Unit 1 - Cardiology (intro to Atrial arrhythmias)

Question 1

What physical exam findings are associated with mild cases of cardiovascular disease?

Answer 1

no clinical signs, reduced exercise tolerance

Question 2

What physical exam findings are associated with moderate cases of cardiovascular disease?

Answer 2

tachycardia, tachypnea, dyspnea post exercise, abnormal arterial pulse, jugular distention, edema over ventral abdomen, edema in the distal limbs, and pathologic arrhythmias

Question 3

What physical exam findings are associated with severe cardiovascular disease?

Answer 3

cool extremities, weight loss, reduced capillary refill time, cough, dyspnea at rest, and collapse

Question 4

What are the reasons for evaluating for cardiovascular disease?

Answer 4

obvious signs of heart disease, poor athletic performance, pre-purchase examination, insurance examination

Question 5

What are the components of a cardiac evaluation?

Answer 5

auscultaion, ECG, echo, and exercise testing

Question 6

What is the normal resting heart rate of the horse?

Answer 6

20-40 beats per minute

Question 7

What is S1?

Answer 7

sound 1 - the lub followed by systole

Question 8

What is S2?

Answer 8

sound 2 - the dub followed by diastole

Question 9

What is S4?

Answer 9

the atrial sound

Question 10

What makes the atrial sound?

Answer 10

it arises from ventricular vibrations set up when pressure wave caused by the atrial contraction reaches the ventricle

Question 11

When arrythmia is an isolated S4 associated with?

Answer 11

2nd (and 3rd) degree A-V block

Question 12

When is S4 absent?

Answer 12

in a sinoatrial block

Question 13

What does S4 immediately preceed?

Answer 13

lub

Question 14

When and where does S1 come from?

Answer 14

It arises mostly from the ventricle, after AV valve closure

Question 15

What does the atrial-S1 interval depend on?

Answer 15

the P-Q interval

Question 16

What is S2 made by?

Answer 16

closure of semi-lunar valves and rapid reversal of blood flow

Question 17

What is S3 made by?

Answer 17

early, rapid ventricular filling

Question 18

Where anatomically is S3 heard? In what percent of horses?

Answer 18

left side, 30-50%

Question 19

What are the semi-lunar valves?

Answer 19

aortic and pulmonic valves

Question 20

Where is S1 the loudest on auscultation?

Answer 20

over the mitral valve - in the intercostal space between ribs 5 and 6, right at the caudal edge of the triceos

Question 21

Where is S2 the loudest on auscultation?

Answer 21

over the aortic valve - in the intercostal space between ribs 4 and 5

Question 22

What makes the P wave on an ECG?

Answer 22

right atrial depolarization with a wave spreading from the S-A node across the right atrium, the interatrial septum, and then the left atrium

Question 23

At rest, how does the P wave appear?

Answer 23

it is often bifid

Question 24

What does the first small ‘hump’ of the p-wave represent?

Answer 24

mostly right atrial depolarization

Question 25

Is the QRS wave due depolarization as a wavefront like the p wave is?

Answer 25

No, the depolarization is NOT as a wavefront across the chambers due to much branching of the conducting system

Question 26

QRS at body surface reflects about ___ of the depolarization of the myocardial mass.

Answer 26

20%

Question 27

What causes the T wave?

Answer 27

repolarization of the ventricles

Question 28

The equine T-wave is very \_\_\_\_.

Answer 28

labile

Question 29

The T-wave changes polarity with \_\_\_\_\_\_.

Answer 29

heart rate

Question 30

What can the T-wave not be used to assess?

Answer 30

heart strain

Question 31

What is ECG only useful for determining?

Answer 31

arrhythmias

Question 32

A.

Answer 32

bifid P wave

Question 33

B.

Answer 33

diastole

Question 34

C.

Answer 34

S4 - ba

Question 35

D.

Answer 35

QRS complex

Question 36

E.

Answer 36

systole

Question 37

F.

Answer 37

S1 - lub

Question 38

G.

Answer 38

T-wave

Question 39

H.

Answer 39

Diastole

Question 40

I.

Answer 40

S2 - dub

Question 41

J.

Answer 41

S3 - ah

Question 42

If a murmur is heard at E, what type of murmur is it?

Answer 42

a systolic murmur

Question 43

If a murmur is heard at B or H, what type of murmur is it?

Answer 43

a diastolic murmur

Question 44

Where will a atrial arrythmia be heard?

Answer 44

at S4

Question 45

Is systole A or B? Diastole?

Answer 45

Systole is A, diastole is B

Question 46

What depth is required for echo in horses? What size transducer?

