Heart disease is the greatest cause of death in the United States. Often, these deaths come in the form of an acute myocardial infarction, or a heart attack. This occurs when blood flow to the heart is interrupted, causing potentially fatal damage to the heart muscle. A heart attack has many symptoms, including sudden pain in the chest. This pain may radiate to the neck, back, and often to the left arm, as the heart is on the left side of the body.
Check for other symptoms of a heart attack. If your left arm pain is heart related it will be accompanied by pressure on your chest, as though there was a weight laying on your ribcage. A squeezing sensation in the chest, shortness of breath, sweating, and feeling faint or nauseated are other symptoms that will accompany heart-related left arm pain. Call 911 immediately, and take aspirin immediately thereafter. Chewing a 325 mg tablet of fast-acting aspirin will help stave off heart failure.
If you don't experience other symptoms of heart attack, consider other causes of the arm pain. Trauma to the arm, neck or shoulders can cause pain to radiate through the arm. Chronic conditions like tendonitis, arthritis, and even diabetes may be the source of the pain. If you know that you're susceptible to these conditions, the pain in your left arm is probably not heart related.
If the pain doesn't go away with painkillers and time, consult your doctor. You may be suffering from an underlying medical condition such as peripheral nerve compression or artery disease, which may or may not be heart related.