Cardiovascular Flashcards
What are the 4 chambers of the emryological heart?
Sinus venosus
Primordial atrium
Primordial ventricle
Bulbus cordis
The atria is separated by septum primum and secundum what occurs if these don’t close?
Patent foramen ovale
The interventricular septum is separated into 3 portions, what are they?
1.Muscular portion
2. Membranous portion
3. Conotruncal ridges
What do the Left and Right 4th aortic arches form?
Left – forms the proximal part of the arch of the aorta
Right – forms the proximal part of the right subclavian artery
What are the pericardium, epicardium, myocardium and endocardium?
Pericardium = sac around the heart
Epicardium = outer surface of the heart
Myocardium = muscle portion of the heart
Endocardium = Inner lining of the heart
What do myocardiocytes look like histologically?
- centrally-placed nuclei
- sarcomeric cross-striations
- ratio muscle fibre: capillaries1:1
- Purkinje fibres
- arranged in bundles
- connective tissue
What are the post-mortem alterations?
*blood clotting - red clots in the atria, right ventricle and large
vessels at the base of the heart.
*Rigor mortis - occurs in the left myocardium and produces contracted rigid ventricular walls
*“Chicken fat clots” - sedimentation of erythrocytes, clot consists of colourless fibrin
*Haemoglobin imbibition - Postmortem lysis of erythrocytes produces diffuse red staining of the endocardium.
*Barbiturate crystals - injection of euthanasia solution and other substances can lead to the presence of crystalline deposits.
What are the Pathophysiological mechanisms of
cardiovascular dysfunction (heart failure)?
*Pump failure - weak contractility, myocardial disease
*Obstruction of flow -valvular stenoses, vascular narrowing
*Regurgitant flow - valvular dysfunction
*Shunted flow - congenital defects
*Ruptures - heart wall, major vessels
*Conduction disorders
What are the reasons for cardiac syncope?
change in heart rate or blood pressure = acute from cardiac disease
What is congestive heart failure?
- Slow, gradual loss of cardiac pumping efficiency
- Associated with:
* pressure overload (hypertension or stenosis)
* volume overload (shunts, valvular regurgitation)
* progressive myocardial damage - Reduced renal blood stimulates RAAS = sodium and
water retention - Increased plasma volume and increase the workload on the
already failing heart
What are the hearts response to congestive heart failure?
- cardiac dilation
- hypertrophy
- decompensation
- death from cardiac failure
What are the causes, subacute and chronic signs of left sided heart failure?
- Causes: left sided cardiomyopathies, dysfunction of aortic and mitral
valves. - Subacute: pulmonary congestion and oedema
- Chronic: pulmonary congestion, oedema, fibrosis and haemosiderosis
(heart failure cells)
What are the causes, subacute and chronic signs of right sided heart failure?
- Causes: right sided cardiomyopathies, pulmonary hypertension,
dysfunction of tricuspid and pulmonary valves. - Subacute: passive systemic congestion, hepatomegaly and
splenomegaly - Chronic: systemic oedema, nutmeg liver
What are the causes of Congenital defects of heart and pericardium?
- Single or multiple gene defects.
- Toxins (thalidomide, ethanol),
- Physical agents (irradiation)
- Nutritional deficiencies (vit A, Zinc).
What are the congenital defect of the heart?
*Agenesis of the heart (acardia) - no heart
*Amorphus globosus - abnormal - covered in hair
*Ectopia cordis - heart outside of body cavity
*Patent ductus arteriosus (PDA)
*Atrial septal defects
*Ventricular septal defects
*Pulmonic stenosis
*Subaortic stenosis
*Tetralogy of Fallot
*Valvular haematomas
*Persistent right aortic arch
*Valvular dysplasias
*Endocardial cushion defects
What is a patent ductus arteriosus?
Blood between pulmonary artery and aorta = bypass lungs
* blood is shunted from the left to the right side resulting in:
* pulmonary hypertension - RV pressure overload concentric hypertrophy = increased muscle thickness
- LA/ LV - volumen overload and eccentric hypertrophy = increased chamber dilation
What happens with failure of closure of foramen ovale?
blood bypass lungs of fetus - can cause low blood oxygen
What are true septal defects?
Failure of development of interatrial septum
What breeds are susceptible to failure of the interventricular septum?
What happens in the RV/LV?
Bulldog, Springer Spaniel, West highland terriers
RV = pressure hypertrophy
LV = Volume hypertrophy
What are the 3 different types of semilunar valve stenoses?
- Supravalvular
- Valvular
- Subvalvular
What is pulmonic stenosis?
