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Vet clinics of N. America-Equine > 2019.Iss1.clinical cardiology > Flashcards

2019.Iss1.clinical cardiology Flashcards

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1
Q

equine acquired valvular disease

degenerative valve disease is common on which valves in horses?

A

aortic
mitral valves

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2
Q

equine acquired valvular disease

what are recognized risk factors for equine aortic regurgitation?

A

male sex
increasing age

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3
Q

equine acquired valvular disease

describe aortic valve regurgitation murmur

A

-descrescendo holodiastolic murmur
-can be musical in character
-loudest over the aortic valve, on left, right or both sides of thorax

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4
Q

equine acquired valvular disease

What factors are associated with eexrcise intolerance or death within 2 years of identifying aortic regurge?

A

-abnormal pulse quality
-pulse pressure >60 mmHg measured at coccygeal artery
-supraventricular premature depolarizations occurring at a rate of greater than 1 per hour

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5
Q

equine acquired valvular disease

Using pulse pressure to assess aortic regurge severity, what differentiated mild-moderate from severe?

A

severe >67 mmgHg

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6
Q

equine acquired valvular disease

using echocardiography to assess aortic regurgitation is based on what parameters?

A
  1. regurgitant jet size
  2. subjective assessment of left ventricular size & shape
  3. M-mode measurement of internal diameter of left ventricle in diastole

Others: high-frequency vibrations on mitral valve, aortic vale or septum; early closure of the mitral valve; dilation of the aortic root; and increased fractional shortening

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7
Q

equine acquired valvular disease

describe mitral valve regurgitation murmur

A

-systolic murmur
-loudest over mitral valve on the left (radiates in caudodorsal direction)

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8
Q

equine acquired valvular disease

mitral valve regurgitation is classified as mild with what characteristics:

A

-no left atrial enlargement
-color flow doppler echo demonstrates 1 or 2 thin regurgitant jets (whose height is subjectively no more than 1/3 of the height of the left atrium

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9
Q

equine acquired valvular disease

what are characteristics of severe mitral valve regurgitation?

A

-left atrial, left ventricular & pulmonary artery dilation
–> lead to pulmonary a rupture, affected horses will show signs of CHF at rest

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10
Q

equine acquired valvular disease

infective endocarditis, what is the most common site of infection?

A

mitral valve

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11
Q

equine acquired valvular disease

which bacteria have been reported in cases of infectious endocarditis in horses?

A

Pasteurella/Actinbobacillus sp.
Pseudomonas spp
Rhodococcus spp

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12
Q

equine acquired valvular disease

prior to treating infectious endocarditis, what is recommended?

A

3 serial blood cultures at 1 hour intervals

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13
Q

equine acquired valvular disease

what is the most common site of ruptured chordae tendineae?

A

mitral valve

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14
Q

equine acquired valvular disease

horses with ruptured chordeae tendinae will develop signs of acute left-sided heart failure, such as:

A

coughing
foamy nasal discharge
moist crackles on auscultation of the lung
sudden death

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15
Q

equine acquired valvular disease

describe the murmur associated with a ruptured chordeae tendinae

A

honking or musical murmur
flail of affected valve visualized on echo

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16
Q

Cardiovascular Response to Exercise and Training, Exercise Testing in Horses

when assessing poor performance, what are some parameters that are recommended

A

-historical questionnaires
-lameness examinations
-exercise electrocardiograms (ECG)
-echocardiograms
-respiratory sampling
-dynamic upper airway endoscopy
-measurement of laboratory values (lactate, SAA CK, electrolytes, cardiac troponins [cTn]

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17
Q

Cardiovascular Response to Exercise and Training, Exercise Testing in Horses

what are common diseases detected during exercise tests?

A

-lameness
-IAD/equine asthma
-upper airway obstruction
-myopathies
-exercising arrythmias

**less commonly detected: myocardial dysfunction, electrolyte abnormalities, neurologic disease

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18
Q

Cardiovascular causes of poor performance & exercise intolerance & assessment of safety in the equine athlete

List bradyarrhythmias that are a normal finding, as long as a sympathetic stimulation restores sinus rhythm at an appropriate heart rate

A

sinus bradycardia
sinus block
second-degree atrioventricular block

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19
Q

Cardiac therapeutics in horses

What is the drug of choice for pharmacologic cardioversion of atrial fibrillation?

