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Pathology
Lecture 26 Valvular Heart Disease
1) Define and describe stenosis and insufficiency of one or more heart valves and
their physiologic consequences.
Stenosis: the failure of valve to open completely, almost always a valve tissue injury.
May result in a murmur (abnormal heart sounds) due to turbulence or a jet lesion
(focal endocardial fibrosis) due to blood flow directed at the lesion by defective
valve.
Insufficiency (regurgitation): failure to close completely, may be due to injury to
valve cusps or supporting tissue. Functional regurgitation resulting from ventricular
dilation, which dilate the valve ring (normal valve).
Isolated: one heart valve involved.
Combined: more than one valve involved.
2) List the major etiologies of left-sided valvular lesions.
Degenerative calcific (senile) aortic stenosis - age-related (80s and 90s)
Congenitally bicuspid valve with degeneration - 1-2% of pop., symptomatic in adults.
Postinflammatory aortic stenosis (rheumatic) - less common.
Endocarditis - vegetations, masses of fibrin, inflammatory cells, and microorganisms.
Diseases that dilate the aorta (syphilis, medial degeneration)
3) Describe mitral prolapse as a clinical entity and give its pathology. Mitral valve
prolapse is the most frequent valvular lesion, occurring approximately 7% population,
most often in young women. It is characterized by myxoid degeneration of the
ground substance of the valves which results in stretching of the posterior mitral
valve leaflet, producing a floppy cusp with prolapse into the atrium during systole.
These changes produce a characteristic systolic murmur with a midsystolic click. It is
usually benign and asymptomatic but can result in mitral regurg. Mitral prolapse is
often associated with arrhythmias and predisposes to infective endocarditis.
4) Define rheumatic fever and rheumatic heart disease.
Rheumatic fever is a multisystem inflammatory disorder with major cardiac
manifestations and sequelae, most often affecting children 5-15 years of age. It
usually occurs 1-4 weeks after an episode of tonsillitis or other infection caused by
group A β-hemolytic streptococci. Clinically RF presents as a fever, migratory
polyarthritis (one joint after another become sore), and possibly cardiac symptoms.
Acute RF is a pancarditis affecting the myocardium (Aschoff bodies), pericardium,
and endocardium (small vegetations, verrucae).
Rheumatic heart disease is caused by rheumatic fever and is characterized by a
thickening and stenosis of one or more of the heart valves. RHD often requires
surgery, to repair or replace the involved valve(s). The mitral valve is always
involved, combined mitral and aortic in 25% of cases with tricuspid and pulmonic
involvement being much less common. Valves display diffuse fibrosis, and often
with calcification, commissural fusion, and shortened, thickened and fuse Chordae.
5) Explain the etiology of rheumatic fever and heart disease. It is postulated to occur
as a result of streptococcal antigens that elicit an antibody response reactive to
streptococcal organisms as well as to human antigens in the heart and other tissues.
Repeat and prolonged infections increase the risk of RF and can exacerbate RHD. It
is unknown why some people don't get RF/RHD or what the antigens are.
6) Contrast the most severe and the least severe clinical profiles of infective
endocarditis. Infective endocarditis (IE) is the colonization or invasion of heart
valves or mural endocardium by microbiologic agent. Vegetations are attached.
Most severe (acute): on normal heart valve, virulent organism such as Staphylococcus
aureus (50% of cases), destroys valve, leads to death rapidly.
Least severe (subacute): on previously diseased heart (like RHD), less pathogenic
organism (Streptococcus viridans >50%), less injury to valve, course takes months.
7) List and describe the complication of endocarditis. Complications include:
1. Cardiac changes - valvular insufficiency, sometimes stenosis; myocardial ring
abscess forms and fibrous ring at attachment of valve.
2. Distal embolization occurs when vegetations fragment. Can result in septic
infarcts in the brain or in other organs.
3. Glomerulonephritis, focal necrotizing glomerulitis, caused by immune complex
disease (Ag-Ab or microembolic).
8) Define non-bacterial thrombotic endocarditis.
Nonbacterial thrombotic endocarditis (marantic endocarditis) is associated with
debilitating disorders, such as metastatic cancer and other wasting conditions
(probably hypercoagulable state) and is characterized by small, sterile fibrin/RBC
deposits (vegetations - no bugs, no neutrophils) randomly arranged along the line of
closure of the valve leaflets, usually left-sided.
9) List the major complications of each of the two types of artificial valves.
Valve
Mechanical Valve
Tilting Disks
Tissue (Bioprosthesis) Valve
Porcine (Pig) Aortic Valve
Major complications
Coagulation related – thrombus of valve, distal thromboemboli,
hemorrhage secondary to anticoagulation. Infective endocarditis at tissue
interface. Paravalvular leak.
Degeneration - calcification/tearing of leaflets. Thrombus of valve.
Infective endocarditis at tissue interface, vegetation on leaflets.
Paravalvular leak.