Flashcards in Cardiology - Endocardial disease Deck (66):
What is valvular stenosis?
Stenosis is the failure of the valve to open completely, which impedes forward flow of blood.
What is valvular insufficiency or regurgitation?
Insufficiency results from failure of a valve to close completely, thereby allowing reversed flow of blood.
What is functional regurgitation?
This is used to describe the incompetence if a valve stemming from an abnormality in one of its support structures, as opposed to a primary valve defect. For example, dilation of the right or left ventricle can pull the ventricular papillary muscles down and outward, thereby preventing proper closure of otherwise normal mitral or tricuspid leaflets. Functional mitral valve regurgitation is particularly common and clinically important in IHD, as well as dilated cardiomyopathy.
What is the most common cause of mitral stenosis?
Mitral stenosis is almost always rheumatic in origin. The valve orifice is slowly diminished by progressive fibrosis, leaflet calcification and fusion of the cusps and subvalvular apparatus.
How is blood flow affected in mitral stenosis?
Restricted blood flow from the left atrium to the left ventricle causes a rise in left atrial pressure which is reflected back across the pulmonary system causing pulmonary venous congestion and breathlessness, while a low cardiac output may cause fatigue.
Outline the clinical course of mitral stenosis
Patients usually remain symptomatic until the mitral valve area is approximately 1 cm2 (or >70% stenosed). At first, symptoms occur only on exercise; however, in severe stenosis left atrial pressure is permanently elevated and symptoms may occur at rest. AF due to progressive dilatation of the left atrium is very common. The onset of AF causes a rapid rise in left atrial pressure because ventricular filling depends on left atrial contraction and adequate diastolic filling time.
Pulmonary hypertension may lead to RV hypertrophy and dilatation, tricuspid regurgitation and right heart failure. All patients with mitral stenosis and particularly those with AF, are at risk from left atrial thrombosis and systemic VTE.
What are the clinical features of mitral stenosis?
Effort related dyspnoea is usually the dominant symptom and produces a gradual reduction in exercise tolerance over many years.
Onset of AF may precipitate acute pulmonary oedema.
Haemoptysis and systemic embolism may occur.
- patient is usually in AF
- mitral facies/ malar flush may be apparent
- tapping apex beat
- loud first heart sound, an opening snap and a low pitched mid-diastolic murmur
- elevated JVP, RV heave, loud pulmonary component of the second heart sound and features of triscupid regurgitation all signify the presence of pulmonary hypertension
How should mitral stenosis be investigated?
ECG may show bifid P waves (P mitrale) due to left atrial hypertrophy or AF.
CXR may show enlarged left atrium and features of pulmonary congestion.
Echo provides the definitive diagnosis, allowing estimation of valve area, pressure gradient across the valve and pulmonary artery pressure.
How should mitral stenosis be managed?
Medical management consists of diuretics for pulmonary congestion, and anticoagulants and rate limiting agents in the presence of AF.
Valve replacement (or where possible, balloon valvuloplasty or valvotomy) should be considered if symptoms persist or if pulmonary hypertension develops.
Name some causes of mitral regurgitation
- mitral valve prolapse
- dilatation of the left ventricle and mitral valve ring (e.g. coronary artery disease, cardiomyopathy, myocarditis)
- damage to papillary muscles
- damage to valve cusps and chordae (e.g. rheumatic heart disease, endocarditis, valvotomy or valvuloplasty)
How is blood flow affected in mitral regurgitation?
Chronic mitral regurgitation causes gradual dilatation of the left atrium with little increase in pressure; progressive LV dilatation occurs due to chronic volume overload. Acute mitral regurgitation causes a rapid rise in left atrial pressure resulting in pulmonary oedema.
What are the clinical features of mitral regurgitation?
Chronic mitral regurgitation typically causes progressive exertional dyspnoea and fatigue, while sudden onsent mitral regurgitation usually presents with acute pulmonary oedema.
The regurgitant jet causes an apical systolic (pan) murmur that radiates to the axilla. The first heart sound is quiet and there may a third heart sound.
