Myocarditis

myocarditis

[‚mī·ə‚kär′dīd·əs] (medicine) Inflammation of the myocardium.

Myocarditis

inflammation of the heart muscle (myocardium). Myocarditis may be caused by infectious diseases, including viral ones, and by an allergic reaction, which is the main pathogenic factor in drug-induced and serum myocarditis. The role of autoimmunities and allergies is manifested in postinfluenzal myocarditis, in which the acute infectious disease (influenza) passes but the myocarditis caused by it persists for many months. Contemporary medicine generally accepts the theory that most forms of myocarditis are caused by infections and allergies. Myocarditis is a common symptom of collagen diseases, such as rheumatism, systemic lupus erythematosus, and scleroderma. In South America, Africa, and Polynesia myocarditis may be caused by parasitic diseases. In many cases the cause of myocarditis is unidentified.

Myocarditis may be diffuse or focal. Depending on the course of the disease, cases are categorized as acute, subacute, and chronic (recurrent). Cases may be mild, extremely severe, or fatal. In acute myocarditis patients commonly complain that they feel weak, tire easily, and are short of breath. They suffer from rapid heartbeat (tachycardia), arrhythmia, and pain in the heart. Pallor is also a common symptom. Arterial pressure is low, and venous pressure high, owing to the decreased force of heart contractions. The cervical veins in the neck swell, and the heart becomes enlarged. Various irregularities in cardiac contractions and conduction, to the point of complete atrioventricular heart block, are common and are accompanied by specific electrocardiographic changes. Often there are no clear-cut symptoms of myocarditis, and death occurs unexpectedly from severe injury to the myocardium. Of particular importance in diagnosing such cases are electrocardiography and laboratory tests, including blood count, analysis of protein and protein fractions, determination of enzymic activity, and immunologic studies.

The characteristics of myocarditis vary, depending on the origin of the disease. The most common form, rheumatic myocarditis, is usually accompanied by endocarditis, which results in heart defects. Pain in the heart and irregularities in cardiac rhythm and conduction are the most common symptoms of active rheumatic endocarditis. The causes and developmental mechanisms of idiopathic myocarditis, the most severe form of the disease, are still obscure. Nonetheless, a number of varieties have been distinguished. In one of them, symptoms of cardiovascular insufficiency prevail, accompanied by arrhythmia and the development of pulmonary and renal infarctions and of circulatory disorders in the cerebrum. Another variety is associated with pain in the heart and with EKG changes, and still another, with the development of relative valvular inefficiency due to cardiomegaly. One type of idiopathic myocarditis is manifested by a mixture of symptoms associated with other varieties of the disease.

Diphtherial myocarditis, which occurs in approximately 25–30 percent of all diphtheria patients, usually develops in the second week of the disease. Its most characteristic symptom is disturbance of conduction, to the point of complete atrioventricular heart block. Prompt therapy usually results in recovery, and cardiac disorders persist in only a few patients.

Treatment includes complete rest and the prescription of vitamins (C, B-complex), steroid hormones, and anti-infectious and antiarrhythmic medicines. Salicylates are prescribed in cases of rheumatic endocarditis, and appropriate drugs are prescribed for cardiovascular insufficiency.

REFERENCE

Kedrov, A. A. Bolezni myshtsy serdtsa. Leningrad, 1963.

N. R. PALEEV

myocarditis

Myocarditis

Definition

Myocarditis is an inflammatory disease of the heart muscle (myocardium) that can result from a variety of causes. While most cases are produced by a viral infection, an inflammation of the heart muscle may also be instigated by toxins, drugs, and hypersensitive immune reactions. Myocarditis is a rare but serious condition that affects both males and females of any age.

Description

Most cases of myocarditis in the United States originate from a virus, and the disease may remain undiagnosed by doctors due to its general lack of initial symptoms. The disease may also present itself as an acute, catastrophic illness that requires immediate treatment. Although the inflammation or degeneration of the heart muscle that myocarditis causes may be fatal, this disease often goes undetected. It may also disguise itself as ischemic, valvular, or hypertensive heart disease.An inflammation of the heart muscle may occur as an isolated disorder or be the dominating feature of a systemic disease (one that affects the whole body, like systemic lupus erythematosus).

