An arrhythmia (ah-RITH-me-ah) is a problem with the speed or rhythm of the heartbeat. During an arrhythmia, the heart can beat too fast, too slow, or with an irregular rhythm. A heartbeat that is too fast is called tachycardia. A heartbeat that is too slow is called bradycardia.
Most arrhythmias are harmless, but some can be serious or even life threatening. When the heart rate is too slow, too fast, or irregular, the heart may not be able to pump enough blood to the body. Lack of blood flow can damage the brain, heart, and other organs.
The heart has an internal electrical system that controls the speed and rhythm of the heartbeat. With each heartbeat, an electrical signal spreads from the top of the heart to the bottom. As it travels, the electrical signal causes the heart to contract and pump blood. The process repeats with each new heartbeat.
Each electrical signal begins in a group of cells called the sinus node, or sinoatrial (SA) node. The SA node is located in the right atrium (AY-tree-um), which is the upper right chamber of the heart. In a healthy adult heart at rest, the SA node fires off an electrical signal to begin a new heartbeat 60 to 100 times a minute.
From the SA node, the electrical signal travels through special pathways to the right and left atria. This causes the atria to contract and pump blood into the heart’s two lower chambers, the ventricles (VEN-trih-kuls). The electrical signal then moves down to a group of cells called the atrioventricular (AV) node, located between the atria and the ventricles. Here, the signal slows down just a little, allowing the ventricles time to finish filling with blood. The electrical signal then leaves the AV node and travels along a pathway called the bundle of His. This pathway divides into a right bundle branch and a left bundle branch. The signal goes down these branches to the ventricles, causing them to contract and pump blood out to the lungs and the rest of the body. The ventricles then relax, and the heartbeat process starts all over again in the SA node.
A problem with any part of this process can cause an arrhythmia. For example, in atrial fibrillation, a common type of arrhythmia, electrical signals travel through the atria in a fast and disorganized way. This causes the atria to quiver instead of contract.
For more information on the heart’s electrical system and a detailed animation, go to the Diseases and Conditions Index article on How the Heart Works.
There are many different types of arrhythmia. Most arrhythmias are harmless but some are not. The outlook for a person with an arrhythmia depends on the type and severity of the arrhythmia. Even serious arrhythmias can often be successfully treated. Most people with arrhythmias are able to live normal, healthy lives
Sudden cardiac arrest (SCA) is a condition in which the heart suddenly and unexpectedly stops beating. When this happens, blood stops flowing to the brain and other vital organs.
SCA usually causes death if it's not treated within minutes.
To understand SCA, it helps to understand how the heart works. The heart has an internal electrical system that controls the rate and rhythm of the heartbeat. Problems with the electrical system can cause abnormal heart rhythms called arrhythmias (ah-RITH-me-ahs).
There are many types of arrhythmias. During an arrhythmia, the heart can beat too fast, too slow, or with an irregular rhythm. Some arrhythmias can cause the heart to stop pumping blood to the body. These are the type of arrhythmias that cause SCA.
SCA is not the same as a heart attack. A heart attack occurs when blood flow to part of the heart muscle is blocked. During a heart attack, the heart usually doesn't suddenly stop beating. SCA, however, may happen after or during recovery from a heart attack.
People who have heart disease are at increased risk for SCA. However, most SCAs happen in people who appear healthy and have no known heart disease or other risk factors for SCA.
Ninety-five percent of people who have SCA die from it—most within minutes. Rapid treatment of SCA with a defibrillator can be lifesaving. A defibrillator is a device that sends an electric shock to the heart to try to restore its normal rhythm.
Automated external defibrillators (AEDs), which often are found in public places like airports and office buildings, can be used by bystanders to save the lives of people who are having SCA.
Marilyn Fowler, Vincent DePaul, Wolfgang Podolski, and Thomas Staton
To honor the 40th anniversary celebration, in June 2009, of the Stonewall Riots, OutHistory.org is, for the first time, publishing nine pages of New York City Police Department records created early on the morning of the rebellion’s start, June 28, 1969.
Reproduced in facsimile with transcriptions, these sometimes hard-to-read but historic documents provide an immediate sense of what the police called an "Unusual Occurrence" at the Stonewall -- the rebellion that has come to symbolize the start of the modern, militant LGBTQ movement for civil rights and liberation.
The NYPD records include new, important, and striking details:
Seven pages of NYPD records reproduced on OutHistory.org were obtained in May 2009 by Jonathan Ned Katz, Director of the website, in consultation with historian David Carter, and two additional pages reproduced were obtained in 1988 by the late Michael Scherker, under the New York State Freedom of Information Law.[7]
For the first time, in the seven documents obtained by Katz, the names of those arrested are not blacked out, providing the public and historians with important new evidence about the rebellion's participants. None of the nine NYPD reports made available on OutHistory.org have earlier been published
Katz asks that anyone with knowledge of the persons arrested or charged, or any knowledge of the police officers named, contact him at: outhistory@gc.cuny.edu. Any information about arrestees Vincent DePaul, Marilyn Fowler, Wolfgang Podolski, and Thomas Staton would be "greatly appreciated," says Katz. Any information about Fowler is of “special interest,” he says.