infective endocarditis



Overview

Definition

Infective endocarditis is an inflammatory disease caused by infection of the endocardial surface of the heart by pathogenic microorganisms such as bacteria and fungi, with the heart valves being the most commonly affected area, often accompanied by the formation of redundant organisms.

Classification

Infective endocarditis is categorized into the following 2 groups according to the course of the disease.

Acute infective endocarditis: the disease lasts for a few days to a few weeks, with obvious symptoms, mostly due to Staphylococcus aureus infection.

Subacute infective endocarditis: the disease lasts from a few weeks to a few months, with mild symptoms, mostly due to Streptococcus oxysporus infection.

Pathogenesis

There is a lack of authoritative epidemiologic data on infective endocarditis in China, and the annual incidence in Europe is (3-10)/100,000 people, with a male-to-female ratio of ≥2:1.

The proportion of infective endocarditis due to rheumatic valve disease has decreased in recent years, while the incidence of infective endocarditis due to prosthetic valve replacement, transvenous drug use, cardiac catheterization, and interventional therapy has increased.

Causes

Causes

Infective endocarditis is mainly caused by pathogenic microorganisms directly attacking the endocardium through the bloodstream pathway. Bacteria (streptococcus, staphylococcus, etc.) are the most common, but can also be caused by fungi, viruses, rickettsiae, chlamydiae, and leptospires.

Predisposing factors

Organic cardiovascular disease

Infective endocarditis mostly suffers from organic heart disease, such as heart valve disease, rheumatic valve disease, ventricular septal defect, arterial catheterization, tetralogy of Fallot and so on.

Medical factors

Prosthetic valve replacement, cardiac catheterization, interventional therapy, tonsil removal, tooth extraction and other operations can easily lead to pathogenic bacteria into the blood circulation and cause disease.

Other factors

Long-term use of antimicrobial drugs, glucocorticoids and immunosuppressants may also increase the risk of pathogenic microbial infection.

Pathogenesis

Normal heart lining can resist the adhesion of pathogenic microorganisms in the blood circulation and prevent the formation of infection. The above predisposing factors can cause different degrees of cardiac damage and increase the risk of pathogenic microbial infection by the following mechanisms.

Acute infective endocarditis

The pathogenesis is not clear, but may be due to the large amount of pathogenic microorganisms in the blood circulation and the high virulence of pathogenic microorganisms, which are highly invasive and have the ability to adhere to the cardiac endocardium, thus causing the disease.

Subacute infective endocarditis

Organic cardiovascular diseases may cause localized damage to the endocardium, which facilitates the aggregation of platelets and fibrin on the endocardium and the formation of sterile organisms.

Infective endocarditis can occur when pathogenic microorganisms invade the blood circulation when the body’s defenses are low or when operations such as prosthetic valve replacement, cardiac catheterization, or interventional therapy are performed, and when pathogenic microorganisms settle on the sterile organisms.

Symptoms

Main symptoms

Clinical manifestations of infective endocarditis vary greatly, and the main manifestations are as follows.

Fever is the most common symptom, usually with a temperature > 38°C. Fever may be absent in advanced age, after antibiotic treatment, immunosuppressed state, weak virulence of pathogens, or atypical patients.

It may be accompanied by general malaise, malaise, headache, muscle and joint pain, lack of appetite and weight loss.

Other symptoms

Other systemic symptoms may be seen, but they have become rare in recent years, as follows.

Petechiae: red or dark red colored spots appear on the oral mucosa, trunk and skin of the limbs.

Linear red lines appear under the finger (toe) nails, which are caused by microvascular hemorrhage.

Janeway’s spots: erythema or hemorrhagic petechiae without tenderness on the palms of the hands and soles of the feet.

Osler’s nodules: painful pea-sized red or purple nodules on the pads of the fingers (toes).

Complications

Acute left heart failure

Acute left heart failure can be induced by acute valve closure insufficiency due to valve perforation or tendon cable rupture.

The main manifestations are sudden dyspnea, purple lips, face, and finger (toe) ends, pink foamy sputum, blurred consciousness or coma.

Myocardial abscess

Commonly seen in acute patients, mainly due to the spread of infection to neighboring tissues, with perivalvular tissues, especially in the aortic annulus, which can lead to atrioventricular and intraventricular conduction block.

The main manifestations are fatigue, weakness, dizziness and angina pectoris.

Acute myocardial infarction

It is caused by the detachment of debris from the cumbersome organisms and the formation of embolus to block the coronary artery, resulting in necrosis of myocardial cells due to ischemia and hypoxia, and it is more common in the case of infection of the aortic valve.

