Lecture 14 9/17/24 Flashcards

1
Q

What is cardiomyopathy?

A

-primary heart muscle disorder in which the heart muscle is structurally and functionally abnormal

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2
Q

What is dilated cardiomyopathy?

A

left ventricular dilation and systolic myocardial dysfunction +/- right ventricular involvement

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3
Q

What causes ventricular dilation in DCM?

A

hypokinesis

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4
Q

What is the etiopathogenesis of DCM?

A

-cardiomyocytes in the mature individual cannot reproduce to correct abnormalities and/or damage
-dilated heart works at mechanical disadvantage
-dilation tends to be progressive

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5
Q

What can cause systolic myocardial dysfunction?

A

-loss of cardiomyocytes due to necrosis
-ultrastructural abnormalities of the contractile apparatus
-persistent tachycardia
-nutritional deficiencies

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6
Q

Why is DCM considered a phenotype?

A

it is an “end-stage heart” that can result from virtually any pathologic insult to the myocardium

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7
Q

What are the potential pathways of DCM?

A

-toxic
-metabolic
-immune
-infective
-nutritional

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8
Q

Which dogs have a genetic predisposition for DCM?

A

-doberman pinscher
-great dane
-newfoundland
-irish wolfhound

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9
Q

What is the pathophysiology of DCM?

A

-impaired systolic myocardial function results in progressive ventricular dilation
-high ventricular filling pressures are reflected back upon the upstream capillary bed
-reflection results in edema and/or cavitary effusion

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10
Q

What is the typical signalment of DCM patients?

A

-large or giant breed dog
-middle aged
-doberman, boxer, great dane, irish wolfhound, or cocker spaniel

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11
Q

What are the clinical signs seen in DCM patients?

A

related to CHF:
-dyspnea
-cough
-weight loss
-syncope
-ascites

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12
Q

What are the physical exam findings seen in DCM patients?

A

-soft systolic murmur of MR origin and/or gallop sounds
-arrhythmia
-crackles suggestive of pulmonary edema
-tachycardia
-ascites

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13
Q

What are the diagnostic findings for DCM on chest rads?

A

-enlargement of cardiac silhouette
-LAE with pulmonary infiltrates (left CHF)

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14
Q

What are the diagnostic findings for DCM on ECG?

A

-ventricular arrhythmias/AFib
-chamber hypertrophy patterns
-intraventricular conduction disturbances

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15
Q

What are the diagnostic findings for DCM on echo?

A

-increased end-systolic and end-diastolic volumes
-secondary MR

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16
Q

What are the characteristics of DCM in doberman pinschers?

A

-high incidence of ventricular tachyarrhythmia and sudden cardiac death
-heart failure associated with brief and rapid progressive course
-affects left ventricle primarily
-diffusely distributed edema
-straightening of caudal border of cardiac silhouette
-increase in cardiac silhouette dorsoventral dimension
-DCM is slowly progressive, insidious disorder
-should screen outwardly normal dogs; can delay clinical signs with pimobendan when criteria are met

17
Q

What are the characteristics of DCM in boxers?

A

arrhythmogenic form of CM is common

18
Q

What are the characteristics of DCM in giant breeds?

A

-pleural effusion and ascites are relatively common
-AFib is common
-likely a sex-linked trait in great danes

19
Q

What are the characteristics of DCM in cocker spaniels?

A

-valvular disease is more common but DCM does occur
-affected dogs have low plasma taurine conc. and often respond to taurine supplementation

20
Q

What therapy is indicated for stage B DCM?

A

-pimobendan
-ACE inhibitors and beta-blockers for cardioprotective effect

21
Q

What therapy is indicated for stage C DCM?

A

-furosemide
-ACE inhibitor
-pimobendan
-possibly spironolactone
-digoxin if AFib is present

22
Q

What are the characteristics of taurine supplementation in DCM patients?

A

-deficiency is associated with DCM in cocker spaniels, golden retrievers, and newfoundlands
-may be able to withdraw cardiac drugs and only treat with taurine supp.
-should measure plasma taurine any time an at risk or atypical breed presents with DCM

23
Q

Why is L-carnitine sometimes supplemented in DCM patients?

A

it may favorably affect myocardial energetics

24
Q

What is arrhythmogenic right ventricular cardiomyopathy?

A

inherited heart muscle disease characterized by fibrofatty replacement, VTA and sudden cardiac death

25
What are the categories of ARVC?
Cat. 1: VTA in the absence of clinical signs; most common Cat. 2: syncope, presumably related to ventricular tachycardia Cat. 3: CHF due to systolic myocardial dysfunction
26
What are the characteristics of ARVC?
-many boxers present with VTA in the absence of myocardial dysfunction -progression between categories is NOT inevitable -evidence of an association between a striatin mutation and DCM in boxers -not exclusively a right ventricular disease
27
What are the ECG findings with ARVC?
-ventricular ectopic complexes -ventricular premature complexes, potentially in couplets or triplets -ventricular tachycardia
28
What are the rad. findings with ARVC?
typically normal
29
What are the echo findings with ARVC?
-typically normal -possible to see RA/RV dilation and LV systolic dysfunction
30
What ECG/Holter finding is suggestive of ARVC diagnosis?
100 VPC/day or greater
31
What is the diagnosis and treatment approach for ARVC?
-treat subclinical arrhythmias only if ECG characteristics provide indication -use sotalol to control ventricular arrhythmias when associated with syncope/weakness
32
What are the characteristics of ARVC prognosis?
-association exists between severity of arrhythmia and syncope and survival -no association between anti-arrhythmic treatment and survival -longevity of patients in not statistically different from unaffected control group -echo finding of systolic dysfunction is risk factor for poor outcome
33
What is hypertrophic CM?
hypertrophy of a non-dilated ventricle that develops in the absence of other diseases that would result in myocardial growth
34
What are the characteristics of HCM?
-terriers predisposed -heart failure is rare -sudden death occurs occasionally