Non-bacterial thrombotic endocarditis
Medikoe Health Expert
Koramangala, bengaluru, karnataka, india, Bengaluru Feb 9, 2017
Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves.
There are several ways to classify endocarditis. The simplest classification is based on types of endocarditis: either infective or non-infective, depending on whether a microorganism is the source of the inflammation or not.
Infective endocarditis: It is an infection of the inner surface of the heart, usually the valves. Symptoms may include fever, small areas of bleeding into the skin, heart murmur, feeling tired, and low red blood cells. The cause is typically a bacterial infection and less commonly a fungal infection. The bacteria most commonly involved are streptococci or staphylococci. Diagnosis is suspected based on symptoms and supported by blood cultures or ultrasound. The usefulness of antibiotics following dental procedures for prevention is unclear. Some recommend them in those at high risk. Occasionally heart surgery may be required. Males are affected more often than females. The risk of death among those infected is about 25%. Without treatment, it is almost universally fatal.
Non-infective endocarditis: It is a form of endocarditis in which small sterile vegetations are deposited on the valve leaflets. Formerly known as asmarantic endocarditis, which comes from the Greek marantikos, meaning “wasting away.” The term nonbacterial thrombotic endocarditis (NBTE), or marantic endocarditis, refers to a spectrum of lesions ranging from microscopic aggregates of platelets to large vegetations on previously undamaged heart valves (most often aortic and mitral) in the absence of a bloodstream bacterial infection. NBTE is a rare condition that refers to a spectrum of noninfectious lesions of the heart valves that is most commonly seen in advanced malignancy. The term "marantic endocarditis" is still sometimes used to emphasize the association with a wasting state such as cancer. It is a non-infectious process affecting normal or degenerative cardiac valves that is due to fibrin thrombi deposits in patients with hypercoagulable states associated with adenocarcinomas of the lung, colon, or pancreas that produce mucin.
The exact pathogenesis of NBTE is not known, but the thrombi form on sites of minute mechanical injuries of the endothelium. Such injuries occur normally but are repaired by endothelial regeneration. In debilitated people (e.g., those who have terminal cancer or chronic infection), normal repair mechanisms are defective, and the endothelial defect is filled in with platelets and fibrin. Nonbacterial thrombotic endocarditis (NBTE) is a common cause of thrombotic and embolic ischemic stroke related to systemic thrombotic coagulopathy and sterile cardiac valve vegetations.
Libman Sacks endocarditis is a noninfectious valvular abnormality associated with autoimmune disorders such as systemic lupus erythematosus and the antiphospholipid antibody syndrome. It is defined as sterile, verrucous, atypical valvular lesions associated with SLE and antiphospholipid syndrome.
Marantic vegetations are often associated with previous rheumatic fever.
Other risk factors include:
- Hypercoagulable states
- Malignant cancers, especially mucin-producing adenocarcinomas (most commonly associated with pancreatic adenocarcinomas)
- Systemic lupus erythematosus: Referred to as Libman-Sacks endocarditis
- Trauma (e.g., catheters)
- Blood cultures
Non-infective endocarditis should be suspected when chronically ill patients develop symptoms suggesting arterial embolism. Serial blood cultures and echocardiography should be done. Echocardiography may be used to further assess for valvular lesions. Due to the non-invasive nature of NBTE, clinical examination may or may not reveal a new murmur. An embolic stroke may be the first feature to suggest the diagnosis of NBTE.
Anticoagulation: Treatment consists of anticoagulation with heparin (either intravenous unfractionated or subcutaneous low molecular weight). New oral anticoagulants (NOACs) and warfarin are not regarded as effective, although no comparative trials have been undertaken in this rare condition. Predisposing disorders should be treated whenever possible.
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