Infective Endocarditis

Infective Endocarditis (IE) is a condition that is characterized by inflammations of the inner lining of the heart. Read on to find out more about the types, causes, symptoms, diagnosis and treatment of this disease.

Infective Endocarditis Definition

It can be defined as a form of inflammation or Endocarditis that affects the inner tissue or the inner lining of the heart and the valves. It is caused by several infectious agents such as bacteria, fungi and other forms of microbes. Infectious agents attack the heart and valves by entering through the blood stream. It leads to scarring of valve tissue and development of holes or growths on the valves. Without proper treatment, the disorder can prove to be fatal.

The condition is sometimes also referred to as Bacterial Endocarditis.

Infective Endocarditis Types

The disease can be classified into two types, depending on the severity of the disease and its rate of progression:

Acute Infective Endocarditis

Also referred to as Acute Bacterial Endocarditis, it is most likely caused by Staphylococcus aureus and is characterized by fulminant illness that continues for days and weeks. Staphylococcus aureus has a great virulence than streptococci and is often responsible for metastatic infection.

Subacute Infective Endocarditis

It is mainly caused by streptococci that have a low virulence. It is characterized by moderate to mild illness that gradually progresses over several weeks and months with a low risk of hematogenous seeding of extracardiac sites.    Untreated patients having Subacute Infective Endocarditis tend to live longer than the untreated patients having Acute Infective Endocarditis.

The condition is also known as Subacute Bacterial Endocarditis.

Infective Endocarditis Causes

It normally results from blood infections. Bacteria and other infectious substances may enter bloodstream when certain medical procedures like dental procedures are being conducted. Dental procedures are also risky for children having congenital heart disorders. These bacteria can settle themselves on the damaged heart valves. They can grow and form infected clots which break off and deposit in the lungs, brain, spleen or kidneys.

The majority of people who have been affected by the disease get underlying heart diseases or valve problems.

An organism known as Streptococcus viridians which is usually found in the mouth is held responsible for nearly 50% of all infective endocarditis cases. It is due to this agent that dental procedures increase the chances for developing Infective Endocarditis.

Enterococcus and Staphylococcus aureus are two other well-known agents responsible for the development of the disease. Staphylococcus aureus infects the normal heart valves. Staphylococcus aureus is also held responsible for most cases of the condition among intravenous drug users.

Pseudomonas, candida and serratia are believed to cause Infective Endocarditis in some cases.

The following conditions of the heart may increase the possibility of being affected by Infective Endocarditis.

  • Heart valve problems like mitral insufficiency
  • History of rheumatic heart diseases
  • Congenital heart diseases, such as patent ductus arteriosus, atrial septal defect and others
  • Artificial heart valves

Intravenous drug users can also get affected by this disease as bacteria can enter the bloodstream through unsterilized needles. Other conditions that can lead to the development of the disorder include

  • Low white blood cell levels
  • Immunosuppression, or immunodeficiency
  • Diabetes
  • Malignancy
  • Alcohol abuse

Infective Endocarditis Risk Factors

Certain factors can aggravate the risk of developing the disease. These are listed below:

  • A previous case of infective endocarditis
  • Certain forms of congenital heart diseases
  • Usage of artificial or prosthetic heart valves, including homograft and bioprosthetic valves
  • Acquired valve diseases such as rheumatic heart disease
  • Heart valve diseases which develop after a heart transplantation operation
  • HCM or Hypertrophic cardiomyopathy
  • Patients having a prolapsed mitral valve, combined with valve leaking or regurgitation, and displaying thickened valve leaflets have a high risk of being affected by the disorder.

Infective Endocarditis Symptoms

The classic symptoms of this infectious disease are as follows:

  • Fever
  • Chills
  • Rigors
  • Nausea
  • Malaise
  • Diarrhea
  • Paleness
  • Joint pain
  • Weakness
  • Headaches
  • Night sweats
  • Nasal congestion
  • Shortness of breath
  • Muscle pains and aches
  • Endurance fatigue
  • Loss of weight
  • Roth’s spots
  • Murmur
  • Emboli
  • Anemia
  • Coughing
  • Osler’s nodes
  • Blood in urine
  • Renal infarcts
  • Splenomegaly
  • Splenic infarcts
  • Septic embolism
  • Janeway lesions
  • Glomerulonephritis
  • Abnormal urine color
  • Intracranial hemorrhage
  • Conjunctival hemorrhage
  • Swelling of abdomen, feet and legs
  • Splinter hemorrhages or Nail hemorrhages

Pathophysiology of Infective Endocarditis

Although not proven, it is assumed that the cardiac valves and the other endocardial surfaces get infected once they are exposed to microemboli from fungi and bacteria that circulate in the bloodstream. Streptococcus mutans, a Dextran-producing bacterium, have got a virulence factor which allows adherence to the endovascular surfaces. The Coagulase-negative bacterium called staphylococci produces a biofilm on the prosthetic surfaces that allows adherence.

