Equine Arrhythmias

Question 1

The p wave is __, the QRS is __ and T is __

Answer 1

The p wave is atrial depolarization, the QRS is ventricular depolarization and T is repolarization of the ventricles

Question 2

Why are ECG’s more difficult to map in horses?

Answer 2

Their heart is large and has spiral fibers

Question 3

The __ node depolarizes the fastest followed by a short pause at the __ node

Answer 3

The SA node depolarizes the fastest followed by a short pause at the AV node

Question 4

Explain how to place leads for a negative QRS complex in Lead 1

Answer 4

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)

Question 5

Equine normal sinus rhythm

Answer 5

A normal and consistent p wave preceded each QRS complex by a consistent and credible PR interval

Question 6

Sinus tachycardia is > __ bpm

Answer 6

Sinus tachycardia is > 50 bpm

Question 7

Why would a bradyarrhythmia go away during exercise?

Answer 7

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.

Question 8

Sinus arrhythmia are pauses < or equal to __ normal p-p intervals

Answer 8

Sinus arrhythmia are pauses < or equal to 2 normal p-p intervals

Question 9

Second degree AV block

Answer 9

Occasional P waves that are not followed by a QRS complex, this is the most common physiologic arrhythmia in horses

Question 10

Advances second degree AV block when __ p waves are not followed by a QRS but all QRS complexes are followed by a __

Answer 10

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

Question 11

3rd Degree AV Block

Answer 11

• 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

Question 12

How do we treat a third degree AV block?

Answer 12

Atropine or a pacemaker

Question 13

Supraventricular Tachyarrhythmias

Answer 13

Premature atrial complexes and atrial fibrillation

Question 14

Ventricular tachyarrhythmias

Answer 14

VPC’s, ventricular tachycardia, torsades de pointes

Question 15

Premature atrial complexes

Answer 15

Abnormal looking p wave that may or may not conduct and may predispose a horse to atrial fibrillation

Question 16

Atrial fibrillation happens in the absence of __ that create a __ rhythm and irregular ___

Answer 16

Atrial fibrillation happens in the absence of p waves that create a irregular- irregular rhythm and irregular RR

Question 17

When should you attempt to convert a horse to NSR when they have AF?

Answer 17

If they are athletes without structural heart disease

Question 18

Atrial fibrillation can be treated by Quinidine sulfate or transvenous electrocardioversion

Answer 18

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

Question 19

Premature ventricular complexes (VPC’s) are associated with __, __ , __and __ .

Answer 19

Premature ventricular complexes (VPC’s) are associated with colic , electrolyte abnormalities, exercise, and myocarditis .

Question 20

Ventricular tachycardia is__ or more PVCs that are often __ and __. It has a __ rhythm that may sound __.

Answer 20

Ventricular tachycardia is 3 or more PVCs that are often wide and bizarre. It has a rapid rhythm that may sound regular.

Question 21

Is uniform or multi form ventricular ectopy worse?

Answer 21

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

Question 22

Torsade de pointes

Answer 22

Disorganized ventricular electrical activity undulating across the baseline

Question 23

Treatment of ventricular ectopy

Answer 23

Lidocaine, magnesium sulphate, sotalol

Question 24

Treatment of supraventricular ectopy

Answer 24

Sotalol

Question 25

Treatment of AV block

Answer 25

Parasympatholytics (atropine)

Question 26

Lidocaine is a __ channel blocker that __ the action potential and __ cardiac excitability and abnormal automacity and __ the threshold for excitability

Answer 26

Lidocaine is a sodium channel blocker that shortens the action potential and decreases cardiac excitability and abnormal automacity and increases the threshold for excitability

Question 27

when should you not give lidocaine?

Answer 27

If they have an AV node block

Question 28

Magnesium sulfate is a __ physiological channel blocker that __ inappropriate cardiac automaticity and depolarizations. What is it the treatment of choice for?

Answer 28

Magnesium sulfate is a calcium physiological channel blocker that decreases inappropriate cardiac automaticity and depolarizations. It is the treatment of choice for torsades de pointes and digitalis toxicity.

Question 29

Sotalol is a __ blocking agent and __ channel blocker that __ the HR and __ the QT interval which __ conduction at the AV node.

Answer 29

Sotalol is a beta blocking agent and calcium channel blocker that decreases the HR and prolongs the QT interval which prolongs conduction at the AV node.