Cardiac system pathology Flashcards
What is volume overload?
Adaptation to compensate for abnormal increase in blood volume within the heart chambers
What is pressure overload?
Adaptation to compensate for increase in resistance in blood flow
What are some causes of volume oveload?
Shunts
Valvular insufficiencies
What are some causes of pressure overload?
Increased pulmonary/systemic pressure
Stenosis (narrowing) of ventricular outflow
What does volume overload cause?
Eccentric hypertrophy
Also atrial dilation
Is volume overload a problem with diastole or systole?
Diastole - increased end diastolic volume
What does eccentric hypertrophy look like?
Ventricular wall is thickened but due to enlargement of the chamber it can appear normal when stretched
What causes atrial dilation to occur due to volume overload?
Left atrioventricular valve insufficiency- blood goes backwards into atrium
What does pressure overload cause?
Concentric hypertrophy
What is concentric hypertrophy?
Thickened ventricular walls - new sarcomeres forming in parallel to generate more force to eject blood
Is concentric hypertrophy an issue with diastole or systole?
Systole - excessive afterload causing increased systolic wall stress
More pressure needed during systole
What is pulmonic stenosis?
Narrowing of the pulmonary valve opening
What does pulmonic stenosis cause?
Pressure overload and concentric hypertrophy
What does concentric hypertrophy look like?
Thickened ventricular wall
Lumen normal or reduced in size
Why is myocardial hypertrophy bad?
Insufficient blood supply
Cardiomyocyte death/fibrosis
Reduced ventricular wall compliance
What congenital malformations cause left to right shunting of blood?
Patent ductus arteriosus
Atrial/ventricular septal defect
Endocardial cushion defects
Where does the blood shunt from in a patent ductus arteriosus?
Aorta into the pulmonary artery
What are secondary effects of patent ductus arteriosus?
Pulmonary oedema
LHS systolic murmur
Volume overload - more blood draining from lungs
Pressure overload - pulmonary hypertension
Where is an atrial septal defect located?
Foramen ovale
Where is a ventricular septal defect located?
Ventricular muscle
What are potential secondary effects of ventricular septal defect?
Left to right shunt
Murmur
Left side volume overload
Right side volume and pressure overload
What are endocardial cushion defects?
Poorly formed walls separating the chambers of the heart – blood mixes easily
What are the different locations of stenosis?
Supravalvular
Valvular
Subvalvular - tissues beneath valve in ventricle
What is the most common location/cause of pulmonic stenosis?
Valvular - leaflet thickening, fusion/ hyperplasia of valve annulus
What is the most common location/cause of aortic stenosis?
Subvalvular - plaques, ridges of connective tissue
What is atrioventricular valve dysplasia?
Irregular leaflet & Chordae Tendineae
What are some consequences of atrioventricular valve dysplasia?
Irregular leaflets & Chordae Tendineae
Fusion of leaflet
What is transposition of aorta/pulmonary artery?
Switching of Aorta/ Pulmonary artery
Presence of ventricular septal defect allows for blood mixing
What is an overriding aorta?
Aorta right above the VSD – Aorta able to receive blood from both ventricles
What is the name for the condition with 4 congenital heart defects all at once?
Tetralogy of Fallot
What are the 4 conditions of Tetralogy of Fallot?
VSD
Pulmonary stenosis
Overriding Aorta
RV hypertrophy
What are the 3 different types of pericarditis?
Fibrinous
Suppurative(purulent)
Constrictive
What animals is fibrinous pericarditis mostly found in?
Farm animals
What is fibrinous pericarditis mostly associated with?
Bacterial septicaemia and haematogenous infections
What are the main features of fibrinous pericarditis?
Fibrin strands attached or free floating within pericardial sac
What causes suppurative pericarditis?
Infection with pyogenic bacteria causing purulent/ fibrinopurulent exudate
What is constrictive pericarditis?
Formation of severe adhesions from organized fibrous granulation tissue within the pericardium
What is hydropericardium?
Excess volume of clear fluid within the pericardial space
What can cause hydropericardium?
Causes of generalised oedema
Toxaemia
Neoplasms - cardiac haemangiosarcoma
Where does cardiac haemangiosarcoma arise from?
Right atrium/auricle blood vessels
What is haemopericardium?
Accumulation of pure blood in pericardial cavity
What can cause haemopericardium?
Rupture of atrium or blood vessel
Clotting defect
Neoplastic disease
What is cardiac tamponade?
Rapid accumulation of fluid in the pericardial sac which compresses/restricts heart expansion
What are the consequences of cardiac tamponade?
Impaired cardiac filling
Reduced CO
Heart failure
Cardiogenic shock
What are the 3 main types of cardiomyopathy/myocardial diseases?
