heart and blood vessel disorders
Atrial Fibrillation and Atrial Flutter
Atrial flutter
During atrial flutter, unlike in atrial fibrillation, electrical activity in the atria is coordinated. Thus, the atria do contract, but at a very rapid rate (250 to 350 times per minute). This rate is too fast to allow every impulse to be conducted through the atrioventricular node to the ventricles. For most people who are not being treated, every second atrial impulse gets to the ventricules, resulting in a ventricular rate of about 150 beats per minute. 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 ventricles must then undergo an electrical change to get ready for the next heart beat. This electrical 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 weaker 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 flutter is a regular rhythm with characteristic "flutter" waves in a sawtooth pattern. 