Cardiovascular Flashcards
2 components of the cardiovascular system
- Blood
- Heart & vessels
Functions of the cardiovascular system
- Circulation
- Thermoregulation
- Fluid homeostasis
3 layers of the heart wall
- Epicardium (visceral pericardium)
- Myocardium
- Endocardium
Flow of electrical impulses through the heart
- SA
- AV
- HIS bundle
- Bundle branches
- Purkinje fibers
Systemic compensatory mechanisms in response to injury
- Increased heart rate
- Increased peripheral vascular resistance
- Increased blood volume
- Redistribution of blood flow
Cardiac compensatory mechanisms in response to injury
- Dilation
- Hypertrophy
Increase in heart chamber volume
Dilation
Increase in myocardial mass via increased cell size
Hypertrophy
Gradual loss of pumping efficiency due to cardiac disease or increased workload
Results in decreased blood flow to tissues (ischemia) and pooling of blood behind failing chambers (congestion)
Congestive Heart Failure (CHF)
Right-sided heart failure results in:
- Chronic hepatic congestion (“nutmeg liver”)
- Ascites
- Subcutaneous edema
Left-sided heart failure results in:
Pulmonary congestion and edema
Right/Left sided heart failure results in:
Hydrothorax
Myocardial Diseases
- Hypertrophic cardiomyopathy (HCM)
- Thyrotoxic cardiomegaly
- Dilated cardiomyopathy (DCM)
- Arrhythmogenic right ventricular cardiomyopathy (ARVC)
- Restrictive cardiomyopathy (RCM)
- Feline left ventricular endocardial fibrosis (LVEF)
- Myocardial necrosis
- Nutritional myopathy
- Myocarditis
Increase in size of cardiac myocytes, leading to increased overall mass
Myocardial hypertrophy
True/False
Secondary myocardial hypertrophy is usually reversible
True
True/False
Primary myocardial hypertrophy is usually irreversible
True
Type of myocardial hypertrophy caused by pressure overload, resulting in increased wall thickness and decreased chamber volume
Concentric
sarcomeres added in parallel -> wider
Type of myocardial hypertrophy caused by volume overload, resulting in increased chamber volume and normal or decreased wall thickness
Eccentric
sarcomeres added in series -> longer
Disorder of myocardium
Cardiomyopathy
3 main types of cardiomyopathy
- Hypertrophic
- Dilated
- Restrictive
- Common in cats (esp. young to middle-aged males)
- Due to genetic mutation (MYBPC3) in Mainecoon and Ragdolls
- Gross Findings: cardiomegaly, concentric hypertrophy of LV (thickened wall & decreased volume), +/- LA dilation & thrombosis
Hypertrophic Cardiomyopathy (HCM)
DDx for HCM is thyrotoxic cardiomegaly due to hyperthyroidism in cats
- Primary in some dogs breeds and cattle
- Secondary to nutritional imbalances in dogs & cats
- Gross Findings: cardiomegaly, eccentric hypertrophy of entire heart (dilated chambers & thin walls), enlarged rounded heart
Dilated Cardiomyopathy
ARVC is a variant of DCM found in Boxers
- Primary heritable variant of DCM in Boxers
- Rare in cats
- Predisposition to ventricular arrythmias, syncope, heart failure, sudden death
- Gross Findings: RV myocytes replaced by adipose (or fibroadipose) tissue, RV normal or dilated, similar gross appearance to DCM
Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)
“Boxer Dog Cardiomyopathy”
- Rigid ventricular walls causing impaired ventricular filling
-
Includes multiple forms:
- LVEF
- Excessive moderator bands
- Congenital endocardial fibroelastosis in Burmese cats
- Endocardial fibrosis in aged rats
Restrictive Cardiomyopathy (RCM)
- Most common variant of RCM
- Endocardial fibrosis restricts ventricular filling
- Results from endomyocarditis (idiopathic inflammation)
- Gross Findings: thick opaque endocardium in LV
form of restrictive cardiomyopathy
Feline Left Ventricular Endocardial Fibrosis (LVEF)
- Variant of RCM often found in cats
- Congenital defect that manifests later in life
- Gross Findings: bands of purkinje fibers and collagen in LV
form of restrictive cardiomyopathy
Excessive Moderator Bands
Cardiomyopathy sequale
- Arrhythmia -> syncope, sudden death
- Thrombosis -> thromboembolism -> ischemia, infarcts
- Congestive heart failure -> death
True/False
Cardiac myocytes are able to regenerate
False
True/False
Small areas of myocardial necrosis generally do not cause any problems
False
True/False
Necrotic myocardiocytes are hypereosinophilic & fragmented
True
Is this acute or chronic myocardial necrosis?
Acute
myocardial pallor, dry +/- gritty texture, dystrophic mineralization
Is this acute or chronic myocardial necrosis?
