Unit 1 - Cardiology (Ventricular arrythmias to end)

Question 1

What occurs when there is a first degree AV block?

Answer 1

There is an increase in the P-R interval above .4 seconds at rest - as the interval increases, so does the time in between S4 and S1

Question 2

Is first degree AV block clinically significant?

Answer 2

no

Question 3

What horses is second degree AV block common in?

Answer 3

large, fit horses

Question 4

What does Mobitz I mean?

Answer 4

In reference to second degree AV block, there may be a gradual increase in the P-R interval, then impulse blocked at the AV node

Question 5

What does Mobitz II mean?

Answer 5

In reference to second degree AV block, there may be no apparent increase in the P-R interval, with spontaneous occasional block at the AV node

Question 6

What does second degree AV block sound like on auscultation?

Answer 6

the diastolic pause is twice the normal length with S4 in the middle of the pause

Question 7

What is likely the cause of a second degree AV block?

Answer 7

It is probably a baroreceptor feedback that is vagally mediated

Question 8

What can induce a second degree AV block?

Answer 8

alpha-2 agonists

Question 9

Third degree AV block is due to a complete _________ with the AV node.

Answer 9

dissociation

Question 10

What is a premature ventricular contraction?

Answer 10

When the beat is earlier and louder than normal, not preceded by the atrial sound - often followed by a compensatory pause

Question 11

What is the etiology associated with premature ventricular contractions?

Answer 11

It isn’t completely understood - most horses have no cardiac lesions, 10-12% have inflammatory/degenerative lesions, some substances cause severe myocardial damage

Question 12

When horses drop dead while being watched, or are found dead, what is the likely cause?

Answer 12

They probbaly suffer acute ventricular arrythmias - ventricular fibrillation or sustained ventricular tachycardia

Question 13

In what population of horses are flow disorders typically detected in? Are they clinically significant?

Answer 13

older horses, most are not significant

Question 14

True or False: The loudness of a murmr is not a good indication of size or significance of a lesion.

Answer 14

TRUE - the area over which a murmur radiates is usually more useful in determining the significance than is loudness

Question 15

What are most equine murmurs due to?

Answer 15

non-infectious acquired lesions

Question 16

Where are systolic murmurs audible?

Answer 16

over the aortic root or over the mitral valve

Question 17

What is a common systolic murmur over the aortic root?

Answer 17

physiologic ejection murmur

Question 18

What are systolic murmurs audible over the mitral valve mostly due to?

Answer 18

mild forms of mitral insufficiency

Question 19

What happens if the mitral chordae tendinae ruptures?

Answer 19

animals drop dead, there is a sudden onset of pulmonary edema with dyspnea, heart failure develops in 24-48, and there is often a loud, widely radiating pansystolic murmur, often with a palpable thrill

Question 20

What are over 90% of diastolic murmurs due to?

Answer 20

aortic insufficiency

Question 21

What do diastolic murmurs sound like?

Answer 21

they vary from musical, a pure tone, to a noisy mixed murmur - usually pandiastolic

Question 22

What valve is commonly affected by endocarditis?

Answer 22

the aortic valve

Question 23

What clinical signs are associated with endocarditis?

Answer 23

fever, anorexia, and weight loss

Question 24

When do murmurs associate with endocarditis typically develop?

Answer 24

late in disease - heart failure is common late in disease

Question 25

What is the prognosis for horses with endocarditis?

Answer 25

grave

Question 26

What is the most common congenital heart lesion in horses?

Answer 26

ventricular septal defect (VSD)

Question 27

What horse breed is commonly affected by congenital heart lesions?

Answer 27

Arabian

Question 28

What congenital lesion is very rare in horses?

Answer 28

Patent ductus arteriosis (PDA)

Question 29

What treatment is required for maintaining patency of PDA?

Answer 29

Eicosanoids

Question 30

What other medications are important for treatment of PDA?

Answer 30

NSAID’s

Question 31

How long does it take for PDA to close?

Answer 31

in four days

Question 32

Characterize pericarditis in horses.

Answer 32

It is often septic, a chronic, progressive disease course

Question 33

Sound 3 of the cardiac cycle is produced by the sound associated with:

a. Closure of the aortic and pulmonic valves
b. Closure of the semilunar valves
c. rapid ventricular filling
d. Closure of the atrioventricular valves

Answer 33

c. rapid ventricular filling

Question 34

Sound 4 of the cardiac cycle is produced by the sounds associated with:

a. closure of the aortic and pulmonic valves
b. rapid ventricular contraction
c. atrial contractio
d. closure of the ductus arteriosis

Answer 34

c. atrial contraction

Question 35

A twice normal diastolic pause is auscultated in a horse. During the pause, a distinct heart sound is detected. The findings are most consistent with:

a. Atrical fibrillation
b. 2nd degree atrio-ventricular heart block
c. Atrial arrest with subsequent idioventricular contraction
d. sinoatrial block

Answer 35

b. 2nd degree atrio-ventricular heart block

Question 36

In the attached ECG, the impulse is blocked at (which arrow) which produces a twice normal diastolic pause? (A, B, or C)

Answer 36

A. it is a sinoatrial block