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Tuesday, September 7, 2010

Sudden Cardiac Arrest – Is There Hope?

On June 25, 2009, Michael Jackson, well-known as the King of Pop, died of cardiac arrest.

Cardiovascular disease (CVD) is the leading cause of mortality in the U.S. and the majority of CVD deaths are attributable to Sudden Cardiac Arrest (SCA) which claims more than 250,000 lives each year. One person dies of SCA-related events every two minutes. This is equivalent to more 650 deaths each day. Each year, more people die from SCA than from breast cancer, lung cancer, stroke, or AIDS combined. 95% of SCA cases are fatal and two-thirds of SCA events occur in people without any previous indications of heart disease.

According to the American Heart Association (AHA), SCA occurs when electrical impulses in the heart become rapid or chaotic, which causes the heart to suddenly stop beating. The blood supply to the rest of the body ceases and without the blood supply, the oxygen supply is also cut off, resulting in tissue damage and death. Because of its suddenness, cardiac arrest is also called sudden death or sudden cardiac arrest (SCA) or sudden cardiac death.

Cardiac arrest is not a heart attack. It is a widespread misconception that SCA is synonymous to a heart attack. In order to educate the public, the AHA and the Sudden Cardiac Arrest Coalition (SCAC) are quick to point out the difference. A heart attack or myocardial infarction occurs when the arterial supply or coronary arteries are compromised or blocked, thus cutting off the blood supply to the heart. And if allowed to continue will eventually lead to infarction or injury to the heart muscles. “The term “massive heart attack” is often wrongly used in the media to describe sudden death.” The SCAC has a beautiful analogy to explain to the general public: “If you think of your heart as a house – SCA would be a problem with the electricity; a heart attack would be a problem with the plumbing.”

Cardiac arrest is not heart failure. In cardiac arrest the electrical failure of the heart is sudden and unexpected, whereas heart failure is progressive but slow, thus allowing time for heart failure patients to eventually be considered as possible heart transplant candidates.

Some people are more at risk for SCA than others.

(1) SCA deaths are more common among women aged 35 to 44 years old compared to men of the same age. Women have also a less chance of recovering from SCA than men.

(2) African Americans have a much higher risk to suffer from SCA-related events than whites and other ethnic groups. They also have less than a 1% chance of surviving, much lower compared to the 5% survival chance in the general population.

(3) Some underlying conditions especially heart problems make people more susceptible to SCA than others. Yet, even healthy individuals without any health problems may suffer from SCA.

There many things that can cause the heart to stop abruptly. Most of the cardiac arrests that lead to sudden death occur when the electrical impulses in the diseased heart become rapid (ventricular tachycardia) or chaotic (ventricular fibrillation) or both. This irregular heart rhythm (arrhythmia) causes the heart to suddenly stop beating. Some cardiac arrests are due to extreme slowing (bradycardia) of the heart.

So what causes the electrical system of the heart to fail?

(1) Cardiovascular disease. According to the AHA, in 90% of adult victims of sudden cardiac death, two or more major coronary arteries are narrowed by fatty buildups. Scarring from a prior heart attack is found in two-thirds of victims.

(2) Electric shock/electrocution. A strong electric shock, e.g. electrocution and lighting strikes can cause the heart to stop. Conversely, it also takes an electric shock to restart the heart.

(3) Respiratory arrest. When people cannot breathe during to choking, suffocation, drowning, or injury, SCA can also occur.

(4) Strenuous physical activity. There are cases of athletes suddenly collapsing during training or competitions. This may be caused by underlying heart abnormalities. Adrenaline released during intense physical activity acts as a triggering mechanism for arrhythmia and sudden death.

(5) Medications. Certain drugs, prescription or illegal, can interfere with heart rhythms. When taken in excessive amounts, certain medications can completely stop the heart. Some of these drugs are: performance-enhancing drugs used in sports, prescription drugs for heart problems, pain, and sleeping disorders especially insomnia, and illegal or “recreation” drugs.

