Infective Endocarditis
Definition
An inflammation of the membrane lining the heart: usually confined to the external lining of a valve, although it may affect the lining of the heart or great vessels
Etiology
- An invasion of microorganisms, usually bacterial; the classic manifestation is a vegetation
- The most-common bacterial organisms are Streptococcus viridans and Staphylococcus aureus
- High-Risk Patients
- Prosthetic heart valve
- Aortic valve disease
- Mitral regurgitation
- Patent ductus arteriosus
- Ventricular septal defect
- Coarctation of the aorta
- Marfan’s syndrome
- Intravenous drug abuse
- Intermediate-Risk Patients
- Mitral valve prolapse
- Pure mitral stenosis
- Tricuspid valve disease
- Pulmonary valve disease
- Previous infective endocarditis
- Asymmetrical septal hypertrophy
- Calcific aortic sclerosis
- Hyperalimentation or pressure-monitoring lines that reach the RA
- Nonvalvular intracardiac prosthetic implants
- Low-Risk Patients
- Atrial septal defects
- Arteriosclerotic plaque
- Coronary artery disease
- Syphilitic aortitis
- Cardiac pacemakers
Signs and Symptoms
- Fever of unknown origin (FUO)
- New heart murmur
- Positive blood cultures
- Night sweats
- Arthralgia
- Weight loss
Complications
- Valve leaflet disruption with resultant regurgitation
- Embolization (pulmonary or systemic, depending on valve involved)
- Congestive heart failure
- Cardiac muscle or valve ring abscess
- Peripheral abscess formation due to embolization
Electrocardiogram
- Conduction abnormalities
Chest X-ray
- Limited
- May demonstrate signs of congestive heart failure
Treatment
- Endocarditis prophylaxis, especially for high-risk patients
- Antimicrobial therapy
- Valve repair or replacement
M-Mode
- Vegetation on a valve leaflet usually does not restrict valve motion
- Mitral valve leaflets appear thickened, “smudged”,"shaggy"
- Diastolic thickening of the aortic valve leaflet(s)
- Diastolic fluttering of the aortic valve leaflet(s)
- Linear or nonuniform echo(s) in the left ventricular outflow tract may indicate an aortic valve vegetation or flail aortic valve leaflet
- Severe acute aortic regurgitation may cause premature closure of the mitral valve
- Severe acute aortic regurgitation may cause premature opening of the aortic valve (aortic valve is of. en before onset of QRS complex)
2-D
- Vegetations, usually found on the atrial side of the mitral, tricuspid valves or on the ventricular surface of the aortic/pulmonic valves
- Chamber enlargement, if regurgitation is significant
- Ventricular function usually normal or hyperdynamic
- Flail leaflets best seen by 2-D echocardiography
- Ring abscess is a serious complication of infective endocarditis: Possible echocardiographic findings include:
- Echo-free cavity in valve annulus
- Echo-free cavity in adjacent structures including interventricular septum, aortic root, and anterior mitral leaflet
- Localized echo density in mitral annulus resembling calcification
- Localized echo density in septum > 13 mm
- Posterior aortic root wall > 9 mm or anterior aortic wall > 9 mm
- Sinus of Valsalva aneurysm
- Aortoseptal discontinuity caused by abscess cavity
- Prosthetic valve rockin
Doppler
- Determine the presence and seventy of valvular regurgitation
- When there is severe, acute aortic regurgitation, the mitral valve should be sampled at the leaflet tips with PW Doppler and the deceleration time measured; < 150 msec with an increased E/A ratio indicates significant hemodynamic changes due to severe AR
- An abscess may cause an abnormal continuous flow pattern within the site
Important to Note
- Vegetation < 3 mm in size may not be detected by transthoracic echocardiography
- Vegetation > 1 cm may indicate a higher morbidity and mortality
- The absence of a vegetation by echocardiography does not rule out the diagnosis of infective endocarditis
- Transesophageal echocardiography may be the test of choice
- Infective endocarditis is often associated with patients who have pre-existing valve disease, e. g., mitral stenosis., mitral valveprolapse, bicuspid aortic valve
- The reason for infection is often evident (e.g. dental, surgical, traumatic)