Arrhythmias
Arrhythmias are abnormal heart rhythms which are produced
when the natural electrical
conduction system of the heart malfunctions. Not all
arrhythmias pose health risks. For instance, a person
may have a persistent minor arrhythmia which is in fact
normal for his heart. Similarly, a temporary arrhythmia
caused by alcohol, caffeine, or insomnia is not usually
a cause for concern.
Arrhythmias are generally classified into two groups:
 Bradycardia
– an abnormally slow heart rhythm;
Tachycardia
– an abnormally fast heart rhythm.
Patients with bradycardia generally have a heart rate
of only about 40 to 60 beats per minute. They tend to
experience fatigue, dizziness, and episodes of fainting
as their hearts do not pump enough blood to supply their
brains and other vital organs with sufficient oxygen.
In contrast, patients with tachycardia have abnormally
rapid heart rhythms, usually of more than 100 beats per
minute. The main symptoms of this condition are similar
to those associated with bradycardia.
Tachycardia may arise in either the atria or the ventricles.
The former occurs when the atria become enlarged by hypertension,
inflamed, or damaged by coronary
heart disease. The resultant rapid irregular beating
of the atria is known as atrial fibrillation or atrial
flutter. If atrial fibrillation remains untreated, there
is an increased risk of stroke.
Ventricular tachycardia is much more dangerous in comparison.
When the ventricles beat too rapidly, the heart does not
have enough time to fill with blood in between beats,
causing blood pressure to drop. Ventricular tachycardia
may worsen and turn into ventricular fibrillation, a potentially
fatal condition in which the ventricles merely quiver
and do not pump any blood at all. If untreated, ventricular
fibrillation will lead to immediate loss of consciousness
and death. |
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