(6) Trauma. A strong sudden blow to the heart during sports competition for example, can cause a condition called Commotio cordis that can trigger ventricular fibrillation and lead to SCA. An injury that damages the heart can also lead to cardiac arrest.

(7) Unknown causes. Unfortunately, a lot of cases of SCA are put down to unknown causes, often in young, healthy people with no apparent heart disease or other risk factors.

How can death from SCA be prevented? Not easy, in fact, 95% of SCA cases are fatal. To have a chance of surviving, victims of SCA must receive life-saving defibrillation within the first 4 to 6 minutes of an attack, when brain and organ damage start to occur.

Following are ways to restart the heart during SCA:

(1) Defibrillators. These are the so-called paddles applied to the chest to deliver an electric shock to make the heart beat again. Defibrillators are only available in emergency services and hospitals and can only be operated by medical professionals.

(2) Automatic External Defibrillators (AEDs) are battery-operated portable defibrillators. Current AEDs are designed to be operable by almost anybody, even without formal medical training. AEDs are now widely available in public places where crowds tend to gather.

(3) Implantable Cardioverter Defibrillators (ICDs) are implanted in patients who have a high risk for cardiac arrest from recurrent, sustained ventricular tachycardia or fibrillation. An ICD automatically reacts to irregular rhythms of the heart and applies an electrical jolt to restore normal heart rhythms. According to the SCAC, ICDs are 98% effective at protecting those at risk for SCA, but only 35 percent of patients who require this device have one. According to a New York Times article “in the last two years the number of patients receiving defibrillators has actually declined, as more doctors and patients decide the risks and uncertainties the devices pose may outweigh their potential benefits.” More recently, the European Society of Cardiology (ESC) issued a statement on driving restrictions for patients implanted with ICDs.

(4) Cardiopulmonary resuscitation (CPR) works by attempting to maintain the blood flow to the heart and the brain until more effective defibrillation can be performed. About 80% of SCA cases happen at home, just like in the case of Michael Jackson. Therefore, CPR needs to be performed by bystanders, family members, and people, even without medical training. Unfortunately, only a third of out-of-hospital SCA victims receive bystander CPR and many die before the arrival of emergency services. Immediate effective bystander CPR can double or even triple a victim’s dismal survival chances. A 2008 survey by the AHA revealed that 80% of respondents said they were willing and able to do something to help if they witnessed a medical emergency. However, only a few (12%-20%) are confident that they would know when it is appropriate to perform CPR or use an AED.

So, what could have caused Michael Jackson’s cardiac arrest? Some of the possible causes based on Jackson’s personal and medical history (Source: heartwire) include:

(1) Overdose of prescription medications. Expectedly this is the most popular theory but without a toxicology report, this remains speculative. It seems that Jackson was on prescription painkillers and two that may possibly be implicated in his death are Demerol (meperidine) and Oxycontin (oxycodone). Dr Douglas Zipes of Indiana University Medical School, Indianapolis tells heartwire: “It’s really where I would go, but it’s all very speculative at this point. We know that depending on the type of painkillers, they can depress respiration. The initial stories are that he gradually slowed his respiratory rate and stopped breathing. That can create hypoxia, which can produce ventricular fibrillation.” The use of Diprivan for his insomnia has also been implicated. Without an official toxicology report, all these however, remain as speculations.

(2) Complications from lupus. It is not a well-known fact, but Jackson seemed to have been suffering from lupus, an inflammatory disease that can also affect the heart and lead to a heart block.

(3) Other heart diseases. A heart attack has also been speculated but the singer did not have a history of heart disease and no other heart conditions were detected during the most recent routine physical exam.

(4) Stress. It cannot be denied that Jackson was under too much stress. He was having major financial problems and he was busy preparing for an international concert tour about to start in two weeks.

It is without doubt that SCA is a major and deadly health concern. Advocacy groups including the American Heart Association and the Sudden Cardiac Arrest Coalition are actively involved in bringing this issue to the forefront. There are even those who advocate the routine placement of AEDs in the homes of patients who are at high risk.

Yet SCA mortality remains high even in the setting of bystander CPR and AEDs. WE have a long way to go!