heart and blood vessel disorders
Overview of Abnormal Heart Rhythms
Diagnosis of Abnormal Heart Rhythms
Electrocardiography Often, a person’s description of symptoms can help doctors make a preliminary diagnosis and determine the severity of the arrhythmia. The most important considerations are whether the palpitations are Fast or slow Regular or irregular Brief or prolonged Another important consideration is whether the arrhythmia causes symptoms. Doctors also need to know whether the palpitations occur at rest or only during strenuous or unusual activity and whether they start and stop suddenly or gradually. Certain diagnostic procedures are usually needed to determine the exact nature of the arrhythmia and its cause. Electrocardiography None Because arrhythmias are often intermittent, a portable ECG monitor (called a Holter Monitor: Continuous ECG Readings or an To detect dangerous arrhythmias that occur very infrequently, doctors sometimes implant a recording device under the skin below the left collarbone (clavicle). The device can be left in place for long periods. It electronically transmits stored recordings of abnormal heart rhythms painlessly through the skin. People with suspected life-threatening arrhythmias are usually hospitalized. Their heart rhythm is continuously recorded and displayed on a television-type monitor by the bedside or at the nursing station. Thus, any problems can be identified promptly. Other diagnostic procedures include Stress Testing None Blood pressure measurement during exercise Echocardiography and Other Ultrasound Procedures to detect anatomic abnormalities Electrophysiologic Testing None During electrophysiologic testing, catheters with tiny electrodes at their tip are inserted through a vein and threaded into the heart. The electrodes are used to stimulate the heart, and the heart’s response is monitored, so that the type of arrhythmia and the preferred treatment options can be determined. 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. 