About idiopathic giant cell myocarditis

What is idiopathic giant cell myocarditis?

General Discussion

Giant cell myocarditis is a rare cardiovascular disorder that occurs for unknown reasons (idiopathic). It is characterized by inflammation of the heart muscle (myocardium), a condition referred to as myocarditis. Inflammation is caused by widespread infiltration of giant cells associated with other inflammatory cells and heart muscle cell destruction. Giant cells are abnormal masses produced by the fusion of inflammatory cells called macrophages. Individuals with giant cell myocarditis may develop abnormal heartbeats, chest pain and, eventually, heart failure. Many individuals eventually require a heart transplant. The disorder most often occurs in young adults.

What are the symptoms for idiopathic giant cell myocarditis?

The onset of symptoms of giant cell myocarditis is often rapid. Initial symptoms may include Swelling of the ankles, Chest pain, heart Palpitations, Fatigue, and Shortness of breath (dyspnea) especially upon exertion or lying flat. Affected individuals eventually develop Irregular heartbeats (arrhythmias) such as abnormally fast (tachycardia) or slow (brachycardia) heartbeats. Arrhythmias may cause sudden episodes of Lightheadedness or loss of consciousness.

The above mentioned symptoms of giant cell myocarditis occur due to congestive heart failure or heart block. These two heart abnormalities are progressive and eventually result in life-threatening complications. In individuals with giant cell myocarditis, the average time from symptom onset to life-threatening complications or heart transplant is five and a half months.

The normal heart has four chambers. The two upper chambers, known as atria, are separated from each other by a fibrous partition known as the atrial septum. The two lower chambers are known as ventricles and are separated from each other by the ventricular septum. Valves connect the atria (left and right) to their respective ventricles. The valves allow for blood to be pumped through the chambers. Blood travels from the right ventricle through the pulmonary artery to the lungs where it receives oxygen. The blood returns to the heart through pulmonary veins and enters the left ventricle. The left ventricle sends the now oxygen-filled blood into the main artery of the body (aorta). The aorta sends the blood throughout the body.

Congestive heart failure is a condition in which abnormal enlargement or widening (dilatation) of one or more of the chambers of the heart results in weakening of the heart’s pumping action, causing a limited ability to circulate blood to the lungs and the rest of the body. This leads to fluid buildup in the heart, lungs and various body tissues. In some cases, all four chambers of the heart may be affected. Symptoms may include Fatigue, Shortness of breath (dyspnea) upon exertion, Swelling of the legs and feet, and Chest pain.

Heart block may be partial or complete. In the mild form of heart block (first degree), the two upper chambers of the heart (atria) beat normally, but the contractions of the two lower chambers (ventricles) slightly lag behind. In the more severe forms (second degree), not all of the atrial beats are conducted to the ventricles. In complete heart block (third degree), the atria and ventricles beat independently. Individuals with first or second degree heart block may not experience symptoms (asymptomatic). However, individuals with complete heart block may experience episodes of unconsciousness (syncope), breathlessness, and/or Fatigue.

What are the causes for idiopathic giant cell myocarditis?

The exact cause of giant cell myocarditis is unknown. Approximately 20 percent of cases occur in individuals with autoimmune disorders suggesting that autoimmunity may play a role in the development of giant cell myocarditis. Autoimmune disorders are caused when the body’s natural defenses against “foreign” or invading organisms begin to attack healthy tissue for unknown reasons.

Autoimmune disorders associated with giant cell myocarditis include inflammatory bowel disease such as Crohn’s disease. Some cases of giant cell myocarditis have been associated with a tumor of the thymus (thymoma). The thymus is a relatively small organ behind the breastbone that is thought to play an important role in the immune system until puberty.

What are the treatments for idiopathic giant cell myocarditis?

Treatment Standard and supportive treatment options for cardiac failure and arrhythmias are recommended. These treatment options may include the insertion of a pacemaker or implantable heart defibrillator.

Affected individuals may require a heart transplant. Affected individuals are often evaluated for heart transplantation shortly after diagnosis. In 20-25% of cases, infiltration of giant cells has recurred after heart transplantation. Immunosuppresssion with drugs that include cyclosporine prolong survival free of transplantation. GCM can recur after therapy in both the native and allografted heart.

What are the risk factors for idiopathic giant cell myocarditis?

Clinically, myocarditis is defined as inflammation of the heart muscle (myocardium). In clinical practice, it is used to describe inflammatory heart diseases that affect cardiac muscle and its function, either directly or indirectly, with a wide variety of infectious and noninfectious causes.

  • Idiopathic giant-cell myocarditis (IGCM) is a rare and frequently fatal type (mortality rate of 50% or more in patients) of myocarditis that often affects relatively young adults.
    •The term idiopathic is used to describe a disease with unknown causes.
    •It is characterized by progressive congestive heart failure, frequently associated with ventricular arrhythmias or heart block.
    •Due to its unidentifiable causes, it escapes diagnosis and defies proper treatments. It responds to immunosuppressive treatment, and transplantation is the treatment of choice for most patients.
  • The pathogenesis of IGCM is unknown, but it is commonly attributed to T cell-mediated autoimmunity.
    •Research shows a meager amount of patients being associated with an autoimmune disorder.
    •The disease can recur in a transplanted heart. So the efficacy of transplantation is called into question.
    •Rarity and deadliness render controlled treatment trials virtually impossible. The diagnosis is uniformly based on historical findings of the biopsy.
    •The causes, effects of treatment, and natural history of idiopathic giant cell myocarditis have not been studied systematically.
chest pain, dyspnea (shortness of breath), heart palpitations, fatigue, and swelling of the ankle.
Inflammation of the upper portion of the heart. It typically mimics more common disorders such as coronary artery disease.
Multi-drug immunosuppressive therapy (cyclosporine, azathioprine, or both), cardiac transplantation.

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