lecture 4/tutorial 5: valvular heart disease Flashcards
What are the 2 key classifications of valve pathology?
Stenosis, regurgitation/incompetence
What is valve stenosis?
Failure of a valve to open completely leading to obstruction to blood flow/pressure overload
What is valve regurgitation?
Failure of a valve to close completely leading to reversed/retrogade flow and volume overloads
What are functional valve pathologies?
Issues with structurally normal valves arising from issues with larger heart structures that transmit to the valves - e.g. ventricular dilation pulling on papillary muscles preventing proper closure
What is the effect of valve stenosis on cardiac muscle?
Pressure overload leads to chamber muscle hypertrophy, which later causes failure and dilation
What is the effect of valve regurgitation on cardiac muscle?
Chamber dilation, particularly in the atria
Which type of valve pathology is most likely to cause atrial fibrillaton, and why?
(mitral) valve regurgitation - causes left atrial dilation which leads to the formation of re-entry pathways causing atrial fibrillation
Which valve is most commonly affected by congenital valve disease, and with which pathology?
Aortic valve - stenosis due to congenitally bicuspid aortic valve
What is the most common cause of calcific aortic stenosis?
Degeneration with age - 7-9th decades
What infection causes rheumatic fever?
Group A streptococcus
What is the pathogenesis of Acute Rheumatic Fever?
- Patient acquires GAS pharyngitis
- Antibody to M protein in bacteria cross reacts with valve tissue (antigen mimicry), and T cells also cross-react
- Inflamed heart valves rub together exposing collagen and tissue factor to blood flow
- Microthrombi/vegetations called verrucae form at the commisssures of the valves.
What are the features of valves affected by chronic rheumatic heart disease?
Thickened leaflets, fused comissures, scarring, thick/short chordae tendinae - valve stenosis/incompetence
What are the clinical features of rheumatic fever?
pancarditis, migratory polyarthritis, subcutaneous nodules, erythema marginatum, sydenham chorea
What valve is most commonly involved in rheumatic fever?
Mitral valve
What is the most common valve deformity in rheumatic heart disease?
Mitral valve stenosis
What are the effects of rheumatic fever on the rest of the heart, apart from the valves?
Rheumatic pancarditis - endocarditis, myocarditis, pericarditis
What are the effects of rheumatic myocarditis?
Causes the myocardium to be soft and flabby, resulting in chamber dilation and heart failure in some cases
What examination can help to diagnose rheumatic pericarditis?
Chest auscultation - listen for pericardial friction rub as the layers of inflamed pericardium rub together
What are the foci of inflammation in rheumatic myocarditis?
Aschoff bodies
What are Aschoff bodies, and what are their constituents?
Foci of inflammation in rheumatic myocarditis. Consist of central necrosis surrounded by lymphocytes and activated macrophages (caterpillar cells)
What is the gross morphology of rheumatic pericarditis?
Inflamed pericardial surface has a shaggy fibrin-rich exudate on top - ‘bread and butter pericarditis’
What are the names for fused, stenotic fissures in rheumatic heart disease?
button-hole, fish-mouth
What is the pathogenesis of subacute infective endocarditis?
- bacteria enters the blood of a person with previously damaged valves.
- turbulent blood flow around the damaged valves causes endothelial injury, resulting in microthrombi formation that are easily colonised by bacteria.
- bacteria cause inflammation forming large friable vegetations
What valve is typically affected by infective endocarditis in injecting drug users?
Tricuspid valve
What is the key histological feature of vegetations of acute bacterial endocarditis?
Abundant with neutrophils, and are septic (contain bacteria)
What valve pathologies cause a diastolic murmur?
Mitral valve stenosis, Aortic valve regurgitation, Tricuspid valve stenosis, Pulmonary valve regurgitation
What valve pathologies cause a systolic murmur?
Mitral valve regurgitation, aortic valve stenosis, tricuspid valve regurgitation, pulmonary valve stenosis