The main manifestations are chest pressure, chest pain, shortness of breath, fatigue, etc., which can be life-threatening in severe cases.

Bacterial aneurysm

Bacterial aneurysm is mostly seen in subacute patients, mainly caused by infectious organisms spreading to other parts of the body with blood circulation and eroding the arterial wall.

The affected arteries are the proximal aorta (including the aortic sinus), brain, visceral and limb arteries in that order, which are usually seen in the late stage of the disease, and most of them are asymptomatic.

Renal or splenic infarction

It is caused by dislodgment of fragments of the organism to form emboli that occlude the renal arteries, resulting in localized ischemic necrosis of the kidney.

Renal infarction is mainly characterized by sudden back pain and hematuria of the naked eye.

Splenic infarction may be asymptomatic or present with gastrointestinal symptoms such as abdominal pain and nausea.

Cerebral infarction

Cerebral infarction is caused by the dislodgement of fragments of the cerebral organisms and the formation of emboli that block the cerebral arteries, resulting in ischemia and hypoxic necrosis of the local brain tissues.

Symptoms such as hemiplegia, hemianopsia, speech impairment, dysphagia, memory impairment and dizziness are common.

Consultation

Department of Medicine

Cardiovascular Medicine

If symptoms such as fever, fatigue, headache, muscle and joint pain, lack of appetite occur, it is recommended to consult the Department of Cardiovascular Medicine promptly.

Emergency Department

If you experience severe chest pain or difficulty in breathing, we recommend that you consult the Emergency Department or call the “120” emergency number as soon as possible.

Preparation

Consultation: Registration, Preparation of Information, Frequently Asked Questions

Tips for Medical Treatment: Do not abuse drugs without your doctor’s permission.

Do not abuse drugs without the doctor’s permission, so as to prevent the drugs from affecting the relevant examinations and interfering with the diagnosis and treatment of the disease.

Preparation List

Symptom list

Pay special attention to the time of onset of symptoms, special manifestations, etc.

Have you had fever recently? When did it occur? How long has it lasted?

Is it accompanied by general malaise, fatigue, headache, muscle and joint pain, lack of appetite?

Are there any symptoms of chest tightness or precordial pain?

Medical History Checklist

Any previous heart disease such as heart valve disease, rheumatic valve disease, ventricular septal defect, patent ductus arteriosus, tetralogy of Fallot, etc.?

Any previous prosthetic valve replacement, cardiac catheterization, interventional procedures, tonsillectomy or tooth extraction?

Have you been taking certain medications, such as antibiotics, glucocorticoids, etc. for a long time? How long have you been taking them?

Checklist

Test results of the last 3 months, which can be brought to the doctor’s office

Laboratory tests: blood count, erythrocyte sedimentation rate, blood culture

Imaging tests: echocardiogram

Medication list

Medication used in the last 3 months, if available in boxes or packages, bring along with you to the doctor’s office

Glucocorticoids: dexamethasone, hydrocortisone, etc.

Antibacterial drugs: amoxicillin, ampicillin, gentamicin, etc.

Diagnosis

Diagnosis is based on

Medical history

History of heart valve disease, rheumatic valve disease, ventricular septal defect, patent ductus arteriosus, tetralogy of Fallot.

History of surgical procedures such as prosthetic valve replacement, tonsillectomy, tooth extraction, etc.

History of cardiac catheterization or interventional therapy.

History of long-term use of antibacterial drugs, glucocorticoids and other medications.

Clinical manifestations

Fever is the most common symptom, which may be accompanied by general malaise, malaise, headache, muscle and joint pain, lack of appetite and weight loss.

A heart murmur can be heard in 85% of patients.

Laboratory Tests

Blood counts

Acute patients often have an elevated white blood cell count.

In subacute cases, the white blood cell count is normal or mildly elevated.

Erythrocyte sedimentation rate

Almost always elevated in all patients.

Blood Culture

Important in the diagnosis of infective endocarditis, helps to identify the causative organism and is the basis for drug sensitivity testing.

The positive rate can be over 95% in patients who have not been recently treated with antimicrobial drugs. Antibiotics within 2 weeks or improper blood collection and culture techniques often reduce the positive rate of blood cultures.

Echocardiography

A noninvasive method used to examine the anatomy and functional status of the heart and great vessels.

The examination reveals oscillating or non-oscillating masses (redundant organisms) with enhanced echogenicity, intracardiac (perivalvular) abscesses, new partial dehiscence of prosthetic valves or intracardiac repair materials, and valve perforation.

Others

X-rays, CT angiography, CT, magnetic resonance imaging (MRI), and PET/CT are helpful in clarifying the diagnosis of the primary cause or complication.

