Lecture 19 9/26/24

Question 1

What is the normal anatomy of the left and right ventricles?

Answer 1

-left ventricle is thick walled and extends to apex
-right ventricle is thin walled and does not extend to apex

Question 2

What is the normal anatomy of the atria?

Answer 2

-consists of actual atrium chamber plus appendage/auricle
-left atrial auricle is normally smaller than right

Question 3

What is the normal anatomy of the pericardium?

Answer 3

-consists of visceral and parietal pericardium
-small amount of serous fluid within pericardium is normal

Question 4

What is the normal anatomy of the myocardium?

Answer 4

-consists of striated myocytes and conduction system
-blood is supplied via coronary arteries
-papillary muscles are most active part

Question 5

How are the AV valves attached to the papillary muscle?

Answer 5

via chordae tendinae

Question 6

Where are the coronary artery ostia located?

Answer 6

behind the aortic valve cusps

Question 7

What are the characteristics of the endocardium?

Answer 7

-should be transparent
-thick, opaque endocardium is caused by turbulence
-euthanasia may cause red-brown staining and crystalline precipitates

Question 8

What is pericardial effusion?

Answer 8

excess fluid in pericardial sac

Question 9

What are the characteristics of hydropericardium?

Answer 9

-watery effusion with pericardium
-often occurs with watery effusions in other body cavities
-associated with CHF and hypoproteinemia

Question 10

What are the characteristics of hemopericardium?

Answer 10

-most common in dogs with hemangiosarcoma
-ruptures occur in right atrium due to tumor
-other causes are rare

Question 11

What are the characteristics of fibrinosuppurative pericarditis?

Answer 11

-most common in cattle
-can be traumatic due to hardware disease
-have a “bread and butter” appearance due to fibrin
-can see granulation and fibrosis in severe cases

Question 12

What are the characteristics of canine idiopathic pericarditis?

Answer 12

-most common in large breed dogs
-slow onset
-good prognosis due to treatment option of removing pericardial sac
-may predispose to mesothelioma

Question 13

What are the characteristics of epicardial hemorrhage?

Answer 13

-may be petechial, ecchymotic, paintbrush, or diffuse
-associated with septicemia, anoxia, and endotoxemia
-most common in horses

Question 14

What are the potential consequences of ANY myocardial lesion?

Answer 14

arrhythmia and death

Question 15

What are the characteristics of focal ischemic myocardial necrosis?

Answer 15

-myocardial infarct/coagulative necrosis
-thrombus occludes blood vessel(s)
-uncommon in animals and usually only diagnosed at necropsy

Question 16

What are the causes of toxic myocardial necrosis?

Answer 16

-monensin toxicity in horses
-gossypol toxicity in pigs
-doxorubicin/chemo
-ractopamine in greyhounds

Question 17

What are the characteristics of nutritional myocardial necrosis?

Answer 17

-vitamin E/selenium deficiency
-known as white muscle disease in young ruminants
-WMD signified by necrosis and mineralization
-known as mulberry heart disease in pigs
-MHD signified by necrosis and hemorrhage

Question 18

What are the steps of repair for necrotic myocardium?

Answer 18

-inflammation in response to dead tissue
-granulation tissue formation; fibrosis +/- mineralization
-does NOT regenerate

Question 19

What are potential causes of myocarditis?

Answer 19

-canine parvovirus myocarditis
-Clostridium chauvoei/blackleg

Question 20

What are the characteristics of dilated cardiomyopathy?

Answer 20

-rare in large animals
-look at left ventricle to diagnose
-LV will have high chamber volume compared to wall thickness
-rare in cats now, but previously caused by taurine deficiency

Question 21

Which dog breeds are predisposed to DCM?

Answer 21

-giant breeds such as great danes and Irish wolfhounds
-doberman pinschers
-boxers

Question 22

What causes DCM in dobermans?

Answer 22

fibrofatty replacement of myocardium

Question 23

What are the characteristics of DCM in boxers?

Answer 23

-get both DCM and arrhythmogenic right ventricular cardiomyopathy/ARVC
-fibrofatty replacement of myocardium

Question 24

What can cause DCM in breeds that are not predisposed?

Answer 24

boutique, exotic ingredient, and/or grain-free diets

Question 25

Which breeds are predisposed to juvenile onset cardiomyopathy?

Answer 25

-Portuguese water dogs
-toy Manchester terriers

Question 26

What is a dilated heart the end stage for?

Answer 26

cardiac damage:
-ischemic
-toxic
-inflammatory
-nutritional

Question 27

What are the potential consequences of DCM in any breed?

Answer 27

-CHF
-arrhythmias
-sudden death