Equine Arrhythmias Flashcards
The p wave is __, the QRS is __ and T is __
The p wave is atrial depolarization, the QRS is ventricular depolarization and T is repolarization of the ventricles
Why are ECG’s more difficult to map in horses?
Their heart is large and has spiral fibers
The __ node depolarizes the fastest followed by a short pause at the __ node
The SA node depolarizes the fastest followed by a short pause at the AV node
Explain how to place leads for a negative QRS complex in Lead 1
First place the white negative lead on the right point of the shoulder, then place the black positive lead on the left axilla, and then the red can go anywhere on the right other (jugular groove)
Equine normal sinus rhythm
A normal and consistent p wave preceded each QRS complex by a consistent and credible PR interval
Sinus tachycardia is > __ bpm
Sinus tachycardia is > 50 bpm
Why would a bradyarrhythmia go away during exercise?
If its non-pathologic then the increase in sympathetic tone from exercise will make it disappear. The horse likely has bradyarrhythmias from hight parasympathetic tone.
Sinus arrhythmia are pauses < or equal to __ normal p-p intervals
Sinus arrhythmia are pauses < or equal to 2 normal p-p intervals
Second degree AV block
Occasional P waves that are not followed by a QRS complex, this is the most common physiologic arrhythmia in horses
Advances second degree AV block when __ p waves are not followed by a QRS but all QRS complexes are followed by a __
Advances second degree AV block when 2 or more p waves are not followed by a QRS but all QRS complexes are followed by a p wave
3rd Degree AV Block
- The p waves are present but have no association with the QRS
- QRS may be wider and R-R interval irregular
- low HR and decreased CO may result in cardiac syncope and death
How do we treat a third degree AV block?
Atropine or a pacemaker
Supraventricular Tachyarrhythmias
Premature atrial complexes and atrial fibrillation
Ventricular tachyarrhythmias
VPC’s, ventricular tachycardia, torsades de pointes
Premature atrial complexes
Abnormal looking p wave that may or may not conduct and may predispose a horse to atrial fibrillation
Atrial fibrillation happens in the absence of __ that create a __ rhythm and irregular ___
Atrial fibrillation happens in the absence of p waves that create a irregular- irregular rhythm and irregular RR
When should you attempt to convert a horse to NSR when they have AF?
If they are athletes without structural heart disease
Atrial fibrillation can be treated by Quinidine sulfate or transvenous electrocardioversion
Quinidine Sulfate is a sodium channel blocker that also affects K+ channels prolongs the refractory period and slows AP conduction
TVEC is when you place catheters within the right atrium and pulmonary artery via the jugular and then deliver shocks on the R wave
Premature ventricular complexes (VPC’s) are associated with __, __ , __and __ .
Premature ventricular complexes (VPC’s) are associated with colic , electrolyte abnormalities, exercise, and myocarditis .
Ventricular tachycardia is__ or more PVCs that are often __ and __. It has a __ rhythm that may sound __.
Ventricular tachycardia is 3 or more PVCs that are often wide and bizarre. It has a rapid rhythm that may sound regular.
Is uniform or multi form ventricular ectopy worse?
Multi form because the different areas of the ventricle are depolarizing which could cause them to go into fatal arrhythmias and speaks to how wide the myocardial dysfunction is
Torsade de pointes
Disorganized ventricular electrical activity undulating across the baseline
Treatment of ventricular ectopy
Lidocaine, magnesium sulphate, sotalol
Treatment of supraventricular ectopy
Sotalol