A

quinidine

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20
Q

Cardiac therapeutics in horses

what is the MOA of class 1 antiarrhythmic agents?

A

block voltage-gated sodium channels
**slow the propagation of action potentials

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21
Q

Cardiac therapeutics in horses

Class 1a antiarrhythmic agents are recommended for use against which arrythmias?

A

supraventricular & ventricular tachyarrhythmias

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22
Q

Cardiac therapeutics in horses

which drugs belong to class 1a antiarrythmics

A

quinidine
procainamide

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23
Q

Cardiac therapeutics in horses

Which medications belong to the class 1b anti-arrythmics?

A

lidocaine
phenytoin
tocainide
mexilitine

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24
Q

what is the MOA of class 1 c antiarrythmics?

A

inhibitors of fast sodium channels

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25
Cardiac therapeutics in horses which drugs belong to the class 1c antiarrythmics?
flecainide propafenone
26
Cardiac therapeutics in horses What is the MOA of class 2 anti-arrythmics?
beta-adrenocreceptor antagonists (beta blockers) ** prolong phase 4 of the cardiac action potential, suppress SA pacemaker activity & AV nodal conduction **SLOW HEART RATE
27
Cardiac therapeutics in horses which medications belong to class II anti-arrythmics?
propranolol sotalol atenolol esmolol
28
Cardiac therapeutics in horses What is the MOA of class III anti-arrythmics?
suppress inward potassium current **prolonging phase 3 of the action potential & refractory period
29
Cardiac therapeutics in horses Which drugs belong to the class III anti-arrythmics?
amiodarone
30
Cardiac therapeutics in horses What is the MOA of class IV antiarrhythmic agnts?
ca channel blockers **act on phase 2 of the cardiac action potential
31
Cardiac therapeutics in horses Magnesium sulfate can be effective in terminating what arrhythmia?
refractory ventricular arrhythmias *reduces the occurrence of ventricular ectopy & VT in humans
32
Cardiac therapeutics in horses What is the indication for anticholinergic drugs (atropine, glycopyrrolate)?
controlling vagal-mediate bradyarrhythmias
33
Cardiac therapeutics in horses Which drugs are anti-cholinergics?
atropine glycopyrrolate butylscopolamine
34
What makes up stroke volume?
-amount of blood ejected from the left ventricle in early cardiac cycle -cardiac contractility -preload (end-diastolic LV volume) -afterload (ventricular wall tension, largely influenced by systemic blood pressure)
35
Cardiac therapeutics in horses Which drugs reduce preload in the treatment of CHF?
diuretics
36
Cardiac therapeutics in horses What is the MOA of furosemide?
loop diuretic that inhibits the reabsorption of electrolytes in the thick ascending loop of Hnelse **results in increased excretion of Na, Cl, K and water
37
Cardiac therapeutics in horses Potassium-sparing diuretics can be dividing into what 2 categories?
1. amioloride-- inhibit sodium-selective channels in the late distal convoluted tubules & cortical collecting duct 2. potassium sparing diuretics: inhibitors of type 1 mineralocorticoid receptors & act as aldosterone antagonists (spironolactone)
38
Cardiac therapeutics in horses What is the MOA of thiazide diuretics?
inhibit sodium/chloride symporter in the renal epithelial cell of the distal convoluted tubule **increases loss of sodium, chloride & water **excessive sodium & fluid in the distal nephron enhances the secretion of potassium & hydrogen ions
39
Cardiac therapeutics in horses what are drugs that reduce afterload in the the treatment of CHF?
-renin-angiotensin-aldosterone system inhibitors (ACE inhibitors)-- spironolactone
40
Cardiac therapeutics in horses Describe positive ionotropes
increase the force of myocardial contraction by increasing intracellular calcium concentrations or by sensitizing the myocardium to the effects of calcium
41
Cardiac therapeutics in horses What is the MOA of cardiac glycosides (Digoxin) as a cardiac therapeutic?
inhibition of Na/K ATPase --> positive ionotropic effect
42
