Cardiac Arrythmias Flashcards
5 Causes of Arrhythmias
1-Abnormal rhythmicity of the pacemake
2-Shift of pacemaker activity
3-Conduction of blocks
4-Abnormal pathways of impulse transmission
5-Spontaneous generation of abnormal impulses
3 Normal Cardiac Rhythmns
1-Normal sinus rhythm: impulses originate at SA node at normal rate
2-Sinus arrhythmia: impulses originate at SA node at varying rates
3-Wandering atrial pacemaker: impulses originate from varying points in atria
In ALL: PQRST waves are normal. Spacing may just vary.
Primary cause of sinus arrythmia
Breathing
Normal HR for cats and dogs
Cats=140-220
Dogs=70-160
Abnormally fast or slow heart rate originating at SA node
Fast-sinus tachycardia (maybe due to fever or hyperthroidism or in shock)
Slow-Sinus bradycardia
Sinus Arrest
When SA node stops firing
Describe ECG for sinus arrest
Normal PQRST waves then there’s nothing for ~5 seconds because SA node didn’t fire.
First-degree atrioventricular block
There’s a fixed by prolonged PR interval. P-R interval is greater than 0.14 seconds n dog.
No dropped beats
Second degree AV block: Mobitz type I
There’s progressive lengthening of PR interval with intermittent dropped beats.
Dropped beat.
Second degree AV block: Mobitz type II
AV block at bundle of His lvl
There’s a sudden dropped QRS without prior PR lengthening.
Often see P:QRS in ratios
Third degree AV block
Impulses originate at SA node but there’s no coordination with perkinje fibers.
Atria and ventricles are on different pages
P:QRS does not have a relationship.
Depending on if L or R perkinje fibers pick up impulse will give S or R wave.
L=S
R=R
Supraventricular and Ventriculr Abnormalities (3)
Premature contraction
tachycardia
Fibrillation
Reasons for premature contractions
- Contractions occur before they are supposed to
- Pulse deficit:ventricles don’t fill with blood properly and stroke volume is decreased
- Bigeminal pulse: every other beat may be premature
Tachycardia definition
At least 3 or more premature contractions
Paroxysmal:lasts for varying amount off time and can stop whenever
What are fibrillations
Many separate and small waves spreading at the same time in different directions over cardiac muscle.