CARDITIS
Carditis, or inflammation of the heart, is most conveniently broken down into
three categories:
· Pericarditis - Inflammation of the pericardium
· Myocarditis - Inflammation of the heart muscle
· Endocarditis - Inflammation of the endocardium
Pericarditis, inflammation of the fibroserous sac enclosing the heart has multiple infectious and noninfectious causes. Infectious causes of pericarditis exist in three forms:
ETIOLOGY:
Viruses are the most common infectious cause of pericarditis. The viruses usually causing this disease are the Enteroviruses (Coxsackieviruses and Echovirus).
Purulent pericarditis is quite rare now. The most common causes are Staphylococcus aureus, Streptococcus pneumoniae, and other streptococci. Although virtually any bacterium can cause this disease.
Chronic pericarditis is caused by Mycobacterium tuberculosis and various fungi (Candida sp.)
OVERVIEW OF DISEASE:
In most cases the infecting microorganism reaches the pericardium via the circulatory system. Rarely the organism will enter the pericardium by direct extension from the lung or direct inoculation during surgery, invasive medical procedures or trauma. The organism colonizes the pericardium and stimulates an inflammatory reaction, which can result in destruction of heart tissue. If the infecting organism is a virus there is also viral cell lysis.
The inflammatory reaction results in the accumulation of serous or purulent exudate, which may in turn cause cardiac tamponade (the exertion of pressure or compression on the heart) and circulatory failure.
Tuberculous pericarditis results from hematogenous spread
during primary disease, it can spread to the pericardium by lymphatic drainage
from the respiratory tract, or via direct spread from the lungs or pleura.
PATHOLOGY:
Microorganisms reach the pericardium by the blood, lymph, direct extension from pulmonary or myocardial foci of infection, or direct inoculation during surgery, other invasive procedures, or penetrating trauma.
Viral infections are usually blood-borne and often infect the myocardium as well as the pericardium. Pneumococci or other primary pulmonary pathogens usually infect the pericardium by extension from an adjacent pneumonitis; the common causes of bacteremias - staphylococci, meningococci and H. influenzae - are more likely to reach the pericardium through the blood stream. A pre-existing, noninfectious pericarditis, as is seen with uremia or following cardiac surgery, may increase susceptibility to hematogenous bacterial pericarditis. Postoperative infections are most commonly caused by Staphylococcus aureus, Gram negative aerobic rods and Candida sp.
Viral pericarditis. The viruses typically causing this disease produce a relatively mild inflammatory reaction that is associated with focal damage to the adjacent myocardium. The response varies from a small amount of serous fluid with mononuclear cells and fibrinogen to a large, neutrophil-rich, bloody effusion. The tissue damage is the result of:
Mild fibrosis and occasional adhesions between visceral and parietal surfaces may mark the healing of viral pericarditis. However, such a fibrotic reaction rarely gives rise to a constrictive pericarditis. The disease is self-limiting and rarely fatal.
Purulent pericarditis. The bacteria typically causing this disease produce a relatively strong rapidly progressing purulent reaction. The purulent material contains large numbers of polymorphonuclear leukocytes in a large volume of effusion. The tissue damage is the result of:
Healing is associated with extensive fibrosis that may progress to a chronic, constrictive pericarditis. The mortality rate exceeds 50%.
Chronic pericarditis. This is most commonly caused by
M. tuberculosis. About 5% of patients with pulmonary tuberculosis will
have pericardial involvement. The early granulomatous stages are associated
with large pericardial effusions (> 300 ml) that are typically
serosanguinous and contain a predominance of mononuclear cells. As the disease
evolves, the inflammatory process becomes chronic; fusion of the parietal and
visceral pericardium may result, yielding constrictive pericarditis and circulatory
failure.
CLINICAL SYMPTOMS AND SIGNS:
Symptoms vary depending upon the cause of the pericarditis.
Viral pericarditis- usually present with sharp substernal chest pain that is made worse by inspiration. Pain is also worsened by lying supine. The patient prefers to sit up and lean forward to lessen the pain.
