endocarditis

Definition

The endocardium is the inner lining of the heart muscle, which also covers the heart valves. When the endocardium becomes damaged, bacteria from the blood stream can become lodged on the heart valves or heart lining. The resulting infection is known as endocarditis.

Description

The endocardium lines all four chambers of the heart—two at the top (the right and left atria) and two at the bottom (the right and left ventricles)—through which blood passes as the heart beats. It also covers the four valves (the tricuspid valve, the pulmonary valve, the mitral valve, and the aortic valve), which normally open and close to allow the blood to flow in only one direction through the heart during each contraction.

For the heart to pump blood efficiently, the four chambers must contract and relax, and the four valves must open and close, in a well coordinated fashion. By damaging the valves or the walls of the heart chambers, endocarditis can interfere with the ability of the heart to do its job.

Endocarditis rarely occurs in people with healthy, normal hearts. Rather, it most commonly occurs when there is damage to the endocardium. The endocardium may be affected by a congenital heart defect, such as mitral valve prolapse, in which blood leaks through a poorly functioning mitral valve back into the heart. It may also be damaged by a prior scarring of the heart muscle, such as rheumatic fever, or replacement of a heart valve. Any of these conditions can damage the endocardium and make it more susceptible to infection.

Bacteria can get into the blood stream (a condition known as bacteremia) in a number of different ways: It may spread from a localized infection such as a urinary tract infection, pneumonia, or skin infection or get into the blood stream as a result of certain medical conditions, such as severe periodontal disease, colon cancer, or inflammatory bowel disease. It can enter the blood stream during minor procedures, such as periodontal surgery, tooth extractions, teeth cleaning, tonsil removal, prostate removal, or endoscopic examination. It can also be introduced through in-dwelling catheters, which are used for intravenous medications, intravenous feeding, or dialysis. In people who use intravenous drugs, the bacteria can enter the blood stream through unsterilized, contaminated needles and syringes. (People who are prone to endocarditis generally need to take prescribed antibiotics before certain surgical or dental procedures to help prevent this infection.)

If not discovered and treated, infective endocarditis can permanently damage the heart muscle, especially the valves. For the heart to work properly, all four valves must be functioning well, opening at the right time to let blood flow in the right direction and closing at the right time to keep the blood from flowing in the wrong direction. If the valve is damaged, this may allow blood to flow backward—a condition known as regurgitation. As a result of a poorly functioning valve, the heart muscle has to work harder to pump blood and may become weakened, leading to heart failure. Heart failure is a chronic condition in which the heart is unable to pump blood well enough to supply blood adequately to the body.

Another danger associated with endocarditis is that the vegetation formed by bacteria colonizing on heart valves may break off, forming emboli. These emboli

may travel through the circulation and become lodged in blood vessels. By blocking the flow of blood, emboli can starve various tissues of nutrients and oxygen, damaging them. For instance, an embolus lodged in the blood vessels of the lungs may cause pneumonia-like symptoms. An embolus may also affect the brain, damaging nerve tissue, or the kidneys, causing kidney disease. Emboli may also weaken the tiny blood vessels called capillaries, causing hemorrhages (leaking blood vessels) throughout the body.

— Robert Scott Dinsmoor

[ENDOCARD(IUM) + -ITIS.]

For more information on endocarditis, visit Britannica.com.

Inflammation and infection of the inner lining of the heart, usually including the valves. It may be due to a bacterial infection (frequently originating from a dental infection) or rheumatic fever. Endocarditis is characterized by fever, abnormal changes in the rhythm of the heartbeat, and heart murmurs.

Exudative and proliferative inflammatory alterations of the endocardium, characterized by the presence of vegetations on the surface of the endocardium or in the endocardium itself, and most commonly involving a heart valve, but also affecting the inner lining of the cardiac chambers or the endocardium elsewhere.
Lesions on the valves may interfere with the ejection of blood from the heart by causing insufficiency or stenosis of the valves. Murmurs associated with the heart sounds are the major manifestation and if interference with the blood flow is sufficiently severe congestive heart failure develops. The further hazard with endocarditis, especially if it is bacterial in origin, is that of septic emboli in the lungs or in the other organs.

• bacterial e. — infectious endocarditis, acute or subacute, caused by various bacteria, including streptococci, staphylococci, enterococci and gram-negative bacilli. Of particular interest in animals is the predilection of Erysipelothrix rhusiopathiae to cause endocarditis, epecially in pigs.
• ductal e. — due to thrombosis in a persistent ductus arteriosus with resulting mural inflammation.
• infectious e., infective e. — that due to infection with microorganisms, especially bacteria and fungi.
• mural e. — that affecting the lining of the walls of the heart chambers only.
• nonbacterial thrombotic e. — that in which the vegetations, single or multiple, consist of fibrin and other blood elements.
• parietal e. — mural endocarditis.
• tuberculous e. — that resulting from extension of a tuberculous infection from the pericardium and myocardium.
• valvular e. — that affecting the membrane over the heart valves only.
• vegetative e. — endocarditis, infectious or noninfectious, the characteristic lesions of which are vegetations or verrucae on the endocardium. Called also verrucous endocarditis.