Cardiac therapeutics in horses Tacchyarrhythmias occur in hypokalemia for what reason?
inhibition of Na/K atpase exacerbates the hypopolarization of the mycoardium
43
Cardiac therapeutics in horses What positive ionotrope can be used in horses with pathologic bradyarrythmias?
dobutamine ** INC HR, Beta1-adrenergic effects
44
Cardiac therapeutics in horses What is the MOA of phenylephrine?
vasopressor **increasing peripheral blood pressure w/o increasing cardiac output **alpha-1 receptor agonist **does not work on the heart
45
Cardiac monitoring in horses what is a major determinant of afterload?
blood pressure
46
Cardiac monitoring in horses what is blood pressure the product of?
CO (cardiac output) and SVR (stroke volume)
47
Cardiac monitoring in horses What does a central venous pressure >15 mmHg indicate?
patient is fluid overloaded or in a cardiogenic shock
48
Cardiac monitoring in horses List methods used to measure cardiac output:
pulmonary thermodilution transpulmonary thermodilution lithium dilution U/S velocity dilution Ficks principle Rebreathing CO2 Pulse contour analysis echocardiogram
49
Cardiac arrhythmias in horses atrial premature depolarizations often have no negative impact on performance, but especially in large horses, may predispose to...
atrial fibrillation
50
Cardiac arrhythmias in horses For pathologic arrhythmias, one should investigate what sources?
1. cardiac: acquired valvular disease, congenital deformations, myocardial damage, pericarditis & endocarditis 2. noncardiac dz: electrolyte & acid-base disturbances, hypoxemia, endotxemia, toxic causes
51
Cardiac arrhythmias in horses define atrial tachycardia
more than 3 atrial premature depolarizations
52
Cardiac arrhythmias in horses What is the recommendation for treatment for APDs
**thought that the apds originate from dzed or inflammatory myocardium --resting period or low-level exercise period -- steroid treatment
53
Cardiac arrhythmias in horses Describe atrial fibrillation characteristics on ecg
-replacement of p waves by fibrillation waves -irregular RR intervals w/ normal QRS morphology
54
Cardiac arrhythmias in horses What are indicators that increase the risk for collapse or even fatal ventricular arrhythmia during exercise, in a horse with atrial fibrillation?
-abnormal QRS morphology -R on T phenomenon -high maximal heart rates (>220 bpm) during regular exercise
55
Cardiac arrhythmias in horses List non-cardiac and cardiac adverse effects of quinidine administration in horses:
Noncardiac: nasal edema, depression, colic, diarrhea & laminitis Cardiac: hypotension, QRS & QT prolongation, supraventricular & ventricular tachycardia (VT), Torsade de pointes, collapse & death
56
Cardiac arrhythmias in horses IN case of quinidine toxicity, what can be administered?
IV sodium bicarbonate administration (1 mEq/kg) lower the free QS plasma ocncentrations
57
Cardiac arrhythmias in horses What medication is recommended for digoxin toxicity?
phenytoin
58
Cardiac arrhythmias in horses what are clinical signs associated with third degree AV block?
stress or exercise does not affect ventricular rate -exercise intolerant -numerous episodes of collapse
59
Cardiac arrhythmias in horses What is this arrhythmia?
third-degree AV block resulted in atrioventricular dissociation and a slow & junctional) escape rhythm at rate of 25 bpm
60
Pericardial Disease, Myocardial Disease, and Great Vessel Abnormalities in Horses What are the consequences of pericarditis leading to pericardial effusion?
-reduced ventricular filling -diastolic dysfunction = impaired venous return to the right heart
61
Pericardial Disease, Myocardial Disease, and Great Vessel Abnormalities in Horses Describe the 3 different types of pericarditis.
1. Effusive: pericardial inflammation resulting in fluid accumulation w/in pericardial sac 2. fibrinous: accumulation of fibrin in the pericardium, with or w/o free fluid 3. Constrictive: fibrotic & thickened, resulting in cardiac compression
62
Pericardial Disease, Myocardial Disease, and Great Vessel Abnormalities in Horses As part of mare reproductive loss syndrome, what is the the most commonly identified bacterial isolate?
Actinobacillus spp.
63