The apex beat feels hyperdynamic and is usually displaced to the left, indicating LV dilatation. Signs of AF, pulmonary venous congestion and pulmonary hypertension may be present.
How should mitral regurgitation be investigated?
CXR may show left atrial or ventricular enlargement or features of pulmonary venous congestion (pulmonary oedema if acute).
Echocardiography allows assessment of chamber dimensions, LV function and severity of regurgitation as well as detection of structural abnormalities of the valve.
How should mitral regurgitation be managed?
Medical treatment includes diuretics and afterload reduction with vasodilators (e.g. ACE inhibitors). Regular review is important to detect worsening symptoms, progressive cardiac enlargement and LV impairment as all of these are indicators for surgical intervention (mitral valve replacement or repair). Acute severe mitral regurigtation necessitates emergency valve repair or replacement.
What is myxomatous mitral valve? Is this the same as mitral valve prolapse?
In myxomatous degeneration of the mitral valve, one or both mitral leaflets are "floppy" and prolapse - they balloon back into the left atrium during systole. Mitral valve prolapse is a primary form of myxomatous mitral degeneration and is sometimes a feature of connective tissue disorders such as Marfan's syndrome. Men and women are equally affected.
Secondary myxomatous mitral degeneration can occur in any one of a number of settings where mitral regurgitation is caused by some other entity (e.g. IHD).
What is the pathogenesis of myxomatous mitral degeneration?
The basis of primary myxomatous degeneration is unknown. But an underlying (possibly systemic) intrinsic defect of connective tissue synthesis or remodelling is likely. Thus myxomatous degeneration of the mitral valve is a common feature of Marfan's syndrome (due to fibrillin-I mutations) and occasionally occurs in other connective tissue disorders. In some patients with primary disease, additional features such as scoliosis and a high arched palate may indicate structural abnormalities in systemic connective tissue.
Secondary myxomatous change results from injury to the valve myofibroblasts, probably due to chronically aberrant haemodynamic forces.
What are the clinical features of mitral valve prolapse?
Most patients are asymptomatic. In mild mitral polapse, the valve remains competent but bulges back into the atrium during systole, causing a mid systolic click but not murmur. In the presence of a regurgitant valve, the click is followed by a late systolic murmur. The condition is associated with a variety of benign arrhythmias and atypical chest pain but the overall long term prognosis is good. If regurgitation becomes severe, mitral valve repair can be used to treat most forms of mitral valve prolapse, and is preferred to mitral valve replacement.
Patients with primary myxomatous degeneration are also at an increased risk for the development of infective endocarditis as well as sudden cardiac death.
What are the morphological features of myxomatous degeneration of the mitral valve?
Myxomatous degeneration of the mitral valve is characterised by ballooning of the mitral leaflets. The affected leaflets are enlarged, redundant, thick and rubbery, and the tendinous cords tend to be elongated, thinned and occassional rupture. In those with primary disease, concomitant tricuspid valve involvement is frequent (20-40%); less commonly aortic and pulmonic valves can also be affected.
The essential change is thinning of the valve layer known as the fibrosa layer, on which the structural integrity of the valve depends, accompanied by expansion of the middle spongiosa layer because of increased depoisition of myxomatous (mucoid) material.
The SAME changes occur whether the myxomatous degeneration is due to an intrinsic ECM defect, or is caused by regurgitation secondary to another process.
What are the 3 most common causes of aortic stenosis?
1) Rheumatic fever (usually associated with mitral valve disease)
2) Calcification of a congenitally bicuspid valve
3) In the elderly, calcification of a structurally normal valve
How is cardiac function affected by aortic stenosis?
Cardiac output is initially maintained but the left ventricle becomes increasingly hypertrophied. Eventually, it can no longer overcome the outflow tract obstruction and heart failure supervenes. Patients with aortic stenosis typically remain asymptomatic for many years but deteriorate rapidly when symptoms develop.
How common is a congenital bicuspid aortic valve? What causes it and what are its features?