Valvular defect = pressure overload = R concentric hypertrophy
Seen in Beagle, Bulldog, Chihuahua
What is subaortic stenosis?
Subvalvular defect = pressure overload = L concentric hypertrophy
Seen in Pigs and Dogs
What is tetralogy of fallot?
Complicated cardiac anomaly with four lesions.
1. Ventricular septal defect (A)
2. Pulmonic stenosis (B)
3. Dextroposition of the aorta (C)
4. Secondarily- Hypertrophy of the right ventricular myocardium
Bulldog and Keeshond.
What are Valvular haematomas common in?
AV valve of ruminants
What does Persistent right aortic arch cause?
- The ligamentum arteriosum forms a vascular ring over the oesophagus and trachea.
- Oesophageal obstruction and proximal dilation (megaoesophagus) → regurgitation
What is Peritoneopericardial diapragmatic hernia?
Abdominal viscera in pericardial sac
What does normal pericardial fluid consist of?
Clear/ viscous - horse/cow = 100ml
- Dog/cat = 10ml
What is hydropericardium?
*Accumulation of clear to light yellow,
watery, serous fluid (transudate: specific gravity < 1.015) in the
pericardial sac.
What is a haemorrhagic pericardial effusion?
What breeds are susceptible?
Deposition of small amounts of blood, chronically. Unknown
aetiology. Great Dane, Saint Bernard, German Shepherd.
What is a haemopericardium?
Accumulation of large amount of blood. Cardiac tamponade (compression of the heart),
leading to compression and interfering with cardiac filling and
emptying.
* Atrial rupture due to haemangiosarcoma of the right atrium
in dogs
* Rupture of the intrapericardial aorta in horses
* Complication of intracardiac injections
What is pneumopericardium?
Air filled pericardial sac
What is chylopericardium?
Rupture of thoracic duct, exudate = SG >1.015
What are the causes of Serous atrophy of epicardial adipose tissue?
What are the gross changes?
Anorexia, starvation, cachexia, as fat is catabolised to
maintain energy balance
Important change in forensic pathology in cases of emaciation
grossly = Transformation of the white or yellow epicardial fat
deposits e.g. coronary groove, into grey gelatinous material.
What is Epi/pericarditis and its causes?
Inflammation of the epi/pericardium
*Foreign body penetration: From reticulum (cattle)
*Local extension of severe inflammatory processes from adjacent structures
(thoracic cavity / lungs / oesophagus)
*Haematogenous spread of viruses / bacteria
What is the difference between fibrin and fibrous tissue?
What is the difference between fibrin and fibrinosuppurative?
Fibrin = acute
Fibrous tissue = chronic
Fibrin turns into fibrous tissue over time
Fibrinosuppurative = contains neutrophils = acute
What is hardware disease?
Wire perforates rumen + into pericardial sac = bacteria, fibrin + pus
What is visceral gout?
uric acid - excreted from kidneys - common in exotics
pericardial gout = white gritty deposits
What causes mineralisation of the endocardium?
*excessive amounts of vitamin D
*intoxication by calcinogenic plants (solanum, cestrum, trisetum sp.) in cows.
*Hyperparathyroidism
* renal failure
* Johne ́s disease
What causes fibrosis?
*chronic dilated hearts
*healed ulcerative endocarditis in dog (uraemia)
*jet lesions (valvular stenosis / regurgitation).
What valves are more likely to have valvular endocardiosis + what happens?
Mitral>Tricuspid>Aortic>Pulmonary
Degeneration of valvular collagen - valves shortened, thickened + appear smooth and shiny.
Valve insufficiency leads to congestive heart failure
What is left ventricular endocardial fibroelastosis?
Defect in myocardial lymph drainage = chronic oedema + fibroelastic tissue proliferation
What are the most common causes of endocarditis?
Bacteria>Parasites>Fungi
What does right cardiac endocarditis cause?
*Stenosis of right valve
*chronic hepatic congestion
*pulmonary embolism
What does left cardiac endocarditis cause?
*Stenosis of left valve
*chronic pulmonary congestion
*systemic embolism (kidney)
What causes ulcerative endocarditis?
- Uraemia (acute renal insufficency) induce endocardial ulceration in dogs.
What does endocarditis lead to?
Embolic showers - multifocal purulent, lesions scattered randomly throughout an organ
What causes traumatic rupture of the myocardium?
Perforating trauma - bullet
What causes spontaneous trauma of the myocardium?
*Insufficiency of mitral valve
*chronic left atrial dilation
What causes of cardimegaly?
*Hypertrophy
*Dilation
*Cardiomyopathy
What causes ventricular hypertrophy?
