Intoxication syndrome
The clinical presentation of infective endocarditis traditionally manifests with a pronounced intoxication syndrome. These are subjective and objective signs of an active infectious process that often prompt the patient to seek medical attention.
- Classic triad: Hectic fever (often up to 38–39 °C), which is accompanied by severe chills and profuse night sweats.
- General asthenia: Patients complain of increased fatigue, loss of appetite (anorexia), and a noticeable decrease in body weight.
Important nuance: In individuals with implanted prosthetic heart valves, fever may be the only symptom of developing inflammation.
Cardiac manifestations: valve and myocardial involvement
The leading syndrome in this disease is the destruction of the valve apparatus. The infection destroys the cusps, leading to severe hemodynamic disorders.
Auscultatory findings The main diagnostic criterion is the appearance of new heart murmurs or a change in the character and timbre of existing ones (which is especially relevant in secondary endocarditis against the background of an old rheumatic mitral valve disease). Changes in the auscultatory picture occur rapidly: within a few weeks, less commonly months.
In approximately one-third of patients, the aortic valve is affected in isolation. In this case, aortic regurgitation develops:
- A diastolic murmur is auscultated.
- The point of maximum auscultation is Botkin-Erb's point (to the left of the sternum in the 3rd–4th intercostal space).
- Characteristic hemodynamics with a high pulse pressure (e.g., BP 160/30 mmHg) are formed.
Myocardium and complications Infection rarely limits itself solely to the endocardium. The process can spread to the heart muscle and pericardium, causing myocarditis and pericarditis. This leads to progressive heart failure. The development of arrhythmias (especially AV conduction disturbances) is also characteristic. Myocardial infarction is less common, with a mechanism related to thrombosis or thromboembolism of the coronary arteries.
Extracardiac manifestations: skin, blood vessels, and target organs
Infective endocarditis is a systemic process. Symptoms extend far beyond the chest due to immune reactions and microbial embolism.
Skin and mucous membranes
- “Coffee with milk” color: Paleness with an earthy tint, arising due to a combination of anemia and severe intoxication.
- Petechial rash: A manifestation of hemorrhagic vasculitis or microembolism.
- Lukin's spots: Small petechiae on the conjunctiva (in the area of the lower conjunctival fornix).
- Osler's nodes: Painful reddish inflammatory infiltrates in the skin and subcutaneous tissue, a consequence of microbial embolism.
- Rumpel-Leede sign (endothelial sign): The appearance of fresh petechiae after applying a sphygmomanometer cuff.
With a prolonged disease course (chronic hypoxia), the fingers acquire a “clubbing” appearance, and the nails resemble “watch glasses”.
Renal involvement Occurs in half of patients and presents in two forms:
- Immune complex glomerulonephritis: Manifests with urinary syndrome, proteinuria, and moderate arterial hypertension. Rarely, it may be complicated by nephrotic syndrome or rapidly progress to chronic renal failure.
- Renal infarction: The result of thromboembolism. Manifests with sharp lower back pain and hematuria.
Thromboembolic syndrome and blood vessels Infection affects the blood vessels of the arteries themselves (vasa vasorum), leading to inflammation, aneurysm formation, and a high risk of thrombosis (especially in the limbs). The detachment of vegetations from the valves causes infarctions of internal organs: the spleen (with the development of splenomegaly), the brain, the lungs, and the abdominal cavity.
Briefly: answers to topical questions
What Duke major and minor criteria are used to confirm the diagnosis of infective endocarditis?
To establish the diagnosis, the integrated criteria of the Duke University Endocarditis Service are used.
- Major criteria — proven bacteremia (isolation of the pathogen from the blood) and echocardiographic signs of endocardial involvement (vegetations).
- Minor criteria — multiple clinical and laboratory signs.
The diagnosis is verified based on a specific combination of major and minor criteria.
Which microorganisms are the most frequent causative agents of infective endocarditis?
The most frequent causative agents of infective endocarditis are streptococci and staphylococci; the etiological structure depends on the form of the disease and the economic status of the country.
- Viridans streptococci (Streptococcus viridans) — the most frequent causative agent (more than 50% of cases), typical for secondary endocarditis.
- Staphylococci (Staphylococcus aureus, Staphylococcus epidermidis) — cause 10–20% of cases and are the most common cause of primary endocarditis.
- In developing countries, streptococcal etiology predominates; in developed countries, there is an increase in staphylococcal and enterococcal infective endocarditis.
- In intravenous drug users, Staphylococcus aureus is the primary causative agent — 60% of cases.
What changes in the complete blood count and blood biochemistry are typical for infective endocarditis?
According to the cited sources, the following laboratory data and mandatory examination parameters are indicated for infective endocarditis.
- Complete blood count — a general (clinical) blood count is performed; in the clinical example of infective endocarditis, anemia with a drop in Hb to 80 g/L was noted.
- Blood biochemistry — the mandatory list of parameters includes blood creatinine levels, serum C-reactive protein (CRP) levels, and the activity of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in the blood.
Typical changes in these biochemical parameters are not specified in the sources.
Clinical rule: in any fever of unknown origin (FUO), a thorough auscultation of Botkin-Erb's point is mandatory to search for a diastolic murmur.
Class and exam questions
The difficulty lies in the fact that against the background of pre-existing old heart valve diseases (and existing murmurs), catching changes in the auscultatory picture is extremely difficult. The physician has to rely on a combination of fever and echocardiography data.
The difficulty lies in the fact that against the background of pre-existing old heart valve diseases (and existing murmurs), catching changes in the auscultatory picture is extremely difficult. The physician has to rely on a combination of fever and echocardiography data.
What are Osler's nodes?
This is a specific extracardiac symptom: painful reddish indurations that appear in the skin or subcutaneous tissue. They form as inflammatory infiltrates in response to microbial embolism of small vessels.
Why do lower back pain and hematuria occur in endocarditis?
Such a clinical picture is typical for an embolic renal infarction — a formidable complication of the disease. In the presence of such symptoms, infectious valve involvement must always be ruled out.
What else to study on this topic
- Laboratory markers: bacteremia, blood cultures, and anemia
- Echocardiography (EchoCG): visualization of valvular vegetations
- Combination antibiotic therapy (penicillin and gentamicin)
- Pathogenesis of systemic thromboembolism formation
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