Atrial tachycardia or atrial fibrillation happens when electrical signals in the atria are fired in a very fast and uncontrolled manner. This causes the atrial chambers of the heart to quiver instead of pump.
When this happens only part of the blood is forced out of the heart chamber. The blood pools inside the atrium and sometimes clots. These blood clots can cause a stroke if they break off and block an artery in the brain.
Although atrial fibrillation isn't life threatening, it can lead to other rhythm problems, chronic fatigue and congestive heart failure.
Some people with atrial fibrillation do not feel anything different. Others notice an abnormal feeling right away. If you have atrial fibrillation, you may feel a racing, uncomfortable, irregular heartbeat and a 'flopping' in your chest. Dizziness, sweating, and chest pain or pressure can also occur. Other symptoms include shortness of breath, overall weakness, and the inability to exercise.
Certain risk factors make it more likely to develop atrial fibrillation, but often the cause remains unclear. Leading risk factors include:
- coronary heart disease
- heart attack
- heart failure
- medication and chemical changes
- heart valve disease
- endocarditis (inflamed heart muscle or lining)
- recent heart surgery
- atherosclerosis (arteries lined with fatty deposits)
- angina (chest pain due to reduced blood flow to the heart muscle)
- a birth defect in the heart
- severe lung disease
- blood clots in the lung
Gender and age also affect both the likelihood of developing atrial fibrillation and the severity of the condition. Men are slightly more likely than women to have atrial fibrillation, but women who are diagnosed with the disease have a greater risk over time for premature death. Older people are more likely to have atrial fibrillation than younger people. Additional risk factors include thyroid disorders, diabetes, high blood pressure, excessive alcohol intake, and cigarette or drug use (including caffeine).
Arrythmias that begin above the ventricles are called supraventricular tachycardia (SVT). In this condition a series of early beats in the atria speeds up the heart rate. There are two main types of supraventricular tachycardia:
Sinus tachycardia is a normal increase in the heart rate. It is caused when the sinus node sends out signals faster than usual. It often occurs with fever, excitement and exercise. No treatment is needed. Rarely, a disease such as anemia (low blood counts) or increased thyroid activity can cause this fast heart rate. In these cases, when the disease is treated, the tachycardia goes away.
Wolff-Parkinson-White (WPW) syndrome
In Wolff-Parkinson-White (WPW) syndrome, an abnormal path between the atria and ventricles cause the electrical signal to arrive at the ventricles too soon to be sent back into the atria. Very fast heart rates may begin as the electrical signal bounces between the atria and ventricles. Many people with WPW syndrome do not have noticeable symptoms.
Ventricular tachycardia (VT) or ventricular fibrillation is one of the most severe types of arrhythmias. It is a fast heart rate that starts in the lower chambers of the heart (ventricles). The heart beats so quickly that it cannot effectively pump blood. If a more normal rhythm is not restored within three to five minutes, the patient will suffer brain and heart damage and can die. When VT occurs, there is no pulse and the person must receive CPR or defibrillation immediately. A defibrillator gives an electrical shock to the heart to restore a normal rhythm.
Ventricular tachycardia can lead to shortness of breath, chest pain, lightheadedness or loss of consciousness, weakness, dizziness, and fainting.
Ventricular tachycardia is mainly caused by heart disease. Rarely, it can occur rarely with exercise or anxiety. In this case, the electrical impulses and rhythmic beats is similar to a normal beat but at a much faster rate.
Most people with VT receive medication therapies, including:
- Anticoagulants such as Coumadin® or an antiplatelet such as aspirin that help to prevent blood clots and stroke.
- Anti-arrythmics such as procainamide, verapamil, Cardizem®, and inderal that help to control the heart rate and rhythm.
- Beta-blockers such as Lopressor® or Tenormin® that help to lower blood pressure.
Premature Ventricular Complexes (PVC)
Premature beats or extra beats most often cause irregular heart rhythms. If you've ever felt your heart "skip a beat," it was probably from a premature beat.
Just as with PACs the heart doesn't really skip a beat. Instead an extra beat comes sooner than normal. Then there's a pause that causes the next beat to be more forceful.
Typically no cause can be found and no special treatment is needed for PVC. The premature beats may disappear. In some cases, PVCs are caused by disease or injury to the heart and certain individuals may require medical therapies. PVCs can also be related to high or low potassium levels.
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