Causes and symptoms

While there are several contributing factors that may lead to myocarditis, the primary cause is viral. Myocarditis usually results from the Coxsackie B virus, and may also result from measles, influenza, chicken pox, hepatitis virus, or the adenovirus in children. If an acute onset of severe myocarditis occurs, a patient may display the following symptoms:

Rhythm disturbances of the heart
Rapid heartbeat (Ventricular tachycardia)
Left or right ventricular enlargement
Shortness of breath (Dyspnea)
Pulmonary edema (the accumulation of fluid in the lungs due to left-sided heart failure)
Swollen legs.

Additional causes of myocarditis include:

Bacterial infections, such as tetanus, gonorrhea, or tuberculosis
Parasite infections, such as Chagas' disease (which is caused by an insect-borne protozoan most commonly seen in Central and South America)
Rheumatic fever
Surgery on the heart
Radiation therapy for cancer that is localized in the chest, such as breast or lung cancer
Certain medications.

As of 1996, research has shown that illegal drugs and toxic substances may also produce acute or chronic injury to the myocardium. These studies also indicate an increase in the incidence of toxic results from the use of cocaine. This illegal drug causes coronary artery spasm, myocardial infarction (heart attack), and arrhythmias, as well as myocarditis.Further studies conducted in 1996 indicate that malnutrition encourages the Coxsackie B virus to flourish, leading to the potential development of myocarditis. Human immunodeficiency virus (HIV) is also now recognized as a cause of myocarditis, though its prevalence is not known.Symptoms of myocarditis may start as fatigue, shortness of breath, fever and aching of the joints, all characteristic of a flu-like illness. In contrast to this type of mild appearance, myocarditis may also appear suddenly in the form of heart failure, or sudden cardiac death without any prior symptoms. If an inflammation of the heart muscle leads to congestive heart failure, symptoms such as swollen feet and ankles, distended neck veins, a rapid heartbeat, and difficulty breathing while reclining may all appear.

Diagnosis

The best way to diagnose myocarditis may be through a person's observation of his or her own symptoms, followed by a thorough medical history and physical exam conducted by a doctor. Further tests usually include laboratory blood studies and echocardiography. An electrocardiogram (ECG) is also routinely used due to its ability to detect a mild case of the disease. Cardiac catheterization and angiography are additional diagnostic tests used to determine the presence of myocarditis, or to rule out other possible heart diseases that may lead to heart failure.Another measure used to diagnosis myocarditis is the endomyocardial biopsy procedure. This invasive catheterization procedure examines a biopsied, or "snipped," piece of the endocardium (the lining membrane of the inner surface of the heart). The tissue sample is examined to verify the presence of the disease, as well as to try to determine the infective cause. An approach used only with a patient's consent, this procedure may also confirm acute myocarditis, allowing close monitoring of potential congestive heart failure.

Treatment

While myocarditis is a serious condition, there is no medical treatment necessary if it results from a general viral infection. The only steps to recovery include rest and avoidance of physical exertion. Adequate rest becomes more important to recovery if the case is severe myocarditis with signs of dilated cardiomyopathy (disease of the heart muscles). In this case, medical treatment for congestive heart failure may include the following medications: angiotensin converting enzyme (ACE) inhibitors, diuretics to reduce fluid retention, digitalis to stimulate a stronger heartbeat, and low-dose beta-blockers.If myocarditis is caused by a bacterial infection, the disease is treated with antibiotics to fight the infection. If severe rhythm disturbances are involved, cardiac assist devices, an "artificial heart," or heart transplantation may be the only option for complete recovery.

Prognosis

The outlook for a diagnosed case of myocarditis caused by a viral infection is excellent, with many cases healing themselves spontaneously. Severe or acute myocarditis may be controlled with medication to prevent heart failure. Because this disease may be mild or may be extreme and cause serious arrhythmias, the prognosis varies. Cases of myocarditis may vary from complete healing (with or without significant scarring), to severe congestive heart failure leading to death or requiring a heart transplant.Inflammation of the myocardium may also cause acute pericarditis (inflammation of the outer lining of the heart). Due to the potential effects of the disease, including sudden death, it is imperative that proper medical attention is obtained.

Prevention

Although myocarditis is an unpredictable disease, the following measures may help prevent its onset. Individuals should:

Take extra measures to avoid infections, and obtain appropriate treatment for infections.
Limit alcohol consumption to no more than one or two drinks a day, if any.
Maintain current immunizations against diphtheria, tetanus, measles, rubella, and polio.
Avoid anything that may cause the abnormal heart to work too hard, including salt and vigorous exercise.