Biscuspid aortic valve occurs with a frequency of 1-2% in all live births and has been associated with a number of mutations including those affecting proteins of the Notch signally pathway. The two cusps are of unequal size, with the larger cusp exhibiting a midline raphe resulting from incomplete cuspal separation.
What are the clinical features of aortic stenosis?
Mild to moderate aortic stenosis is usually asymptomatic but may be detected incidentally on routine examination. The three cardinal symptoms are angina, syncope and breathlessness:
- angina arises because of the increased oxygen demands of the hypertrophied left ventricle working against the high pressure outflow tract obstruction (or co-existing coronary artery disease)
- syncope usually occurs on exertion, when cardiac output fails to rise to meet demand because of severe outflow obstruction, causing a fall in BP. Exertional breathlessness suggests cardiac decompensation as a consequence of chronic excessive pressure overload
What are the characteristic clinical signs of aortic stenosis?
Slow rising carotid pulse
Narrow pulse pressure
Heaving but undisplaced apex beat
Harsh ejection systolic murmur radiating to the neck (often with a thrill)
Soft second heart sound
How should aortic stenosis be investigated?
The ECG usually shows features of LVH, often with down-sloping ST segments and T inversion ("strain pattern"), but can be normal despite severe stenosis.
Doppler echo may show calcified valves with restricted opening and permits calculation of the gradient across the valve.
Cardiac catheterisation is usually necessary to assess coronary arteries before aortic valve replacement.
How is aortic stenosis managed?
All patients with asymptomatic aortic stenosis should be kept under review, as the development of symptoms is an indication for prompt aortic valve replacement.
Surgery in the absence of symptoms is controversial.
Old age is NOT a contraindication to valve replacement.
What is the pathogenesis of calcific aortic stenosis in the elderly?
Progressive age asociated "wear and tear" has been the pathologic mechanism most often proposed, but cuspal fibrosis and calcification are increasingly seen as valvular counterparts of age related arteriosclerosis. Thus, chronic injury due to hyperlipidaemic, hypertension, inflammation and other factors implicated in atherosclerosis probably play a significant role in the pathogenesis.
What is the morphology of calcific aortic stenosis?
The hallmark of calcific aortic stenosis is heaped up calcified masses on the outflow side of the cusps. These protrude into the sinuses of Valsalva and mechanically impede valve opening. It is important to note that the commissure are not fused as in rheumatic aortic valve stenosis. An earlier, haemodynamically insignificant stage of the calcification process is called aortic sclerosis.
What is the pathology of aortic regurgitation?
This condition may be due to disease of the aortic valve cusps (e.g. rheumatic fever, infective endocarditis) or dilation of the aortic root (e.g. ankylosing spondylitis, Marfan's syndrome, aortic dissection). The LV dilates and hypertrophies to compensate for the regurgitation producing a large increase in stroke volume. As disease progresses, LV diastolic pressure rises and breathlessness develops.
What are the clinical features of aortic regurgitation?
In mild to moderate aortic regurgitation, patients are frequently asymptomatic but may experience an awareness of the heart beat due to increase stroke volume. Exertional dyspnoea is the dominant symptom in more severe disease. The pulse is typically of large volume and collapsing in nature, the pulse pressure is wide and the apex beat is heaving and displaced (due to volume overload). The characteristic soft early diastolic murmur is usually best heard to the left of the sternum with the patient leaning forward, with the breath held in expiration. A systolic murmur due to the increased stroke volume is common. In acute severe aortic regurgitation (e.g. perforation of aortic cusp in endocarditis) there may be no time for compensatory LV hypertrophy and dilatation to develop and the features of heart failure may predominate.
How should aortic regurgitation be investigated?
CXR - may show dilatation of the heart and possibly of the ascending aorta
ECG - typically shows evidence of LV hypertrophy
Echo - confirms the diagnosis and may show a dilated, hyperdynamic left ventricle
Cardiac catheterisation and aortography - can also be helpful in assessing the severity of regurgitation, aortic dilatation and the presence of coexisting coronary artery disease
How is aortic regurgitation managed?
