Cardiovascular pathology 2 Flashcards
Describe the appearance of normal pericardial fluid.
What is the normal volume in horses and dogs/cats?
- Clear, viscous fluid
- Horse/cow 100 ml
- Dog/cat: 10 ml
Describe a hydropericardium
Accumulation of clear to light yellow, watery, serous fluid (transudate: specific gravity < 1.015) in the pericardial sac
In which disease is a hydropericardium associated with vascular injury?
Mulberry heart disease in pigs
- a few fibrin strands are present, and the fluid could clot following exposure to air (exudate: specific gravity >1.015).
Describe the gross appearance of a hydropericardium in acute and chronic cases
Acute - pericardial surfaces are smooth and glistening
Chronic - pericardial surfaces are opaque with mild fibrous thickening due to villous proliferation of fibrous tissue
A hydropericardium is associated with diseases that have…?
Generalised oedema
Hydropericardium: Associated with those diseases that have generalized oedema - give examples
- Increased vascular permeability: viruses, bacteria, type III hypersensitivity, toxins
- Increased intravascular hydrostatic pressure: pulmonary hypertension, iatrogenic fluid overload
- Decreased intravascular osmotic pressure: decreased albumin production, protein loss
- Decreased lymphatic drainage: inflammation, obstruction
What is a cardiac tamponade?
Compression caused by fluid surrounding the heart which impairs cardiac filling and venous return to the heart
What is a haemorrhagic pericardial effusion?
Deposition of small amounts of blood, chronically - unknown aeitiology
What is a haemopericardium?
Accumulation of large amounts of blood in the pericardium
What are the consequences of a haemopericardium?
Cardiac tamponade, leading to compression and interfering with cardiac filling and emptying
What are 3 possible causes of a haemopericardium?
- Atrial rupture due to a haemangiosarcoma of the right atrium in dogs
- Rupture of the intrapericardial aorta in horses
- Complications with intracardiac injections
What is the name given to a pericardial sac filled with air, how might this occur?
Pneumopericardium
- perforations in the oesophagus/stomach pass through the mediastinum near the pericardium
How does a chylopericardium occur?
Rupture of the thoracic duct which releases chyle - often white and gelatinous
Why would serous atrophy of epicardial adipose tissue occur?
Anorexia, starvation, cachexia, as fat is catabolised to maintain energy balance
- cases of emaciation
How does atrophy of epicardial adipose tissue appear grossly?
Transformation of the white or yellow epicardial fat deposits e.g. coronary groove, into grey gelatinous material
How does atrophy of epicardial adipose tissue appear microscopically?
Lipocytes are atrophic and oedema fluid is present in the interstitial tissue
Peri- / Epicarditis is?
Inflammation of peri/ epicardium
What are the portals of entry for inflammatory processes to get to the heart?
- Foreign body penetration: From reticulum (cattle)
- Local extension of severe inflammatory processes from adjacent structures (thoracic cavity / lungs / oesophagus)
- Haematogenous spread of viruses / bacteria
Describe the different types of exudate
- Serous = watery, low in protein and inflammatory cells
- Fibrinous = acute
- Purulent = dominated by neutrophils
- Sero-fibrinous
- Fibrino–purulent
- Proliferative fibrosing = chronic inflammation
- Granulomatous = chronic, macrophage dominated
Which of the following is acute and which is chronic:
- Fibrous
- Fibrinous
- Fibrinous = acute
- Fibrous = chronic
How is the specific gravity of transudate and exudate different?
Transudate SG less than 1.015
- metabolic disorders
Exudate SG more than 1.015
- inflammatory
How does fibrinous pericarditis appear grossly?
- Pericardial surfaces are covered by variable amounts of yellow fibrin deposits, adherence between the parietal and visceral layers.
- When the pericardial sac is opened upon necropsy, these attachments are torn away
How does fibrinous pericarditis appear microscopically?
An eosinophilic layer of fibrin admixed with few neutrophils lies over a congested pericardium.
What are the two outcomes of fibrinous pericarditis?
- Early death by septicaemia
2. Constrictive pericarditis (proliferative fibrosing) - becomes thickened and scarred
Describe constrictive pericarditis as an outcome of fibrinous pericarditis
- Survival is prolonged => fibrous organization of the exudate forming fibrous adhesions between the surfaces
- This obliterates the pericardial sac constricting the heart with fibrous tissue interfering with cardiac filling and output
- Compensatory myocardial hypertrophy develops diminishing ventricular chamber volumes and contributing to eventual congestive cardiac failure
What are some diseases in different species that causes fibrinous pericarditis?
- Cats: FIP
- Cattle: Pasteurellosis
- Pigs: Glasser’s disease, pasteurellosis, Mycoplasma hyopneumoniae
- Horses: Streptococcus spp
What causes Glasser’s disease in pigs?
Haemophilus parasuis
Describe the features (subacute and chronic) and cause of Glasser’s disease in pigs
Subacute lesions - pleuritis, pericarditis, peritonitis with or without bronchopneumonia
Chronic lesions - proliferating fibrosing
Cause - stress (weaning, transport)
A horse with a streptococcal infection will have what changes to their heart?
Proliferative fibrosing - fibrin covering of the heart
Muscular hypertrophy
What is the difference between fibrinous and Fibrino-suppurative?
