My Clinical Notes

Functional regurgitation

• When a valve becomes incompetent due to either;
  • Dilation of the ventricle which causes the papillary muscles to be pulled out and down
  • Dilation of the aortic or pulmonary artery, pulling the valve commissures apart and preventing full closure

 

Valvular stenosis is almost always due to a primary cuspal abnormality and is virtually always a chronic process

Valvular regurgitation may result from either intrinsic disease of the valve cusps or damage or distortion of the supporting structures e.g. aorta, tendinous cords, papillary muscles and the ventricular free wall

 

Major aetiologies of acquired heart valve disease

 

Mitral stenosis

• Post inflammatory scarring – rheumatic heart disease

 

Mitral regurgitation

• Abnormalities of leaflets and commisures
  • Post inflammatory scarring
  • Infective endocarditis
  • Mitral valve prolapse
• Abnormalities of tensor apparatus
  • Rupture of papillary muscle
  • Papillary muscle fibrosis
  • Rupture of chordae tendineae
• Abnormalities of the left ventricle and/or annulus
  • LV enlargement
  • Calcification of mitral ring

 

Aortic stenosis

• Post inflammatory scarring – rheumatic heart disease
• Senile calcific aortic stenosis
• Calcification of congenitally deformed valve – bicuspid , predisposed to degenerative change

 

Aortic regurgitation

• Intrinsic valvular disease
  • Post inflammatory scarring
  • Infective endocarditis
• Aortic disease
  • Degenerative aortic dilation
  • Syphilitic aortitis
  • Ankylosing spondylitis
  • Marfan syndrome

 

 

Congenital Valvular Defects

 

Pulmonary stenosis

• An obstruction in the pulmonary valve that might be mild to severe
• It may be an isolated defect or part of a more complex anomaly e.g Tetralogy of Fallot or transposition of the great arteries
• There is often RV hypertrophy

 

Aortic stenosis

• There are three types of aortic stenosis;
  • Valvular
    • The cusps may be hypoplastic, dysplastic or abnormal in number
    • In severe cases obstruction may lead to;
      • Underdevelopment of the left atria and ascending aorta
  • Subaortic stenosis
    • Thickened ring or collar of dense fibrous tissue below the level of the cusps
  • Supravalvular stenosis
    • An inherited form of aortic dysplasia in which the ascending aortic wall is greatly thickened, causing luminal constriction
    • May be related to Williams syndrome

 

Rheumatic Heart Disease

 

• Rheumatic fever is an acute immunologically mediated multisystem inflammatory disease that occurs a few weeks following an episode of Group A Streptococcal pharyngitis
• The most important consequence of RF are chronic valvular deformities, characterised by fibrotic valvular disease, most commonly mitral stenosis which produces permanent dysfunction
• Incidence and mortality have decreased due to;
  • Improved socioeconomic conditions
  • Improved treatment and diagnosis of streptococcal pharyngitis
  • Unexplained decrease in the virulence of Group A strep

 

Morphology

• During acute RF, focal inflammatory lesions are found in various tissues and are most distinctive in the heart where they are called ASCHOFF BODIES – foci of collagen, surrounded by T cells, plasma cells are macrophages called ANITSCHKOW cells (pathognomonic for RF)
• During acute AF, there may be inflammation in any of the three heart layers e.g. pancarditis. The pericarditis is associated with a serofibrinous pericardial exudates called a ‘bread and butter’ pericarditis
• Inflammatory valvulitis of the left sided valves, consisting of beady fibrinous vegetations called verrucae

 

• Chronic rheumatic heart disease is characterised by organisation of the acute inflammation and fibrosis. This results in;
  • Fibrinous thickening of the leaflets
  • Bridging fibrinosis across valve commissures, generating buttonhole stenosis
  • Thickened, fused and shortened chordae
  • Calcification around the fibrous leaflets
  • Subendocardial collections of Aschoff nodules, usually in the left atrium, forming thickened MacCallum plaques
• In chronic death the mitral valve is generally always affects by the aortic valve can also be affected and this is often more clinically significant

 

• 99% of cases of mitral stenosis are caused by rheumatic heart disease

 

Pathogenesis

• Acute rheumatic fever is believed to be a hypersensitivity reaction induced by group A strep although exact pathogenesis is uncertain
• It is thought that antibodies directed at the M proteins of certain strains of strep cross react with glycoprotein antigens in the heart, joints and other tissues
• It has been suggested that the streptococcal infection evokes and autoimmune response against self-antigen
• Because only a minority of patients with the infection develop rheumatic fever, there appear to be genetic susceptibility
• The chronic sequelae result from progressive fibrosis due to healing of the acute inflammatory lesions and the turbulence induced by ongoing valvular deformities