Underlying conditions, such as endocarditis and syphilis, should be treated. Replacement of the aortic valve (and root, if dilated) is indicated in symptomatic regurgitation. Asymptomatic regurgitation patients should be followed up annually to detect the development of symptoms or increasing ventricular size on echo. If the end systolic dimension increases to >55mm, then aortic valve replacement should be undertaken. Systolic BP should be controlled using vasodilating drugs such as nifedipine or ACE inhibitors.
What causes tricuspid stenosis?
Tricuspid stenosis is uncommon and is usually rheumatic in origin. It is almost always associated with mitral and aortic valve disease. It may cause signs and symptoms of right heart failure.
What causes tricuspid regurgitation?
This is common and most frequently "functional" as a result of RV dilatation. It may also be caused by endocarditis (especially in IV drug users) rheumatic fever or carcinoid syndrome. Symptoms result from reduced forward flow (tiredness) and venous congestion (oedema, hepatic enlargement).
What signs are associated with tricuspid regurgitation?
The most prominant sign is a large systolic wave in the JVP (giant c wave). Other features include pansystolic murmur at the left sternal edge and pulsatile hepatomegaly. Tricuspid regurgitation due to RV dilatation often improves when the cause of RV overload is corrected, e.g. diuretic and vasodilator therapy in CCF. TV replacement is uncommon.
What is the pathophysiology of tricuspid regurgitation?
There is retrograde blood flow into the right atria during systole due to stretching of the tricuspid valve ring or damage to the valve itself. This causes right atrial dilatation and hypertrophy and a back up of pressure into the venous system. There is also eccentric RVH due to volume overload of the right ventricle.
What causes pulmonary valve stenosis? What are the clinical features and consequences?
This is an uncommon valvular lesions.
It is associated with CHD or carcinoid heart disease.
It presents with an ejection systolic murmur in the left second intercostal space.
It causes concentric right ventricular hypertrophy.
The diagnosis is confirmed on echo and replacement may be needed in some cases.
What causes pulmonary valve regurgitation?
Most often a functional murmur from stretching of the PV ring (e.g. pulmonary hypertension - called a Graham Steele murmur).
Volume overload of the right ventricle leads to eccentric RVH and dilatation.
It produces a diastolic murmur heard after the 2nd heart sound.
What is carcinoid heart disease?
Liver metastases from a primary carcinoid tumour of the small intestine is the most common cause.
Serotonin is produced by the metastatic cancer in the liver and gains access to the hepatic vein --> IVC --> right side of the heart.
In the right side of the heart, serotonin increases fibrosis of the TV and PV, producing TV regurgitation and PV stenosis.
What is infective endocarditis?
This is an infection of the endocardial surface of the heart, which may encompass one or more valves or a septal defect in CHD.
It most frequently occurs in adults between the ages of 45-65.
What risk factors are associated with infective endocarditis?
Diabetes, mellitus, HIV infection
Poor dental hygiene, CHD
MVP, AV stenosis
Haemodialysis, prosthetic heart valve
Intravenous catheters, IVDU
What agent is responsible for causing acute endocarditis?
Staphylococcus aureus is the most common cause of acute endocarditis. Streptococcal group A through to G, Haemophilus influenza and Strep pneumonia are next most common.
Endocarditis in an IVDU is most probably caused by
Staphylococcus aureus is most common again, followed by Pseudomonas aureginosa, Candida spp, enterococci.
What causes subacute endocarditis?
Subacute IE is a less fulminant disease in which less virulent organisms infect structurally ABNORMAL valves, which has typically been destroyed by rheumatic heart disease.
The viridans group of streptococci (most common overall pathogen for causing endocarditis) followed by streptococcus bovis, enterococci, and staph aureus.
If strep bovis is cultured then an urgent CT abdo is required, as this agent is associated with bowel malignancy.
What is the most common cause of endocarditis in prosthetic valves?
