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LA DX & TX I > Exam 2 - Equine Cardiology > Flashcards

Exam 2 - Equine Cardiology Flashcards

1
Q

what is the maximum heart rate of a horse during exercise?

A

250 bpm

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2
Q

what may the client report in terms of cardiac history of their horse?

A

poor performance, exercise intolerance, lethargy, collapse (syncope), & lethargy

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3
Q

what may the veterinarian note as abnormal on the cardiac exam of a horse?

A

tachycardia, arrhythmia, murmur, abnormal pulses, venous distention/jugular pulses, & abnormal mucus membranes/CRT

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4
Q

what points do you listen to on the left side of the horse during cardiac evaluation?

A

pulmonic valve - 3rd intercostal space/rib

aortic valve - 4th intercostal space/rib

mitral valve - 5th intercostal space/rib

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5
Q

what points do you listen to on the right side of the horse during cardiac evaluation?

A

tricuspid valve - 4th intercostal space/rib

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6
Q

how many heart sounds can be heard in a healthy horse?

A

4

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7
Q

you are listening to a 15 year old Thoroughbred gelding and detect a diastolic murmur on the left side at approximately the 4th ICS. what do you expect is affected? do you think this is pathologic or innocent? why?

A

aortic valve - valvular disease

pathologic - degenerative or idiopathic

older horse - no other signs given, but could see bounding pulses if volume overload is present

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8
Q

what does s4 correspond with?

A

atrial contraction

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9
Q

what is the first sound heard in each cardiac cycle?

A

S4 - atrial contraction

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10
Q

where is S4 best heard?

A

best heard near the apex of the heart

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11
Q

in relation to an ecg, when does S1 occur?

A

conclusion of QRS complex

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12
Q

what does S1 correspond with in the cardiac cycle?

A

onset of ventricular contraction (systole) - closure of the AV valve

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13
Q

what are some causes for an accentuated S1 sound?

A

increased sympathetic tone

thin animal

anemia

fever

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14
Q

what are some causes for a diminished S1 sound?

A

obese animal

pleural/pericardial fluid

decreased contractility

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15
Q

where is S1 best heard?

A

apex of the heart

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16
Q

in terms of frequency & duration, how does S1 compare to S2?

A

S1 is lower in frequency & longer duration in sound

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17
Q

what does S2 correspond with in the cardiac cycle?

A

termination of systole - closure of semilunar valves

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18
Q

in relation to an ecg, when does S2 occur?

A

coincides with or comes just after the T wave

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19
Q

why can S2 sometimes be ‘split’?

A

the closure of the aortic & pulmonary valves isn’t simultaneous

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20
Q

where can S2 be heard best?

A

best heard at the base of the heart

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21
Q

what does S3 correspond with in the cardiac cycle?

A

early diastole - rapid/passive ventricular filling

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22
Q

where is S3 best heard?

A

best heard at the apex

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23
Q

what heart sound can sometimes sound like a ‘squeaky gate’?

A

S3

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24
Q

what is an ecg especially helpful for evaluating?

A

arrhythmias

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25
Q

what does an echocardiogram assess?

A

heart structure, contractions, valvular competence, evidence of pericardial effusion etc.

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26
Q

what lab tests may help when assessing cardiovascular health?

A

cardiac troponin I for inflammation

CBC/fibrinogen/SAA

chemistry panel - renal & muscular values

blood culture - endocarditis

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27
Q

what diagnostic test is critical for evaluating an arrhythmia?

A

ecg

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28
Q

where do you put the leads of an ecg on a horse for a standing base/apex reading?

A

positive over the left heart apex

negative in the right jugular furrow

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29
Q

how does an ecg of a horse differ from one in small animals?

A

P wave is often notched

QRS complex is mostly negative

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30
Q

why do horses get physiological arrhythmias?

A

result from high vagal tone

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31
Q

how can you test a horse for a suspected physiologic murmur?

A

can get rid of it by elevating the heart rate/sympathetic tone

excitement/fright, exercise, or vagolytic drugs

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32
Q

what is the most common physiological arrhythmia that occurs in >50% of horses at rest?

A

second degree AV block - usually wenckebach or type-1

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33
Q

T/F: a physiologic murmur is associated with clinical signs

A

false - no clinical signs

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34
Q

what murmur is shown on this ecg?

A

2nd degree av block - p wave missing a qrs complex

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35
Q

when do sinus arrhythmias often occur in horses?