Endocarditis
Classification and external resources
Bartonella henselae bacilli in cardiac valve of a patient with blood culture-negative endocarditis. The bacilli appear as black granulations.
ICD-10	I33.
ICD-9	421
DiseasesDB	4224
MedlinePlus	001098
eMedicine	emerg/164 med/671 ped/2511
MeSH	D004696

Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves (native or prosthetic valves). Other structures which may be involved include the interventricular septum, the chordae tendinae, the mural endocardium, or even on intracardiac devices. Endocarditis is characterized by a prototypic lesion, the vegetation, which is a mass of platelets, fibrin, microcolonies of microorganisms, and scant inflammatory cells.^[1] In the subacute form of infective endocarditis, the vegetation may also include a center of granulomatous tissue, which may fibrose or calcify.^[2]

There are multiple ways to classify endocarditis. The simplest classification is based on etiology: either infective or non-infective, depending on whether a microorganism is the source of the inflammation. Regardless, diagnosis of endocarditis is based on the clinical features, investigations such as echocardiogram, as well as any blood cultures demonstrating the presence of endocarditis-causing microorganisms.

Contents 1 Infective endocarditis 2 Non-infective endocarditis 3 References 4 External links

Infective endocarditis

Main article: Infective endocarditis

Since the valves of the heart do not receive any dedicated blood supply, defensive immune mechanisms (such as white blood cells) cannot directly reach the valves via the bloodstream. If an organism (such as bacteria) attaches to a valve surface and forms a vegetation, the host immune response is blunted. The lack of blood supply to the valves also has implications on treatment, since drugs also have difficulty reaching the infected valve.

Normally, blood flows smoothly through these valves. If they have been damaged (from rheumatic fever, for example) the risk of bacteria attachment is increased.^[2]

Non-infective endocarditis

Nonbacterial thrombic endocarditis (NBTE) or marantic endocarditis is most commonly found on previously undamaged valves^[2]. As opposed to infective endocarditis, the vegetations in NBTE are small, sterile, and tend to aggregate along the edges of the valve or the cusps^[2]. Also unlike infective endocarditis, NBTE does not cause an inflammation response from the body^[2]. NBTE usually occurs during a hypercoagulable state such as system wide bacterial infection, or pregnancy, though it is also sometimes seen in patients with venous catheters^[2]. NBTE may also occur in patients with cancers, particularly mucinous adenocarcinoma^[2] where Trousseau syndrome can be encountered. Typically NBTE does not cause many problems on its own, but parts of the vegetations may break off and embolize to the heart or brain, or they may serve as a focus where bacteria can lodge, thus causing infective endocarditis^[2].

Another form of sterile endocarditis, is termed Libman-Sacks endocarditis; this form occurs more often in patients with lupus erythematosus and is thought to be due to the deposition of immune complexes^[2]. Like NBTE, Libman-Sacks endocarditis involves small vegetations, while infective endocarditis is composed of large vegetations^[2]. These immune complexes precipitate an inflammation reaction, which helps to differentiate it from NBTE. Also unlike NBTE, Libman-Sacks endocarditis does not seem to have a preferred location of deposition and may form on the undersurfaces of the valves or even on the endocardium^[2].

References

1. ^ Kasper DL, Brunwald E, Fauci AS, Hauser S, Longo DL, Jameson JL (May 2005). Harrison's Principles of Internal Medicine. McGraw-Hill. pp. 731–40. ISBN 0-07-139140-1. OCLC 54501403 56437106 56801936 56967424. 
2. ^ ^{a b c d e f g h i j k} Mitchell RS, Kumar V, Robbins SL, Abbas AK, Fausto N (2007). Robbins Basic Pathology (8th ed.). Saunders/Elsevier. pp. 406–8. ISBN 1-4160-2973-7. 

