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.