The Beat Goes On ... Or Does It?

Sudden Cardiac Arrest (SCA), an electrical malfunction in the heart, has recently been a topic for discussion.

Taking a look at how the heart functions can be confusing.  The heart has two components, mechanical and electrical.

The mechanical is the pulse that can be felt as the blood pumps through the body.  The heart muscle contracting is the “pump.”  How the heart contracts is determined by electrical impulses.  These impulses come from the heart’s natural pacemaker, usually a special group of heart muscle cells called the sinus node.  There are specific paths that the electrical impulses travel causing the heart ventricles to contract, sending blood to the lungs to get oxygen or sending oxygen rich blood through the body.

The pulse or heart rate speeds up or slows down depending upon the demands placed upon your body.  Rest will slow down the heart rate while exercise speeds it up.  In a healthy heart, there is an even heart rate, often referred to as sinus rhythm.  The mechanical system is regulated by the electrical system.

Sudden Cardiac Arrest (SCA) is a condition of an electrical malfunction in the heart.  The heart rate becomes very irregular and dangerously fast.  When a condition called ventricular fibrillation occurs, the ventricles just flutter instead of contracting and they do not send enough blood to the body.  A person may become very dizzy and lose consciousness quickly as there is very little blood reaching the brain.  Unless a regular heart rate and rhythm is restored, death will occur.

Heart Attacks are different than SCA.  A heart attack usually happens when a blockage occurs in one or more of the arteries that supply blood to the heart.  Most often during a heart attack a person will complain about pain in the chest, arm or jaw, nausea or a feeling of being unwell.  Heart attack victims often remain conscious, sometimes even denying that something is wrong.

Sudden Cardiac Arrest (SCA) is not the same as a heart attack.  When a Sudden Cardiac Attack occurs, the person will most likely become unconscious quickly, before ever complaining.  In the athletic population, there may be some underlying cardiovascular disease but SCA can also be caused by a direct blow to the chest, undiagnosed congenital heart conditions, dehydration, hyperthermia or hypothermia.

Emergency treatment is critical; this includes early access to cardiopulmonary resuscitation (CPR) and defibrillation.  Defibrillation is an electric shock delivered through the chest, from a device such as an automated external defibrillator (AED), which can help return a normal heart rhythm.

By Joanna McClarey, MS, ATC LAT

Posted: 2006-08-01