External links

• Endocarditis information from Seattle Children's Hospital Heart Center

v • d • e Cardiovascular disease: heart disease · Circulatory system pathology (I00-I52, 390-429) Ischaemic CD/CHD CAD · Coronary thrombosis · Coronary vasospasm · Coronary artery aneurysm · Coronary artery dissection · Myocardial Bridge Active ischemia Angina pectoris (Prinzmetal's angina, Stable angina) · Acute coronary (Unstable angina, Myocardial infarction / heart attack) Sequelae hours (Myocardial stunning, Hibernating myocardium) · days (Myocardial rupture) · weeks (Aneurysm of heart/Ventricular aneurysm, Dressler's syndrome) Layers Pericardium Pericarditis (Acute, Chronic/Constrictive) · Pericardial effusion (Hemopericardium, Cardiac tamponade) Myocardium Myocarditis (Chagas disease) Cardiomyopathy: Dilated (Alcoholic) · Hypertrophic · Restrictive (Loeffler endocarditis, Cardiac amyloidosis, Endocardial fibroelastosis) Arrhythmogenic right ventricular dysplasia Endocardium/ valves Endocarditis Infective endocarditis (Subacute bacterial endocarditis) · noninfective endocarditis (Nonbacterial thrombotic endocarditis, Libman-Sacks endocarditis) Valves mitral (regurgitation, prolapse, stenosis) · aortic (stenosis, insufficiency) · tricuspid (stenosis, insufficiency) · pulmonary (stenosis, insufficiency) Conduction/ arrhythmia Bradycardia Sinus bradycardia · Sick sinus syndrome Heart block: Sinoatrial · AV (1°, 2°, 3°) · Intraventricular (Bundle branch/Right/Left, Left anterior fascicular/Left posterior fascicular, Bifascicular/Trifascicular) · Adams-Stokes syndrome Tachycardia (paroxysmal and sinus) Supraventricular Atrial (Multifocal) · Junctional (AV nodal reentrant, Junctional ectopic) Ventricular Torsades de pointes · Catecholaminergic polymorphic · Accelerated idioventricular rhythm Premature contraction Atrial · Ventricular Pre-excitation syndrome Wolff-Parkinson-White · Lown-Ganong-Levine Flutter/fibrillation Atrial flutter · Ventricular flutter · Atrial fibrillation (Familial) · Ventricular fibrillation Pacemaker Wandering pacemaker · Ectopic pacemaker/Ectopic beat · Parasystole · Multifocal atrial tachycardia · Pacemaker syndrome Long QT syndrome Romano-Ward syndrome · Andersen-Tawil syndrome · Jervell and Lange-Nielsen syndrome Cardiac arrest Sudden cardiac death · Asystole · Pulseless electrical activity · Sinoatrial arrest Other/ungrouped hexaxial reference system (Right axis deviation, Left axis deviation) · QT (Short QT syndrome) · T (T wave alternans) · ST (Osborn wave, ST elevation, ST depression) Cardiomegaly Ventricular hypertrophy (Left, Right/Cor pulmonale) · Atrial enlargement (Left, Right) Other Cardiac fibrosis · Heart failure (Cardiac asthma) · Rheumatic fever heart navs: anat/physio/dev, noncongen/congen/neoplasia, symptoms+signs/eponymous, proc

v • d • e Inflammation Acute Plasma derived mediators Bradykinin · complement (C3, C5a, MAC) · coagulation (Factor XII, Plasmin, Thrombin) Cell derived mediators preformed: Lysosome granules · vasoactive amines (Histamine, Serotonin) synthesized on demand: cytokines (IFN-γ, IL-8, TNF-α, IL-1) · eicosanoids (Leukotriene B4, Prostaglandins) · Nitric oxide · Kinins Chronic Macrophage · Epithelioid cell · Giant cell · Granuloma Processes Traditional: Rubor · Calor · Tumor · Dolor (pain) · Functio laesa Modern: Acute-phase reaction/Fever · Vasodilation · Increased vascular permeability · Exudate · Leukocyte extravasation · Chemotaxis Specific types Nervous CNS (Encephalitis, Myelitis) · Meningitis (Arachnoiditis) · PNS (Neuritis) · eye (Dacryoadenitis, Scleritis, Keratitis, Choroiditis, Retinitis, Chorioretinitis, Blepharitis, Conjunctivitis, Iritis, Uveitis) · ear (Otitis, Labyrinthitis, Mastoiditis) Cardiovascular Carditis (Endocarditis, Myocarditis, Pericarditis) · Vasculitis (Arteritis, Phlebitis, Capillaritis) Respiratory upper (Sinusitis, Rhinitis, Pharyngitis, Laryngitis) · lower (Tracheitis, Bronchitis, Bronchiolitis, Pneumonitis, Pleuritis) · Mediastinitis Digestive mouth (Stomatitis, Gingivitis, Gingivostomatitis, Glossitis, Tonsillitis, Sialadenitis/Parotitis, Cheilitis, Pulpitis, Gnathitis) · tract (Esophagitis, Gastritis, Gastroenteritis, Enteritis, Colitis, Enterocolitis, Duodenitis, Ileitis, Caecitis, Appendicitis, Proctitis) · accessory (Hepatitis, Cholangitis, Cholecystitis, Pancreatitis) · Peritonitis Integumentary Dermatitis (Folliculitis) · Cellulitis · Hidradenitis Musculoskeletal Arthritis · Dermatomyositis · soft tissue (Myositis, Synovitis/Tenosynovitis, Bursitis, Enthesitis, Fasciitis, Capsulitis, Epicondylitis, Tendinitis, Panniculitis) Osteochondritis: Osteitis (Spondylitis, Periostitis) · Chondritis Urinary Nephritis (Glomerulonephritis, Pyelonephritis) · Ureteritis · Cystitis · Urethritis Reproductive female: Oophoritis · Salpingitis · Endometritis · Parametritis · Cervicitis · Vaginitis · Vulvitis · Mastitis male: Orchitis · Epididymitis · Prostatitis · Balanitis · Balanoposthitis pregnancy/newborn: Chorioamnionitis · Omphalitis Endocrine Insulitis · Hypophysitis · Thyroiditis · Parathyroiditis · Adrenalitis Lymphatic Lymphangitis · Lymphadenitis

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