Resources

Organizations

American Heart Association. 7320 Greenville Ave. Dallas, TX 75231. (214) 373-6300. http://www.americanheart.org.National Heart, Lung and Blood Institute. P.O. Box 30105, Bethesda, MD 20824-0105. (301) 251-1222. http://www.nhlbi.nih.gov.

Key terms

Adenovirus — One type of virus that can cause upper respiratory tract infections.Angiography — A procedure which uses x ray after injecting a radiopaque substance to examine the blood vessels and lymphatics.Arrhythmia — An irregular heartbeat or action.Cardiac catheterization — A diagnostic procedure that gives a comprehensive examination of how the heart and its blood vessels function; performed by inserting one or more catheters through a peripheral blood vessel in the arm or leg.Coxsackie B virus — A mild virus belonging to a group of viruses (coxsackievirus) that may produce a variety of illnesses, including myocarditis.Echocardiography — A noninvasive diagnostic procedure that uses ultrasound to examine internal cardiac structures.Electrocardiogram — A record of the electrical activity of the heart, with each wave being labeled as P, Q, R, S, and T waves. Often used in the diagnosis of cases of abnormal cardiac rhythm and myocardial damage.Hypertensive heart disease — High blood pressure resulting in a disease of the heart.Ischemic heart disease — Insufficient blood supply to the heart muscle (myocardium).Valvular heart disease — A disease of any one of the four valves that controls blood flow into, through, and out of the heart.Ventricular tachycardia — An abnormally rapid heartbeat. It includes a series of at least three beats arising from a ventricular area at a rate of more than 100 beats per minute, usually ranging from 150-200 beats per minute.

myocarditis

[mi″o-kahr-di´tis] inflammation of the muscular walls of the heart (the myocardium); it may result from bacterial or viral infections or it may be a toxic inflammation caused by drugs or toxins from infectious agents. Other systemic diseases that may be accompanied by myocarditis are trichinosis, serum sickness, rheumatic fever, and collagen diseases. In many cases the etiology is unknown.Symptoms. Symptoms are flulike; in acute myocarditis there is usually pain in the epigastric region or under the sternum (either ischemic, atypical, or pericardial), as well as dyspnea and cardiac arrhythmias. If the condition persists and becomes chronic, there is pain in the right upper quadrant of the abdomen, owing to hepatic congestion. The latter symptom is a sign of left biventricular failure and often is accompanied by edema and other signs of congestive heart failure.Treatment (for both symptoms and underlying cause). Acute myocarditis usually subsides when the primary illness improves. It is considered incidental to the systemic disease and, though it may be a serious manifestation of a systemic illness, acute myocarditis often does not require specific treatment. Steroids may be used to reduce the inflammatory process. Antiarrhythmic drugs may be required, as well as therapy to combat congestive heart failure.
If the heart involvement becomes chronic, treatment then must be aimed at management of the chronic heart failure. See also heart failure" >congestive heart failure.

my·o·car·di·tis

(mī'ō-kar-dī'tis), Inflammation of the muscular walls of the heart.

myocarditis

(mī′ō-kär-dī′tĭs)n. Inflammation of the myocardium.

myocarditis

Cardiology Myocardial inflammation Etiology Idiopathic, viral, toxic Complications Dilated cardiomyopathy. See Acute myocarditis, Borderline myocarditis, Fulminant myocarditis, Giant cell myocarditis, Lymphocytic myocarditis.

my·o·car·di·tis

(mī'ō-kahr-dī'tis) Inflammation of the muscular walls of the heart.

myocarditis

Inflammation of the heart muscle. This may result from bacterial or viral infection, from RHEUMATIC FEVER, from DIPHTHERIA toxin, from TRYPANOSOMIASIS (CHAGAS' DISEASE) or from nutritional deficiency. See also CARDIOMYOPATHY.

my·o·car·di·tis

(mī'ō-kahr-dī'tis) Inflammation of the muscular walls of heart.

myocarditis

my·o·car·di·tis

myocarditis

my•o•car•di•tis

myocarditis

myocarditis

Myocarditis

myocarditis

Myocarditis

REFERENCE

myocarditis

Myocarditis

Definition

Description

Causes and symptoms

Diagnosis

Treatment

Prognosis

Prevention

Resources

Organizations

Key terms

myocarditis

my·o·car·di·tis

myocarditis

myocarditis

my·o·car·di·tis

myocarditis

my·o·car·di·tis

myocarditis

Synonyms for myocarditis

noun inflammation of the myocardium (the muscular tissue of the heart)

Synonyms

Related Words