Infective Endocarditis
Infective Endocarditis
LHoward
Introduction:
What Is Infective Endocarditis?
Infective endocarditis also referred to as IE, is an inflammatory disease in which the heart muscle, valves, and the lining of the heart chambers are affected. This inflammation may lead to valvular insufficiency which can progress to congestive heart failure and myocardial abscesses. Endocarditis can be broken down into categories. These categories are…
- Native Valve Endocarditis (NVE)-acute and subacute
- Prosthetic Valve Endocarditis (PVE)- early and late
- Intravenous Drug Abuse (IVDA) Endocarditis. Acute NVE
- Pacemaker IE
Native Valve Endocarditis (NVE)
Acute NVE
- Usually has an aggressive course
- Frequently involves normal valves
- Illness progresses rapidly in healthy and debilitated person
Subacte NVE
- Usually has a more indolent course that may extend over many months
- Frequently involves abnormal valves
Prosthetic Valve Endocarditis (PVE)
- Accounts for 10-20% of infective endocarditis cases
Early PVE
- Occurs within 60 days of valve implantation
Late PVE
- Occurs 60 days or more after valve implantation
Intravenous Drug Abuse Endocarditis (IVDA)
- No underlying valvular abnormalities are noted in 70% of cases
- 50% of infections involve the tricuspid valve
Pacemaker IE
- Least common
- Most challenging to treat
Pathogenesis:
How It Starts, Progresses, and Resolves
- Typically in a healthy person, bacteria can get into the bloodstream by means of a wound or cut and be cleared quickly without adverse reactions.
- However, if a heart valve is damaged, a blood clot can form providing a place for bacteria to adhere and cause an infection.
- Streptococcus viridans are the most common bacteria that cause infective endocarditis
- Ways the valves can be damaged include surgery, old age, pacemaker wires and auto-immune mechanisms.
- Over time, the microorganisms proliferate, resulting in a classic vegetation
- Microorganisms are then released into the circulation continuously
Signs & Symptoms
The symptoms of infective endocarditis may develop slowly or suddenly. The classic symptom that may last for days without other symptoms is fever. Other symptoms are:
- Pains and aches in muscles and joints
- Discolored or bloody urine
- Fatigue
- Chills
- New or changing heart murmur
- Weight loss
- Coughing
- Weakness
- Paleness
- Vascular
- Night sweats
- Anemia
- Painful lesions on skin, such as fingers and toes
Etiology
The cause of infective endocarditis is usually a blood infection. During medical procedures and dental procedures, infectious substances like bacteria can enter the bloodstream and travel to the heart. There, the bacteria settle in the damaged heart valves and grow. As they grow, they form clots that could break off and spread to other parts of the body such as the brain, kidneys, or lungs.
Some conditions that increase the chances for developing endocarditis include: artificial heart valves, congenital heart disease, heart valve problems, and a history of rheumatic heart disease
Bacteria Involved:
- Steptococcus viridians are the most common
- Responsible for 50% of all infective endocarditis cases
- Staphylococcus aurerus affects normal heart valves
- Most common cause in IVDA endocarditis
Diagnosis
What Tests Are Needed?
Once infective endocarditis is suspect, that person will be admitted into the hospital to have tests taken via blood samples. Bacteria and fungi are being tested in the blood samples. If bacteria are found in the blood, more tests will be performed to determine the best antibiotic to use. Some bacteria may be resistant to certain antibiotics.
The following tests may be used:
- Blood culture and sensitivity (used to detect bacteria)
- Chest x-ray
- Complete blood count (used to show mild anemia)
- CT scan of chest
- Echocardiogram
- Erythrocyte Sedimentation Rate (ESR)
- Transesophageal echocardiogram
The type and timing of laboratory tests to diagnoses infective endocarditis have not been standardized. For those who are suspected to have infective endocarditis, standard diagnostic protocol will be used. This protocol consists testing for the following…
- Coxiella burnetii
- Bartonella spp.
- Aspergillus spp.
