DEAR DR. DONOHUE: Please answer some heart attack questions for me. I can’t find the answers. Is it possible to have a heart attack and not know it? What’s going on when a heart attack happens? What’s considered standard treatment? – P.R.

ANSWER: A heart attack takes place when there’s an obstruction of blood flow in an artery serving a particular area of heart muscle. It’s when plaque ruptures. Plaque is a mound of cholesterol, fat, protein, platelets, white blood cells and other material that clings to and invades the walls of arteries. Some plaque is called “vulnerable.” It is covered by a fragile coat that tears easily. When the tear occurs, the body attempts to repair it by covering it with a clot. The clot grows and completely occludes the artery. Blood flow stops. The heart muscle that is deprived of blood dies. That’s a heart attack.

Usually a person having a heart attack feels crushing or squeezing pain in the left chest. Pain can radiate from the chest to the neck, jaw, teeth, shoulders, arms or the back. In older people, pain is often less intense, and they might complain of suddenly feeling very short of breath or of feeling quite dizzy. In as many as one-quarter of victims, regardless of age, there is no pain, or, if there is, it is so minor that people dismiss it as being nothing.

Standard treatment of a heart attack is the administration of clot-preventing drugs like aspirin and heparin. Oxygen, morphine and medicines to raise blood pressure are given as needed. Then a decision is made about using clot-busting medications or arranging for immediate angioplasty. Angioplasty is the procedure where a catheter – a flexible, soft tube – is passed into the clotted-off heart artery from an artery in the groin. When the clot site is reached, a balloon at the catheter tip is inflated to smash the clot.

DEAR DR. DONOHUE: You wrote that hepatitis A is an acute illness that can, on occasion, lead to death. However, you also wrote that all three kinds of hepatitis – A, B and C – cause liver cell death. You also said that hepatitis A does not cause chronic liver disease, cirrhosis or liver cancer. If it does not cause liver disease, cirrhosis or liver cancer, what organs does hepatitis A damage? – C.J.

ANSWER: The hepatitis A virus does not cause chronic liver disease. Underline “chronic” – it means of “long duration, lifelong.” Hepatitis A causes an acute infection of the liver.

Liver cells do die during the acute infection, but most people make a complete recovery. They generate new liver cells. For a very small number, hepatitis A ends in death during the acute illness. It does not lead to a chronic infection, as the other two kinds do. It does not cause liver cirrhosis or liver cancer.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.