A

often occurs during heart rate recovery following exercise

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36
Q

T/F: sinus arrhythmias are more common in dogs than horses, but more common in horses than cats

A

true

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37
Q

what is the single most common pathological arrhythmia of the horse?

A

atrial fibrillation

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38
Q

what is the most common atrial fibrillation type seen in horses?

A

lone ‘afib’

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39
Q

other than lone afib, what other types can occur?

A

paroxysmal, persistent, & permanent

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40
Q

what is the suggested cause of lone afib?

A

no underlying disease cause!!

high vagal tone & large atrial myocardial volume

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41
Q

apart from lone afib, what other etiologies may cause paroxysmal/persistent/permanent atrial fibrillation?

A

atrial chamber enlargement

electrolyte/acid base disturbance

atrial myocardial disease

myocarditis

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42
Q

what is the primary disease cause of afib in cattle?

A

gi disease

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43
Q

what horse breeds are most commonly affected by afib?

A

standardbreds, thoroughbreds, & draft breeds

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44
Q

T/F: horses with afib are often asymptomatic

A

true

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45
Q

what clinical signs may be seen in a horse with afib?

A

epistaxis & poor performance

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46
Q

‘shoes in a dryer’ describes what arrhythmia in horses?

A

afib

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47
Q

what will be heard upon auscultation of a horse with afib?

A

irregularly, irregular rhythm

variable intensity of the first & second heart sound

absence of the 4th heart sound

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48
Q

what arrhythmia is present on this ecg?

A

afib

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49
Q

what will be seen on ecg of a horse that has atrial fibrillation?

A

normal QRS-T morphology, but frequency is variable

no p waves

isoelectric line undulates - fibrillation/flutter waves, f waves

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50
Q

why would an echo be used on a horse with atrial fibrillation?

A

used to look for structural heart changes - determine prognosis

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51
Q

what is the major finding seen on an echo of a horse with atrial fibrillation?

A

large left atria!!

mild decrease in shortening fraction, loss of atrial contribution to ventricular filling, & absence of the 2nd atrial opening of the mitral valve

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52
Q

what medication is the most common treatment given for horses with atrial fibrillation?

A

quinidine sulfate - class 1a sodium channel blocker

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53
Q

how is quinidine sulfate dosed? what are the conditions that must be met to stop dosing?

A

22 mg/kg via NGT

conversion to a sinus rhythm, adverse or toxic effects occur, or a total or 4-6 doses

54
Q

what is the downside of using quinidine for treating afib in horses?

A

narrow therapeutic index: 2-5ug/mL

55
Q

what are some adverse effects caused by quinidine sulfate?

A

lethargy, colic, diarrhea, urticaria, laminitis, nasal edema, etc

56
Q

what factors influence the prognosis of afib?

A

structural heart changes

duration greater than 3 months

higher heart rate: >60 bpm

murmur

associated cardiac disease

57
Q

what is the recurrence rate of lone afib?

A

15-20%

58
Q

what is the prognosis for afib in horses?

A

many may return to full performance

59
Q

this is an echo showing an enlarged left atrium - what do you suspect?

A

afib

60
Q

what does APC stand for?

A

atrial premature complex

61
Q

what is an APC?

A

premature beat originating from the atrium

62
Q

VPCs are linked to what other abnormal rhythm?

A

ventricular tachycardia

63
Q

what are APCs/VPCs?

A

premature beats originating in the atrium or ventricles that interrupt an otherwise regular rhythm & may be followed by a compensatory cause

64
Q

APCs may cause what other arrhythmias?

A

afib or flutter

65
Q

T/F: in a horse with APCs/VPCs, cardiac output is usually not affected at rest

A

true

66
Q

how are APCs/VPCs diagnosed?

A

ecg/exercising ecg

67
Q

what arrhythmia is shown on this ecg?

A

APCs/VPCs

68
Q

how are APCs/VPCs treated?

A

rest for 60-120 days

anti-inflammatories

anti-arrhythmic if cardiac output is affected at rest

69
Q

what is ventricular tachycardia?

A

defined as an abnormal rhythm caused by 3 or more repetitive or linked VPCs

70
Q

what are the main concerns if a horse has ventricular tachycardia?

A

collapse & sudden death

71
Q

how is v tach diagnosed?

A

ecg

72
Q

what may be heard upon auscultation & seen on physical exam in a horse with v tach?