Purulent pericarditis- suddenly develops fever and dyspnea. Only about 1/3 has chest pain as above. No specific symptoms many times and is oftentimes misdiagnosed.
Tuberculous pericarditis- more insidious clinical onset. Vague, dull chest pain, weight loss, night sweats, cough and dyspnea.
Physical findings in any of the three types of pericarditis depend on how much exudate accumulates in the pericardial space and can include:
DIAGNOSIS:
Determining the cause in viral pericarditis is difficult and not usually done.
Pericardiocentesis can be used in some cases (purulent pericarditis, with cardiac tamponade) to culture for the infecting agent.
EKG- not specific usually
Echocardiography- detects pericardial thickening and pericardia fluid accumulation
TREATMENT:
Viral pericarditis- bed rest. Nonsteroidal anti-inflammatory agents can be used to reduce chest pain. However, they should be avoided if the patient also has myocarditis.
Purulent pericarditis- emergency surgical drainage (pericardiocentesis) and systemic antibiotics (mortality still up to 30%)
Tuberculous pericarditis- four drug anti-tuberculous
regimen, Prednisone to prevent constriction. If calcifications form
pericardectomy is required.
Most cases are self-limited and are followed by full recovery. Fulminant myocarditis can be fatal or lead to chronic congestive heart failure. The true incidence of this disease is unknown however it is estimated that 1-5% of cases of viral illnesses have myocardial involvement.
ETIOLOGICAL AGENTS:
Many species of viruses, bacteria, chlamydia, rickettsia, fungi and protozoans can cause myocarditis. However, viruses are the most important infectious agents. Of these, the enteroviruses are the single most important group (Coxsackieviruses B are the most common). Other viruses have been implicated in causing myocarditis and include CMV, EBV, VZV, and the Mumps virus. Patients with asymptomatic HIV infection have a high incidence of myocarditis.
Bacterial causes include Legionella, Chlamydia, and Borrelia burgdorferi.
Fungi include Aspergillus sp., Candida sp., and Cryptococcus sp.
Parasites include Trypanosoma cruzi and Trichinella spiralis.
OVERVIEW OF DISEASE:
The disease is an infection of the myocardium or muscle of
the heart. The virus is ingested in fecally contaminated water and/or food and
eventually, either directly or indirectly, reaches the heart. There may be a
prior skin infection before heart effects are seen. The virus invades the heart
muscle cells and causes necrosis of the cells and clinical effects.
PATHOLOGY:
Viruses directly invade the myocytes and cause damage to the infected cells. The immune response to infection also causes damage to the myocytes. Immune cell infiltration of the myocytes includes T-cells predominantly accompanied by macrophages and B-cells. Circulating autoantibodies directed against mitochondria and contractile proteins are frequently detected and may cause further damage. Cytokines and oxygen free radicals have also been implicated in causing damage to the myocytes.
Forced exercise, pregnancy, use of steroids or nonsteroidal
anti-inflammatory agents, use of ethanol and nutritional deficiencies are
factors that predispose a patient to symptomatic myocarditis.
CLINICAL SYMPTOMS, SIGNS AND DIAGNOSIS:
Many are asymptomatic.
If symptoms are present the pace of the illness and the symptoms vary greatly. Symptoms include; flu-like illness with chest pain when the pericardium is involved, arrhythmias, or signs of right- and left-sided congestive heart failure. Left ventricular dilatation can lead to expansion of the mitral valve ring and a mitral regurgitant murmur. A S3 gallop indicates left-sided CHF. If the pericardium is also involved then a friction rub may be present.
Only in a minority of patient are cardiac enzymes elevated (CK-MB in 5% of patients and cardiac troponin I in 34% of patients).
EKG- may demonstrate ST and T wave changes, ventricular or atrial arrhythmias, and conduction defects
Chest X-ray- to detect pulmonary edema in CHF and cardiac dilatation
Echocardiography- to assess cardiac contractility, chamber size, valve function, and wall thickness.
