Tachycardia is a heart rate of more than 100 beats per minute. The heart normally beats at a rate of 60 to 100 times per minute, and the pulse (felt at the wrist, neck or elsewhere) matches the contractions of the heart's ventricles, the heart's two powerful lower chambers.
Tachycardia can be part of the body's normal response to anxiety, fever, rapid blood loss or strenuous exercise. It also can be caused by medical problems, such as an abnormally high level of thyroid hormones, called hyperthyroidism. In some people, tachycardia is the result of a cardiac arrhythmia (a heart-generated abnormality of heart rate or rhythm). Tachycardia can also be caused by lung problems, such as pneumonia or a blood clot in one of the lung's arteries.
Bradycardia is an abnormally slow heart rate of less than 60 beats per minute. A normal heartbeat is between 60 and 100 beats per minute.
Here's what happens during a normal heartbeat: The electrical signal that starts a heartbeat comes from the heart's sinus node, the natural pacemaker located in the upper portion of the right atrium. From the sinus node, the heartbeat signal travels to the atrioventricular (A-V) node, located between the atria, and then through the bundle of His (pronounced "hiss") -- a series of modified heart-muscle fibers located between the ventricles -- to the muscles of the ventricles. This triggers a contraction of the ventricles and produces a heartbeat.
It sounds like melodrama: People hear bad news or see blood, and the next thing you know they've fainted.
But it's a reality for many Americans who are prone to fainting (called "syncope" by doctors). Fainting is a loss of consciousness, which leads to falling down or needing to lie down, followed by spontaneous recovery. Fainting by itself is not a problem, but it could be a sign of a serious health condition. It is usually caused by a sudden decrease in blood flow to the brain. Stress, standing too long, and other fairly simple causes can trigger fainting.
Fainting is more common in the elderly. In the young, fainting usually isn't of great concern, although sometimes it can be caused by something serious, such as a heart problem. Other triggers include:
With advances in technology, pacemakers and ICDs generally last 5 to 6 years (depending upon usage and the type of device) and, in most cases, allow a person to lead a normal life. In addition, advances in device circuitry and insulation have reduced the interference risk from machinery, such as microwaves, which, in the past, may have altered or otherwise affected these surgically implanted cardiac devices. Even so, certain precautions must be taken into consideration when a person has a pacemaker or ICD.
The following precautions should always be considered. Discuss the following in detail with your physician:
Although it is generally safe to go through airport security detectors (they will not damage the pacemaker or ICD), inform airport security personnel that you have a pacemaker before you go through security, as the device may set off the alarm. Also, is you are selected for a more detailed search, politely remind security that the hand-held metal-detecting wand should NOT be held over the pacemaker for a prolonged period of time (more than a second or two), as the magnet inside the detecting wand may temporarily change the operating mode of a pacemaker.
Avoid magnetic resonance imaging (MRI) machines or other large magnetic fields, as these may affect the programming or function of the pacemaker. Also, the rapidly changing magnetic field within the MRI scanner can, in theory, cause heating of the pacemaker leads. In general, there are alternatives to MRI for persons with pacemakers, but if your doctor determines that you absolutely need an MRI scan, discuss this thoroughly with your cardiologist before proceeding. If he or she and you agree to go ahead, you should be closely monitored by a cardiologist, with a pacemaker programming device immediately available, during MRI scanning.
Abstain from diathermy (the use of heat in physical therapy to treat muscles).
Turn off large motors, such as cars or boats, when working on them (they may temporarily "confuse" your device).
Avoid certain high-voltage or radar machinery, such as radio or television transmitters, arc welders, high-tension wires, radar installations, or smelting furnaces.
If you are having a surgical procedure performed by a surgeon or dentist, tell your surgeon or dentist that you have a pacemaker or ICD. Some surgical procedures will require that your ICD be temporarily turned off or set to a special mode; however, this will be determined by your cardiologist. Temporarily changing the mode on your pacemaker can be performed noninvasively (no additional surgery is required), but should only be performed by qualified medical personnel.
Always carry an ID card that states you have a pacemaker/ICD. It is recommended that you wear a medic alert bracelet or necklace if you have a device.
You may have to take antibiotic medication before any medically invasive procedure to prevent infections.
Everyone experiences stress and its effects. Short-term effects of stress include headaches, shallow breathing, difficulty sleeping, anxiety, and upset stomach. Long-term chronic stress can increase the risk for heart disease, back pain, depression, persistent muscle aches and pains, and a weakened immune system, according to the National Institute for Occupational Safety and Health.
Chronic stress can affect your emotions and behavior by making you irritable, impatient, less enthusiastic about your job, and even depressed.
To keep stress at a minimum and reduce its effects on your life, you need to find and practice healthy ways to manage it, advises the American Academy of Family Physicians. Try the following techniques to see what works best for you.
Arrhythmias can cause problems by not allowing the ventricles (lower chambers) to fill with an adequate amount of blood because the electrical signal is causing the heart to pump too quickly. Arrhythmias also can prevent a sufficient amount of blood from being pumped out to the body because the electrical signal is causing the heart to pump too slowly or too irregularly.
When the heart doesn't pump blood effectively, the body's organs can't work properly and may shut down or be damaged.
The heart is, in the simplest terms, a pump made up of muscle tissue. Like all pumps, the heart requires a source of energy in order to function. The heart's pumping action comes from a built-in electrical conduction system.