An atrial premature beat is an extra heartbeat caused by electrical activation of the atria from an abnormal site before a normal heartbeat would occur.
Atrial premature beats occur in many healthy people and rarely cause symptoms. Atrial premature beats are common among people who have lung disorders and are more common among older people than among younger people. These beats may be caused or worsened by consuming coffee, tea, or alcohol and by using some cold, hay fever, and asthma remedies.
ECG: Reading the waves
An electrocardiogram (ECG) represents the electrical current moving through the heart during a heartbeat. The current's movement is divided into parts, and each part is given an alphabetic designation in the ECG.
Each heartbeat begins with an impulse from the heart's pacemaker (sinus or sinoatrial node). This impulse activates the upper chambers of the heart (atria). The P wave represents activation of the atria.
Next, the electrical current flows down to the lower chambers of the heart (ventricles). The QRS complex represents activation of the ventricles.
The electrical current then spreads back over the ventricles in the opposite direction. This activity is called the recovery wave, which is represented by the T wave.
Many kinds of abnormalities can often be seen on an ECG. They include a previous heart attack (myocardial infarction), an abnormal heart rhythm (arrhythmia), an inadequate supply of blood and oxygen to the heart (ischemia), and excessive thickening (hypertrophy) of the heart's muscular walls.
Certain abnormalities seen on an ECG can also suggest bulges (aneurysms) that develop in weak areas of the heart's walls. Aneurysms may result from a heart attack. If the rhythm is abnormal (too fast, too slow, or irregular), the ECG may also indicate where in the heart the abnormal rhythm starts. Such information helps doctors begin to determine the cause.
Atrial premature beats may be detected during a physical examination and are confirmed byelectrocardiography (ECG).
Rarely, when these beats occur frequently and cause intolerable palpitations, treatment is necessary. Antiarrhythmic drugs are usually effective (see Table: Some Drugs Used to Treat Arrhythmias).
People with Wolff-Parkinson-White syndrome are born with an extra electrical pathway between the upper chambers of the heart (atria) and the lower chambers (ventricles). This extra pathway makes which of the following more likely to occur?