Contrast-enhanced MRI- detect the extent and degree of inflammation and determine parameters that correlate with left ventricular function and clinical status
Definitive diagnosis- requires endomyocardial biopsy. Not
usually done.
TREATMENT:
Viral myocarditis is typically a mild disease and responds well to bed rest. Cardiac monitoring may be required to alert staff to potentially life-threatening arrhythmias.
Bacterial, fungal and protozoan myocarditis can be treated with the appropriate antibiotics. Glucosteroids and other immunosuppressive drugs are CONTRAINDICATED.
In fulminant disease the patient may die and can only be
corrected by cardiac transplantation.
OVERVIEW:
Infective endocarditis is a relatively uncommon infection. The incidence is around 2/100,000. It is more common in males than females and the disease is becoming more a disease of the elderly.
Microorganisms growing in the normal flora of the body cause most cases of infective carditis. They gain access to the blood intermittently, as a result of minor trauma to the mucosa of the oropharynx, gastrointestinal tract or genitourinary tract. Such transient bacteremias usually occur without ill effects but they will lead to endocarditis in patients with an underlying cardiovascular lesion or with a suppressed immune system.
Intravenous drug abusers commonly have infective endocarditis due to Staphylococcus aureus from contaminated needles. Blood-borne organisms are deposited on the downstream side of the valves where they colonize and cause disease.
ETIOLOGY:
The etiology depends on the condition of the heart valve, if the person is an IV drug abuser, if the patient has a prosthetic heart valve and how long the prosthetic heart valve has been in place before an infection results in symptoms.
Native heart valve- Streptococcus sp.(60-80%); Viridans streptococci (30-40%), Streptococcus bovis (10%), Enterococci (S. faecalis and S. faecium; 5-18%)
Staphylococci (20-35%); Usually Staphylococcus
aureus
Rare causes: Gram-negative bacilli and HACEK group (Haemophilus sp. (H. aprophilus and H. paraaphrophilus), Actinobacillus actinoinycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae
); slow-growing (longer than 7 days) and require CO2
Very rare: Anaerobic bacteria, Coxiella burnetii (Q fever), Chlamydia sp.
Intravenous drug abusers- Staphylococcus aureus (50%), Gram negative bacilli (15%; Pseudomonas aeruginosa is most common Gram negative).
Also will see Streptococcus (15%) particularly viridans group and enterococci.
Fungi (5%), mostly Candida albicans is more frequently a problem. Polymicrobial infections are also more frequent.
Prosthetic valve infections- depends on the timing of the infection.
Early (within first 2 months)- nosocomial pathogens= Staphylococci (50%; coagulase positive and coagulase negative), gram-negative aerobic bacilli (20%), fungi (5%)
Late (more than 2 months post surgery)- organisms from mouth and skin flora; Viridans Streptococcus sp. (35%), coagulase negative staphylococci (20%), and Staphylococcus aureus (10%) are most common. Gram-negative bacilli and fungi are less common but still important.
PATHOLOGY:
Infective endocarditis is usually preceded by the formation of a predisposing cardiac lesion. Damage to the endothelial cells that line the inside of the heart and the heart valve can become damaged leading to the accumulation of platelets and fibrin producing a nonbacterial thrombotic endocarditis (NBTE). This sterile lesion serves as an ideal site for bacteria to attach to when in the bloodstream. Various conditions lead to endothelial cell damage and predispose a patient to the formation of NBTE. They include: rheumatic heart disease, congenital heart disease (bicuspid aortic valve, ventricular septal defect, coarctation of the aorta, tetralogy of Fallot), mitral valve prolapse, degenerative heart disease (calcific aortic valve disease) and prosthetic valve placement. Intravenous drug users are at higher risk of developing endocarditis due to their propensity to inject bacterially contaminated solutions intravenously. Patient recovering from endocarditis are also at increased risk of having a second episode of endocarditis.
Shear stress can also damage the surface of the valves. The valves that get the most shear stress are the ones on the left side of the heart (mitral and aortic valves). With the exception of intravenous drug abusers right-sided endocarditis is uncommon. When right-sided endocarditis does occur it is usually on the tricuspid valve. Propensity to develop vegetations following trauma goes as follows (greatest to least) mitral>aortic>tricuspid>pulmonary valve.