Pericardial Disease, Myocardial Disease, and Great Vessel Abnormalities in Horses what are neoplastic causes of pericarditis in horses?
lymphoma (most common) mesothelioma, hemangiosarcoma intra- or extrapericarial mass compressing the heart
64
Pericardial Disease, Myocardial Disease, and Great Vessel Abnormalities in Horses Why are diuretics contraindicated in pericarditis?
b/c ventricular filling is impaired & cardiac function highly dependent on increased filling pressures
65
Pericardial Disease, Myocardial Disease, and Great Vessel Abnormalities in Horses what is the prognosis for pericarditis?
idiopathic= good bacterial/neoplasia= guarded to poor
66
Pericardial Disease, Myocardial Disease, and Great Vessel Abnormalities in Horses List parasitic causes of myocardial diseases:
strongylus vulgaris-- statistically assoc with focal ischaemic lesions in myocardium onchocerca
67
Pericardial Disease, Myocardial Disease, and Great Vessel Abnormalities in Horses List nutritional causes of myocardial disease in horses
-Vit E & selenium def: whit emm disease (predom in foals in selenium def areas -copper def/molybdenum tox
68
Pericardial Disease, Myocardial Disease, and Great Vessel Abnormalities in Horses List toxins & drugs as a cause of myocardial disease in horses.
-snake venom: rattlesnake, viper -ionophores: monensin, lasalocid, salinomycin -Plants containing cardiac glycosides: digitalis spp (foxglov), taxus pp (yew), Nerium oleander), Adonis aestivalis (summer pheasant's eye), Lilly of the vallley, Rhododendron -other plants: malva parviflora (marshmallow), atypical myopathy/seasonal pasture myopathy caused by ingestion of hypoglycin-A from seeds of maple trees (Acer spp) -Cantharidin (blister beetle) -sodium flouroacetetate rodenticides -heavy metals
69
Pericardial Disease, Myocardial Disease, and Great Vessel Abnormalities in Horses which breed is predisposed to aortic rupture? (with or w/o formation fo a pseudoaneurysm and/or aortopulmonary fistula)
fresians
70
Pericardial Disease, Myocardial Disease, and Great Vessel Abnormalities in Horses If horses survive the acute phase of aortopulmonary fistulas assoc with aortic rupture proximal to the ligamentum arteriosum, what C/s can be seen:
-recurrent colic -increased rectal tempreature -tachycardia -respiratory signs --> right-sided congestive heart failure develops
71
Pericardial Disease, Myocardial Disease, and Great Vessel Abnormalities in Horses What are predisposing factor to pulmonary artery rupture?
-long standing pulmonary hypertension --> caused by LCHF, left to right shunting with pulmonary artery dilation
72
Equine Congenital Heart Disease List diagnostic findings in horses with ventricular septal defects that suggest an unfavorable prognosis.
73
Equine Congenital Heart Disease In foals with large ventricular septal defects, what are potential clinical findings
-C/S of heart failure or pulmonary overicrculation -Thoracic radiographs: congestion
74
Equine Congenital Heart Disease The arterial duct is a normal structure in the fetus that allow the diversion of blood away from the lung, by what time period is it closed in the horse postpartum?
3 days post partum d/t increased O2 tension
75
Equine Congenital Heart Disease Describe the murmur of a persistent ductus arteriosus.
continuous, machinery-type murmur at the left heart base
76
Equine Congenital Heart Disease What are the 4 components of the tetralogy of fallot?
1. right ventricular outflow tract obstruction 2. right ventricular hypertrophy 3. ventricular septal defect 4. overriding aorta
77
Equine Congenital Heart Disease Describe what a double outlet right ventricle malformation is.
-both great vessels arise entirely or predominantly from the right ventricle **cyanosis related to insufficient pulmonary flow and heart failure assoc with left-to-right shunting
78
Equine Congenital Heart Disease How do vascular ring anomalies present?
pediatric animals with dysphagia or stridor **rare reports in horses
79
Equine Electrocardiography Describe the phases of the cardiac action potential.
80
Equine Electrocardiography Describe how the ECG electrodes are placed.

Vet clinics of N. America-Equine (14 decks)

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