Essay about Case Study 15: Endocarditis

5890 Words May 12th, 2011 24 Pages
Case Study 15

Scenario
J.F. is a 50-year-old married homemaker with a genetic autoimmune defi ciency; she has suffered from recurrent bacterial endocarditis. The most recent episodes were a Staphylococcus aureus infection of the mitral valve 16 months ago and a Streptococcus mutans infection of the aortic valve 1 month ago.
During this latter hospitalization, an ECG showed moderate aortic stenosis, moderate aortic insuffi - ciency, chronic valvular vegetations, and moderate left atrial enlargement. Two years ago J.F. received an 18-month course of parenteral nutrition (PN) for malnutrition caused by idiopathic, relentless nausea and vomiting (N/V). She has also had coronary artery disease (CAD) for several years, and 2 years ago
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2. What is the significance of the abdominal tenderness, hematuria, joint pain, and petechiae? [2 points for pathophysiological basis for each of the four symptoms] Vegetations, the primary lesions of IE, consist of fibrin, leukocytes, platelets, and microbes that adhere to the valve surface or endocardium (Fig. 37-2). The loss of portions of these friable vegetations into the circulation results in embolization. As many as 22% to 50% of patients with IE will experience systemic embolization. This occurs from left-sided heart vegetation, progressing to various organs (particularly the brain, kidneys, and spleen) and to the extremities, causing limb infarction. Right-sided heart lesions embolize to the lungs (Lewis, 2007, pg 866).

Once microorganisms establish themselves on the surface of the vegetation, platelet aggregation and fibrin deposition accelerate at the site. As the bacteria multiply, they are covered by ever-thickening layers of platelets and thrombin, which protect them from neutrophils and other host defenses. Organisms deep in the vegetation hibernate because of the paucity of available nutrients and are therefore less susceptible to bactericidal antimicrobials that interfere with bacterial cell wall synthesis. The microscopic appearance of acute bacterial endocarditis differs markedly from that of subacute disease. Vegetations

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