Biochemistry - University of Arizona



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 |Major complications |

|Mechanical Valve |Coagulation related – thrombus of valve, distal thromboemboli, hemorrhage secondary to |

|Tilting Disks |anticoagulation. Infective endocarditis at tissue interface. Paravalvular leak. |

|Tissue (Bioprosthesis) Valve |Degeneration - calcification/tearing of leaflets. Thrombus of valve. Infective |

|Porcine (Pig) Aortic Valve |endocarditis at tissue interface, vegetation on leaflets. Paravalvular leak. |

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download