Subacute Bacterial Endocarditis

Subacute bacterial endocarditis (SBE)is an inflammation of the inner lining of the heart or endocardium. Acute endocarditis may be classified into simple or benign and ulcerative or malignant. Bacterial endocarditis is identified as a subacute pathologic condition.

Etiology. SBE is caused by engraftment of Streptococcus viridans on a valve already damaged by rheumatic infection. S. viridans causes great damage to the heart valves producing lesions called vegetations. These vegetations may break off into the bloodstream as emboli (floating clots or thrombi).

Signs and symptoms. The symptoms of SBE are similar to those of any infection but are less severe than an acute endocarditis.

SBE is characterized by fever of varying grades. Sometimes it none at all, sometimes with wide daily amplitude e.g., fever may be normal or subnormal in the mornings and elevated (up to 40 º C) in the evenings. Usually fever is recurrent and followed by chills and sweats.

SBE is accompanied by anorexia, malaise, prostration, weight and strength loss, though at the onset the patient may experience a feeling of fatigue with little fever.

In SBE the emboli may lodge in the brain arteries resulting in ischemia and paralysis. Emboli may appear in the kidney and cause hematuria. Emboli may be accumulated in the dermal small vessels forming multiple pinpoint hemorrhages known as petechiae. When embolism starts resulting from clots in the heart, local pain and other symptoms appear depending upon the organ or body part affected. Splenic, renal and cerebral infarctions are common. With increasing anemia there may be bleedings from the nose, lungs and stomach.

When the process of healing of valvular lesions occurs, scar tissue in the valve leaflets contracts and insufficiency of the valves develops. The degree of functional valve impairment depends on the severity of endocardial lesion.

Examination Techniques. A history of rheumatic fever is of diagnostic value. On auscultation a soft blowing murmur over the valve area is heard. As the mitral valve is most commonly involved, a soft systolic mitral murmur is present. A murmur alone must not be taken as positive evidence of SBE because in any acute febrile disease, a systolic murmur may be caused by the developed cardiac dilatation. However, a murmur occuring with a rise in fever and an increase of leukocytes are proved to be of endocarditic origin.

Treatment. Treatment of SBE is always conservative. Conventional antibiotic therapy is effective in curing this pathologic condition. Bed regimen, rest, balanced diet and proper nursing will lead to cure.

Complications. In cases when inflammatory valve lesion fails to heal during the usual period of a few months, SBE is followed by increasing toxic state of a patient. Finally, with an increase of toxic state, weakness and mental confusion may become marked and complicated by concomitant acute myocarditis, dyspnea and hepatic pains.

Дата добавления: 2015-11-14