Endocarditis associated with an artificial heart valve (early ; <60 days) = staph epidermidis (coagulase negative; most common cause), Candida spp, gram negative bacilli
Endocarditis associated with an artificial heart valve (late; > 60 days) = staph aureus, enterococci, group D strep
What agents cause nosocomial endocarditis?
Staph aureus is the most common cause in patients with intravenous catheters. Enterococci are the most common cause in patients with indwelling urinary catheters.
What endocarditis is associated with ulcerative lesions in the colon (e.g. UC, colon cancer)?
Streptococcus bovis (gallolyticus)
What valves are affected in IE?
Majority of valves involved are left sided (>90%)
- right sided valves with IE are usually associated with IVDU.
Mitral valve is the most common overall valve affected in IE. TV and AV are the most common valves involved in IE due to IVDU.
What is the pathogenesis of IE?
Turbulent blood flow damages valves leading to adherence of fibrin and platelets to the areas of damage. This traps circulating bacteria/ fungi. Pathogens proliferate and fibrin deposition encases the vegetations. Staph aureus infects normal AND previously damaged valves. Viridans group of strep infect previously damaged valves.
Vegetations destroy the valve leaflet and chordae tendineae. Valve destruction leads to regurgitant murmurs.
What are the clinical findings of IE?
a) Fever is the most common sign (90% of cases) - IE is the most common cause of pyrexia of unknown origin.
b) Immunocomplex vasculitis (if IE is SUBACUTE)
- e.g. glomerulonephritis (nephritic type), Roth spots (irregular red area with central white dot 2-10% of cases)
c) Microembolization findings (occur in >50% of cases)
(1) Splinter haemorrhages = linear haemorrhages that are present in the nail beds
(2) Janeway lesions are PAINLESS areas of haemorrhage on the palms and soles of the feet
(3) Osler's nodes are PAINFUL haemorrhagic nodules on the pads of the fingers or toes
(4) Infarctions may occur in different tissues sites (e.g. digits and BRAIN)
Changing heart murmurs (regurgitant type) due to microembolization and progressive damage to valves and splenomegaly (subacute) are other features.
1/3 of patients manifest some evidence of neurologic dysfunction, because of frequent embolization to the brain.
What laboratory findings are associated with IE?
Positive blood cultures are present in 80% of cases (low percentage reflects the fact that many patients are taking antibiotics when the cultures are drawn).
Neutrophilia may occur in acute IE.
Monocytosis occurs in subacute IE.
Mild anaemia is most frequently due to anaemia of chronic disease.
How is IE diagnosed?
Blood cultures (3 sets in the first 24 hours).
Echocardiography or TOE to detect vegetations on the valves.
What is Libman-Sacks endocarditis?
Definition - endocarditis associated with SLE
Occurs in 30-50% of patients with SLE
Sterile vegetations are located over the MV surface and chordae - produces valve deformity and MV regurgitation.
What is acute rheumatic fever?
Rheumatic fever is a multisystem childhood disease that follows a streptococcal infection and is characterised by an inflammatory reaction involving the heart, joints and CNS.
What causes rheumatic fever?
RF is a complication of an acute streptococcal infection, almost always pharyngitis caused by group A beta haemolytic strep (strep pyogenes).
First attack of RF usually occurs between ages of 5 to 15. RF develops 1 to 5 weeks after group A strep infection.
Is strep throat the only method of contracting RF?
Yes. Pharynx is the only site of infection leading to RF. Nephrogenic strains of group A strep that produce poststreptococcal glomerulonephritis lacks the types of matrix (M) proteins (virulence factors) in their cell wall that are present in pharyngeal strains.
What are the risk factors for developing RF?
(1) Crowding, poverty
(2) Young age
(3) Geography - Salt Lake City, Utah
What is the pathogenesis of RF?
RF is an antibody mediated disease that follows a group A streptococcal infection of the pharynx in genetically susceptible individuals.