- Secondary - compensatory response to increased workload - reversible
- Primary - irreversible idiopathic hypertrophic cardiomyopathy
What is eccentric ventricular hypertrophy?
What is the cause?
Enlarged ventricular chambers + Decreased wall thickness
Produced by volume overload
What is concentric ventricular hypertrophy?
What is the cause?
Small ventricular chambers + thickened walls
Produced by pressure overload (hypertension)
What are causes of right ventricular hypertrophy?
Dirofilariosis and congenital pulmonic stenosis in dogs
High altitude disease (pulmonary hypertension) in cattle
Chronic alveolar enphysema in horses (heaves)
What is Cor pulmonale?
abnormal enlargement of the right ventricle of the heart as a result of disease of the lungs or the pulmonary blood vessels.
What are causes of left ventricular hypertrophy?
Systemic hypertension (chronic renal failure)
Congenital subaortic stenosis
What is ventricular dilation?
- Myocardium cannot undergo hypertrophy because of insufficient time, inadequate nutrition or diseases.
- Terminal lesion in many cardiac diseases.
- Compensatory response to achieve increased cardiac output.
- Dilation allows stretching of cardiac muscle cells to increase contractile force and an increase in stroke volume is the result.
What are the 3 different cardiomyopathies?
- hypertrophic cardiomyopathy
- dilated cardiomyopathy
- restrictive cardiomyopathy
What does hypertrophic cardiomyopathy look like grossly?
What species are they common in?
- Hearts are enlarged
- Prominent concentric hypertrophy of the left ventricle, interventricular septum
- Dilation of the left atrium.
*common in young adult to middle aged cats - uncommon in dogs
What does dilated cardiomyopathy look like grossly?
What species are they common in?
- Biventricular dilation
- White thickened endocardium
- Increased heart weight, >1% heart:body weight ratio.
*Common in middle aged dogs + cats w low tissue taurine conc.
What cows are susceptible to bovine dilated cardiomyopathy?
What are the signs?
- Holstein 2-3y/o
*peripheral oedema, jugular distension,
*fluid accumulations in the body cavities.
*enlargement of the heart with a rounded “globose” shape
What is restrictive cardiomyopathy?
- Walls are rigid and the heart is restricted from stretching and filling with blood properly.
- Rhythmicity and contractility of the heart may be normal
- Stiff walls of the heart chambers keep them from adequately filling.
- Cats with endocardial lesions (inflammation, fibrosis, fibroelastosis) that
impair the ventricular flow.
Causes of Myocardial necrosis? (6)
- Nutritional deficiencies: Vitamin E / Selenium deficiency [calves, lambs, foal]
mulberry heart disease [pigs] - Ischemia: hypoxia
- Ionophore toxicity: Monensin intoxication
- Plant intoxication - plants containing heart glycosides (avocado intoxication in sheep / goats)
- Doxirubicin: Dogs, treatment of lymphosarcoma (depression of cardiac function, direct injury to muscle fibres and hypersensitivity reactions)
- Secondary to myocarditis
What does myocardial necrosis look like grossly and histologically?
Grossly - affected areas = pale yellow to white and dry
Histologically - (recent necrosis) fibres appear swollen, hypereosinophilic
(24-48hr) inflammatory cells
(weeks) persistent stromal tissue - fibroblasts, collagen + capillaries
What are the causes of myocarditis?
*Haematogenous dissemination
*Embolic dissemination
*virus / bacteria / fungi /protozoan + metazoan parasites
What are the different types of myocarditis?
- purulent (from vegetative endocarditis)
- necrotising (toxoplasmosis in dogs and cats)
- haemorrhagic (black leg)
- lymphocytic ( parvoviral myocarditis)
- eosinophilic (sarcocystosis)
- granulomatous (fungi)
What are the protozoan parasites of the heart?
Sarcocystis sp. [ruminants / equids / porcine]rarely myocarditis
Toxoplasma sp. [canine possibly lethal]
Neospora sp.
What are the metazoan parasites of the heart?
Cestodes -Cysticercus sp.
-Hydatid cyst.
Nematodes -Dirofilaria immitis [dogs, cats]
adults: right ventricle / pulmonary arteries
larvae: microfilariae in peripheral circulation
-Angiostrongylus vasorum [dogs]
What is the most common tumour of the heart?
Haemangiosarcoma
What are the 4 parts of the vascular system?
Arteries
Capillaries
Veins
Lymph vessels
What are the 2 types of arteries?
What are the 3 layers called?
Elastic arteries
Muscular arteries - fewer layers of smooth muscle cells without elastic lamina
1.Tunica intima
2.Tunica media
3.Tunica adventitia
What are the 3 types of capillaries and where are they found?