The enteric gram-negative bacteria and beta-hemolytic streptococci lack the familiar adherence factors, and are considered to be less responsible for causing infectious endocarditis. The Endocardial surfaces that were previously damaged from surgery, endocarditis and valvular heart disease or pacemaker wires create a suitable environment for the growth of thrombus. The microorganisms proliferate in thrombus over the course of time and gives rise to a classic vegetation. The microorganisms generally enter regular blood circulation on a continual basis.

Infective Endocarditis Diagnosis

While diagnosing the disease, a doctor may listen to a number of abnormal sounds (known as murmurs) through a stethoscope. A physical examination may reveal an enlarged spleen and the presence of splinter hemorrhages in fingernails. An eye examination may show presence of Roth’s Spots. Various other tests may also be performed to diagnose the condition. These include:

  • Chest X-Ray
  • Echocardiogram
  • Transesophageal echocardiogram
  • Erythrocyte sedimentation rate or ESR
  • Blood work and sensitivity for detecting bacteria
  • A Computerized Tomography Scan of the chest of a patient
  • Complete blood count, which may show signs of mild anemia

The various signs and symptoms of this heart disorder are also taken into consideration while diagnosing the disease.

Duke Criteria for Infective Endocarditis

The Duke Criteria can be defined as a collection of several major and minor guidelines or criteria that are used to conclusively establish a proper diagnosis of this cardiac disorder. The criteria were first established in the year 1994 by Duke Endocarditis Service, which was later revised and updated in 2000. In order to establish a proper diagnosis of endocarditis, 2 major criteria, 1 major and 3 minor criteria or 5 minor criteria needs to be fulfilled.

Infective Endocarditis Prevention

Generally the patients who were thought to have a high risk of developing IE were all recommended to take antibiotics before any dental, urinary tract or gastrointestinal procedure as a precautionary measure. There has been a long debate over the usage of the antibiotic prophylaxis for the prevention of IE. Although some are of the opinion that only the patients having prosthetic valvular heart disorder or the patients undergoing gingival surgery or dental extractions who have a history of IE can only benefit from the antibiotic prophylaxis, others believe that the antibiotic prophylaxis can be used for preventing IE in all general cases.

Intravenous drug users are highly prone to be affected by infective endocarditis. Hence they should seek treatment for their addiction or at least try to use a fresh needle for every injection. They should also avoid sharing all injection-related paraphernalia as well as use alcohol pads for reducing risk of infection.

Infective Endocarditis Treatment

Once a patient is diagnosed with IE, he or she is admitted to the hospital for further treatment. Firstly, the specific bacteria or fungi responsible for causing IE are identified from blood tests. An intravenous antibiotic therapy course is then started which may go on for as much as 4 to 6 weeks which helps in controlling the infection. The antibiotic that is administered to the patient depends on the type of bacteria or fungi that caused IE. The symptoms are closely observed throughout the course of the therapy and regular blood work is conducted to study the effectiveness of the treatment procedures. Antibiotics are also to be administered before any surgical or dental procedure is carried through.

If damage has occurred in the heart valves, surgery may be needed to fix heart valves and normalize the functioning of the heart. Vegetative growth of the heart also requires surgical treatment. Prevention is required in order to ensure that the symptoms of IE do not get aggravated and no seriously adverse conditions or death may affect the individual patient.

Infective Endocarditis Complications

The possible complications from Infective Endocarditis include the following:

  • Strokes
  • Jaundice
  • Brain abscess
  • Splenic abscess
  • Glomerulonephritis
  • Neurological changes
  • Congestive heart failure
  • Severe damage of the valves
  • Periannular extension of infection
  • Irregular or rapid heartbeats and atrial fibrillation
  • Formation of emboli or blood clots that travel to the brain, lungs, kidneys or abdomen

Infective Endocarditis Prognosis

An early diagnosis and treatment of the disease normally has a favorable outcome. The heart valves may get damaged if the treatment does not occur on time. Neurological complications may be seen in many patients and are needed to be dealt with differently. Before the era of antibiotics, death was common with patients having IE. The main cause of death was congestive heart failure. However with proper usage of antibiotics, the instances of death by IE have been reduced to around 20% to 25%.

Infective Endocarditis Pictures

Here are some pictures that illustrate how a heart affected by this disease looks like.

Picture of Infective Endocarditis

Picture 1 – Infective Endocarditis

Image of Infective Endocarditis

Picture 2 – Infective Endocarditis

Infective Endocarditis is an infection of the inner lining of the heart and its valves which if left untreated, may give rise to serious complications or even death. However, timely diagnosis and treatment allows the patient to lead a long and healthy life in most cases.

References:

http://www.nlm.nih.gov/medlineplus/ency/article/000681.htm

http://my.clevelandclinic.org/heart/disorders/valve/sbe.aspx

http://www.texasheartinstitute.org/HIC/Topics/cond/endocard.cfm

http://www.escardio.org/guidelines-surveys/esc-guidelines/Pages/infective-endocarditis.aspx

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