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Heart Infections
Infections of the Heart
| Question | Answer |
|---|---|
| What is the prognosis of infective endocarditis? | 100% fatal if undiagnosed and untreated. 20% fatal if diagnosed and treated appropriately (IV antibiotics and/or surgery). |
| What is the pathogenesis of infective endocarditis? | 1. Valvular endothelial injury 2. Platelet and fibrin deposition 3. Microbial seeding 4. Microbial multiplication (up to 1010 bugs/gram). |
| Infective endocarditis epidimiology: how common is it, typical population (gender, age) | Uncommon; median age (50); males (1.7:1) |
| What part of the heart does infective endocarditis typically affect? | Commonly see vegetations (friable masses of blood clot and infecting organisms) on VALVES rather than other areas of endocardium |
| What are the three classification of infective endocarditis? | Clinical course, host substrate, and specific infecting organism |
| In infective endocarditis, what are the two sub-classifications of clinical course? What are the chareteristics of the two subtypes? | Acute bacterial endocarditis (ABE) subacute bacterial endocarditis (SBE). ABE usually fulminant due to highly virulent organisms (e.g. S. aureus). SBE typically insidious (~weeks) due to less virulent organisms (e.g. viridians streptococci) |
| In infective endocarditis, what are the three sub-classifications of host-substrate? | Native valve (NVE), prosthetic valve (PVE), intravenous drug user endocarditis. |
| What type of host substrate is typically associated with coagulase negative Staphylococcus epidermis? | PVE (S. epidermis rare in NVE) |
| What clinical course is typically seen patients with IV drug user endocarditis? What valve is typically compromised? | Acute; usually affects tricuspid valve |
| What side of the heart is more likely to be infected? | The left sided valves; from descending likelihood: mitral, aortic, mitral AND aortic, tricuspid, pulmonic |
| What are some predisposing heart diseases that increase the risk of getting infective endocardtis? | Mitral Valve Prolapse, congenital disease, prosthetic valve, degenerative disease, rheumatic disease, previous endocarditis |
| What are some portals of entry for infective endocarditis? | central venous catheterization, dental procedures, gingivitis, chewing, brushing teeth, surgery, bladder catheterization, endoscopy, shaving, intravenous drug abuse, etc. |
| What specific pathogenic factor increases the ability of a pathogen to cause infective endocarditis? | Ability of pathogen to bind to blood clot (e.g. streptococci use dextran to adhere to clot, especially Streptococcus mutans) |
| What are the most likely etiological agents of infective endocarditis (highest to lowest)? | Staph aureus (coag +) > coag - Staph > streptococci (viridians > enterococci > bovis > HACEK > other gram - aerobes > fungi (Candida) |
| What is the gross pathology of infective endocarditis? | Large friable vegetations (tan, gray, red, or brown); can be one or many; usually along commissures of valves upstream of flow (e.g. atrial side of AV valve or LV side of Aortic valve) |
| What damage to the heart can vegetations do? | destructive of tissue-->perforation of valve, adjacent abscess, fibrotic scarring, and calcification |
| What makes up a vegetation (microscopic findings)? | fibrin, platelets, masses of organisms, necrosis and neutrophils; later: lymphocytes, macrophages, and fibroblasts (leads to fibrosis) |
| What are the most common symptoms of infective endocarditis? | Most common: FEVER, CHILLS, WEAKNESS, DYSPNEA. Less common: cough, sweats, anorexia, weight loss, malaise, skin lesions, nausea/vomiting, stroke, headache, myalgia/arthralgia, edema, chest pain, abdominal pain, delirium/coma, back pain, hemoptysis |
| What are some of findings of infective endocarditis (KNOW EPONYMS, as they are specific even if uncommon)? | Common: Fever, heart murmur, splenomegaly, petachie. Uncommon: osler nodes, subungual splinter hemorrhages, changing heart murmur, Janeway lesions, new heart murmur, and Roth spots. |
| What are Osler nodes? | pea sized tender finger/toe nodules |
| What are Janeway lesions? | small palm/sole hemorrhages |
| What are Roth spots? | White dots with surrounding hemorrhage in retina |
| What are the common laboratory findings of infective endocarditis? | Common: Elevated erythrocyte sedimentation rate (ESR); circulating complexes, anemia, proteinuria. Less common: rheumatoid factor (anti-IgG Abs), hematuria, leukocytosis, hypergammaglobulinemia, elevated creatinine, leukopenia, thrombocytopenia |
| How would diagnose infective endocarditis? | Continuous low-grade bacteremia characteristic (check for fastidious an slow growing organisms); cultures have HIGH PREDICTIVE VALUE; transesophageal echo >90% sensitivity for vegetations; Duke criteria |
| What are the limitations of using a blood culture to diagnose infective endocarditis? | May be negative if patient already received antibiotics; not very sensitive, especially if fastidious or slow growing organisms |
| What are the limitations of echocardiography in diagnosing infective endocarditis? | Transthoracic is 60% sensitive; transesophageal is >90% for showing vegetation, abscess, detached prosthesis, or regurgitation. Negative does not rule out endocarditis, however. |
| What criteria can be used to diagnose infective endocarditis? | The Duke criteria (combines BLOOD CULTURE AND ECHO + general signs) |
| What are the possible complications of infective endocarditis? | Common: Heart failure > septic emboli (kidneys > heart > spleen > brain). Uncommon: myocardial abscess > glomerulonephritis > mycotic aneurysms > pericarditis (rare) |
| What is the epdimiology of myocarditis? | Uncommon; slight male:female ratio (6:4); young healthy individuals (including neonates) |
| What tissue is affected in myocarditis? | Heart muscle; typically occurs at the same time as pericarditis --> "myopericarditis" |
| What is the pathogenesis of myocarditis? | Most commonly viral: parvovirus B19 and human herpes virus 6 most frequent. |
| What are the 2 phases of viral myocarditis? | 1) Early: direct viral infection of myocytes --> 2) auto-immune attack on myocytes |
| What is the typical pathology of myocarditis? | Pale mottled flabby dilated heart with multifocal interstitial (usually mononuclear) inflammation; myocarditis is associated with myocyte injury and necrosis |
| What are the signs and symptoms of myocarditis? | Viral myocarditis is associated with fever, chest pain, dyspnea, malaise, myalgia, tachycardia, a pericardial friction rub and various electrocardiographic findings. It may also cause sudden death due to an arrhythmia. |
| How do you diagnose myocarditis? | Cardiac biopsy is required for a definitive diagnosis, but magnetic resonance imaging and other tests are emerging as alternatives. |
| What is the treatment of acute myocarditis? Chronic myocarditis? | Treatment for acute myocarditis is supportive. Treatment of chronic myocarditis is empirical and experimental |
| What is the prognosis of myocarditis? | 90% of patients recover, but 10% progress to chronic dilated cardiomyopathy. |
Created by:
karkis77
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