Images of Note: In Infective Endocarditis, Not All Organisms Destroy Equally

The organisms causing infective endocarditis are not equally destructive or invasive, as made clear by the four images above.

The explanted tissue valve in Panel 1 was infected with a less-aggressive organism such as an Enterococcus species. Such organisms are generally minimally invasive, causing formation of small vegetations, with recurrent episodes of sepsis.

In contrast, aggressive organisms, such as Staphylococcus aureus, can cause rapid, extensive tissue destruction, usually within a few weeks, with formation of large vegetations. Panels 2 to 4 show a tissue valve (2) and a mechanical valve (3) infected by S. aureus and extensive tissue destruction with aortic root abscess (4) caused by S. aureus prosthetic valve endocarditis.

Additional revealing image series are available in the atlas of infective endocarditis published in the April 2014 Journal of Thoracic and Cardiovascular Surgery by Cleveland Clinic cardiothoracic surgeons Gösta Pettersson, MD, PhD, and Syed Hussain, MD, and detailed here on Consult QD.

“The atlas presents major concepts that collectively describe the main features and basic facts about endocarditis every surgeon needs to know,” Dr. Pettersson says.

The concepts are:

1. Vegetations in endothelial defects or injuries are the primary manifestations of IE.
2. Extra-aortic invasion of native valve endocarditis is localized.
3. Extra-aortic invasion of prosthetic valves is often circumferential.
4. Heart block is caused by bacterial destruction of the atrioventricular node and bundle of His.
5. All organisms are not equally destructive.
6. Congenital heart defects, repaired or not, are associated with increased risk of endocarditis.
7. Mitral valve endocarditis has specific features related to its anatomy and degenerative pathologic features.
8. Right-sided IE is characterized by vegetations and disintegration of valve leaflets or cusps, but almost never by invasion.
9. Complete debridement is the basic principle of successful reconstructive surgery for invasive IE.

Contact Dr. Pettersson at petterg@ccf.org and Dr. Hussain at hussais2@ccf.org.