Infective Endocarditis

Question 1

What are the majority of cases of infective endocarditis caused by?

Answer 1

streptococcus*, staphylococcus, enterococcus, or fastidious gram negative cocco-bacillary forms

Question 2

Why are Staph, Strep, Enterococcus such a problem?

Answer 2

They contain adhesins that attach to the fibrin platelet matrix of non-bacterial thrombotic endocarditis (NBTE). Adhesins also attach to the matrix proteins that coat implanted medical devices

Question 3

What organisms are leading cause of culture negative endocarditis?

Answer 3

HACEK (haemophis, actinobacillus, cardiobacterium, eikenella, kingella). normal oral flora that are slow growing and need 3 wks to grow in culture

Question 4

What is the presentation of infective endocarditis?

Answer 4

fever, heart murmur, petehiae, subungal or splinter hemorrhages, clubbing, splenomegaly

Question 5

Describe characteristics of acute endocarditis

Answer 5

Affects normal heart valves. Rapidly destructive

Metastatic foci, Commonly Staph. If not treated, usually fatal within 6 weeks

Question 6

Describe characteristics of subacute endocarditis?

Answer 6

Often affects damaged heart valves. Indolent nature. If not treated, usually fatal by one year.

Question 7

What locations on the valves are affected by IE?

Answer 7

NVE infection is largely confined to leaflets. PVE infection commonly extends beyond valve ring into annulus/periannular tissue

Question 8

What is the pathophysiology of IE?

Answer 8

Turbulent blood flow (from congenital or acquired heart dz) leads to Endothelial trauma. Platelets and fibrin deposit on damaged endothelium lead to Nonbacterial Thrombotic Endocarditis (NBTE). Bacteremia leads to colonization of NBTE and Bacterial Vegetation

Question 9

What is the venturi effect and how does it related to IE?

Answer 9

High velocity jet -Flow from high pressure to low pressure chamber or Flow across narrow orifice of high velocity. Bacteria deposited on edges of low pressure sink or site of jet impaction

Question 10

What is the predominant organism for IE due to intravenous drug use?

Answer 10

S. aureus and most are tricuspid cases

Question 11

What is the predominant organsim for IE within 60 days (nosocomial) of prosthetic valves?

Answer 11

S. epidermidis

Question 12

What are Osler’s Nodes?

Answer 12

Painful and erythematous nodules. Located on pulp of fingers and toes. More common in subacute IE

Question 13

What are Roth spots?

Answer 13

Roth spot (hemorrhages to retina) are oval, pale, retinal lesions surrounded by hemorrhage and usually located near the optic disk.

Question 14

What is the work-up for IE?

Answer 14

Blood cultures (minimum of 3 from 3 different puncture sites), ESR, and CRP, RF, urinalysis, CXR, and Echocardiography

Question 15

Why might you look at RF for suspected IE?

Answer 15

Occasionally there will be an elevated levels of Rheumetoid Factor, particularly in patients who have been infected for six weeks or more.

Question 16

Why might you get an urinalysis for suspected IE?

Answer 16

Urinalysis may reveal microscopic or gross hematuria, proteinuria, and pyuria. These findings along with a low serum complement level indicate a glomerulonephritis or “immunologic phenomena”.

Question 17

What are you looking for on CXR with IE?

Answer 17

Look for multiple focal infiltrates and calcification of heart valves. may reveal septic pulmonary emboli in a patient with right-sided IE

Question 18

How would an EKG be used as a diagnostic adjunct of IE?

Answer 18

EKG with ST changes may indicate ischemia or infarction from septic emboli. Arrhythmias such as heart block may indicated extension of the infection from the valves into the septum and surrounding cardiac tissue.

Question 19

What are indications for each type of echocardiography with IE?

Answer 19

Transthoracic echocardiography (TTE): First line if suspected IE and Native valves. Transesophageal echocardiography (TEE): Prosthetic valves, Intracardiac complications, Inadequate TTE, Fungal or S. aureus or bacteremia

Question 20

What is the major Duke’s criteria for IE?

Answer 20

(+) blood cultures with appropriate organism, Evidence of Coxiella burnetii infection, New Valvular regurgitation, + Echo findings

Question 21

What is the antibiotic of choice for cases of viridians strep IE?

Answer 21

Penicillin

Question 22

What are indications for surgery for IE?

Answer 22

Refractory CHF, Severe valvular dysfunction
Uncontrolled infection, Valve perforation, 1 embolic event with persistent large vegetation, or >1 episode of embolization, Prosthetic valve infection, Fungal IE, New heart block…

Question 23

Which lesions are at highest risk?

Answer 23

Prosthetic valves, Prior IE, Cyanotic congenital heart disease, Surgical systemic-pulmonary shunts