Cardiac Arrest Symptoms and Causes

Singer Michael Jackson died on June 25, 2009, after being rushed to a hospital suffering from cardiac arrest.




Cardiac arrest is the sudden loss of cardiac function, when the heart abruptly stops beating. A person whose heart has stopped will lose consciousness and stop normal breathing, and their pulse and blood pressure will be absent. Unless resuscitative efforts are begun immediately, cardiac arrest leads to death within a few minutes. This is often referred to by doctors as "sudden death" or "sudden cardiac death (SCD)."

Ventricular fibrillation is the most common cause of cardiac arrest. Ventricular fibrillation occurs when the normal, regular, electrical activation of heart muscle contraction is replaced by chaotic electrical activity that causes the heart to stop beating and pumping blood to the brain and other parts of the body. Permanent brain damage and death can occur unless the flow of blood to the brain is restored within five minutes. Heart attack is the most common cause of ventricular fibrillation. Less common causes of cardiac arrest include respiratory arrest (loss of breathing function), choking, trauma, electrocution, and drowning.

Early cardiopulmonary resuscitation (CPR) and defibrillation (electrical impulses delivered to the chest to restore normal heart rhythm) are the only way to reverse a cardiac arrest. These lifesaving measures must be instituted within a few minutes after cardiac arrest in order to have any chance of success. For every minute that passes without defibrillation, a person's chances of survival decrease by 7% to 10%. In areas where emergency medical services are able to provide defibrillation within five to seven minutes, the survival rate for cardiac arrest has been reported to be as high as 49%. It is rare for a resuscitation to be successful if more than ten minutes have elapsed following a cardiac arrest.

While having coronary artery disease or having a heart attack can increase a person's risk for having cardiac arrest, a heart attack is not the same thing as cardiac arrest. A heart attack (myocardial infarction) occurs when a portion of the heart muscle dies due to lack of blood flow and oxygen to a specific area of the heart. Symptoms of a heart attack typically include chest or other upper body discomfort and shortness of breath. A heart attack can precipitate sudden onset of ventricular fibrillation and cardiac arrest. Heart attack victim that develops ventricular fibrillation will lose consciousness.

Cardiac arrest is obviously a serious medical emergency. The mortality (death rate) from cardiac arrest can be decreased by providing immediate CPR and prompt defibrillation. Many public places are now equipped with automated external defibrillators (AEDs) that allow lay persons to provide emergency defibrillation in case of cardiac arrest.
By.Melissa Conrad Stoppler, MD

The science of sudden cardiac arrest.

Journalists and politicians across the country were in shock Friday afternoon at news that Tim Russert, the prominent and beloved NBC correspondent, had collapsed and died suddenly of a heart attack in the network's Washington office. Russert had previously been been diagnosed with several risk factors for a sudden heart attack, including coronary artery disease and diabetes. But his death is still a sad reminder that cardiac arrest can strike anyone without warning—and that when it does, it is often fatal.




Sudden cardiac arrest accounts for 310,000 deaths in America every year, or 850 a day—more than those caused by breast cancer, lung cancer, stroke, and AIDS combined. But despite how common the condition is, doctors know little about what predisposes one person to it and not another. The National Institutes of Health is currently mounting a major study at 60 trial sites across the country to try and identify risk factors related to both genes and lifestyle, and will begin enrolling patients this week. For now, says Jeffrey Olgin, a cardiologist at the University of California, San Francisco, assessing risk is "a very, very difficult thing. I can't look at you and say you have a 10 percent chance of dying from this."

Doctors do know that a previous history of heart attacks is the most important risk factor. Vice President Dick Cheney, who has suffered four heart attacks, wears a pacemaker to ward off sudden arrest. Age and gender also play roles, and as a 58-year-old male, Russert was in high-risk groups; the average age for suffering sudden cardiac death is between 58 and 62. Other factors involved in all forms of cardiovascular disease—family history, smoking, diabetes, and obesity—can come into play. Russert had some of these too; he had been previously diagnosed with diabetes and and coronary artery disease, and his autopsy on Friday showed an enlarged heart. But doctors do not know which of these factors is most important in causing a sudden heart attack, or why. They also do not know if stress plays a role at all; the data is unclear. "Most of us do not think it is terribly relevant," says Steven Nissen, chair of cardiovascular medicine at the Cleveland Clinic and a past president of the American College of Cardiology. After all, he notes, "many people in this world have stressful jobs," and they don't all die of of heart attacks.

What is clear is that there are ways to lower one's risk of sudden cardiac death: eat healthy, exercise, don't smoke, and take aspirin or statins. The trouble, though, is that patients often don't think they're at serious risk until they are actually experiencing an attack. In about a third of all sudden deaths due to coronary disease, death is the first sign that anything major is wrong. Russert himself was exercising and taking medication for his coronary artery disease, which was asymptomatic. He performed well in a stress test two months ago.

