Valvular Heart Diseases

Valvular Heart Diseases

Dr. Mehzabin Ahmed

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The normal function of cardiac valves is to prevent retrograde flow of blood between the atria and ventricles and between the ventricles and the aorta or pulmonary artery. The vibration of blood as valves close produces heart sounds.

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The first heart sound (S1) is due to the closure of the mitral and the tricuspid valves and the second (S2) by the closure of the aortic and the pulmonary valves.

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A murmur is an abnormal heart sound produced by

Valvular abnormalities 

Valvular stenosis - in which valves become thickened or calcified and obstruct the normal flow of blood into a chamber or vessel.

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Valvular incompetence - also called regurgitation or insufficiency in which there is lose of the normal function of the valves and thus fail to prevent the reflex of blood after contraction of an individual cardiac chamber.

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Vegetations - in which the valves leaflets bear either

Valve lesions 

Mechanical disturbances: – Stenosis – Regurgitation

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Vegetations: – Infective endocarditis – Immunological conditions- SLE- Libman-Sacks endocarditis – Hypercoagulable states like widespread metastatic cancers or severe chronic infections- Marantic

Pathological causes of valvular heart diseases 

Congenital abnormality- due to rubella infection, antiepileptic drugs,

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Post infarction resulting in papillary muscle dysfunction

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Post inflammatory scarring (Rheumatic heart diseases)

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Degeneration with aging

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Connective tissue disorders like Marfan’s syndrome

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Acute destruction by necrotizing inflammation

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Calcification of the valvular leaflets.

Inflammatory disorders of the heart valves 

Immune mediated damage causing an inflammation in the valve cusps

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Damage due to infections as in bacterial and fungal endocarditis

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Valves on the left are more frequently involved

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Consequences: – Vegetations: exposure of the valve collagen results in thrombus deposition as exophytic irregular warty nodules – Inflammation and thrombus formation causes

Rheumatic fever 

An immune disorder that follows a streptococcal tonsillitis or pharyngitis by certain strains of streptococci particularly group A β Hemolytic streptococci

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The antibodies that are formed against the streptococcal antigens cross-react with the host cardiac muscle protein.

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The disease occurs mainly in children between the ages of 5 and 15 years.

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A systemic disorder, which in acute phase presents with

Rheumatic Heart Diseases 

In the acute phase pancarditis is seen

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The pericarditis and myocarditis resolve without any long term effect.

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The endocarditis (valve) damage heals by fibrosis and thickens the valves and the chordae tendinae. The valve leaflets may fuse in some cases causing stenosis.

Diagnostic criteria for Rheumatic fever - Jone's Criteria 

Major manifestations

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Minor manifestations

1) Carditis

1) Polysynovitis (flitting

2) Polyarthritis

arthropathy)

3) Skin rashes (erythema

2) Arthralgia

marginatum & subcutaneous

3) Raised ESR or CRP (C-

nodules)

Reactive protein)

4) Neurological symptoms

4) Prolonged PR interval on

(Sydenham's chorea)

ECG

5) Fever

Diagnosis requires 

two major features or

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one major and two minor features,

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plus raised antistreptococcal antibody levels (anti strepolysin O liter) or positive throat culture for group A βHemolytic streptococcus

Rheumatic heart disease 

Patients develop characteristic inflammatory lesions (Aschoff's nodules) in various parts of the heart

i) Rheumatic Pericarditis: - Aschoff's nodules in the pericardium with acute inflammatory exudate predominantly of serous type ii) Rheumatic Myocarditis: - Aschoff's nodules in the myocardium are associated with interstitial edema and mild inflammation and muscle fiber necrosis. iii) Rheumatic endocarditis: - Aschoff's nodules may form anywhere in the endocardium, producing slight irregularity of the endocardial surface. Aschoff's nodules in the valves leads to greater irregularity, erosion of the overlying endocardium particularly at the points at which the valves contact each other at the line of closure. In these sites small aggregations of fibrin and platelets accumulate to form small vegetation's. The aortic and mitral valves are most prone to

Thickened chordae tendinae

Vegetations on the line of closure of the valve

Mitral valve diseases- Mitral stenosis 

Rheumatic heart disease is an important cause of MS

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The long-term effects of the immune damage causes chronic scarring of valves, by fibrosis, of the valve leaflets and associated chordae tendinae. The valve leaflets become thickened, fibrotic and shrunken producing mitral stenosis

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In addition rigid and immobile mitral cusps can cause incompetence because of ineffective closure.