Diagnostic criteria

The clinical presentation of infective endocarditis lacks specificity, and echocardiography and blood culture are the two cornerstones of diagnosis. The Duke Diagnostic Criteria for Infective Endocarditis (2015 Revision) are often applied for diagnosis.

Main criteria

Positive blood culture

At least one of the following criteria is met.

Two blood cultures at different times detect the same typical infective endocarditis-causing organism (e.g., Streptococcus, Staphylococcus aureus, Streptococcus grasshopperi, community-acquired enterococci).

Multiple blood cultures detecting the same infective endocarditis-causing organism.

2 positive blood cultures at least 12 hours apart.

All 3 positive blood cultures or most of ≥4 positive blood cultures (≥1 hour between first and last blood draw).

1 positive blood culture for Q fever pathogen or its IgG antibody potency > 1:800.

Positive imaging evidence

Meets at least one of the following criteria.

Echocardiographic abnormalities: redundant organisms; abscesses, pseudoaneurysms, intracardiac fistulas; valve perforations or aneurysms; new partial rupture of prosthetic valves.

Abnormal tissue activity around the prosthetic valve implantation site detected by 18F-FDG PET/CT (only if prosthesis implanted >3 months) or radiolabeled leukocytes SPELT/CT.

Perivalvular lesions as determined by cardiac CT.

Secondary criteria

Predisposing factors: the presence of predisposing factors in the heart itself, or intravenous drug addiction.

Fever: Temperature > 38°C.

Vascular signs (including those detected only by imaging): major arterial embolism, infected pulmonary infarction, bacterial aneurysm, intracranial hemorrhage, conjunctival hemorrhage, and Janeway damage.

Immunologic signs: glomerulonephritis, Osler nodules, Roth spots, and positive rheumatoid factor.

Evidence of pathogenic microbial infection: positive blood cultures that do not meet the major criteria, or serologic evidence of active pathogenic microbial infection consistent with infective endocarditis.

Diagnostic Criteria

Confirmed: fulfillment of 2 major criteria, or 1 major and 3 minor criteria, or 5 minor criteria.

Suspected: fulfillment of 1 major and 1 minor criterion, or 3 minor criteria.

Differential Diagnosis

The clinical manifestations of this disease are mainly characterized by fever, which lacks specificity, and there are many diseases that need to be differentiated from it, examples are as follows.

Acute rheumatic fever

Rheumatic fever is a systemic connective tissue inflammatory disease caused by throat infection with group A beta-hemolytic streptococcus.

Typical symptoms are fever, joint swelling and pain, shortness of breath, rash, subcutaneous nodules, and chorea. Combination of blood culture, throat swab culture, immunologic examination, etc. helps in differential diagnosis.

Systemic lupus erythematosus

The main manifestations are erythema distributed in a butterfly shape on the bridge of the nose and cheeks of both cheeks, fever, joint swelling and pain, muscle pain, and malaise.

The combination of medical history, blood culture, immunologic examination, magnetic resonance imaging, CT, etc. helps in differential diagnosis.

Mucinous tumor

A common benign cardiac tumor, the tumor occurs in the subendocardium and 90% grows in the atria, mostly the left atrium.

It mostly manifests as panic, fever, malaise, weight loss, and arthralgia.

The combination of medical history, blood culture, echocardiography, etc. can help in differential diagnosis.

Tuberculosis

Tuberculosis is a chronic infectious disease caused by Mycobacterium tuberculosis, which can invade many organs of the body, and pulmonary tuberculosis is the most common.

The most common form of TB is pulmonary tuberculosis. There may be systemic symptoms such as prolonged low-grade fever, lethargy and night sweats. The main manifestations of pulmonary tuberculosis are coughing, coughing up sputum, hemoptysis, and shortness of breath.

The combination of medical history, blood culture, sputum mycobacterium tuberculosis test, tuberculin test, X-ray examination, etc. will help in differential diagnosis.

Treatment

Treatment purpose:  control the progression of the disease, prevent and control heart failure, arrhythmia, embolism and other complications, save the patient’s life and improve the patient’s quality of life.

Treatment principle: antibiotics should be applied as early as possible to fight infection, and surgery should be performed if necessary.

Drug treatment

The most common pathogenic microorganisms of infective endocarditis are bacteria, and this article mainly introduces the anti-infective drug treatment for those caused by bacteria.

Principles of medication

Early application of antibacterial drugs, adequate amount, high dose, long course of treatment, in order to completely eliminate the pathogenic bacteria hidden in the redundant organisms, the combined application of antibacterial drugs can play a rapid bactericidal effect.

