Filed under: Heart & Vascular
Heart rhythm problems (heart arrhythmias) occur when the electrical impulses in your heart that coordinate your heartbeats don't work properly, causing your heart to beat too fast, too slow or irregularly.
Heart arrhythmias (uh-RITH-me-uhs) are often harmless. Most people have occasional, irregular heartbeats that may feel like a fluttering or racing heart. However, some heart arrhythmias may cause bothersome — sometimes even life-threatening — signs and symptoms.
Heart arrhythmia treatment can often control or eliminate irregular heartbeats. In addition, because troublesome heart arrhythmias are often made worse — or are even caused — by a weak or damaged heart, you may be able to reduce your arrhythmia risk by adopting a heart-healthy lifestyle.
Arrhythmias may not cause any signs or symptoms. In fact, your doctor might find you have an arrhythmia before you do, during a routine examination.
Some people do have noticeable arrhythmia symptoms, which may include:
Noticeable signs and symptoms don't always indicate a serious problem. Some people who feel arrhythmias don't have a serious problem, while others who have life-threatening arrhythmias have no symptoms at all.
When to see a doctor
Arrhythmias may cause you to feel premature heartbeats, or you may feel that your heart is racing or beating too slowly. Other signs and symptoms may be related to reduced blood output from your heart. These include shortness of breath or wheezing, weakness, dizziness, lightheadedness, fainting or near fainting, and chest pain or discomfort. Seek urgent medical care if you suddenly or frequently experience any of these signs and symptoms at a time when you wouldn't expect to feel them.
Ventricular fibrillation (VF) is one type of arrhythmia that is deadly. It occurs when the heart beats with rapid, erratic electrical impulses. This causes pumping chambers in your heart (the ventricles) to quiver uselessly, instead of pumping blood. Without an effective heartbeat, blood pressure plummets, cutting off blood supply to your vital organs. A person with ventricular fibrillation will collapse within seconds and soon won't be breathing or have a pulse. If this occurs, follow these steps:
Portable defibrillators, which can deliver an electric shock that may restart heartbeats, are available in an increasing number of places, such as in airplanes, police cars and shopping malls. They can even be purchased for your home. Portable defibrillators come with built-in instructions for their use. They're programmed to allow a shock only when appropriate.
Many things can lead to, or cause, an arrhythmia, including:
What's a normal heartbeat?
When your heart beats, the electrical impulses that cause it to contract follow a precise pathway through your heart. Any interruption in these impulses can cause an arrhythmia.
Your heart is divided into four hollow chambers. The chambers on each half of your heart form two adjoining pumps, with an upper chamber (atrium) and a lower chamber (ventricle).
During a heartbeat, the atria contract and fill the relaxed ventricles with blood. This contraction starts when the sinus node — a small group of cells in your right atrium — sends an electrical impulse causing your right and left atria to contract.
The impulse then travels to the center of your heart, to the atrioventricular node that lies on the pathway between your atria and your ventricles. From here, the impulse exits the atrioventricular node and travels through your ventricles, causing them to contract and pump blood throughout your body.
In a healthy heart, this process usually goes smoothly, resulting in a normal resting heart rate of 60 to 100 beats a minute. Athletes at rest commonly have a heart rate less than 60 beats a minute because their hearts are so efficient.
Types of arrhythmias
Doctors classify arrhythmias not only by where they originate (atria or ventricles) but also by the speed of heart rate they cause:
Not all tachycardias or bradycardias mean you have heart disease. For example, during exercise it's normal to develop tachycardia as the heart speeds up to provide your tissues with more oxygen-rich blood.
Tachycardias in the atria
Tachycardias originating in the atria include:
Supraventricular tachycardia (SVT). SVT is a broad term that includes many forms of arrhythmia originating above the ventricles (supraventricular). SVTs usually cause a burst of rapid heartbeats that begins and ends suddenly and can last from seconds to hours. These bursts often start when the electrical impulse from a heartbeat begins to circle repeatedly through an extra pathway. SVT may cause your heart to beat 160 to 200 times a minute.
SVT is often caused by an underlying heart condition. Although SVT is generally not life-threatening in an otherwise normal heart, symptoms from the racing heart may feel quite uncomfortable. These arrhythmias are common in young people.
Tachycardias in the ventricles
Tachycardias occurring in the ventricles include:
Ventricular tachycardia (VT). This fast, regular beating of the heart is caused by abnormal electrical impulses that start in the ventricles. Often these are due to a problem with the electrical impulse traveling around a scar from a previous heart attack. VT can cause the ventricles to contract more than 200 beats a minute.
Most VT occurs in people with some form of heart-related problem, such as scars or damage within the ventricle muscle from coronary artery disease or a heart attack. Sometimes VT can last for 30 seconds or less (unsustained), and it might not cause any symptoms, although it causes inefficient heartbeats. Still, an unsustained VT may put you at risk of more-serious ventricular arrhythmias, such as longer lasting (sustained) VT. An episode of sustained VT is a medical emergency. Without prompt medical treatment, sustained ventricular tachycardia often worsens into ventricular fibrillation.
Long QT syndrome. Long QT syndrome (LQTS) is a heart rhythm disorder that carries an increased risk of fast, chaotic heartbeats. The rapid heartbeats, caused by changes in the part of your heart that causes it to beat, may lead to fainting, which can be life-threatening. In some cases, your heart's rhythm may be so erratic that it can cause sudden death.