Bacteria and platelets tend to accumulate tend to accumulate on the downstream or low-pressure side of a valvular lesion (Venturi effect). When bacteria colonize the NBTE they form vegetations. Surface adherence factors are essential for the bacteria to colonize the NBTE (Streptococcus sanguis binds to platelet receptors. Staphylococcus aureus binds to fibronectin.). Colony counts in the vegetations are usually 109-1011 bacteria/gm of tissue. These vegetations vary in size from tiny bodies to masses large enough to occlude valve orifices. Often, they are soft and friable and only loosely attached to the endocardium. Thus, they break off easily to form arterial emboli. Fungal vegetations tend to be bulky, giving rise to large emboli. Apart from the propensity to generate emboli, there is no correlation between size of vegetation and severity of endocarditis.
The bulk of the vegetation is an amorphous mass of fibrin and platelets containing colonies of microorganisms. There may be inflammatory cells attached to the vegetation. There are four consequences to the formation of this vegetation:
Abscesses may develop by direct invasion of the valve rings
of the heart near the vegetations. These are common with pyogenic cocci but
rare with other organisms.
CLINICAL SYMPTOMS:
Basically two types of infectious endocarditis: subacute and acute. Subacute endocarditis is more common and takes more time for symptoms to develop. Oftentimes the symptoms are nonspecific. Acute endocarditis progresses very rapidly with more severe symptoms. Is more common in IV drug abusers and in staphylococcal infections of the heart.
Subacute endocarditis- The interval between the colonization of the endocardium and the onset of symptoms is usually less than two weeks. Because the symptoms are usually nonspecific, on average there is a delay of five weeks between onset of symptoms and diagnosis.
Low-grade fever (range of 38oC) is the most common symptom. Only in acute endocarditis does the temperature go above 40oC. Fever is usually accompanied by chills and sometimes by night sweats. Fatigue, anorexia, weakness, myalgias, arthralgias and malaise are common. Debilitating low back pain is a prominent complaint in a smaller percentage of patients.
Acute endocarditis- rapid onset (hours to days) of signs and symptoms. Most commonly associated with Staphylococcus aureus or enterococcus. Fever is high (40oC) and accompanied by rigors. Patients are very ill and are brought to the emergency room. The likelihood of extravascular complications is higher.
The following can be seen in patients with both types of endocarditis.
Murmurs- Almost all patients will have an audible heart murmur. Although classically described as a changing murmur the murmur usually does not change significantly over time unless a valve leaflet is destroyed or a chordae tendineae ruptures. Detection of a new aortic regurgitant murmur is a bad prognostic sight and is commonly associated with CHF. Murmurs are less common in right-sided endocarditis.
Roth spots or flame-shaped hemorrhages may be observed on funduscopic examination. Roth spots are retinal hemorrhages with pale centers.
Petechial hemorrhages- in the conjunctiva, the buccal mucosa, palate, extremities, splinter hemorrhages under the nail beds of the hands and feet.
Janeway lesions- painless hemorrhagic plaques on the palms and soles.
Osler nodes- small, pea-sized subcutaneous, painful erythematous nodules that occur in the pads of the fingers and toes and the thenar eminence. Usually are present for a brief period of time lasting only a few hours to a couple of days.
Other findings include:
Lab values:
Oftentimes are nonspecific in nature
Complications occur in the majority of patients and include cardiac (most common; CHF, destruction of valve, perivalvular extension of infection), systemic emboli (mycotic aneurysms, neurologic complications, renal complications)
DIAGNOSIS:
Acute endocarditis- rapid diagnosis and treatment are mandatory to reduce valvular destruction and embolic complications.
After a very careful history and physical is performed then a number of tests will help in confirming your diagnosis of endocarditis.
Chest radiographs may demonstrate distinct round cannonball-like pulmonary emboli in right-sided endocarditis. Pulmonary edema may be present in those with acute mitral regurgitation or decompensated left-sided heart failure due to aortic valve regurgitation.