- Legionella pheumonphila
- Rheumatoid factor
According to the American Society for Microbiology, a nine year study in Marseilles, France involving 1,998 suspected cases of infective endocarditis was held from April of 1994 to December 2004. After evaluation a total of 427 patients (a little over 21%) were diagnosed with definite endocarditis. 261 patients (13%) were diagnosed with possible endocarditis. In 397 patients (93%) the etiologic diagnosis was by blood cultures, serological tests, and materials obtained from cardiac valves.
However, diagnosis of infective endocarditis is typically based upon clinical findings rather than a single definitive test result. When a patient has characteristic findings, the diagnosis of infective endocarditis is usually obvious.
The most useful test to determine if a person has infective endocarditis is an echocardiograph, an ultrasound scan of the heart. By using echocardiography, sound waves, vegetations, and damage can be detected.
Treatment
Once diagnosed with infective endocarditis, the patient will be admitted into the hospital and antibiotics will be administered to the patient intravenously. Like said before, to determine the best antibiotic blood tests will be taken. In order to get rid of the bacteria, long-term, high-dose antibiotic treatment is required. Depending on the type of bacteria, 4-6 weeks is typically the time period for treatment. The 4-6 week regimen must be used only in the following situations…
- Slow clinical or microbiological response to antibiotic therapy
- IE by right heart failure
- Vegetations larger than 20 mm
- Acute respiratory failure
- Complications like acute kidney failure
No special diets are recommended for patients with IE except for patients with congestive heart failure. Those patients should have a sodium-restricted diet.
Antibiotic Therapy
- Antibiotic therapy should be instituted as soon as the patient is diagnosed with infective endocarditis. Within an hour to an hour and a half, three to five sets of blood cultures are obtained, followed by appropriate antibiotic treatment. The determination of the antibiotic can be quickened by checking medical history from past clinic and physical examination appointments.
- NVE: Patients with Native Valve Endocarditis (NVE) are commonly treated with penicillin G and gentamicin. This provides a synergistic coverage of streptococci. Rifampin is necessary in treating patients with PVE because it penetrates the biofilm where the pathogens are.
- IVDA: Nafcillin and gentamicin is given to patients who have a history of intravenous drug use such as Intravenous Drug Abusers (IVDA). These two drugs work together to cover methicillin-sensitive staphylococci.
- PVE: Vancomycin and gentamicin are used to cover coagulase-negative staphylococci (CoNS), so they are administered to patients with Prosthetic Valve Endocarditis (PVE).
Incidence and Mortality
- Incidence
- According to the Cleveland Clinic Foundation, the incidence of infective endocarditis in a general population has been estimated at between 2 and 6 cases per 100,000 person-years
- However, it is higher in patients who have heart disease and who have IVDA endocarditis.
- Infective endocarditis is also more common in males rather than women. The ratios range from 3:2 to 9:1
- The elderly also are more likely to have infective endocarditis. More than half of infective endocarditis cases occur in patients who are over 60 years of age. The elderly are more likely to require heart valve replacement, therefore making them more susceptible to IE
- Prevalence
- Each year in the United States, it is estimated that 10,000-15,000cases of infective endocarditis are diagnosed.
- Mortality
- When admitted into the hospital for surgery, the mortality rate decreases. In the elderly it is still risky but doctors believe it is still better to follow through with surgery. The estimate mortality rate associated with IE is about 90 days, (19%).
- Studies show that 23% of patients underwent surgery, but more recent studies show that surgery is performed in about half of cases
Research, Charities, and Support Groups
Research
- National Heart Lung and Blood Institute (NHLBI)
- Provides global leadership for research, training, and education
- Promotes the prevention of treatment of the heart, lung, and blood
- Communicates research advances to the public
- Fosters training and mentoring of scientists and physicians
- Enables translation of basic discoveries into clinical practice
Charities and Support Groups
- The Cardiomyopathy Association (CMA)
- The British Heart Foundation
- The Heart Foundation
Resources
Pathology Project 