A

rapid, usually regular rhythm, with variable intensity, & booming heart sounds (‘bruit de cannon’)

pulse deficits or bounding pulses

73
Q

what arrhythmia is seen on this ecg?

A

ventricular tachycardia

74
Q

what 4 medications are used to treat atrial arrhythmias?

A
  1. beta blockers - sotalol
  2. calcium channel blockers
  3. digoxin
  4. quinidine sulfate
75
Q

what 5 drugs are used to treat ventricular arrhythmias?

A
  1. lidocaine
  2. magnesium sulfate
  3. beta blockers - sotalol
  4. procainamide
  5. quinidine sulfate
76
Q

what is the definition of a murmur?

A

audible vibrations created by turbulent blood flow

77
Q

what is the major difference between physiologic murmurs & pathologic murmurs?

A

pathologic murmurs are associated with structural abnormalities

78
Q

what heart valves are typically involved in physiologic murmurs?

A

aortic or pulmonic

79
Q

how are pathological murmurs diagnosed?

A

physical exam, echo, & doppler

80
Q

how are pathological murmurs characterized?

A

point of maximal intensity, timing, longer duration, harsh/musical/widely radiating, and higher grade

81
Q

if there is degenerative valvular disease/endocardiosis affecting the mitral valve, where would the murmur best be heard in regards to location & timing during the cardiac cycle? what is it associated with?

A

left apical systolic murmur

endocarditis

82
Q

if there is degenerative valvular disease/endocardiosis affecting the aortic valve, where would the murmur best be heard in regards to location & timing during the cardiac cycle? what is it associated with?

A

left basilar diastolic murmur

may get bounding pulse with volume overload - older horses

83
Q

if there is degenerative valvular disease/endocardiosis affecting the tricuspid valve, where would the murmur best be heard in regards to location & timing during the cardiac cycle? what is it associated with?

A

right 4th ICS systolic murmur

jugular pulsation

84
Q

what horses can commonly have acquired valvular disease affecting the tricuspid valve?

A

thoroughbreds & racehorses

85
Q

what is the prognosis of mild valvular disease?

A

mild regurgitation usually doesn’t not affect performance or heart function at rest

86
Q

what is the prognosis of severe valvular disease?

A

may lead to exercise intolerance or heart failure

87
Q

other than structural changes, what are some other causes of valvular disease?

A

chronic active infections - foot abscesses

neoplasia

ruptured chordae tendinae

endocarditis/myocarditis

88
Q

what diagnostic test should be run on any neonatal foal that has a grade 3 or greater heart murmur?

A

echo

89
Q

what is the most common cardiac congenital defect in foals?

A

ventricular septal defect

90
Q

what is the prognosis of VSD?

A

prognosis depends on size

louder = smaller = better prognosis

91
Q

what does a PDA sound like on cardiac auscultation?

A

continuous, machinery murmur

92
Q

what does VSD sound like?

A

right-sided murmur - may hear on left

pansystolic

loud, harsh sound, grade 3 or higher

93
Q

what is tetralogy of fallot?

A
94
Q

what part of the heart is most commonly affected in bacterial endocarditis? how does it spread?

A

mitral valve

aortic > tricuspid > pulmonic

hematogenous dissemination

95
Q

what clinical signs are associated with bacterial endocarditis?

A

fever, weight loss, depression, murmur, tachycardia, & bacterial showering - affects other system

96
Q

how is bacterial endocarditis diagnosed?

A

echo & blood culture

97
Q

what is the prognosis of bacterial endocarditis if the mitral & aortic valves are involved? what about the tricuspid & pulmonic valve?

A

mitral valve & aortic valve - poor

tricuspid valve & pulmonic valve - guarded

98
Q

what is the treatment for bacterial endocarditis?

A

long term IV & oral antibiotics, & antithrombotic agents

99
Q

how is pericarditis diagnosed & treated?

A

pericardiocentesis with culture & lavage

antimicrobial therapy

100
Q

what are the major clinical signs of pericarditis?

A

muffled heart sounds!!

fever, tachycardia, cardiac tamponade, & signs of right-sided heart failure

101
Q

what is pericarditis?

A

effusive, fibrinous, or constrictive inflammation of the pericardial lining

102
Q

what is the etiology of pericarditis?

A

viral - equine influenza virus & eastern tent caterpillar!!!!

others - EHV, EVA, streptococcus, actinobacillus, immune-mediated, & idiopathic

103
Q

what toxins cause myocarditis?