*Continuous epithelium. = fat, muscle, nervous system
*Fenestrated = Endocrine glands, renal glomeruli, small intestine
*Discontinuous = Liver, bone marrow, spleen
What is the structure of veins?
thinner walls, adventitia = thickest part, valves to prevent backflow
What is an aneurysm and what are the causes?
- Localized dilation of a thinned and weakened portion of a vessel.
- Usually arteries affected (large elastic arteries),but can occur in veins.
causes
* Copper deficiency in pigs: Copper neccessary for development of elastic tissue.
* Parasitic infestations: Spirocerca lupi in dogs/strongylus vulgaris in horses.
* Disecting aneurysms: Birds. Disruption of intima. Entry of blood into media dissecting along the wall.
What are common ruptures in horses?
*sudden rupture of ascending aorta - due to trauma from fall - rapid
*rupture of internal carotid artery into adjacent guttural pouch - present as epstaxis
What is the common rupture in cattle?
*rupture of middle uterine artery during parturition, uterine torsion or prolapse
Why does arterial hypertrophy occur?
sustained increased pressure or volume loads
Which layer of the arteries are usually affected? - arterial hypertrophy
Tunica media of muscular arteries
What are the causes of arterial hypertrophy in different animals?
Cats = parasitic infestations
Cows = hypoxia from high altitude
All species = anomalies that shunt blood from left to right
What are the causes of arterial medial calcification?
- calcinogenic plant toxicosis,
- vitamin D toxicosis,
- renal insufficiency
- Johne’s disease.
What does arterial medial calcification look like grossly?
Solid, dense, pipelike structures with raised, solid, white,
intimal plaques.
What is fibrinoid necrosis?
- Deposits of an amorphous, homogeneous, eosinophilic
PAS+ protein material composed of serum proteins and
fibrinogen.
What causes fibrinoid necrosis in pigs/dogs?
Pigs = selenium / Vitamin E deficiency
Oedema disease
Dogs = Uraemia
What is a thrombosis and what are the predisposing factors?
Intravasuclar coagulation
* endothelial damage,
* turbulence or stasis
* hypercoagulative states.
What causes hypocoagulabilities, endothelial damage + abnormal blood flow?
Hypocoagulabilities = Congenital
Hemoconcentration (DH)
High fat diets
Endothelial damage = Arteritis, parasites (strongylosis in mesenteric arteries
in horses and dirofilariasis in dogs in pulmonary arteries)
Abnormal blood flow = Turbulences, stasis
Caudal aortic thromboembolism
(cats with cardimyopathy)
What are the causes of disseminated intravascular coagulation (DIC)?
- Endotoxaemia
- Viraemia (FIP and canine infectious hepatitis)
- Dirofilariasis
- Tumours (hemangiosarcoma and leukemia)
- Shock, haemolysis, extensive necrosis (burns)
What are the consequences of DIC?
Extensive clotting depletes coagulation factors, resulting in widespread haemorrhages.
What is an embolism?
Occlusion of arteries by lodgement of foreign materials such as disrupted fragments of thrombi, neoplastic cells or bacteria.
What are the different types of embolisms and causes?
-Septic: Originate from lesions of vegetative endocarditis in the lung (right side) or the myocardium, kidneys, spleen, joints, leptomeninges (left side).
-Parasitic =Fragments of dead intravascular parasites following adulticides
-Fat = due to bone fractures
-Fibrocartilaginous = embolism of spinal arteries of dogs = posterior paresis
fibrocartilaginous fragment = movement of spinal vasculature
=infarction of spinal cord
-Thromboembolism = altered blood flow, hypercoagulability, endothelial
damage
What is vasculitis (arteritis) and what are the causes?
Inflammation of the blood vessels - arteries
* Haematogenous dissemination
* Local extension of suppurative-inflammatory processes,
* Immunomediated processes
* Parasitic infections.
What does vasculitis look like grossly?
Medium-sized arteries appear thick and tortuous, with associated
haemorrhages, aneurysms and thrombosis
What does vasculitis look like microscopically?
-Fibrinoid necrosis and inflammation of the intima and media.
-Leukocytes present within and surrounding walls; damage to vessel as
fibrinoid necrosis.
-Endothelial damage causes thrombosis leading to infarction.
What is phlebitis + causes?
Inflammation of the veins
* Systemic infections (vasculitis): Salmonellosis, collibacilosis, FIP.
* Local infections: Metritis, hepatic abscesses.
* Intravenous injection sites
What is omphalophlebitis
Inflammation of the umbilical vein
* Common in neonatal farm animals: bacterial contamination of the umbilicus
* Septicaemia, suppurative arthritis, hepatic and umbilical abscesses.