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Failure of the left atrium to empty through the stenosed valve leads to left atrial hypertrophy and dilation . Back pressure causes pulmonary hypertension and pulmonary vascular congestion producing hemoptysis. Left heart failure develops

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Atrial fibrillation is a common complication  atrial thrombosis

Severe mitral stenosis producing a fish mouth appearance

Mitral incompetence 

Causes are – Chronic Rheumatic fever, – Papillary muscle dysfunction after myocardial infarction, – Cusp destruction by infection and – Floppy mitral valve syndrome.

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In most cases regurgitation develops slowly and results in left ventricular enlargement and dilation of left atrium. Progressive left sided cardiac failure

Mitral valve prolapse -Floppy valve syndrome 

Myxoid degeneration of mitral valve, the valve leaflet bulges upward into the atrium during systole;

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The valve incompetence is due to hypermobility of the leaflet.

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It is most common in women and presents in young adulthood.

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In some cases there is a family history

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The posterior leaflet is most commonly affected

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Rupture of one of the chordae tendinae results in

Floppy valve

Aortic valve diseases 

Aortic stenosis is most commonly due to calcification of a congenital bicuspid aortic valve, post inflammatory scarring after rheumatic fever or senile calcific degeneration.

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Severe calcific disease produces rigid cusps  aortic stenosis.

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This causes progressive and left ventricular hypertrophy.

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Most elderly patients with calcific aortic valve disease have pure aortic stenosis,

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In rheumatic heart disease there is some aortic incompetence and involvement of the mitral valves.

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The pathological process responsible for calcification of the aortic valve, largely a disorder of elderly is unknown.

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Approximately 1% of the population have a bicuspid aortic valve, these valves are particularly liable to calcification, sometimes at a relatively young age

Calcific areas in a previously normal valve

Calcific areas in a bicuspid valve

Infective Endocarditis 

Infection of the endocardium and the heart valves.

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There are two broad groups of cases.

1) Patients with a structural abnormality of heart valves or by congenital cardiac defects - are predisposed to infection . The infective organisms responsible are of low pathogenicity and are derived from normal commensal organisms of skin, mouth, urinary tract and gut. The main underlying abnormalities in these groups are congenital bicuspid aortic valves, post-inflammatory scarring, mitral valve prolapse syndrome and artificial

2) Infection of normal valves accounts for remaining cases of endocarditis, in contrast to the first group infection is with pathogenic organism that directly invades the valve and cause rapid destruction. The disease is predisposed by condition that promote the entry of pathogenic organisms into the blood. 

It is common in IV drug abuses, after open heart surgery and following septicemia.

Large friable vegetationsInfective endocarditis

Clinical picture 

Acute infective endocarditis is – due to virulent organism e.g. staphylococcus aureus – can occur in previously normal heart valves. – The proliferation of the bacteria results in necrosis and destruction of valve leaflets and acute disturbance of valve function leading to acute cardiac failure. – The disease is rapidly progressive and often fatal.

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Subacute bacterial endocarditis – generally occurs on structurally abnormal valves. – The causative organisms are poorly virulent, and proliferate slowly forming thrombotic vegetation and gradual valve destruction, the thrombi can embolise. – Many of the effects seen in this pattern of infection are through immunological phenomena and generation of cytokines from persisting low grade infection

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Diagnosis of infective endocraditis – Blood culture to isolate the organism & Echocardiogram

Effects/ Consequences i)  Small emboli of infected thrombotic material enter the systemic circulation, producing infarcts in many organs, particularly brain, spleen and kidneys ii)  Gradual destruction of the valves lead to valve incompetence with cardiac failure iii) Immune complexes against the antigens in infecting organisms are trapped in small vessels, causing skin petechiae and microhaemorrhages in the retina, skin around the nail beds and glomerulonephritis iv) Cytokine generation from the grade infection leads to systemic features of fever, weight loss and malaise

Wart like vegetations

Large friable vegetations

Small bland vegetations

Medium sized vegetations on both sides of the valve leaflets

Artificial valves Replacement of damaged cardiac valves with prosthesis has now become a common and often life saving mode of therapy. Artificial valves are of two categories:i) Mechanical prostheses are various rigid, mobile occluders composed of non physiologic biomaterials ii)Tissue valves are bioprostheses that consist of chemically treated animal tissue, especially porcine aortic valve tissue, these valves are flexible and function some what like natural semi lunar valves. Complications of artificial valves :

i) Thrombosis / thromboembolism

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ii) Prosthetic valve endocarditis

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iii)Structural deterioration tear, fracture, calcification

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iv)Hemolytic induced by high blood shear

At the end of the lesson on Valvular heart diseases , the student should be able to:  List the major causes of Valvular heart diseases.  Define rheumatic fever & infective endocarditis (IE).  Explain the pathogenesis of rheumatic fever.  List the ‘Jones’ criteria for diagnosing rheumatic fever.  List the factors, which predispose to IE.  List the clinical features of IE.  List the cardiac / extra cardiac complications of IE.