Dilated cardiomyopathy
Hypertrophic cardiomyopathy
Restrictive cardiomyopathy
What is a cardiomyopathy?
PRIMARY structural and functional changes affecting the myocardium that no obvious cause is evident (eg. not secondary to congenital defects)
What is dilated cardiomyopathy?
Reduced myocardial contractility and chamber dilation
What type of function does dilated cardiomyopathy affect?
Affects systolic function - cant contract, reduced CO
What is hypertrophic cardiomyopathy?
Ventricular hypertrophy - thickened ventricle walls
Reduced wall compliance
What type of function does hypertrophic cardiomyopathy affect?
Affects diastolic function - ventricles cant fill so reduced end diastolic volume
What is a consequence of hypertrophic cardiomyopathy?
Left atrial enlargement
Left sided congestive heart failure
What is hypertrophic cardiomyopathy related to?
Ventricular hypertrophy
What is restrictive cardiomyopathy?
Endocardial/ myocardial fibrosis Reduced ventricular wall compliance
Increased ventricular stiffness
What are the anatomical features of dilated cardiomyopathy?
Thin ventricular walls
Stretched AV valve annulus
What is the most common cause of heart disease in cats?
Hypertrophic cardiomyopathy
Where does segmental hypertrophic cardiomyopathy primarily affect?
Basal regions of the ventricular septum
What is the main species affected by each type of cardiomyopathy?
Dilated - Dogs
Hypertrophic - cats
Restrictive - cats
What are 2 functional effects of hypertrophic cardiomyopathy?
Dynamic obstruction of the left ventricular outflow tract - narrowing
Systolic anterior motion of the mitral valve
Which type of cardiomyopathy is less common?
Restrictive cardiomyopathy
What is the most common cardiac disease in dogs?
Valvular endocardiosis (NOT ENDOCARDITIS)
What is valvular endocardiosis?
Distortion of valve leaflets - valvular insufficiency
Slowly progressive degenerative condition
What predisposes to valvular endocardiosis?
Small/medium dog breeds
Cavalier king Charles spaniel
What is another name for valvular endocardiosis?
Myxomatous mitral valve disease
Which valve is the most commonly affected valve in valvular endocardiosis (MMVD) in dogs?
Left atrioventricular valve - mitral valve
Which valve is the most commonly affected valve in valvular endocardiosis (MMVD) in horses?
Aortic and left AV/mitral valve
What are the gross features of valvular endocardiosis (MMVD) ?
Thickened leaflet
Smooth pink nodules
What are the consequences of valvular endocardiosis (MMVD)?
Left ventricular eccentric hypertrophy - volume overload Left atrial dilation - regurgitation Murmur Jet lesion Chordae tendineae rupture Atrial rupture
What is valvular endocarditis?
Inflammation of the endocardium - heart valves
What animals are most commonly affected by valvular endocarditis?
Farm animals
What causes valvular endocarditis?
Bacteria and trauma leading to inflammation and fibrin deposition
What are the gross features of valvular endocarditis?
Raised irregular yellow plaques
What are the consequences of valvular endocarditis?
Valvular insufficiency - volume overload
Valvular stenosis - pressure overload
Septic embolism
What is cardiac failure?
Failure to:
Eject sufficient blood to meet requirements
Recieve enough blood to adequately drain systemic/pulmonary systems
What is acute heart failure?
Rapid onset of new/worsening symptoms of HF
What is a consequence of acute heart failure?
Cardiac syncope - big changes to BP and HR
Causes collapse and unconsciousness
What are the two types of chronic heart failure?
Forward and backward failure
What is forward failure?
Inadequate CARDIAC OUTPUT and decreased perfusion of peripheral tissues
What is a consequence of forward heart failure?
Cardiogenic shock
What is backward failure?
Failure to deal with VENOUS RETURN causing congestion of venous and capillary beds
What are the consequences of backward heart failure?
Congestion and oedema
What type of heart failure does left sided heart failure cause?
Backward failure to lungs - pulmonary congestion and oedema
Forward failure to body- ischaemia/hypoxia
What type of heart failure does right sided heart failure cause?
Backward failure to body - systemic congestion and oedema
What are the symptoms of left sided heart failure?
Dyspnoea and cough
Shock, hypotension
What are the symptoms of right sided heart failure?
Ascites
Pleural effusion
Peripheral oedema
(All from backwards failure)
What is the main symptom of right sided heart failure in dogs?
Ascites - fluid in body cavities
What is the main symptom of right sided heart failure in cats?
Pleural effusion
What is the main symptom of right sided heart failure in ruminants and horses?
Peripheral oedema
What is a cardiac biomarker for cardiomyocyte damage?
Cardiac troponin I
What is a cardiac biomarker for cardiomyocyte stretching?
NT-pro BNP