A

monensin, oleander, white snake root, cantharidin, box elder, & snake bites

104
Q

what is an infectious cause of myocarditis?

A

equine influenza virus

105
Q

other than toxins & infectious causes, what else can cause myocarditis?

A

systemic disease/endotoxemia, electrolyte disturbances, colic, colitis, pleuropneumonia, metritis, & selenium deficiency

106
Q

how is myocarditis diagnosed?

A

cardiac troponin 1!!!!

ecg for arrhythmia - APC/VPC/v tach

echo-dilation & reduced pump function

107
Q

how is myocarditis treated?

A

treat the underlying/primary disease

anti-inflammatories, rest, & vitamin e

108
Q

what is the treatment for congestive heart failure?

A

diuretics - furosemide

positive inotropes - digoxin

vasodilators - ace inhibitors

109
Q

what is the prognosis of congestive heart failure?

A

poor to grave - 6 months even with therapy

110
Q

how is congestive heart failure diagnosed in horses?

A

ecg & echo

111
Q

T/F: murmurs may not be severe in congestive heart failure in horses

A

true

112
Q

what causes aortic rupture?

A

during exercise or rest - usually vessel necrosis, but etiology unknown

collagen defect/idiopathic??

113
Q

what breeds have a higher incidence of aortic rupture?

A

friesians

114
Q

what is the cause of sudden cardiac death in horses?

A

in 1/3 of cases - undetermined causes

gi & respiratory diseases approximately 50% of cases

115
Q

what heart sound is lost in a horse with atrial fibrillation?

A

S4

116
Q

list what is happening in the cardiac cycle with each heart sound:
S1 -
S2 -
S3 -
S4 -

A

S1 - closure of the av valves, onset of ventricular contraction (systole)

S2 - closure of semi-lunar valves, termination of ventricular systole

S3 - rapid ventricular filling

S4 - atrial contraction

117
Q

what is the first sound heard in each cardiac cycle?

A

S4 - atrial contraction

118
Q

what is the most common physiologic arrhythmia? pathologic arrhythmia?

A
  1. 2nd degree av block
  2. atrial fibrillation
119
Q

how would you treat this arrhythmia seen on ecg?

A

class 1a sodium channel blocker - quinidine sulfate

22mg/kg every 2 hours through an NG tube until there is a conversion to sinus rhythm, adverse effects are seen, or 4-6 doses are reached

narrow therapeutic index!!

120
Q

what factors would improve the likelihood of successful treatment of this arrhythmia? what about the prognosis long term?

A

less than 4 weeks duration & low resting heart rate of the patient

better prognosis for shorter duration, no structural changes to the heart, no associated cardiac disease, and no murmur

121
Q

list what valve would be associated with the murmur:

left sided systolic
left sided diastolic
right sided systolic

A
  1. left sided systolic - mitral valve
  2. left sided diastolic - aortic valve
  3. right sided systolic - tricuspid valve
122
Q

the most common valvular disease in horses are acquired insufficiency/incompetency of what valves?

A

mitral, aortic, & tricuspid valves

123
Q

you detect a machine-like murmur in a 48 hour old foal on your wellness check. Are you concerned? why or why not?

A

not yet - suspect PDA, should close by 96 hours after birth

124
Q

what heart valve is most commonly affected by bacterial endocarditis?

A

mitral valve!!!

125
Q

what do ‘muffled’ heart sounds indicate?

A

pericarditis - maybe pleural effusion

126
Q

what are some common etiologies that result in muffled heart sounds?

A

EIV, eastern tent caterpillars, bacterial causes, & immune-mediated/idiopathic

127
Q

what is a good diagnostic test for myocarditis?

A

cardiac troponin I test

128
Q

you are listening to a horse that has a regular, dropped beat every 3-4 beats at rest. The heart rate is slow - 32bpm. what do you suspect to be the cause? how could you confirm your suspicion? should the
owner be concerned?

A

2nd-degree av block

exercise the horse to see if it persists

not really - not associated with clinical signs, result of high vagal tone

129
Q

what arrhythmia commonly affects this breed?

A

atrial fibrillation - clydesdales

130
Q

what lesion is seen here?

A

degenerative valvular disease/endocardiosis

131
Q

what condition is seen on this ultrasound?

A

pericarditis - effusive, fibrinous, or constrictive inflammation of the pericardial lining

LA DX & TX I (45 decks)

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