocks?
Partial – first degree, second degree, type 1, type 2
What is a complete heart block?
Complete – third degree
What are heart blocks known as?
Known as conduction disturbances
Signal to AV node and bundle of His is interrupted
How does a first degree AV block appear on a ECG?
Prolonged PR interval, consistent beat to beat
>.20 sec with each cardiac cycle
1 p wave for every QRS complex
HR normal, Bradycardia or tachycardia
Normal P wave shape unless Atrial Enlargement
5 causes of a first degree AV block?
-Enhanced Parasympathetic tone
-AV nodal disease
-Coronary Artery disease
-Medications
-Electrolyte disturbances
Treatment for fist degree AV block?
Benign, No treatment progression but monitor
Bradycardia?? Atropine to elevate HR
What is second degree AV block also called?
Mobitz 1 or Wenckebah phenomenon or Mobitz II
What are characteristics and how does a Mobitz 1 AV appear on an ECG?
1 dropped beat, P wave nonconductive
PR interval progressively increase until p wave appears w/o QRS complex
Generally, 3-5 beats run of progressing PR intervals precede non-conducted beat
Repeats the same pattern
Causes of Mobitz 1?
Medication
Ischemia RCA
Enhanced Vagal Tone
Amyloidosis and sarcoidosis
Acute inferior wall myocardial infarction
Treatment for Mobitz 1?
Benign rhythm, no tx necessary
Watch for progressing block
Atropine if symptomatic bradycardia
Where does Mobitz II occur?
Mobitz II or Type II Occurs below the AV node with high percentage distal to the bundle of HIS
Heart rate possibilities associated with Mobitz II?
Irregular ventricular rate or regular bradycardic ventricular rate
Mobitz type II is often ____ or ____?
Often undiagnosed or misdiagnosed
Severity of Mobitz II?
Can be life threatening
How does Mobitz II appear on an ECG?
Intermittent nonconductive p waves without progressive prolongation of PR intervals
Dropped QRS complex, irregular R-R intervals
Regular non-conducted P waves, regular R-R interval
What is a third degree AV block?
Complete Block – NO Signal between Atria and Ventricles
SA Node Still sends Signals but goes nowhere
How do the ventricles respond to a 3rd degree AV block?
Ventricles have an Escape Pacemaker that initiates Ventricle Depolarization
What is the relation between the ventricles and atria in a 3rd degree AV block?
Atria and Ventricles Depol at independent times and at different rates
Atria Faster
Ventricle – Bradycardic (30-45Bpm)
How does a 3rd degree AV block appear on an ECG?
Appearance on ECG
P-P intervals are constant (atrial rate).
R-R intervals are constant (ventricular rate).
No consistent PR intervals.
QRS complex normal width or wide.
Causes of third degree AV block?
Enhanced Vagal Tone
Toxicity of Cardioactive meds
Acute MI
Symptoms of 3rd degree AV block?
Symptoms – Decreased Cardiac Output
Syncope
Light headedness
Apnea
Seizure
Possible death
Treatment for 3rd degree AV block?
Acute MI? EMERGENCY!!
Meds? – adjust and remove drug causing block
Meds that help depress vagal tone
Atropine or isoproterenol
