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CAEM Pt. 2 > Exam #4: Equine Cardio > Flashcards

Exam #4: Equine Cardio Flashcards

1
Q

Normal adult horse heart rate

A

26-50 bpm

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2
Q

Exercise max heart rate in horses

A

240 bpm - no time for diastolic filling = decreased CO

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3
Q

True or false - vagal arrhythmias are common and usually benign in horses

A

TRUE - horses have high vagal tone at rest

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4
Q

Normal foal heart rates from birth-2 months

A
  • Birth = 40-80 bpm
  • Next several hours = 120-150 bpm
  • First week = 80-100 bpm
  • Adult rate by 2 weeks (26-50 bpm)
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5
Q

What type of murmur occurs between S1 and S2, QRS and T?

A

Systolic murmur

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6
Q

What type of murmur occurs between S2 and S1 and T wave to QRS?

A

Diastolic murmur

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7
Q

What are the characteristics of vagal murmurs?

A
  • Slow to normal HR (not tachycardic)
  • Audible S4, S1, and S2
  • Disappear if you increase the heart rate > 50 bpm
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8
Q

S1 heart sound indicates…

A

Closing of AV valves

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9
Q

S2 heart sound indicates…

A

Closing of semilunar valves

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10
Q

S3 heart sound indicates…

A

End of rapid diastolic filling

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11
Q

S4 heart sound indicates…

A

Atrial contraction

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12
Q

Bee-dum–bump indicates what and what makes it go away usually?

A

2nd degree AV block - goes away with sympathetic stimulation by raising the HR > 50 bpm

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13
Q

How can you differentiate A-fib from 2nd degree AV block or sinus arrhythmias?

A

No S4 with A-fib

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14
Q

True or false - being able to hear more than S1 and S2 in a horse is normal

A

TRUE

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15
Q

What can the base apex ECG lead system diagnose and not diagnose?

A
  • Can dx arrhythmias

- Cannot dx enlargement patterns like conduction blocks, etc

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16
Q

What about the horse cardiac conduction system makes the ECG recordings different, compared to humans or small animals?

A

Purkinje fibers go deep into the ventricular myocardium, from endo to epicardium = FAST depolarization

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17
Q

ECG lead placement for lead I and II in the base apex system - WHERE DO WE PLACE THE ELECTRODES

A
  • Lead I = negative right arm, positive left arm
  • Lead II = negative right arm, positive left foot/leg
  • Negative right arm (I, II) = 2/3 way down the jugular furrow
  • Positive left arm (I) and positive left leg = caudal to left elbow
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18
Q

Normal P wave morphology on equine ECG

A

Notched, usually positive but complete inversion can occur

Wandering pacemaker = strange P wave morphology = normal in a high vagal tone horse

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19
Q

Normal QRS morphology on equine ECG

A

> > rS complex

  • “r” = small positive deflection
  • “S” = large negative deflection
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20
Q

Normal T wave morphology on equine ECG

A
  • Uni or biphasic
  • Positive, negative, or combo
  • Normal as long as it doesn’t have a larger amplitude than QRS
  • Ta = atrial repolarization (after P wave) = due to large muscular heart (may show up on ECG)
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21
Q

How do you measure HR in a horse on ECG? Normal? Bradycardic? Tachycardic?

A

> Count QRS complexes in 6 seconds, then multiply by 10

  • Normal = 26-50 bpm
  • Bradycardia = < 26 bpm
  • Tacycardia = > 50 bpm
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22
Q

How do you determine if there’s a regular rhythm on ECG?

A
  • P waves present?
  • P wave for every QRS?
  • QRS wave for every P wave?
  • Atrial and ventricular rates are similar?
  • Ectopic beats?
  • Pattern to irregular rhythms, or is it irregularly irregular?
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23
Q

Difference between type I and type II second degree AV block on ECG? Which is normal and abnormal?

A
  • Type I = variable PR intervals = NORMAL

- Type II = fixed PR intervals = ABNORMAL

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24
Q

Dx? Irregular rhythm, tachycardic, no P waves, normal QRS and T waves

A

A-FIB

Normal QRS and T = supraventricular in origin

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25
Q

What is the most common pathologic rhythm in horses?