You can be born with a genetic mutation that puts you at risk of long QT syndrome. In addition, more than 50 medications, many of them common, may cause long QT syndrome. Some medical conditions, such as congenital heart defects, also may cause long QT syndrome.
Bradycardia — a slow heartbeat
Although a heart rate below 60 beats a minute while at rest is considered bradycardia, a low resting heart rate doesn't always signal a problem. If you're physically fit, you may have an efficient heart capable of pumping an adequate supply of blood with fewer than 60 beats a minute at rest. However, if you have a slow heart rate and your heart isn't pumping enough blood, you may have one of several bradycardias, including:
Although it often feels like a skipped heartbeat, a premature heartbeat is actually an extra beat. Premature heartbeats occurring in the ventricles come before the ventricles have had time to fill with blood after a regular heartbeat.
Although you may feel an occasional premature beat, it seldom means you have a more serious problem. Still, a premature beat can trigger a longer lasting arrhythmia — especially in people with heart disease. Premature heartbeats are commonly caused by stimulants, such as caffeine from coffee, tea and soft drinks; over-the-counter cold remedies containing pseudoephedrine; and some asthma medications.
Certain factors may increase your risk of developing an arrhythmia. These include:
Certain arrhythmias may increase your risk of developing conditions such as:
If you think you may have a heart arrhythmia, make an appointment with your family doctor. If a heart arrhythmia is found early, your treatment may be easier and more effective. Eventually, however, you may be referred to a heart specialist (cardiologist).
If your heart arrhythmia persists for more than a few minutes or is accompanied by fainting, shortness of breath, or chest pain, seek emergency medical help immediately.
Because appointments can be brief, and because there's often a lot of ground to cover, it's a good idea to be prepared for your appointment. Here's some information to help you get ready for your appointment, and what to expect from your doctor.
What you can do
Your time with your doctor is limited, so preparing a list of questions will help you make the most of your time together. List your questions from most important to least important, in case time runs out. For heart arrhythmias, some basic questions to ask your doctor include:
What to expect from your doctor
Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to spend more time on. Your doctor may ask:
To diagnose a heart arrhythmia, your doctor may ask about — or test for — conditions that may trigger your arrhythmia, such as heart disease or a problem with your thyroid gland. Your doctor may also perform heart-monitoring tests specific to arrhythmias. These may include:
Cardiac computerized tomography (CT) or magnetic resonance imaging (MRI). Although more commonly used to check for heart failure, these tests can be used to diagnose heart problems that might cause heart arrhythmias. In a cardiac CT scan, you lie on a table inside a doughnut-shaped machine. An X-ray tube inside the machine rotates around your body and collects images of your heart and chest.
In a cardiac MRI, you lie on a table inside a long tube-like machine that produces a magnetic field. The magnetic field aligns atomic particles in some of your cells. When radio waves are broadcast toward these aligned particles, they produce signals that vary according to the type of tissue they are. The signals create images of your heart that can help your doctor determine the cause of your heart arrhythmia.
If your doctor doesn't find an arrhythmia during those tests, he or she may try to trigger your arrhythmia with other tests, which may include:
If you have an arrhythmia, treatment may or may not be necessary. Usually it's required only if the arrhythmia is causing significant symptoms or if it's putting you at risk of a more serious arrhythmia or arrhythmia complication.
Treating slow heartbeats
If slow heartbeats (bradycardias) don't have a cause that can be corrected — such as low thyroid hormone levels or a drug side effect — doctors often treat them with a pacemaker. A pacemaker is a small, battery-powered device that's usually implanted near your collarbone. One or more electrode-tipped wires run from the pacemaker through your blood vessels to your inner heart. If your heart rate is too slow or if it stops, the pacemaker sends out electrical impulses that stimulate your heart to beat at a steady, proper rate.
Treating fast heartbeats
For fast heartbeats (tachycardias), treatments may include one or more of the following:
Treatment for heart arrhythmias also may involve use of an implantable device:
Pacemaker. A pacemaker is an implantable device that helps regulate slow heartbeats (bradycardia). A small battery-driven device is placed under the skin near the collarbone in a minor surgical procedure. An insulated wire extends from the device to the right side of the heart, where it's permanently anchored.
If a pacemaker detects a heart rate that's too slow or no heartbeat at all, it emits electrical impulses that stimulate your heart to speed up or begin beating again. Most pacemakers have a sensing device that turns them off when your heartbeat is above a certain level. It turns back on when your heartbeat is too slow. Most people stay in the hospital one to two days after a pacemaker is implanted.
Implantable cardioverter-defibrillator (ICD). Your doctor may recommend this device if you're at high risk of developing a dangerously fast or quivering heartbeat in the lower half of your heart (ventricular tachycardia or ventricle fibrillation). Implantable defibrillator units designed to treat quivering in the upper half of your heart (atrial fibrillation) also are available.
An ICD is a battery-powered unit that's implanted near the left collarbone. One or more electrode-tipped wires from the ICD run through veins to the heart. The ICD continuously monitors your heart rhythm. If it detects a rhythm that's too slow, it paces the heart as a pacemaker would. If it detects VT or VF, it sends out low- or high-energy shocks to reset the heart to a normal rhythm.
In some cases, surgery may be the recommended treatment for heart arrhythmias:
Many arrhythmias can be blamed on underlying heart disease, so your doctor may suggest that, in addition to other treatments, you make lifestyle changes that will keep your heart as healthy as possible. Making healthy lifestyle changes can also help prevent heart arrhythmias from developing in the first place.
These lifestyle changes may include:
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