Infective Endocarditis Flashcards
What is infective endocarditis?
- Microbial infection of the heart valve or other endocardial tissue
- Associated with an underlying cardiac defect
- Fatal if left untreated
Increasing incidence of IE has been seen in
- Elderly
- Intravenous Drug Users
- Patients with prosthetic heart valves
What are predisposing factors of IE?
- Congenital heart disease accompanied by cyanosis
- Rheumatic heart disease following rheumatic fever
- Mitral valve prolapse with regurgitation
- Degenerative valvular lesions; stenosis, regurgitation
- Prosthestiv valves
- IDU
PT is a 25-year-old male presenting with Fever, Cough, Shortness of
Breath, and Pleuritic Chest Pain. He has a III / IV Heart Murmur and Pulmonary Infiltrates on Chest X-Ray. He also has a history of Heroin Addiction for several years. His past medical history is non-contributory. Blood cultures are obtained in the Emergency Room and a TEE (Transesophageal Echocardiography) is scheduled. The patient is admitted for possible Infective Endocarditis.
The most likely Organism and affected Heart Valve in this patient are?
A. Viridians streptococci and Tricuspid Valve
B. Staphylococcus aureus and Tricuspid Valve
C. Viridians streptococci and Mitral Valve
D. Staphylococcus aureus and Mitral Valve
E. Pseudomonas aeruginosa and Tricuspid Valve
B. Staphylococcus aureus and Tricuspid Valve
Etiologic agents of infective endocarditis?
- Streptococci (55-62% of cases)
- Staphylococci (20-35%)
- Enterococci (5-18%)
- Gram-negative bacilli (1.5-13%)
- Fungi (2-4%)
- Miscellaneous (<5%)
- Culture-negative (<5-24%)
Sequence of events leading to IE?
- Endothelial surface of the heart must be damaged
- Platelet and fibrin deposition occurs on the abdominal surface, forming a non-bacterial thrombotic endocarditis (NBTE)
- Bacteremia results in colonization of the endocardial surface
- Staphylococci, viridians streptococci, and enterococci are most likely to adhere to the non-bacterial thrombotic endocarditis probably because of production of specific adhere factors
- After colonization of the endothelial surface, fibrin, platelets, and bacteria continue to aggregate and a “vegetation” forms
What is the physiology of the heart-blood flow?
- The blood vessels that lead into the heart are the superior vena cava and the inferior vena cava - these vessels flow into the heart from the right atrium
- From the right atrium, deoxygenated blood passes through the tricuspid valve into the right ventricle
- From the right ventricle, blood passes into the pulmonary arteries which deliver it to the lungs where it can become oxygenated
- Following oxygenation, blood enters back into the heart at the left atrium
- From the left atrium, blood descends into the left ventricle by passing through the bicuspid (mitral) valve
- Oxygenated blood exits the left ventricle through the aortic valve where it can then travel out to the rest of the body
On a healthy heart, what can you expect to see?
No growths or vegetations
When you develop clots, what is the consistency?
The clots are gel-like in appearance due to fibrin and platelets
If left untreated, what can happen to vegetations in the heart?
The vegetations can continue to grow, developing into a valvular abscess and destroy the affected heart valves
If a patient has a valvular abscess, how do you treat it?
Surgery becomes necessary since antibiotics will have no effect
What are the heart valves involved in IE?
- Mitral (bicuspid) valve (86% of cases)
- Aortic valve (55% of cases)
- Tricuspid valve (20% of cases)
- Pulmonic Valve (1% of cases)
How many cases of IE are from the mitral valve and by which pathogen?
85% of causes are caused by Viridians streptococci when rheumatic heart disease is the underlying abnormality
How many cases of IE are from the aortic valve?
55% of cases, more involved in acute infections
How many cases of IE are from the tricuspid valve and by which pathogen?
20% of cases with the common site of involvement in staphylococcal endocarditis with intravenous drug use
Subacute
more indolent (slow growing) infection caused by less invasive organisms such as viridians streptococci and more recently CNS, usually occurring in a setting of prior valvular heart disease
Acute
Fulminant infection which most frequently follows infection of previously normal valves by virulent bacteria such as staphylococcus aureus, streptococcus pyogenes and streptococcus pneumoniae
Signs and symptoms caused by non-virulent organisms
- Low grade fever
- Malaise
- Fatigue
- Weight loss
Signs and symptoms caused by virulent organisms
- High grade fever
- Chills and sweats
- Septic picture
- Embolization complications
- Heart murmur
- Skin lesions
- Other (renal failure, splenomegaly, back pain, abdominal pain, chest pain)
Peripheral manifestations of IE
- Osler’s nodes
- Roth spots
- Janeway lesions
- Splinter hemorrhages
- Petechiae
- Clubbing of the fingers
Osler’s nodes
-Purplish or Erythematous subcutaneous papules or nodules that may
appear on the palms of the fingers and toes
-2 – 15 mm in size; painful and tender
-Not specific for Infective Endocarditis, but may be the result of Embolic and / or Immunologic phenomena
Roth spots
- Retinal Hemorrhages with white centers composed of coagulated fibrin
- Usually caused by Immune Complex–mediated Vasculitis
- Only visible with an Ophthalmic Exam
Janeway lesions
Hemorrhagic, painless plaques that may develop on the palms of the
hands or soles of the feet; believed to be Embolic in origin
Splinter hemorrhages
-Thin, linear Hemorrhages found under the nail beds of the
fingers or toes
-Not specific for Infective Endocarditis, and more commonly the result of Traumatic Injuries
Petechiae
- Small (1–2 mm) Erythematous, Hemorrhagic lesions that are neither painful, nor tender.
- May be anywhere, but are more evident on the Anterior Trunk, the Buccal Mucosa and Palate, and Conjunctivae
Clubbing of the fingers
Proliferative change in the soft tissues at the Terminal Phalanges that may be observed in chronic, long-standing Infective Endocarditis
Labs and other test findings in diagnosing IE
- Blood cultures
- Hematologic: WBC, BUN/SCr
- ESR
- Echocardiogram: TTE or TEE