A

A-FIB

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26
Q

Non-cardiac causes for equine arrhythmias (6)

A

1) Excitement
2) Fever
3) Toxemia/septicemia
4) Colic - vagal afferents lining the GI tract
5) Electrolyte abnormalities
6) Acid-base disorders

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27
Q

Pathologic arrhythmias in horses (7)

A

1) A-FIB
2) Atrial premature beats
3) Ventricular premature beats
4) Supraventricular tachycardia
5) Ventricular tachycardia
6) 2nd degree AV block type II
7) 3rd degree AV block

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28
Q

Mechanism of A-FIB in horses

A

> Uncoordinated depolarizations in the atria

  • Can occur w/o atrial enlargement or pathologic heart disease
  • Induced by autonomic NS imbalance
    • Sympathetic tone on vagal tone
  • Can occur in normal horses
  • Persistent AF may result in heart disease
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29
Q

Characteristics of A-FIB

A

> Irregular, supraventricular, no P waves, tachycardic

  • Ventricular response is usually normal (26-50 bpm)
  • No S4 sounds audible
  • See marked irregularity in the R-R intervals at rest
  • May see variable QRS duration, amplitudes, and polarities
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30
Q

Causes of A-FIB

A

1) Idiopathic or “lone”
2) Underlying cardiac disease, Ex: myocardial, AV regurg, CHF
3) Electrolyte or acid-base abnormalities, Ex: racing (sweat), colic, other illness
4) Anesthetic drugs or tranquilizers

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31
Q

What breeds is A-FIB common in? (3)

A
  • Thorougbreds
  • Standardbreds
  • Draft breeds
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32
Q

Diagnostic work-up for A-FIB

A
  • CBC = looking for inflammation or infection
  • Electrolytes, esp. K+, Ca++
  • Venous blood gas concentrations = alkalosis that affects K+
  • ECG
  • Echo
  • Cardiac troponin test for cardiac disease
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33
Q

What can happen with A-FIB progression if not treated?

A
  • Decreased diastolic perfusion of the atria = fibrosis

- Dilation = pull valves apart = valvular insufficiency

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34
Q

Options for treatment of acute A-FIB?

A
  • CORRECT UNDERLYING ABNORMALITIES = lyte imbalances, dehydration
  • Medical - quinidine or flecanide
  • Cardioversion
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35
Q

What is the treatment of choice for lone/idiopathic A-FIB?

A

Quinidine- given orally (REQUIRES A STOMACH TUBE), treatment stops at conversion

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36
Q

Side effects of quinidine

A
  • Skin - urticaria
  • Nasal edema
  • Colic and diarrhea (after several doses)
  • Arrhythmias = after 4 or more doses, due to myocardial changes
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37
Q

Medical options (2) for acute A-FIB tx, similarities and differences

A
  • Quinidine = oral w/ stomach tube
  • Flecanide = used parenterally (not safe orally)
  • Side effects = colic, diarrhea, arrhythmias, urticaria, nasal edema
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38
Q

What do you administer as an antidote in a flecanide or quinidine overdose?

A

Sodium bicarb (NaHCO3)

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39
Q

What drug do you use if the animal has a HR > 50 bpm, atrial enlargement, or failed to convert with quinidine for A-FIB?

A

Digoxin (SHOULD ECHO FIRST to determine atrial diameter)

*Increases vagal tone = slows HR and AV node conduction

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40
Q

Treatment of choice for A-FIB - those who are chronic and fail to respond to medical conversion, or have relapsed after conversion

A

> > Cardioversion

  • Usually successful and has a return to athletic ability (even with chronic AF)
  • High conversion rate and low relapse
  • Requires general anesthesia
  • Minimal complications
41
Q

What drug might you try, to treat A-FIB, if quinidine or quinidine+digoxin doesn’t work?

A

Amiodarone

42
Q

What drug can you use to control the heart rate with A-FIB, but doesn’t work to convert them?

A

Diltiazem - Ca++ channel blocker

43
Q

True or false - audible S4, irregular rhythym, normal HR is indicative of a pathologic murmur/rhythm

A

FALSE - most likely a benign sinus rhythm (could still be A-FIB

44
Q

Dx? Normal QRS and T waves, normal P waves, but a block in conduction

A

2nd degree AV block

45
Q

True or false - horses with a-fib are usually asymptomatic at rest, but become symptomatic with exercise

A

True

46
Q

What PE signs should you pay attention to with heart murmurs?