Answer 46

a depth of 30 centimeters, 3.5 mHz transducer

Question 47

What is echocardiography useful in detecting?

Answer 47

congenital anomalies

Question 48

When should exercise testing take place?

Answer 48

cardiac evaluation should be performed at or immediately after expected level of exercise

Question 49

What are the types of atrial arrhythmias?

Answer 49

wandering pacemaker, premature sinus beats, premature atrial beats, sino-atrial block, sinus bradycardia, post exercise sinus arrhythmia, and atrial fibrillation

Question 50

Is wandering pacemaker a true arrhythmia?

Answer 50

not really, it is an ECG finding

Question 51

How does a wandering pacemaker present on ECG?

Answer 51

the p-wave shape may change from beat to beat, but the rhythm is regular

Question 52

Is wandering pacemaker clinically significant?

Answer 52

no

Question 53

How do premature sinus beat arrythmias present on ECG?

Answer 53

P waves are earlier than normal, but of normal conformation. The QRS wave is normal

Question 54

When do premature sinus beats disappear?

Answer 54

with exercise

Question 55

When do premature sinus beats suggest myocardial disease?

Answer 55

when there are frequent ones - it is not significant if there is one occasionally every 5 minutes

Question 56

What is the recommended treatment for horses that have frequent premature sinus beats?

Answer 56

to rest the horses and reevaluate in 4-6 months

Question 57

How do premature atrial beats appear on ECG?

Answer 57

the same as premature sinus beats, but the P waves are of abnormal conformation

Question 58

What causes the abnormal conformation of P waves in premature atrial beat arrhythmias?

Answer 58

there is an ectopic focus in the atrial muscle

Question 59

When do premature atrial beats suggest myocardial disease? Treatment?

Answer 59

If they are very frequent, it suggests myocardial disease. Rest these horses, and then reevaluate in 4-6 months.

Question 60

How do sino-atrial blocks appear on ECG?

Answer 60

There is no P-wave and a twice normal diastolic pause (2 dubs)

Question 61

What horses are sino-atrial blocks more common in?

Answer 61

ponies

Question 62

What abolishes sino-atrial block?

Answer 62

exercise

Question 63

What mediates sino-atrial block?

Answer 63

it is vagally mediated

Question 64

Is sino-atrial block clinically significant?

Answer 64

not usually

Question 65

What horses typically have sinus bradycardia?

Answer 65

mostly ponies - it is rare

Question 66

How does sinus bradycardia present?

Answer 66

as a very slow irregular atrial rhythm

Question 67

What clinical signs are associated with sinus bradycardia?

Answer 67

reduced exercise or even lethargy

Question 68

What may reslove sinus bradycardia?

Answer 68

rest

Question 69

When are post exercise sinus arrhythmias common?

Answer 69

after light trotting exercise in fit horses

Question 70

How do post-exercise sinus arrhythmias occur?

Answer 70

As the heart rate slows, there are sudden pauses, and then a gradual return to the pre-pause rate

Question 71

Are post-exercise sinus arrhythmias significant? How can they be abolished?

Answer 71

Not usually significant, abolished by more rigorous exercise

Question 72

What clinical signs are associated with atrial fibrilation?

Answer 72

they are variable - they could have none up to heart failure, they may have pulse deficits

Question 73

On auscultation, how does atrial fibrilation sound?

Answer 73

there are no atrial sounds, irregularly spaced group of irregular beats, S1 and S2 vary in intensity due to variable ventricular filling

Question 74

What heart rate is associated with atrial fibrilation?

Answer 74

the heart rate can range from 30-40 up to 80-100

Question 75

What treatment is recommended for atrial fibrillation?

Answer 75

It is best if it is done early in the disease - oral quinidine is a drug of choice

Question 76

How is oral quinidine administered?

Answer 76

via a nasogastric tube

Question 77

What is the protocol for oral quinidine treatment for atrial fibrillation?

Answer 77

Give a test dose of 5 grams on day 1, if no adverse reaction then proceed to day 2 On day 2, give 20 grams as a start up dosage and give an additional 10 grams every 2 hours (make sure to perform an ECG before giving each dose)

Question 78

What dosage should you not exceed for oral quinidine per day?

Answer 78

do not exceed 90 grams/day in a 1000 pound horse

Question 79

What toxic signs are associated with atrial fibrillation treatment of quinidine?

Answer 79

Depression (often), tachycardia, diarrhea (often), colic (often), urticaria, nasal edema, weakness, ataxia, and death

Question 80

Aside from oral quinidine, what can be used to treat atrial fibrillation?

Answer 80

IV quinidine (expensive and risky), Digoxin (if heartrate is greater than 60 bpm), and electrical cardioversion (shocking)