Dangerous Heart Valve Infection

Endocarditis diagnosed with imaging probe

(RxWiki News) Patients that develop a dangerous heart valve infection may be difficult to diagnose. It requires lengthy treatment and can even be deadly if not detected early.

A new imaging probe still being tested may make it possible to accurately diagnose an infection of the tissue lining the heart valves, called endocarditis. Endocarditis caused by S. aureus, better known for causing Staph infections, is the most deadly with up to half of all cases resulting in death.

"Ask about a blood test to check for endocarditis."

Dr. Matthias Nahrendorf, a co-author of the study from the Massachusetts General Hospital Center for Systems Biology and assistant professor of radiology at Harvard Medical School, said the probe was able to determine whether Staphylococcus aureus was present in abnormal growths that hinder the normal function of heart valves.

He noted that it has been exceptionally difficult to identify the bacteria involved in endocarditis, but a precise diagnosis is important for well-adjusted antibiotic therapy.

Diagnosing endocarditis caused by S. aureus can be difficult because symptoms such as fever and heart murmur seem vague, and blood tests do not always detect the bacteria. The heart valve infection can progress rapidly to damaging or destroying heart valves without appropriate antibiotic treatment.

Initial experiments in mice confirmed that optical imaging technology could detect a fluorescence-labeled version of prothombin, a protein involved in the process that usually conceals infecting bacteria from the immune system. The labeling allowed the protein to be detected.

Researchers then found S. aureus in a mouse model through use of a PET scan with the previously labeled  version of the protein involved in the process.

Following development and U.S. Food and Drug Administration approval, researchers said combined PET-CT imaging could be used to detect the bacteria in humans. Researchers are currently improving the technology for eventual testing in patients.

Dr. Nahrendorf said that in addition to detecting endocarditis, such imaging testing could determine infection severity and whether it was caused by S. aureus. They also could the imaging to track the effectiveness of antibiotics or other treatments.

The research was published in Nature Medicine.

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Review Date: 
August 25, 2011