A sudden cardiac arrest is, of course, unexpected, but the process that causes it may begin many years before. "In middle-aged men, it's virtually always caused by degeneration in the wall of a coronary artery," says Dr. Thomas Risser, a cardiologist at Cambridge Health Alliance. "It starts with fat deposits and inflammation, and these plaques just lie there silently." They can do so for decades until one of them fractures, at which point the body tries to plug the hole with a blood clot—and ends up blocking off the whole blood vessel. This condition is known as a coronary thrombosis, and it is extremely dangerous. The heart muscle, now starved for oxygen-rich blood, falls out of rhythm; it quivers but doesn't pump. "In the final stage, the ventricle looks like a bag of worms. It's chaotically beating very fast and therefore is completely inefficient at pumping blood," says Olgin. "Soon, there's no blood flow anywhere, including the brain, and people just suddenly collapse."

Once a patient's heart has gotten out of a normal rhythm, it can't get back on beat on its own. But a defibrillator—either an internally implanted one such as Cheney's, or an external one with electrical paddles—can get the heart beating steadily again, provided it is used in time. "If people get there with an external defibrillator within three minutes of a collapse, the survival rate for the kind of thing Russert may have had can be as high as 50 percent," says Robert J. Myerburg, a cardiologist at the University of Miami Miller School of Medicine. "But time is the whole issue. If you rely on fire/rescue teams to bring one, the chance of survival drops seven to ten percent" with every minute that passes after a collapse. It's unclear whether Russert had access to a defibrillator. His internist said on Friday that "resuscitation" had begun immediately after the collapse and continued at the hospital, to no avail.
http://www.newsweek.com/id/141450

Omega-3 And Sudden Cardiac Arrest

Not just like Michael jackson.....Sudden Cardiac Death (SCD) is responsible for numerous deaths in the U.S. and other countries around the world. It is not the same as a heart attack. A heart attack normally occurs when advanced atherosclerosis (clogging of the arteries) slowly starves the heart causing irreversible damage. The heart finally cannot function properly and stops. Sudden cardiac death occurs when the electrical impulses that control heart function become erratic resulting in an irregular heartbeat (arrhythmia). When the arrhythmia is severe enough the heart suddenly stops, starving the brain of needed blood. Death often follows quickly unless emergency care is administered immediately. Often sudden cardiac death occurs when no other heart disease is detected.




It has long been understood that eating fish can reduce the likelihood of heart attack and other cardiovascular diseases. The reason? Fish, especially cold-water fatty fish, is high in two omega-3 polyunsaturated fatty acids (PUFA). These two fatty acids are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Omega-3 has been shown to reduce the build-up of artery clogging atherosclerosis and keep blood platelets from sticking together thus reducing the risk of heart attack and stroke.

But more recent studies suggest that omega-3 fatty acids also have an effect on the dangerous arrhythmias that can cause sudden cardiac death by regulating the impulses that control heart rhythm.

One study involved the use of mycocytes (cells that beat independently). By adding the free fatty acids to these cells arrhythmias were aborted. When the fatty acids were extracted from the mycocytes the arrhythmias would reoccur thus indicating that omega-3 fatty acids have a stabilizing effect on heart rhythm. The apparent mechanism for controlling rhythm involved cell ion channels, proteins that control the movement of sodium, calcium and potassium ions across the membrane of the cell.

Another study, conducted by Danish researchers, examined the relationship between heart rate variability and omega-3 fatty acids in healthy subjects. It had already been determined that heart arrhythmias could be positively impacted in patients who were recent heart attack victims. These researchers wanted to determine if people otherwise free of heart disease could gain the same arrhythmia controlling benefits from omega-3 fatty acids.

Sixty healthy adults were randomly divided into three groups. The first group received daily supplements containing 6.6 g of omega-3 (containing 3.0g EPA and 2.9g DHA). Group two received 2.0g of omega-3 (containing 0.9g EPA and 0.8g DHA). The remaining group received only an olive oil placebo. The supplements were given for 12 weeks. Before and after the supplements were consumed heart rate variability and blood cell fatty acids were measured. It was found that heart rate variability was favorably influenced by the amount of omega-3 consumed. In other words, the more omega-3 one consumed the higher the heart rate variability, especially in men with low heart rate variability before supplementing.

The researchers concluded that omega-3 fatty acids positively affected heart rate variability thus having a protective effect on heart function. These finding were similar to those of earlier studies showing that omega-3 positively affects heart rhythm in patients who had suffered a previous heart attack. Since sudden cardiac death is the result of erratic heart rhythm, omega-3’s heart protective qualities show great promise in the fight against sudden cardiac arrest. The mechanical studies completed by these and other researchers seemed to confirm other studies that the oral ingestion of fish and fish oils provide prophylaxis for the prevention of fatal cardiac arrhythmias when taken regularly in small amounts. In simple terms, consuming fish and fish oil supplements can save lives.
by: Greg Post