PHYSIOLOGY - ARRYTHMIAS Flashcards
What are the different causes of Arrhythmias?
1) Abnormal rhythmicity of the pacemaker
2) Shift of pacemaker activity
3) Conduction Blocks
4) Abnormal pathways of impulse transmission
5) Spontaneous generation of abnormal impulses
7 Questions that must be asked to determine whether or not arrythmias are present
1) What is the heart rate? 2) What is the rhythm? 3) Are P waves present? 4) Is there a P wave for every QRS complex? 5) Is there a QRS for every P? 6) Are the P’s and QRS’s consistantly related? 7) Do all the P’s and QRS’s look alike?
3 Different Types of Normal Cardiac Rhythms
1) Normal Sinus Rhythm 2) Sinus Arrhythmia 3) Wandering Atrial Pacemaker Look at Lead 2 (60 Degrees)
What Arrhythmias produce different speeds of heart rate?
Sinus Brachycardia
Sinus Tachycardia
Sinus arrhythmia
Impulses originate at the SA node at a varying rate = fires FASTER and then SLOWER
All complexes are normal but RHYTHMICALLY IRREGULAR
Longest PP or RR interval exceeds shortest by 0.16 sec or more
CAUSED BY HEAVY RESPIRATION
Wandering atrial pacemaker
Impulses originate from varying points in atria between SA and AV nodes
P Wave changes configuration as signal begins at different areas
QRS is NORMAL
Sinus Brachycardia
Impulses originate at SA Node at a SLOW rate
Normal sinus rhythm w/ HR
Parasympathetic Causes - increased vagal tone, beta-blockers, propanolol, digitalis
Sinus Tachycardia
Impulses originate at the SA Node at a RAPID rate
Normal sinus rhythm w/ HR > 160 bpm
Sympathetic Causes = exercise, fever, hyperthyroidism, shock, etc.
Sinus arrest
Abnormal Arrhythmia
SA node stops firing (beats with a pause = NORMAL PACING WITH A BASELINE PAUSE
Escape Beat = first large upward deflection after pause
A dog faints due to loss of blood to the brain. What would be the compensatory effect to help blood get to brain since blood is not fighting gravity?
Sinus Arrest
Abnormal Rythms that result from Impulse Conduction Blocks
1) 1st Degree Atrioventricular Block
2) 2nd Degree AV Block
3) 3rd Degree AV Block
Causes of AV Blocks include: ischemia of AV node, compression or inflammation of AV node/Bundle, and increased stimulation of heart by vagus nerve
First degree AV block
Abnormal rhythm that results from Impulse Conduction Blocks (potential wide P Wave)
Fixed but PROLONGED PR INTERVAL
Partial block above OR below AV Node
Potential Causes = Mitral insufficiency, Digoxin toxicity
Not dangerous but will progress
Second degree AV block
Abnormal rhythm that results from Impulse Conduction Blocks
2 Different Types:
1) Mobitz Type I - PROGRESSIVE LENGTHENING of PR interval before dropped beat
Coduction starts off normal but gets progressively work with accompanied lengthening B4 dropped QRS = AV node recovers and PR Interval is normal again
Wenckbach Phenomenom
Potential Causes = Digoxin Toxicity
2) Mobitz Type II - SUDDEN QRS dropped W/OUT prior PR Interval lengthening
AV Block at level of Bundle of His OR at bilateral bundle branches OR at trifascicular
Atrial rate is greater than the ventricular rate (MORE P waves due to QRS drop)
Non-Wenkebach
Can have MULTIPLE P waves without a QRS Complex
Third degree AV block
Abnormal rhythm that results from Impulse Conduction Blocks
COMPLETE AV BLOCK
NO RELATIONSHIP BETWEEN P WAVES AND QRS COMPLEXES
2 different scenarios - SA Node conducts impulse in atria (P waves) BUT:
1) Block ABOVE AV Node = AV Node conducts impulses to ventricles
2) Block BELOW AV Node = Purkinje Fibers conduct impulse to ventricles
Atria and Ventricles fire a DFFERENT rates
QRS rate is SLOWER than the P rate bc AV node and Purkinje fibers fire at slower rates than the SA Node
Pacemake placed in ventricles to allow P wave and QRS complexe rates to match up
Supraventricular (ABOVE) and Ventricular Abnormalities
Different Types:
1) Premature Contraction:
2) Tachycardia
3) Fibrillations