Increased numbers of neutrophils in Fibrino-suppurative
How does Fibrino-suppurative pericarditis appear grossly?
Pericardial surfaces are thickened by white, often rough, shaggy-appearing masses of fibrin with purulent exudate i.e .neutrophils
What are the two outcomes of Fibrino-suppurative pericarditis ?
- Early death by septicaemia.
- Constrictive pericarditis: When survival is prolonged, there is a fibrous organization of the exudate forming fibrous adhesions between the surfaces => obliterates the pericardial sac and constricts the heart with fibrous tissue interfering with cardiac filling and output => myocardial hypertrophy develops diminishing ventricular chamber volumes and contributing to the eventual congestive cardiac failure
Which disease in cattle is an example of Fibrino-suppurative pericarditis?
Traumatic reticulopericarditis “Wire” or “Hardware disease” in cattle
Describe traumatic reticulopericarditis “Wire” or “Hardware disease” in cattle
- Due to foreign bodies, often sharp / pointed that accumulate in the reticulum
- Contraction of the reticulorumen caused the foreign body to penetrate the reticular wall and diaphragm enters the adjacent pericardial sac.
- Bacteria are transferred with the foreign body to establish infection
What is visceral gout, what are 3 causes of it?
Imbalance between production and excretion of uric acid
- Congenital enzymatic deficiencies
- Dietary: animal protein to herbivorous species in reptiles
- Increased catabolism (debilitating diseases, tumours)
What are some other causes of visceral gout?
- Renal diseases: nephritis, tubular damages, Urolithiasis (kidney stones)
- Dehydration
In which species is visceral gout seen?
Reptiles and birds
Describe the gross lesions seen in pericardial gout (uric pericarditis)
- Uric acid deposition (urate crystals) in peri- and epicardium elicit a peripheral mixed cellular inflammatory response (macrophages and heterophils)
- Grossly: white, gritty deposits (tophi)
Describe the histological appearance of pericardial gout (uric pericarditis)
Urate crystals and mixed cell inflammation (macrophages and heterophils - avian granulocyte)
What are the causes of endocardial mineralisation?
- Excess vitamin D intake
- Intoxication by carcinogenic plants
- Hyperparathyroidism
- Renal failure
- Johne’s disease
How does endocardial mineralisation appear grossly?
Multiple, large, white, rough, firm plaques of mineralised fibroelastic tissue within endocardium and intima of large elastic arteries
When does endocardial fibrosis occur (2 examples)?
- chronically dilated hearts
- healed ulcerative endocarditis
- jet lesions e.g. valvular stenosis/regurgitation
Describe valvular endocardiosis
Myxomatous degeneration
- Age-related cardiac disease of small and toy breeds (Cavalier King Charles Spaniel)
- Associated with degeneration of valvular collagen
How does valvular endocardiosis appear grossly?
Affected valves are shortened and thickened (nodular) appearing smooth and shiny
What are the consequences of valvular endocardiosis?
Results in valvular insufficiency and congestive heart failure
- Development of jet lesions and rupture of chordae tendineae are common.
What is the order of likeliness for each valve being affected by valvular endocardiosis?
mitral > tricuspid > aortic > pulmonary
Describe left ventricular endocardial fibroelastosis
- Defect in myocardial lymph drainage leads to chronic oedema and fibroelastic tissue proliferation
- Restricted myocardial motion produces a reduction in output and can cause failure
What can cause endocarditis?
Haematogenous spread of infectious agents (bacteria>parasites>fungi)
- Pigs: Strep and E.rhusiopathiae
- Cattle: Arcanobacterium pyogenes
- Dogs/cats: Strep and E.coli
How does endocarditis appear grossly?
The surface is rough and granular, with large, adhering, friable, yellow to grey masses “vegetations”
How does endocarditis appear microscopically - cells and chronic lesions?
- Fibrin, platelets, bacteria, leukocytes and erythrocytes.
- In chronic lesions, the fibrin deposits are organized by fibrous connective tissue to produce irregular nodular masses that can become mineralised
Describe the pathogenesis of endocarditis
Extracardiac infection - one or more bouts of bacteraemia
Injured valves - bacteria adhere, proliferate and initiate an inflammatory reaction
Death due to endocarditis is a result of?
- Cardiac failure from valvular dysfunction
- Bacteraemia
- Septic emboli leading to infarction or abscess formation in other organs (lungs, kidneys).
Describe right cardiac endocarditis
Stenosis of right valve, chronic hepatic congestion and pulmonary embolism
Describe left cardiac endocarditis
Stenosis of left valve, chronic pulmonary congestion and systemic embolism (kidney)
Endocarditis is seen most commonly on which side of the heart?
Left - except in cows
What is sequela to endocarditis?
- Septic emboli disseminate throughout the body: “Embloic showers”, multifocal purulent lesions scattered randomly throughout an organ e.g. kidney
Endocarditis is rare in which species?
Cats
Describe ulcerative endocarditis and its gross appearance
- Uraemia (acute renal insufficency) induce endocardial ulceration in dogs.
- Grossly after the initial ulcer heals, the area is replaced by raised, white plaques of fibrous and mineralised tissue.
