Issues Surrounding Sudden Cardiac Arrest and Early Defibrillation

Sudden Cardiac Arrest

Preventing Death from Sudden Cardiac Arrest

Television programs such as ER and Rescue 911 have familiarized the public with external defibrillators - the devices used to shock victims whose hearts have stopped or faltered. There is a common misperception that these people have collapsed from heart attacks, but they are actually victims of sudden cardiac arrest - a leading cause of death in the United States. Unlike a heart attack, in which blood flow to the heart muscle is temporarily blocked, sudden cardiac arrest is usually triggered by an electrical malfunction of the heart that causes the heart's pumping function to abruptly cease. When the heart stops pumping blood, the victim immediately loses consciousness, and - without intervention - will die within minutes.

Sudden cardiac arrest, or sudden cardiac death as it is sometimes called, strikes an estimated 350,000 people per year in the United States, representing a major public health problem. Sudden cardiac arrest is unpredictable, often striking patients who have no previous symptoms. Presently in the United States, the probability of surviving a sudden cardiac arrest is less than one in 20. Yet, definitive treatment exists and tens of thousands of these deaths each year could be prevented with immediate intervention. Defibrillation, the treatment delivered by the defibrillators seen on television programs, is highly effective in real life for restoring a normal heartbeat to victims of sudden cardiac arrest. The problem is that defibrillators often reach the scene too late - or not at all.

Sudden Cardiac Arrest: Causes and Incidence

When Loyola Marymount University basketball star Hank Gathers collapsed during a game and died several years ago, people were shocked that someone so young and fit could be stricken suddenly and unpredictably. Gathers' death heightened public awareness of sudden cardiac arrest and its ability to end a life within minutes, but also raised questions about who it strikes and why. Although there are several causes of sudden cardiac arrest, the most common is ventricular fibrillation (VF), in which the electrical signals that normally induce a regular, coordinated heartbeat suddenly go awry, instead causing ineffective ventricular "quivering" or fibrillation. The lack of blood flow that results from VF causes a loss of pulse, blood pressure, and consciousness almost immediately and results in death in a matter of minutes.

While VF is the most common precursor of sudden cardiac arrest, little is known about its causes. Most cardiac arrests are sudden not only in the sudden onset of symptoms but also in the lack of warning signs. It is the lack of warning and limited time for intervention, not a lack of effective treatment, which account for the high death rate following sudden cardiac arrest.

Treatment of Sudden Cardiac Arrest: Early Defibrillation

Unlike diseases like cancer or AIDS, sudden cardiac arrest can be effectively and inexpensively treated. The vast majority of sudden cardiac arrests are caused by VF, which can often be reversed with defibrillation. A defibrillator stops VF by delivering an electrical shock to the heart via electrode pads that are applied to the patient's chest. This shock eliminates VF and enables the heart to resume coordinated, rhythmic beating so that effective pumping of blood can resume.

Studies have clearly demonstrated that survival rates are high when defibrillation treatment is administered within the first few minutes following sudden cardiac arrest. In three studies of cardiac arrest occurring in supervised cardiac rehabilitation centers, more than 90 percent of victims were successfully resuscitated. Unfortunately, most cardiac arrests do not occur in supervised settings, and often when, or if help arrives with a defibrillator, it is too late. The likelihood of successful resuscitation decreases by approximately 10 percent with each minute following sudden cardiac arrest. After 10 minutes, very few resuscitation attempts are successful.

Victims who survive sudden cardiac arrest have an excellent prognosis: 83 percent survive for at least one year, and 57 percent survive for five years or longer. When analyzed by age group, survival rates are comparable with those for members of the same age group who have not experienced sudden cardiac arrest. These statistics reveal the opportunity for early intervention to preserve productive and fulfilling lives for victims of sudden cardiac arrest.

In 1990, the American Heart Association developed what it calls the Chain of Survival - a series of four crucial steps toward resuscitation. Step One is early access to care (i.e., calling 911 or another emergency telephone number); Step Two is early cardiopulmonary resuscitation (CPR); Step Three is early defibrillation; and Step Four is early institution of advanced life support as needed. A break in any of the four links in the chain can compromise the victim's chance for survival; however, early defibrillation is recognized as most important for victims of sudden cardiac arrest. While CPR is effective for temporarily maintaining oxygenation of the blood and blood flow to the brain, it is only a stop-gap measure, buying time for the victim until a defibrillator is available. Defibrillation is the only effective method of restoring normal cardiac rhythm and resuscitating the victim following sudden cardiac arrest from VF. Defibrillation should be administered as quickly as possible following cardiac arrest, ideally by the first responder, i.e., the first appropriately trained person to arrive on the scene.

