Cardiovascular Pathology


Death in acute RF is rare, and is usually due to myocardial involvement (heart failure)

:)


Download 167.33 Kb.
Page8/9
Date conversion05.11.2016
Size167.33 Kb.
1   2   3   4   5   6   7   8   9

Death in acute RF is rare, and is usually due to myocardial involvement (heart failure)

  • RF and post-streptococcal glomerulonephritis rarely coexist


  • See Appendix I for more



    Infective Endocarditis




    • Infection of the heart valves or other endocardial surfaces by a wide variety of bacterial and fungal organisms

    • Can be divided by clinical and pathologic features into acute and subacute types




    Acute Endocarditis




    • Rapidly destroys heart valves & has a high mortality ~ 50%

    • Virulent organisms; example Staph. aureus

    • Rapid development of chills, fever

    • May rapidly destroy valve  insufficiency

    • May  ring abscess  perforation of heart

    • Large vegetations common, may embolize

    • May cause acute glomerulonephritis due to Ag-Ab complexes deposited in glomeruli

    Note:

    Embolic complications: If right-sided, may embolize to lungs & cause abscesses. If left-sided, may embolize to brain, kidneys or other sites & cause abscesses, or may embolize to coronary arteries & cause MI.




    Subacute Endocarditis



    • May have a long course – weeks to months

    • Lower virulence organisms; example Strep. viridans

    • Smaller vegetations, less destructive than acute

    • Is on the differential diagnosis of “fever of unknown origin”

    • Clinical features range from flu-like symptoms, fever, wt loss, murmur especially if left-sided

    • Most can be successfully treated with antibiotics

    Note:

    Subungual hemorrhages, petechiae and Roth spots in the eyes may be seen with subacute bacterial endocarditis secondary to embolized bits of vegetations.



    Bugs That Cause Infectious Endocarditis




    • Staph. aureus10 to 20% of cases, can attack normal or abnormal valves, highly virulent

    • Strep. viridans (alpha hemolytic strep.) can attack damaged native valves

    • Other bugs include Haemophilus, Actinobacillus, Cardiobacterium, Eikenella & Kingella (HACEK group)

    • Many others can cause, including GNRs and fungi

    • About 10% of cases are blood culture negative

    Infectious Endocarditis – Predisposing Lesions

    • Any anatomic cardiovascular lesion predisposes to IE. Examples:

      • Bicuspid aortic valve

      • Any type of congenital heart disease

      • Calcific aortic stenosis; calcified mitral annulus

      • Rheumatic valve disease

      • Prosthetic valves

      • Previously damaged native valves

      • Floppy mitral valve

    Note:

    Dentists and cardiologists have long known of the need for prophylactic antibiotics with any dental or surgical procedure that may cause bacteremia in patients with predisposing anatomic lesions.




    Two Types of Non-infectious Valvular Vegetations



    • Non-bacterial thrombotic endocarditis (marantic endocarditis) – occurs in extremely debilitated patients (cancer, sepsis)

    • Endocarditis of systemic lupus erythematosus (Libman-Sacks endocarditis)

    Note:

    Marantic endocarditis probably results from a hypercoagulable state such as disseminated intravascular coagulation (DIC) or some forms of cancer (can be part of Trousseau syndrome). The vegetations are sterile, small and do not damage valves, but can embolize. The vegetations form on normal valves. Microscopically there is no inflammation.

    SLE vegetations are small and sterile, and frequently form on the undersides of AV valves. They may be seen on the endocardium and chordae too. Microscopically there may be intense inflammation and fibrinoid necrosis involving the leaflet. Scarring of the valves can occur.

    Diseases of the Myocardium



    General categories:

    • Myocarditis (including transplant rejection)

    • Cardiomyopathy (noninflammatory myocardial dysfunction of unknown [now sometimes known] cause)

    • Other (cardiac tumors, metabolic and storage diseases, toxic injury)

    Note:

    There is some overlap. Old, burned out viral myocarditis may become dilated cardiomyopathy. A metabolic disease of the myocardium may also, in a sense be considered a cardiomyopathy.




    Myocarditis




    • Refers to inflammation of the heart which injures cardiac myocytes

    • May be infectious or noninfectious:

      • Viruses, Chlamydia, Rickettsiae, bacteria, fungi, protozoa, helminths


      • Diphtheritic – due to a toxin released by the bug – not direct infection of the heart
      • Rheumatic fever, postviral, lupus, drug hypersensitivity, other autoimmune

      • Heart transplant rejection

      • Unknown cause (sarcoidosis, giant cell myocarditis)

    Note:

    See Table 12-13, p. 571, Robbins 9th Ed. for major causes of myocarditis.




    Viral Myocarditis




    • The most common cause of myocarditis in the US is viral, usually due to coxsackieviruses A and B and other enteroviruses (less commonly CMV, HIV, influenza)

    • These are very difficult to isolate by viral culture of a myocardial biopsy; PCR may help

    • The inflammatory injury in viral myocarditis may be secondary to an immune cross reaction with myocytes and not by direct viral cytopathic injury



    Viral Myocarditis Clinical






  • 1   2   3   4   5   6   7   8   9
    :)


    The database is protected by copyright ©hestories.info 2017
    send message

        Main page

    :)