Host develops antibodies against group A streptococcal carbohydrate epitope (N-acetyl-beta D-glucosamine). These cross react with cardiac myosin and laminin and damage vascular endothelium. Endothelial damage leads to upregulation of adhesion molecule VCAM-1 on endothelial cells resulting in early inflammation and infiltration of T cells. T cell clones in heart tissue react with the bacterial M5 protein and cardiac myosin. This is an example of a type II hypersensitivity reaction.
What are the myocardial features of RF?
RF is a pancarditis, affecting all three layers of the heart.
Myocardial features are:
- early dilatation and non specific inflammation
- fibrinoid degeneration of collagen; fibres become swollen, fragmented and eosinophilic
- myocarditis most common cause of death in RF
- Aschoff bodies are present in myocardial tissue; lesions have a central area of fibrinoid necrosis surrounded by Anitschkow cells (reactive histiocytes)
Anitschkow cells are unusual cells that contain a central band of chromatin that appears as an "owls eye" in cross section.
How is the pericardium affected by RF?
Fibrinous (bread and butter) pericarditis presents with precordial chest pain with or without a friction rub. It has little functional effect and ordinarily does NOT lead to constrictive pericarditis.
What are the endocardial features of RF?
Endocarditis refers to inflammation of cardiac valves.
It most commonly affects the MV, followed by the AV, followed by the TV.
Sterile verrucous vegetations (fibrin deposition) develop along the line of closure of the valve. Embolism is uncommon, but does rarely occur.
MV regurgitation or AV regurgitation occurs depending upon which valve is inflamed. LHF may occur (systolic heart failure).
What are the important clinical features of RF?
1) Migratory polyarthritis (75%)
- most common initial presentation
- involves the large joints, ankles, and wrists
- No permanent joint damage
2) Carditis (35%)
3) Subcutaneous nodules occur on the extensor surfaces of forearms
- nodules are very similar to those found in rheumatoid arthritis
- centres of the nodules show fibrinoid necrosis
4) Erythema marginatum presents as evanescent circular rings or C shaped areas erythema around normal skin
5) Sydenham's chorea is characterised by reversible rapid, involuntary movements affecting all muscles
- late manifestation
How is a diagnosis of RF made?
Diagnosis is made using the revised Jones criteria.
One major and two minor criteria if supported by evidence of an antecedent group A streptococcal pharyngitis.
Major criteria include:
- carditis, migratory polyarthritis, chorea, erythema marginatum, or subcutaneous nodules
Minor criteria include:
1) Previous RF or rheumatic heart disease
2) Arthalgia (pain without joint swelling)
3) Increased acute phase proteins - neurtophilia, CRP, ESR
4) Prolonged PR interval (first degree heart block)
What investigations are useful to diagnose acute RF?
Increased antistreptolysin O (ASO) titres >400 Todd units.
- titres peak at 4 to 5 weeks after streptococcal pharyngitis
- high titres are supportive but NOT diagnostic of acute RF
Increased anti-DNase B titres (less reliable than ASO titres).
Throat cultures possibly positive.
What is the pathology of chronic RF?
Myocarditis and pericarditis of RF typically resolve without permanent sequelae.
Acute endocarditis often results in long term structural and functional alterations. Severe valvular scarring may occur months or years after a single bout of RF. Recurrent episodes of acute RF are also common and result in repeated and increasing damage to the heart valves. The MITRAL valve is most commonly affected in chronic rheumatic heart disease. Chronic mitral valvulitis leads to irregular thickening and calcification of the leaftlets, often with fusion of the commissures. In severe disease, the valve orifice becomes reduced to a fixed narrow opening that has the appearance of a "fish mouth" when viewed from the ventricle. Mitral stenosis is the predominant functional lesion, but such a valve is also regurgitant.
What are the complications of chronic rheumatic heart disease?
1) Bacterial endocarditis - follows episodes of bacteraemia in persons with risk factors (e.g. during dental procedures)
2) Mural thrombi - form in atrial or ventricular chambers in 40% of patients with rheumatic valvular disease. They give rise to thromboemboli, which can produce infarcts in various organs
3) Congestive cardiac failure