Q. I get confused by different terms I hear used to describe serious heart events, including "heart attack" and "sudden cardiac death." Are they the same thing?
A. No, they are quite different. Here's the background: The heart requires two crucial energy sources to function - nutrients and oxygen supplied by the blood, and electrical impulses generated by specialized tissues within the heart itself. The nutrients and oxygen are needed to fuel and keep the heart muscle cells alive and functional, and the electrical impulses sequentially stimulate different regions of the heart to have it contract in an organized fashion. Blood (containing nutrients and oxygen) is supplied to the heart by tubes (arteries) that traverse the surface of the heart.
A heart attack occurs when cholesterol deposits and a superimposed blood clot form in a heart artery and obstruct the flow of blood to a portion of the heart and thus cause damage to the heart muscle fed by the artery. The primary goal in treating a heart attack is to restore the flow of blood as rapidly as possible by using a clot-busting drug or by inflating a balloon at the end of a catheter to flatten the blockage against the artery wall or both along with inserting a stent to prop open the narrowed artery.
Sudden cardiac death, on the other hand, occurs when there is a short circuit of the electrical impulses of the heart that results most commonly in a condition called "ventricular fibrillation," a disorganized electrical rhythm that results in no effective beating of the heart and thus death of the patient. It is treated by an electrical shock applied to the chest wall that terminates the VF and allows normal electrical activity to resume, along with normal beating of the heart.
Because a heart attack can also lead to VF and death, the terms heart attack and sudden cardiac death often are confused, but the key feature of sudden cardiac death is that it is unanticipated, sudden and unassociated with a heart attack or other similar preceding event. The patient typically is perfectly fine one minute and then suddenly collapses and dies if not properly treated.
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Q. What is the treatment for sudden cardiac death?
A. The treatment consists of applying an electrical shock to the heart to terminate the VF and restore normal electrical heart activity. Two methods are used to do this - one is used by the public at large, and the other is used by health-care providers for patients who have been identified as being at high risk for SCD.
For the public, there are automatic external defibrillators available in many public areas. We have one on the first floor of the UND School of Medicine and Health Sciences building in Grand Forks, for example, and many businesses in the community also have AEDs available. The devices are automated and can be used successfully to treat SCD by bystanders who may have little or no medical training.
On the other hand, patients who have been identified as being at high risk of SCD - especially those who have survived a prior episode of SCD - are treated with an implantable cardioverter defibrillator (ICD), a device that is like a pacemaker and is implanted under the skin in the chest, but it functions in a similar manner as an AED.