EKGs should be obtained and closely monitored for conduction defects.
Blood cultures- are critical for making the diagnosis. Infective endocarditis is associated with a constant low-level bacteremia. Obtain 3 blood samples (at least 10 mls of blood) at least 15 minutes between each blood letting over a 24-hour period. If the patient is acutely ill do this over a 45 minute period of time. DO NOT GIVE ANTIBIOTICS UNTIL THE BLOOD CULTURES ARE CONFIRMED TO BE POSITIVE FOR BACTEREMIA.
Echocardiography- is also essential. Transesophageal echocardiography (TEE) is the most sensitive and can detect vegetations as small as 3 mm. It readily detects extravalvular extension of infection and visualized valve perforations. Doppler color flow analysis allows for assessment of valve function, myocardial contractility and chamber volume. This information is important in deciding if surgery is needed.
Your diagnosis is confirmed if you have good bacterial growth from the blood samples and if you see damage to the heart valves by TEE.
What do you do to diagnose this infection if you can’t detect any valve tissue histopathology or if you can’t get organisms to grow from blood samples?
o
Definite endocarditis
§ Histologic and/or microbiologic evidence of infection at surgery or autopsy
§ 2 major criteria
§ 1 major criterion and 3 minor criteria
§ 5 minor criteria
o
Possible endocarditis
§ 1 major criterion and 1 minor criterion
§ 3 minor criteria
Major criteria
§ Typical microorganism consistent with IE isolated from 2 separate blood cultures, as noted below
§ viridans streptococci, Streptococcus bovis, Staphylococcus aureus, or HACEK group
§ Community-acquired enterococci in the absence of a primary focus
§ Microorganisms consistent with IE isolated from persistently positive blood cultures defined as:
§ At least 2 positive cultures of blood samples obtained > 12 hours apart
§ All of 3 or a majority of 4 or more separate cultures of blood, the first and the last sample obtained > 1 hr apart
§ Positive results of echocardiography for IE (transesophageal echocardiogram recommended for prosthetic valve, possible IE by clinical criteria, or complicated IE [i.e., a paravalvular abscess]) defined as:
§ Oscillating intracardiac mass on the valve or supporting structures in the path of regurgitant jets or on implanted material in the absence of an alternative anatomic explanation
§ Abscess
§ New partial dehiscence of a valvular prosthesis
§ New valvular regurgitation (worsening or changing or preexisting murmur not sufficient)
Minor criteria
§ Predisposing heart disease or injection drug use
§ Temperature of > 38C
§ Vascular phenomenon: major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial or conjunctival hemorrhage, Janeway lesions
§ Immunologic phenomenon: glomerulonephritis, Osler's nodes, Roth's spots, rheumatoid factor
§ Microbiologic evidence: a positive blood culture that does not meet a major criterion (as noted above) or serologic evidence of active infection with an organism consistent with IE
HACEK= Haemophilus species (H. aprophilus and H. paraaphrophilus), Actinobacillus actinoinycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae
TREATMENT:
Antibiotic therapy must persist for 4 to 6 weeks, even if symptoms disappear prior to that time. One exception is subacute bacterial endocarditis caused by viridans Streptococcus sp. in which the combination of penicillin G and gentamicin for two weeks works as well as treatment for 4 weeks. A combination of antibiotics, rather than a single antibiotic, is always used. If no organism has been isolated after repeated attempts the recommended therapy for subacute bacterial endocarditis is:
Ampicillin, given IV every 4 hours + Gentamicin, given every 8 hours.
Empiric therapy for acute bacterial endocarditis:
Vancomycin, ampicillin, and gentamicin.
If an organism has been isolated, then the antibiotic regimen is based on the species of the etiologic agent, the age of the patient and the extent of the disease. The regimens are complex and are listed in various reference books.
If antibiotic therapy is not successful surgical removal of infected endocardium may be necessary. This is especially true with fungal infections and when the patient has an infected prosthetic valve.