A
  • Heart rate, rhythm, sounds audible (S4? Irregular rhythm?)
  • Lung sounds for edema
  • Mucous membranes (poor perfusion)
  • Edema = generalized, pain, temperature
  • Jugular vein distension or pulsations
  • Strength of arterial pulses
  • LN’s
  • Tachycardia
  • Muffled heart sounds
  • Exercise intolerance, syncope, weakness
47
Q

What heart disease/valve disease do we see water hammer pulses with?

A

Aortic insufficiency and leakage

48
Q

How do you interpret if a murmur is pathologic or not?

A
  • Clinical signs?
  • Location in cardiac cycle - diastolic? systolic (more likely benign)?
  • Intensity = higher = more pathologic
  • Shape or frequency of murmur
  • Radiation = more pathologic
  • PMI
49
Q

Which murmur sounds like a dive-bomber?

A

Aortic valve regurgitation

50
Q

How do you determine if the murmur is systolic or diastolic?

A
  • Palpate for a peripheral pulse = at the same time = systolic
  • Look at a phonocardiogram
51
Q

Differences between grades of murmurs

A

> Grades 1-6

  • Grades 5 & 6 = palpable thrill
  • Grade 4 = no thrill but loud and radiates
52
Q

Are ejection murmurs systolic or diastolic?

A

Systolic

53
Q

What shape are regurgitant murmurs?

A

Plateau

54
Q

What shape are diastolic murmurs?

A

Decrescendo

55
Q

Lesion if murmur is at the left apex

A

Mitral v. (point of elbow)

56
Q

Lesion if murmur is at the left base

A

Aortic, pulmonic v. (underneath the triceps m)

57
Q

Lesion if murmur is on the right side

A

Tricuspid

Also = PDA’s, VSD’s

58
Q

What is the PMI and radiation with ejection murmurs (not usually pathologic)?

A

Localized (doesn’t radiate), usually at left base

59
Q

What is the PMI and radiation with mitral valve regurgitation?

A

Radiation, usually left apex towards the base

60
Q

Characteristics of functional/non-pathologic murmurs in horse?

A
  • Low to moderate intensity (grade 1-3)
  • Usually an ejection pattern, peaks in mid systole
  • Usually localized at left heart base
  • Ends before S2 (not diastolic)
  • No radiation
  • Normal HR
  • Normal arterial and venous pulses
61
Q

What is a common location for benign and functional heart murmurs?

A

Left base - localized, no radiation

62
Q

Conditions/type of horse that functional murmurs are common in ? (3)

A

1) Foals
2) Fever
3) Anemia

63
Q

What are characteristics of normal foal murmurs?

A

> Systolic for 2-4 months

  • Heart base
  • Continuous murmurs or heard on both sides of chest
  • Low grade (should exam grades > 3)
  • No cyanosis
64
Q

Which foals should have cardiac work-ups, aka pathologic murmurs?

A
  • Intensity = grade > 3/6
  • Cyanotic
  • Premature or dysmature foals
  • Murmur radiates over a large area and is present on both sides
  • Marked tachycardia (> 100 bpm)
  • Marked dyspnea or tachypnea
  • Abnormal venous or arterial pulses
65
Q

Most common foal congenital defects

A

PDA, VSD

66
Q

Dx? systolic or continuous murmur, goes away within 3 days

A

PDA

67
Q

Dx? PMI on right side, softer relative murmur on the left side (volume overloads, ejection murmur)

A

VSD

68
Q

Dx? PMI at left heart base or right side, cyanotic foal

A

Tetralogy of Fallot

69
Q

True or false - louder VSD’s are usually pathologically worse

A

FALSE

70
Q

True or false - patent foramen ovale and ASD’s are commonly benign

A

TRUE

71
Q

What should you always do if you suspect a congenital cardiac defect?

A

ECHO THE ANIMAL = may have other defects

72
Q

When, in the cardiac cycle, do you hear mitral valve regurg?

A

Holosystolic - loudest at left apex

73
Q

When, in the cardiac cycle, do you hear aortic valve regurg?

A

Holodiastolic - loudest at heart base

74
Q

When, in the cardiac cycle, do you hear tricuspid valve regurg?

A

Holosystolic - loudest on right side

75
Q

When, in the cardiac cycle, do you hear pericarditis?

