Cardiovascular Pathology 2 Flashcards
What is hydropericardium and what is its cause?
Serous transudate- congestive heart failure, neoplasms, anaemia, uraemia.
What are the three types of non-inflammatory fluid accumulation?
1) hydropericardium
2) haemopericardium
3) ideopathic pericardial haemorrhagic effusion
What is haemopericardium and what causes it?
Accumulation of whole blood in the pericardium.
Rupture of large vessels- horses
Dilated atria due to AV valve regurgitation-dogs
RTA, puncture wounds. Death from cardiac tamponade.
What are the presenting signs of ideopathic pericardial haemorrhagic effusion?
Large breeds. Slowly developing right sided heart failure followed by left side.
What are 4 causes of pericarditis and what do they do?
1) haematogenous spread- septicaemia
2) extension of infection from surrounding tissues
3) traumatic penetration of the pericardium
4) extension of myocardial inflammation
Restrict ventricular movement- acute circulatory failure.
What do acute vs chronic infections cause?
Acute- rapid death esp. in the young, if the lesion is chronic then it will be more organised e.g. fibrosis.
What type of bacteria causes serofibrinous fluid and purulent fluid?
Clostridia/pasturella
Staph/Strep
What are the 4 possible outcomes of pericarditis?
1) resolution- no clinical problem
2) adhesion- organisation of fibrin following serofibrinous pericarditis (bread and butter), can result in fibrosis
3) constriction- gradual tamponade and cardiac atrophy, constrictive pericarditis.
4) myocarditis- traumatic reticulitis/pericarditis- foreign body
What is the myocardium and its structure?
The muscle of the heart- cardiomyocytes form myocardial muscles arranged in complex bands and layers.
Where does the blood supply to t he myocardium come from?
The coronary arteries, arise in sinuses behind the aortic valve cusps.
What are the 6 types of myocardial conditions?
1) hypertrophy and dilation
2) metabolic disturbances
3) myocardial infarction
4) myocarditis
5) parasitic infestations
6) Cardiomyopathy
What causes myocardial hypertrophy?
physiological response- increased exercise
pathological- valvular stenosis
What causes dilation to occur?
When the disease process is too rapid to allow cardiac compensation. May indicate onset of failure in a compensating heart (dogs)
How is hypertrophy and dilation assessed?
By weighing and measuring thickness of ventricular walls, size of papillary muscles and dimensions of muscle fibres.
What are the 6 examples of metabolic disturbances?
1) hydropic degeneration
2) fatty change
3) hyaline degeneration
4) calcification
5) visceral gout
6) fatty infiltration
What is hydropic degeneration?
Cell switches to anaerobic resp= depleted glycogen= inc. inorganic phospahates and lactate. Lack of ATP= failure of Na/K pump= water moves into the cell.
What is hyaline degeneration and what does it present as?
Vitamin E/selenium deficiency- “White muscle disease”, cardiomyocyte necrosis, inflammation and dystrophic calcification.
Acute left sided heart failure or ataxia/collapse, grey patches on the myocardium.
What is visceral gout?
Reptiles and birds- uric acid precipitates in tissues as crystals. Can affect the kidneys.
Dalamation.
How does a myocardial infarction occur?
usually as a result of an embolism of the coronary vessels.
Rare to be as a result of athero/arterio sclerosis.
It is an ischaemic event and there is a reduction of contractility.
What are the three types of myocarditis?
Acute (suppurative)
Acute (non suppurative)
Chronic
What usually causes a myocarditis?
Generalised infection by bacteria, virus, protozoa.
What causes an acute (suppurative) myocarditis?
Septic emboli released from a non-cardiac foci that lodge in the heart vasculature. Or extension from endocardium or pericardium.
What are the causes of acute (non-suppurative) myocarditis?
septicaemia or viraemia e.g. leptospirosis, FMD, parvovirus.
What happens in chronic myocarditis?
Cardiomyocyte loss with replacement by fibrous tissue- can get granulomas. Sequel to sub-acute myocarditis
What are 5 examples of parasitic infestations that encyst in the myocardium?
1) cysticercosis
2) sarcocysts
3) toxoplasmosis
4) neosporosis
5) trypanosomiasis
What is cardiomyopathy?
Myocardial disease leading to cardiac failure.
What are the 9 types of cardiomyopathy?
1) ‘Mulberry Heart’
2) Malignant hyperthermia
3) Feline hyperthyroidism
4) ideopathic cardiomyopathy
5) dilated cardiomyopathy
6) hypertrophic cardiomyopathy
7) restrictive cardiomyopathy
8) Arrythmogenic right ventricular cardiomyopathy
9) eosinophilic myostitis
What causes the Vit E/ Se deficiency that causes Mulberry heart Disease?
Lack of dietary vitE/Se, high levels of polyunsaturated fats (destroy vitE), genetic derangements of vitE/Se metabolism.
What additional presenting signs are seen in Mulberry Heart Disease, how do they arise and how is the animal found?
myocardial haemorrhages due to arteriolar fibrinoid necrosis=acute cardiac failure. Dead, pulmonary oedema, sero-fibrinous pericardial fluid and myocardial haemorrhages in the thorax. Fibrinous fluid and hepatic congestion in the abdomen.
What is malignant hyperthermia and what does it cause?
Cardiomyopathy in pigs-genetic disease due to a point mutation in Skm ryanodine receptor. Triggered by stress and halothane anaesthesia= necrosis of cardiac and Skm= thin, soft and pale: PSE. (pale soft, exudative)
What are the clinical signs of feline hyperthyroidism?
Uni/bilateral enlargement of the thyroids.
Hyperactive, thin, big appetite, tachycardic, hypertensive.
They have left ventricular hypertrophy due to increased demand.
What does dilated cardiomyopathy look like?
Enlarged heart with bi-ventricular dilation, they are pale and flabby.
What breeds are most effected by DCM and what is it linked to?
Giant breeds of cats and dogs, horses as well.
Associated with taurine deficiency in cats and monensin deficiency in horses.
Use of adriamycin and doxorubicin in dogs.
What does the histology of a hypertrophic cardiomyopathy look like and what species does it tend to affect?
Myocardial fibres are hypertrophied and arranged haphazardly, accompanied by interstitial fibrosis and arteriosclerosis.
Common in cats esp. maine coons and ragdolls
What does the heart look like with hypertrophic cardiomyopathy?
Cardiomegaly from LV concentric hypertrophy, thickening of the interventricular septum and reduced LV chamber size
How is the left atrium involved in hypertrophic cardiomyopathy?
thrombi tend to form here and when it breaks off it will lead to aorto-iliac thromboembolism= sudden-onset hindlimb paresis.
What happens in restrictive cardiomyopathy?
Myocardial fibrosis or endomyocardial fibrosis of the LV endocardium. = loss of compliance and inability to fill during dystole= LA dilation and LV normal.
What do cats develop with restrictive cardiomyopathy?
cardiac dysrhythmias with pulmonary oedema and left aortic thromboembolism.
R sided congestive heart failure with RA dilation.
What happens in arrhythmogenic right ventricular cardiomyopathy?
BOXERS- RV myocardium is replaced by fat and fibrous tissue.
Present with syncope, heart failure or sudden death.
What is eosinophilic myostitis and what is its probable cause?
Green-grey colour of the muscle resulting from myodegeneration and eosinophilic inflammation- sheep and cattle.
Parasitic infestations
What is the hypertrophy an dilation of cardiomyocytes in DCM and HCM due to?
Cardiomyocyte derangement not functional changes!