Limited Access to Defibrillators - The Weak Link in the Chain of Survival

Since early defibrillation is so critical to survival from sudden cardiac arrest, it stands to reason that defibrillators should be widely available and accessible. However, that has not been the case in the United States. Only 50 percent of ambulances, 10-15 percent of first-response fire department vehicles, and less than 1 percent of police vehicles are equipped with defibrillators.

When defibrillators were first developed, operators determined whether or not to deliver a shock by reading complex electrocardiograms (ECGs) to interpret the patient's heart rhythm. This was simplified in the 1980s with the development of the automatic external defibrillator (AED). The AED automatically interprets the victim's heart rhythm, identifies ventricular fibrillation, and advises the operator whether or not a shock is appropriate.

This advance greatly decreased the amount of training required to use a defibrillator; responders using defibrillators no longer needed to be physicians or highly trained paramedics. As a result, an increasing number of people could potentially use a defibrillator to save a person experiencing sudden cardiac arrest. Indeed, lay people and even children have successfully saved lives by using AEDs.

Despite this improvement in defibrillator technology, access to defibrillators is still limited in many communities. In Seattle, Washington, where first-responder defibrillation has been extended to emergency medical technicians (EMTs) and firefighters, nearly 30 percent of sudden cardiac arrest victims are resuscitated, compared with fewer than five percent nationwide. The time from patient collapse to delivery of the first shock is an average of seven to eight minutes. In Rochester, Minnesota where police officers carry AEDs because they often reach the scene of an arrest first, the resuscitation rate has jumped to over 45%. A study published in the Journal of the American Medical Association found that in New York City, where the average time from patient collapse to delivery of the first shock is more than 12 minutes, only one percent of patients survive sudden cardiac arrest. New York's low survival rate is attributable in part to a low rate of public CPR knowledge, and in part to traffic congestion and difficulties in reaching victims in high-rise buildings, all of which lengthen the elapsed time at every step in the Chain of Survival. If Seattle and Rochester's high survival rates could be achieved nationally, as many as 100,000 unnecessary deaths could be prevented each year.

Improving Access to Defibrillators

The American Heart Association endorses the position that defibrillators be widely deployed in the hands of first-response personnel as a means of increasing survival rates. This entails installing defibrillators in more first-response vehicles and extending the use of defibrillators to an expanded group of physician-authorized responders such as emergency medical technicians, fire service personnel, police officers, flight attendants, and safety officers. Until recently, wider deployment of defibrillators had been constrained by deficiencies in AED technology itself, including extensive daily maintenance, technical complexity, and high cost. A new generation of defibrillators that is now available addresses these shortcomings and is revolutionizing the treatment of sudden cardiac arrest by making it practical for communities, as well as public and private organizations, to equip a broader range of responders with these life-saving devices.

Cost Effectiveness of Defibrillation

One study estimated the cost per year of life saved with defibrillation by specially trained emergency medical personnel at $2,100-2,300. This is far less than most interventional therapies, such as renal dialysis ($35,000-45,000 per year of life saved) and cholesterol reducing drug therapy ($50,000 per year of life saved).

Our country has invested extensively in many areas of emergency care, from 911 emergency telephone numbers to highly equipped emergency vehicles operated by extensively trained personnel. An estimated five million citizens are trained in CPR. Despite this significant investment in the emergency-response infrastructure, survival from sudden cardiac arrest remains unacceptably low, largely because early defibrillation remains the weak link in the Chain of Survival. The incremental cost of strengthening this last link by widely deploying defibrillators among first-response personnel is likely to be a worthy investment for the emergency care infrastructure given the tremendous life-saving potential of early defibrillation.

Automated External Defibrillators (AEDs)

Limitations of AEDs

Although all AEDs cleared by the FDA must demonstrate their effectiveness, previously available devices do not have the characteristics that make widespread deployment practical. These devices require a high level of maintenance with batteries that must be checked daily to ensure that they are properly charged. They are also large and cumbersome, weighing as much as 25 pounds. They are complicated to use and require frequent re-training of operators. And their cost can be prohibitive, ranging from $5,000-$8,000 with additional expenses required for accessories.