Chronic
firm, depressed (sunken) myocardial scar (fibrosis)
Causes of myocardial necrosis
- Nutritional
- Toxic
- Ischemic
- Genetic
- Traumatic
True/False
Heart attacks are common in animals
False
uncommon in animals due to low incidence of coronary artery disease
Examples of myocardial toxins
- Ionophores
- Cantharidin
- Gossypol (cottonseed oil)
- Doxorubicin
- Poisonous plants
True/False
Vitamin E / selenium decifiency is a cause of nutritional myopathy
True
“White Muscle Disease in ruminants, Mulberry Heart Disease in swine
Vitamin E / selenium deficiency sequale
decreased antioxidant activity -> oxidative membrane damage -> myocyte necrosis
Inflammation of the myocardium
Myocarditis
Causes of myocarditis
Often infectious:
* Viral (CPV-2, encephalomyocarditis virus, FMDV, WNV)
* Bacterial (Clostridium chauvoei, C. piliforme, Corynebacterium pseudotuberculosis, Histophilus somni)
* Fungal (Aspergillus)
* Parasitic (Toxoplasma gondii, Sarcocystis, Neospora, Trypanosoma cruzi, Theileria parva, cysticercosis)
Granulomatous myocarditis in a dog
from Aspergillus terreus infection
Suppurative myocarditis in a cow
from Histophilus somni infection
- Idiopathic degeneration of valvular collagen
- Common in small, aged dogs (e.g. Cavalier King Charles)
- Mitral valve most commononly affected
- Gross Findings: thickened nodular valve margins, smooth, glistening, opaque
- Microscopic Findings: loose fibroblastic tissue, NON-INFLAMMATORY
Endocardiosis
“Myxomatous Valvular Degeneration”
Endocardiosis sequale
- Valvular insufficiency -> regurgitation, heart murmur
- Atrial volume overload -> eccentric hypertrophy +/- CHF
- Atrial subendocardial fibrosis -> jet lesion
- Atrial thrombosis -> thromboembolism +/- infarcts
- Chordae tendinae rupture
- Atrial rupture -> hemopericardium
The arrow is an example of:
Atrial Jet Lesion
commonly seen in endocardiosis
The arrows are examples of (2 lesions):
Atrial Thrombosis & Chorda Tendinea Rupture
commonly seen in endocardiosis
Inflammation of endocardium
Endocarditis
- Inflammation of endocardium
- Usually bacterial
- Tricuspid valve lesions most common in cattle
- Mitral valve lesions most common in other species
- Gross Findings: thrombi vegetations on valvular endocardium
- Microscopic Findings: fibrin, bacteria, neutrophils
Endocarditis
“Vegetative Valvular Endocarditis”
True/False
Vegetative endocarditis is caused by idiopathic inflammation following a stressful event, leading to thrombosis
False
caused by chronic sustained bacteremia & endocardial damage
Endocarditis sequale
- Valvular insufficiency -> CHF
- Bacteremia -> septic thromboemboli to heart, kidney, brain
- Infarcts
- Inflammation
Endocardial Mineralization
Causes of endocardial mineralization
- Vitamin D Toxicosis (oversupplementation, cholecalciferol rodenticides, calcinogenic plants)
- Johne’s Disease (Mycobacterium avium ssp. paratuberculosis)
- Uremia in dogs
True/False
There are two continuous serous layers that enclose the pericardial cavity:
1. Visceral layer = epicardium, adherent to heart
2. Parietal layer = pericardial sac, associated with fibrous outer portion
True
- Fluid accumulation in pericardial cavity
- Named according to fluid composition
- Clinical significance depends on whether fluid accumulates slowly or rapidly
Pericardial Effusion
Hydropericardium, Hemopericardium, Pericarditis (inflammatory exudate)
Heart compression due to rapid increase in pressure in pericardial cavity. Can lead to cardiogenic shock & death.
Cardiac Tamponade
Routes of pathogen entry during pericarditis
- Hematogenous (e.g. septicemia)
- Direct Penetration (e.g. hardware disease)
- Local Extension (from myocardium, pleural cavity, mediastinum)
Is this acute or chronic pericarditis?
Acute
Is this acute or chronic pericarditis?
Chronic
This is the heart of a severely emaciated dog, why does it have a translucent gelatinous appearance?
Serous Atrophy of Pericardial Fat
True/False
Serous atrophy of pericardial fat is a common finding in obese animals
False
indicator of emaciation
True/False
In the normal postnatal heart, the right side of the heart is HIGH pressure & the left side of the heart in LOW pressure
False
right (pulmonary) = LOW pressure
left (systemic) = HIGH pressure
Examples of systemic to pulmonary shunts (LEFT to RIGHT)
- Patent Ductus Arteriosis (PDA)
- Foramen Ovale failure to close
- Ventricular Septal Defect (VSD)
may have reversal of flow (RIGHT to LEFT) later in disease
What congenital anomaly does this depict?
Patent Ductus Arteriosus (PDA)
What congenital anomaly does this depict?
