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Examination with a stethoscope,
electrocardiograms, and electrophysiologic studies is used to
diagnose arrhythmias. Sometimes arrhythmias can be identified by
listening to the patient's heart through a stethoscope, but, since
arrhythmias are not always present, they may not occur during the
physical exam.
An electrocardiogram (ECG) shows the heart's
activity and may reveal a lack of oxygen from poor circulation (ischemia).
Electrodes covered with conducting jelly are placed on the patient's
chest, arms, and legs. They send impulses of the heart's activity
through an electrical activity monitor (oscilloscope) to a recorder
that traces them on paper. The test takes about 10 minutes and is
performed in a physician's office. Another type of ECG, commonly
known as the exercise stress test, measures how the heart and blood
vessels respond to exertion while the patient is exercising on a
treadmill or a stationary bike. This test is performed in a
physician's office or an exercise laboratory and takes 15-30
minutes. Other types of ECGs include 24-hour ECG monitoring and
transtelephonic monitoring. In 24-hour ECG (Holter) monitoring, the
patient wears a small, portable tape recorder connected to disks on
his/her chest that record the heart's rhythm during daily activities.
Transtelephonic monitoring can identify arrhythmias that occur
infrequently. Similar to Holter monitoring, transtelephonic
monitoring can continue for days or weeks, and it enables patients
to send the ECG via telephone to a monitoring station when an
arrhythmia is felt, or the patient can store the information in the
recorder and transmit it later.
Electrophysiologic studies are invasive
procedures performed in a hospital to identify the origin of serious
arrhythmias and responses to various treatments. They involve
cardiac catheterization, in which catheters tipped with electrodes
are passed from a vein in the arm or leg through the blood vessels
into the heart. The electrodes record impulses in the heart,
highlighting where the arrhythmia starts. During the procedure,
physicians can test the effects of various drugs by provoking an
arrhythmia through the electrodes and trying different drugs. The
procedure takes one to three hours, during which the patient is
awake but mildly sedated. Local anesthetic is injected at the
catheter insertion sites. |