Technological Advances In AEDs

While AEDs have proven the benefits of early defibrillation, a new-generation AED incorporates all of the characteristics required for widespread deployment in order to revolutionize the treatment of SCA. This device is significantly smaller, weighing less than four pounds with a size roughly that of a hardcover book. It is extremely rugged and requires no maintenance for extended periods of time. Most importantly, this device is easy to use, with just a few simple steps guided by both comprehensive voice and text prompts. (For more detail on this new AED, see the Technology category).

With these technological advancements, AEDs have the potential to assume a role similar to that of the fire extinguisher - omnipresent and always ready in case of emergency. In addition to first responders such as police officers and firefighters, this new AED is appropriate in a variety of other settings. For example, companies with large campuses or high-rise buildings without easy access, such as Boeing, Dow Chemical Company, General Mills, General Motors, Gillette, Home Depot, IBM, Lucent Technologies, and many more now keep an AED on the premises for use by physician-authorized responders. American Airlines and Delta Air Lines carry them on board all their aircraft for flight attendants to use. In addition, many health clubs, golf courses, hotels, and casinos across the country also now make AEDs accessible. AEDs are beginning to expand into the realm of the hospital, where they enable nurses to become first-tier responders, eliminating the wait required for the assembly of a code team. Walk-in medical clinics and urgent care clinics also are keeping AEDs on hand. With ever-increasing access to easy-to-use AEDs, more and more victims of sudden cardiac arrest are being given the chance to survive.

Liability Concerns Surrounding Widespread Use of AEDs

One of the barriers to widespread access to AEDs is the concern over legal liability. According to legal experts, however, there are very few true legal impediments to the widespread use of AEDs. In fact, it is increasingly clear that the use of AEDs represents the standard of medical care. For example, the American Heart Association strongly endorses the use of AEDs by all emergency responders whose jobs require that they perform basic CPR. They believe that the failure of emergency personnel to have a defibrillator available when treating a victim of sudden cardiac arrest is increasingly difficult to defend. In addition, the Department of Transportation incorporated defibrillation as a basic life-saving skill in the 1995 national EMT curriculum. According to the AHA, the use of AEDs may ultimately extend beyond healthcare professionals and trained emergency personnel to trained citizens. Most states have Good Samaritan laws in place to protect those who help in an emergency situation. With the standard of care now including the use of life-saving devices such as AEDs, the failure to allow, or even mandate, the use of AEDs by first response personnel could increasingly result in enormous legal liability for organizations responsible for providing emergency care. Recent court cases tend to support the concept that lack of an AED may expose companies to litigation. In addition, the availability and cost effectiveness of AEDs, and their demonstrated ability to save lives, may persuade more judges and juries to reach similar judgments.

Conclusion

A recent public health scare centered on a very rare flesh-eating bacterium that killed a handful of victims. The attention given sudden cardiac arrest, even though hundreds of thousands of Americans die from it each year, pales by comparison. Yet, definitive therapy for sudden cardiac arrest exists, breakthrough technology is available to overcome the barriers to widespread deployment of AEDs, and the legal concerns have been addressed, so what needs to be done to prevent so many unnecessary deaths from occurring?

At a low cost relative to other life-saving procedures, thousands of unnecessary deaths from sudden cardiac arrest could be prevented with the widespread deployment of defibrillators to more first-response vehicles and to places where large groups gather such as office buildings, corporate campuses, airplanes, health clubs, stadiums, and theaters. This would help shorten the time from collapse to delivery of the first shock. While there has been widespread training and awareness in the lay community about CPR, the public must come to understand that the defibrillator is ultimately the victim's lifeline - CPR will only help to bridge the time gap until this life-saving therapy arrives. Thus, the greatest help the public may provide is to advocate that defibrillators be disseminated throughout the community, workplace, and any other venues where large groups of people gather or response times may contribute to diminished chance of survival. The first-responder force be expanded to include a broad range of physician-authorized personnel, such as fire service and ambulance personnel, police officers, flight attendants, security guards, safety officers, and any other healthcare professional or appropriately trained individual with a duty to respond. Only through dramatic improvement in defibrillator access will sudden cardiac arrest lose its distinction as one of the nation's leading killers.