Ventricular Septal Defect (VSD)
Pulmonic Stenosis (PS) leads to:
Pressure overload in right ventricle, concentric RV hypertrophy
Subaortic Stenosis (SAS) leads to:
Pressure overload in left ventricle, concentric LV hypertrophy
Mitral or Tricuspid Valve Dysplasia leads to:
Valvular insufficiency (regurgitation), volume overload in atria, eccentric atrial hypertrophy
stenosis less common
Raised fibrous ring below aortic valve, concentric LV hypertrophy
Subaortic Stenosis (SAS)
Malformed mitral valve leaflets, eccentric LA hypertrophy
Mitral Valve Dysplasia
Examples of malpositioned great vessels
- Persistent right aortic arch (PRAA)
- Transposition of aorta & pulmonary artery
- Persistent truncus arteriosus
- Double outflow right ventricle
Single blood vessel from RV & LV
Persistent Truncus Arteriosus
Aorta arises from RV instead of LV
Double Outflow Right Ventricle
- Vascular ring anomaly that entraps esophagus and trachea
- Aortic arch on right, ligamentum arteriosum on left
- Can result in megaesophagus, regurgitation, aspiration pneumonia
Persistent Right Aortic Arch (PRAA)
Congenital anomaly where the heart develops outside of the thoracic cavity
Ectopia Cordis
Translocation of peritoneal viscera into pericardial sac
Peritoneal-Perircardial Diaphragmatic Hernia
Congenital anomaly consisting of four concurrent lesions, resulting in RIGHT to LEFT shunt and cyanosis
* pulmonis stenosis
* RV hypertrophy (secondary to PS)
* ventricular septal defect
* aortic dextroposition
Tetralogy of Fallot
Common incidental cardiac anomaly of ruminants
Valvular Hemocysts / Lymphocysts
Inflammation of arteries
Arteritis
Inflammation of many arteries
Polyarteritis
Inflammation of veins
Phlebitis
Inflammation of lymphatic vessels
Lymphangitis
- Gross Findings: thickened vessels
- Microscopic Findings: leukocytes +/- fibrin around vessel walls
Vasculitis
Infectious causes of vasculitis
- Viral (equine viral arteritis, African horse sickness, malignant catarrhal fever, bluetongue, classic swine fever, African swine fever, FIP)
- Bacterial (Salmonella, Erysipelothrix rhusiopathiae, Haemophilus, Histophilus somni, Rickettsia rickettsia, Borrelia burgdorferi)
- Fungal (Aspergillus)
- Parasitic (Strongylus vulgaris, Dirofilaria immitis, Angiostrongylus vasorum)
Immune-mediated/idiopathic causes of vasculitis
- Polyarteritis nodosa
- Idiopathic necrotizing polyarteritis (“Beagle Pain Syndrome”)
Hardening of arteries
Arteriosclerosis
rarely of clinical significance in animals
- Subset of arteriosclerosis
- Hardening of arteries accompanied by plaques of fatty material
- Narrowing or arterial lumen -> ischemia, infarct
- Occurs in pigs, rabbits, chickens fed high cholesterol diet
- Associated with hypothyroidism & diabetes mellitus in dogs
Atherosclerosis
True/False
Heart attacks are common in animals
False
- Localized vascular dilation due to thinning or weakening of vessel wall, can lead to fatal rupture
- Causes include: copper deficiency, Strongylus vulgaris migration, idiopathic
Aneurysm
- Benign neoplasm of vascular endothelial cells
- Sharply demarcated
- Blood-filled spaces lined by well-differentiated endothelial cells
- Common in dogs
Hemangioma
- Malignant neoplasm of vascular endothelial cells
- Commonly found on right atrium, liver, spleen, skin, fat around urinary bladder
- Blood-filled spaces lined by pleomorphic endothelial cells
- Rupture can lead to hemopericardium, hemothorax, hemoabdomen
Hemangiosarcoma
Infiltrative endothelial neoplasm affecting ventral abdominal dermis/subcutis in cats, bruised edematous tissue
Feline Ventral Abdominal Lymphangiosarcoma
Neoplasm originating from aortic body (a chemoreceptor) at base of heart, common in brachycephalic dogs
-may compress great vessels
Chemodectoma
Bulging tan masses in heart, associated with bovine leukemia virus (BLV) in cattle
* Common sites: right atrium, abomasum, uterus, spinal canal, retrobulbar region, kidney, lymph nodes
Cardiac Lymphosarcoma (LSA)
Which cell adaptation is primarily responsible for increased myocardial mass in an adult animal?
Hypertrophy
Concentric hypertrophy occurs when sarcomeres are added in parallel due to what?
Pressure Overload
Eccentric hypertrophy occurs when sarcomeres are added in series due to what?
Volume Overload
An inflammatory condition of the endocardium and usually develops secondary to bacteremia and endocardial injury.
Endocarditis
A non-inflammatory condition of the endocardium (usually seen in dogs) characterized by idiopathic degeneration of the valvular collagen.
Endocardiosis
This two-word term refers to a life-threatening condition in which the heart is compressed and prevented from adequately filling due to accumulation of fluid in the pericardial cavity:
Cardiac Tamponade
