The heart is composed of four chambers that function to pump blood through the body. The heart walls are made of muscles. Electrical impulses cause the muscles to contract, providing the pumping action. Some conditions, such as myocarditis, can cause damage to the muscles in the heart. When there is damage to the heart, it becomes impaired and the amount of blood it can pump lessens. It can still have enough capacity so that no symptoms appear, but sometimes the heart's ability to pump sufficient blood deteriorates enough that symptoms begin to appear.
Arrhythmia
An arrhythmia is an irregular heartbeat. According to the Mayo Clinic, arrhythmias can be caused by damaged or weak hearts. The signs of arrhythmia include heartbeats that are slow, fast or irregular. An arrhythmia can cause the heart to pump blood ineffectively, which can result in pooled blood. Pooled blood can form a clot which can become dislodged and travel to the brain, causing a stroke.
Myocarditis
Myocarditis is caused by an infection, most often by a virus but sometimes by bacteria, and causes inflammation of the heart. Signs of myocarditis include heart palpitations, including a racing heartbeat and skipped heartbeats. People with myocarditis can experience low energy levels and not be able to tolerate exercise well. Skin can become clammy, and a poor appetite can lead to lessened weight gain in children. Swelling can occur in feet, hands and around the eyes. Other congenital heart conditions, such as an anomalous left coronary artery, cause similar signs.
Acute Coronary Syndrome
When the cells in heart muscles are damaged, pain can result. This pain can be felt in the chest as well as in the neck, jaws, back and abdomen. Pain can radiate to the arms or shoulder. Nausea and lightheadedness are also signs of damaged heart muscle. Labored breathing is another sign of acute coronary syndrome. Laboratory blood tests can detect elevated levels of certain proteins in the bloodstream that result from the damaged cells in the heart.