Intravenous drugs are mainly used to maintain high and stable blood concentration.

When the pathogenic microorganisms are unknown, acute patients can use broad-spectrum antibacterial drugs that are effective against Staphylococcus aureus, Streptococcus aureus and gram-negative bacilli; subacute patients can use antimicrobial drugs against most Streptococcus aureus (including enterococci).

When the pathogenic microorganisms have been identified, anti-microbial drugs should be selected according to the sensitivity of the pathogenic microorganisms to the drugs.

Commonly used drugs

Doctors will choose anti-infective drugs based on experience or drug sensitivity tests. Individualized treatment regimens are chosen based on the specific condition, drug effectiveness, and other considerations.

Commonly used drugs include amoxicillin, ampicillin, gentamicin, penicillin sodium, meropenem and so on.

Precautions

During drug treatment, you should adhere to the strict accordance with the doctor’s instructions, do not change the dose of drugs without authorization or suddenly stop the drug, to ensure that the treatment plan is implemented.

Those who are allergic to penicillin antibiotics may also be allergic to cephalosporin and carbapenem antibiotics, and should use the medication cautiously under the guidance of a physician.

Surgery

Determining the timing of surgery requires balancing the urgency of surgical indications, surgical risk factors, and relative contraindications; patients with complications who have indications for surgery and acceptable surgical risk should be operated on as early as possible.

Infective endocarditis causing valvular dysfunction leading to acute heart failure is recommended to be treated early (before completion of a standardized course of antibiotic therapy) or as an emergency limited-duration procedure (in the shortest possible time, not exceeding 48 hours).

Early surgery is recommended for concomitant perivalvular infections leading to abscesses in the annulus or aortic root, destructive penetrating lesions of the blood vessels and/or myocardium, and emerging atrioventricular block.

Early surgery is recommended for those caused by Staphylococcus aureus, fungi, or highly drug-resistant bacteria.

Infections that cannot be controlled, i.e., persistent bacteremia or hyperthermia with application of regular antimicrobial drugs for more than 5 to 7 days, early surgery is recommended.

Surgery for prosthetic valve endocarditis requires removal of all infected foreign bodies, including the initially implanted prosthetic valve as well as calcified tissue left over from previous surgeries.

Early surgery is recommended for right heart valve infective endocarditis with significant valvular dysfunction, or right heart failure secondary to tricuspid regurgitation with poor diuresis, the presence of large redundant organisms (>10 mm), persistent bacteremia or fever for more than 5 to 7 days despite standardized antibiotic therapy, or manifestations of septic pulmonary embolism.

Prognosis

Cure

Infective endocarditis has a high mortality rate and poor prognosis.

With rational treatment, the mortality rate can be effectively reduced, and some patients may recur.

Hazards

Infective endocarditis can cause fever, generalized weakness, muscle pain and other symptoms, which affects patients’ work, study and life.

If infective endocarditis is not treated in time, serious complications such as acute myocardial infarction, cerebral infarction and acute left heart failure may occur, which may be life-threatening in severe cases.

Daily

Daily Management

Dietary management

Eat small and frequent meals, and each meal should not be too full.

The principle of diet is light and easy to digest, you can eat more green vegetables and fresh fruits.

If combined with heart failure, also need to reduce the input of salt, avoid eating pickled and processed food, follow the doctor’s advice to control the amount of water.

Avoid cholesterol-rich foods such as fatty meat and animal offal.

Avoid drinks such as coffee and strong tea.

Abstain from alcohol.

Life management

Patients with high fever should rest in bed, and clothes and blankets soaked by sweat should be changed in time.

Ensure sufficient sleep and avoid exertion.

Maintain oral hygiene, brush teeth in the morning and evening and after meals.

Pay attention to the change of climate and season, increase or decrease clothing appropriately, prevent cold and flu, and avoid crowded places as much as possible.

Under the premise of cardiac function, exercise appropriately, do not do strenuous exercise.

Psychological support

Facing the disease with a positive and optimistic mindset, and building up confidence in overcoming the disease.

Talk to your family and friends about your inner feelings.

Family members should give sufficient care and comfort, and say more positive and encouraging words.

Prevention

Regular physical examination and active treatment of heart valve disease, rheumatic valve disease, ventricular septal defect and other primary diseases.

Maintain good oral hygiene habits and skin cleanliness.

Perform tooth extraction or other invasive operations in regular hospitals.

For high-risk infective endocarditis patients with pre-existing heart disease, antibacterial drugs can be applied prophylactically and in accordance with medical advice during invasive operations.