MHD: Valvular Heart Disease Flashcards
Which heart valves are the semilunar valves?
Aortic and pulmonary
Which heart valves are the atrioventricular valves?
Tricuspid and mitral
What are the components of the valve apparatus?
Leaflets, annulus, chordae tendinae, papillary muscles, ventricular wall
-Valvular competency depends on the integrity of all of these components
What components of valve tissue are visible on histology?
Valve tissue has a connective tissue core (spongiosa, fibrosa, reticularis) made up of collagen and elastic fibers
What is a bicuspid aortic valve?
When the (normally tricuspid) valve has only two valves due to incomplete separation during embryogenesis -This condition causes early aortic stenosis
What is the most common valvular abnormality?
Calcification, often due to wear and tear
Describe the pathogenesis of calcific aortic stenosis
The aortic cusps are calcified, which prevents the cusps from properly opening and obstructs outflow. This causes an increase in the pressure gradient across the valve leading to left ventricular hypertrophy
What are the symptoms of calcific aortic stenosis?
Congestive heart failure
Myocardial ischemia
Syncope
How does hypertrophy cause ischemia?
Thicker myocardial walls result in more tissue to perfuse from the same arterial supply. Oxygen diffusion may not be sufficient if the walls become too thick.
What happens during mitral valve prolapse?
The mitral valve becomes enlarged and floppy, balloons into the atrium during systole
What histological changes are seen in mitral valve prolapse?
Mucoid/Myxomatous deposition within the valvular tissue and thinning of the fibrosa
What abnormal heart sound is associated with mitral valve prolapse?
Midsystolic click
What rare, but serous complications are associated with mitral valve prolapse?
Infective endocarditis
Mitral insufficiency
Stroke/systemic infarct
Arrhythmias
What is infective endocarditis and what is its most common cause?
Destructive inflammation of cardiac valves and endocardium
Most commonly caused by bacterial infection
What is a vegetation?
An abnormal outgrowth on the valves of the heart
Typical of endocarditis
What are the categories of infective endocarditis?
Acute: emergency with high mortality
Subacute: non-emergency often affecting previously deformed valve
Which bacteria are most commonly associated with acute infective endocarditis? Subacute?
Acute: Staph Aureus
Subacute: Strep Viridans
What patients are at risk for infective endocarditis?
Patients with valvular disease or prosthetic valves Immune deficient Diabetic IV drug user Alcoholics
What are the portals of entry for infective endocarditis?
Infection elsewhere
Dental procedures leading to bacteremia
Injection of contaminated material into blood
Occult source
How is infective endocarditis diagnosed?
Clinical suspicion
Blood cultures
EKG
What complications are associated with infective endocarditis?
Cardiac: valve insufficiency/stenosis, abscess, dehiscence or leak in prosthetic valves
Emboli: brain, kidney, spleen, lung
Immune: glomerulonephritis
List the lesions associated with infective endocarditis?
Splinter hemorrhage Conjunctival petechiae Osler nodes (fingers, tender) Janeway lesions (feet, not tender)
What is the treatment for infective endocarditis?
IV antibiotics
Surgery
Antibiotic prophylaxis for high risk patients
What are the major non-infected vegetations?
Nonbacterial thrombotic endocarditis
Endocarditis of systemic lupus
Acute rheumatic fever
Describe nonbacterial thrombotic endocarditis
Sterile thrombi form small, non-destructive, loosely attached vegetations
Common in hypercoagulable patients (sepsis, cancer, burns, indwelling catheters)
Describe endocarditis of systemic lupus erythematosus
Lupus patients can form small vegetations on the mitral and tricuspid valves due to immune complex deposition
Leads to valvulitis, fibrosis and valve deformity
Describe rheumatic fever
Onset: 10 days to 6 weeks after group A strep pharyngitis infection
Pathogenesis: immune cross reactivity between M-protein of strep and the heart leads to immune response against your own heart
What are the major manifestations of rheumatic fever?
JONES criteria Joints: migratory polyarthritis Carditis Nodules: subcutaneous nodules Erythema marginatum of skin Sydenham chorea
What is the histological hallmark of rheumatic fever?
Aschoff bodies are seen between myocytes
Appear like mini-granulomas containing macrophages and multinucleated cells
What is the end result of rheumatic fever?
Chronic rheumatic valvular disease: valves become fibrotic and can fuse, cordae become short, thick and can fuse
What valve is most often affected by rheumatic fever?
The mitral valve (65-70% alone)
What is a carcinoid tumor?
A neuroendocrine tumor that secretes bioactive products
Describe carcinoid heart disease
Plaque like endocardial thickening of the right side of the heart and its valves (mucopolysacharide matrix)
Correlated with 5HT levels
What is the most common primary tumor of the heart?
Myxoma (most often of left atrium)
What is a myxoma?
A benign gelatinous appearing tumor composed of mucopolysaccharide matrix
- The tumor can form a ball-valve obstruction
- Tumor is at risk of embolizing
What is the most common primary pediatric tumor of the heart?
Rhabdomyoma
What is an angiosarcoma?
Malignant aggressive endothelial cancer of the heart
What is the most common malignancy of the heart?
Cardiac metastases
