Sudden cardiac arrest occurs when the heart's electrical system malfunctions and produces a lethal arrhythmia known as ventricular fibrillation. This rhythm compromises the ability of the heart to efficiently pump blood to the body and in particular, the brain. If the heart's regular rhythm is not restored in a very short period of time, significant brain function is compromised due to a lack of oxygen and sudden cardiac death (SCD) will quickly follow. Although Cardiopulmonary Resuscitation (CPR) can be utilized to support the circulation of oxygen in the blood; electrical defibrillation with an automated external defibrillator (AED) and certain medications are the only methods to restore a regular heart rhythm.
Who is at Risk?
There are 250,000 to 450,000 sudden cardiac arrests each year in the United States according to a published 2011 Mayo Clinic report. Most events occur in an older population. Factors such as a history of heart disease, genetic make-up, age and lifestyle choices can all contribute to putting an individual at risk. Although extremely rare in an athletic population, the event can still occur and is considered a tragic event when it involves a young athlete.
Causes of Cardiac Arrest
Hypertrophic cardiomyopathy (HCM)is usually the most common cause of cardiac arrest in people under the age of 30. This is a condition in which the heart muscle becomes abnormally thick and impedes the heart's ability to effectively deliver blood to the body. HCM can also trigger an abnormal heart rhythm that can develop into cardiac arrest. Other conditions can include abnormalities of the coronary arteries, long QT syndromes (a heart rhythm disorder) and a variety of other unrecognized heart disorders that can produce a lethal heart rhythm.
Signs and Symptoms
Unfortunately in some cases, sudden cardiac arrest can occur with no previous warning. Certain signs and symptoms to be aware of include unexplained fainting episodes that occurs during exercise or at rest. Shortness of breath, chest pain or sensations of lightheadedness with physical exertion need to be evaluated by medical personnel. An unexplained death of a close family member before the age of 50 is another major warning sign of possible SCD syndrome.
With all of these previously mentioned conditions, a thorough medical exam and physician follow-up are necessary. .
Screening Tests for HCM
If your physician suspects that you may have HCM based upon your family history and reported signs and symptoms, a variety of cardiac tests may be ordered to clearly define the condition. An echocardiogram is the most common noninvasive test utilized to diagnosis HCM. The echocardiogram uses sound waves to produce the image of the heart. Your doctor will be able to see the thickness of your heart's muscles, the flow of blood through the heart's chambers and the functioning of the valves. An electrocardiogram can also be utilized to monitor the electrical activity of the heart. This test can possibly identify abnormal electrical signals that may result from a thickening of the heart muscle. An invasive test known as a cardiac catheterization can be used to measure the blood flow inside of the heart's chambers. During this procedure, a catheter is inserted into an artery in the groin and carefully threaded to the chambers of the heart. Once inside the heart, a variety of measurements can be recorded to identify any problems associated with HCM or other forms of heart disease.
Prevention of SCD
There is no direct method or protocol to follow to prevent SCD. The most prudent measure is to follow a healthy lifestyle by controlling coronary artery disease risk factors. Regular exercise, eating a healthy diet and maintaining an appropriate body weight are good starting points. Controlling blood pressure, diabetes (if applicable), managing stress and cessation of smoking further contributes to heart health. For those individuals with defined heart disease or a genetic predisposition, compliance with a medication regimen along with regular physician consultation are recommended.. Some individuals may also require the use of an implantable cardioverter- defibrillator to guard against lethal arrhythmias.
Gary J. Benedict, MA, CSCS
Benedict is a exercise physiologist with Somerset Medical Center’s Sports Medicine Program, which has five locations in Central New Jersey. For more information, visit www.somersetsportsmedicine.com or call 855-SPRTS-MED.
References
"Hypertrophic Cardiomyopathy"; Mayo Clinic Staff; 2011 http://www.mayoclinic.com/health/hypertrophic-cardiomyopathy/DS00948
"Sudden Cardiac Arrest"; Mayo Clinic Staff; 2010 http://www.mayoclinic.com/health/sudden-cardiac-arrest/DS00764
"Sudden Death in Young People- Heart Problems often Blamed"; Mayo Clinic Staff; 2011 http://www.mayoclinic.com/health/sudden-death/HB00092
"Circulation: Journal of the American Heart Association"; Sudden Cardiac Death: Better Understanding of Risks, Mechanisms, and Treatment: John C. Lopshire and Douglas P. Zipes.; 114:1134-1136,2006