A

Continuous

76
Q

Which valve is most commonly affected with acquired degenerative valve disease?

A

Aortic&raquo_space; mitral&raquo_space; tricuspid

*More common in older horses (> 8 yo)

77
Q

Clinical signs of decompensated heart disease

A
  • Exercise intolerance
  • Cough
  • Changes in endurance
  • Respiratory distress
  • Tachycardia
  • Weak pulses
  • Loud murmur with radiation
  • Peripheral edema
  • Weight loss
  • Hyponatremia, pre-renal azotemia
78
Q

True or false? - Hyperkinetic pulses are compensated

A

True

79
Q

Dx? Loud systolic plateau shaped murmur at left heat apex with radiation to the left base

A

Mitral valve regurg

80
Q

Short and long term complications from mitral valve dz

A
  • LA enlargement
  • AF develops
  • Left sided heart failure
  • Decreased stroke volume = activate RAAS
  • Eventual CHF
81
Q

Dx? Divebomber, loud, holodiastolic murmur at heart base, bounding arterial pulses (LV overload)

A

Aortic valve disease

82
Q

How do we monitor if the heart disease is decompensating?

A

> > Monitor HR

  • Increase in resting heart rate = sustained 5 bpm or more
  • Failure to return to resting heart rate within 20 min of exercise
83
Q

Treatment of degenerative valve disease

A

> Prognosis is guarded

  • Furosemide
  • Digoxin if there is CHF
  • ACE inhibitors aren’t very helpful
  • Hydralazine = arterial dilator
84
Q

Dx? Holosystolic plateau shaped murmur, fever, exercise intolerance, tachycardia, jugular venous pulsations, weight loss

A

Bacterial endocarditis

85
Q

Three top etiologic agents for bacterial endocarditis

A

1) STREPTOCOCCUS
2) Trueperella pyogenes
3) E. coli

86
Q

Clin path lab findings with bacterial endocarditis

A
  • Neutrophilic leukocytosis
  • Anemia of chronic infection
  • Hyperproteinemia due to hyperglobulinemia
  • Positive blood culture
87
Q

Treatment of bacterial endocarditis

A
  • ANTIBIOTIC based on C&S, frequently is a parenteral beta lactam
  • Combine with RIFAMPIN
  • For 4-6 weeks
88
Q

Dx? Petechial hemorrhage, edema (commonly in head, neck, limbs), sloughing of the skin

A

Vasculitis

89
Q

DDx for causes of peripheral edeam

A
  • Heart disease
  • Vasculitis
  • Hypoproteinemia (liver disease)
  • Trauma or injury
  • Neoplasia
  • Decreased activity “stocking up”
  • Lymph system dysfunction = lymphadenopathy, lymphadenitis, lymphangitis, lymph obstruction
90
Q

Characteristics that help you differentiate vasculitis from CHF or hypoproteinemia edema

A
  • Localized
  • Warm
  • Non-pitting
  • Painful
  • Leakage of serum
  • Evidence of petechial hemorrhage
91
Q

Causes of vasculitis (6)

A

1) Purpura hemorrhagica = previous or constant exposure to Strep, vax after infection = immune complexes in endothelium
2) Equine infectious anemia
3) Equine viral anemia
4) Anaplasma phagocytophila
5) Allergic
6) Idiopathic

92
Q

Diagnosis of purpura hemorrhagica

A
  • Skin biopsy for immune complexes

- High Strep. equi titer

93
Q

Diagnosis of equine infectious anemia

A

Coggins or ELISA

94
Q

Diagnosis of equine viral arteritis

A

Virus neutralization, IHC, PCR

95
Q

Diagnosis of equine granulocytic anaplasmosis (Anaplasma phagocytophilum)

A
  • Morulae in neutrophils or eosinophils on peripheral blood smear
  • PCR from buffy coat
96
Q

Treatment of purpura hemorrhagica vasculitis

A
  • Pencillin + corticosteroids

- Supportive care = hydrotherapy, bandaging

97
Q

Treatment of Anaplasma phagocytophilum vasculitis

A
  • Tetracyclines - oxytetracyclines + corticosteroids

- Supportive care = hydrotherapy, bandaging

98
Q

What do we use in horses - prednisone or prednisolone?

A

Prednisolone

CAEM Pt. 2 (27 decks)

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