LA Cardiology

Question 1

What is the most common pathologic arrhythmia in horses?

Answer 1

Atrial fibrillation

Question 2

What are the clinical signs of atrial fibrillation in a horse?

Answer 2

1. Exercise intolerance
2. Epitaxis
3. Dyspnea
4. Edema
5. Weakness
6. Collapse

Question 3

What are the two types of equine atrial fibrillation?

Answer 3

1. Primary

2. Secondary

Question 4

What is an equine flow murmur?

Answer 4

A non-pathologic murmur that is soft and systolic at the heart base

Question 5

What is considered tachcardic on an ECG?

Answer 5

> 40 bpm

Question 6

Do we calculate the MEA or measure the QRD complex in large animals? Why or why not?

Answer 6

No, because the diffuse distribution of the purkinje fibers

Question 7

What is the most common congenital heart defect in horses and food animals?

Answer 7

Ventral septal defect

Question 8

What is the most common non-pathologic arrhythmia in horses?

Answer 8

2nd degree AV node block, Type 1

Question 9

What causes 2nd degree AV node block type 1 in horses?

Answer 9

High vagal tone

Question 10

What is the major issue with horses and heart arrhythmias?

Answer 10

Liability to the rider

Question 11

What kind of horses usually get primary atrial fibrillation? What about secondary?

Answer 11

Young horses: primary

Old horses: Secondary

Question 12

What is the difference in heart rates between primary and secondary atrial fibrillation?

Answer 12

Primary: < 60 bpm
Secondary: > 60 bpm

Question 13

Which type of atrial fibrillation in horses is usually due to structural abnormalities of the heart?

Answer 13

Secondary

Question 14

What is the most likely cause for primary atrial fibrillation in horses?

Answer 14

High vagal tone and large size of the atrial myocardium which predisposes the heart to electrical heterogeneity

Question 15

What can cause paroxysmal primary atrial fibrillation in a horse?

Answer 15

Hypokalemia due to furosemide administration

Question 16

How can primary atrial fibrillation in horses be treated?

Answer 16

1. Transvenous electrocardioversion
2. Transthoracic electrocardioversion ( only in foals)
3. Oral or IV Quinidine

Question 17

How can secondary atrial fibrillation in horses be treated?

Answer 17

1. Treat for congestive heart failure
2. Digoxin
3. Quinidine

Question 18

What is the side effect of treating atrial fibrillation in a horse with quinidine? How would you fix it?

Answer 18

1. Tachycardia and counter with digoxin
2. Edema of nasal mucosa
3. Colic
4. Laminitis

Question 19

How successful is it to treat primary atrial fibrillation?

Answer 19

80% of horses remain converted

Question 20

What are the poor prognostic indicators for an old horse with secondary atrial fibrillation?

Answer 20

1. Severe structural heart disease
2. Recurrent boats of atrial fibrillation
3. Long standing atrial fibrillation ( over months-years)
4. Failure to convert with serum quinidine