 

Clinical features

• Major manifestations of disease;
  • Migratory polyarthritis of the large joints – less common in children
  • Carditis
  • Subcutaneous nodules
  • Erythema marginatum of the skin – bathing suit distribution
  • Sydenham chorea
• Diagnosis is established through the Jones criteria;
  • Evidence of a preceding group A Strep infection and the presence of 2 major manifestations or one major and two minor criteria  (non specific signs, fever, athralgia, raised inflammatory markers)

 

• Acute rheumatic fever general occurs 10 days to 6 weeks after a Group A pharyngitis is 3% of patients
• More often occurs aged 5-15
• Although cultures are negative by the time the disease starts, antibodies to streptococcal enzymes may be present
• Overall prognosis is good, with only 1% of patients dying

 

• After an initial attack there is increased susceptibility to reactivation of the disease with subsequent infection. Cardiac damage accumulates with each reoccurrence

 

• Sequelae of chronic rheumatic heart disease
  • Cardiac murmurs
  • Left atrial hypertrophy and enlargement
  • AF due to atrial dilation
  • Heart failure with pulmonary congestion
  • Right ventricular hypertrophy
  • Arrhythmias
  • Thromboembolic complications from atrial mural thrombi
  • Infective endocarditis superimposed on defective valves

 

Infective Endocarditis

 

• Colonisation of the heart valves or endocardium leading to the formation of bulky, friable vegetations of thrombotic debris and organisms and often associated with destruction of the underlying tissue
• Most causes are bacterial
• Traditionally described as acute or subacute;
• Acute is caused by highly virulent organisms e,g, Staph aureus, often seeding a previously normal valve to produce necrotic ulcerative lesions. Clinically there is rapidly developing fever and rigors. There may be embolic complications and splenomegaly. Mortality of 50%
• Subacute is generally caused by lower virulence organisms e.g Strep viridans, seeding a previously injured valve with lesser valve destruction. Insidious onset with low grade fever, weight loss, flulike syndrome. Less embolic complications and low mortality rate

 

Aetiology/Pathogenesis

• Patient is predisposed if they are prior valvular abnormalities e.g.
  • Rheumatic heart disease
  • Mitral valve prolapse
  • Degenerative valvular stenosis
  • Bicuspid aortic valve
  • Prosthetic valves
• Other predisposing influences are;
  • Neutropenia
  • Immunodeficiency
  • Malignancy
  • Diabetes
  • IV drug use
  • Alcohol

 

• Causative organisms;
  • Strep viridans – in patients with native by previously damaged valves
  • Staph aureus – more common in IV drug users
  • Enterococci
  • HACEK group – haemphilus, actinobacilli, cardiobacterium, eikenella and kingella.
  • S. epidermidis – more common in patients with prosthetic valves
  • Other causative agents are gram negative bacilli and fungi
• In 10% of cases not organism can be cultured

 

• The portal of entry of infection may be;
  • Dental or surgical procedure
  • IV drug use or intravenous cannulaes
  • Occult source from the gut

 

Morphology

• Friable, bulky, potentially destructive vegetations, containing fibrin, inflammatory cells and organisms
• Aortic and mitral valves are the most common sites of infection
• Right sided valves are more commonly affected in IV drug users
• The vegetations may erode into the myocardium to produce an abscess
• Fungal endocarditis tends to cause bigger vegetations than bacterial disease
• Emboli may break off and go to the brain, kidneys and myocardium causing septic infarcts
• Subacute lesions are generally smaller

 

Clinical features

• Fever is the most consistent sign, also weight loss and flu like syndrome
• Complications
• Direct injury to valves causing insufficiency with CHF
• Direct injury to the myocardium causing abscess and perforation
• Emboli to spleen, kidneys, heart and brain, causing infarction or metastatic infection
• Renal injury caused by embolic infarction/infection of antigen-antibody IC mediated glomerulonephritis causing nephrotic syndrome, renal failure or both

 

• Clinical signs include;
  • Splinter haemorrhages
  • Janeway lesions
  • Osler nodes
  • Roth spots

 

• Prevention of IE is done by prophylactic antibiotics in patients with some form of cardiac anomaly or artificial valve who is about to have a surgical or dental procedure

 

Duke criteria for diagnosis

• Major criteria
  • Positive blood cultures
  • ECHO findings
  • New valvular regurgitation
• Minor criteria
  • Predisposing heart lesion of IV drug use
  • Fever
  • Vascular lesions
  • Immunological phenomena
  • Microbiological evidence e.g. a single positive culture

Must have 2 major or 1 maj

This entry was posted on Monday, February 11th, 2008 at 4:36 pm and is filed under Cardiovascular. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.