When is lightheadedness not caused by an arrhythmia?
Dizziness can be caused by conditions other than arrhythmia. For
this reason, your doctor will try to determine whether your
dizziness is caused by a heart condition, medicine, or other factors.
Other causes of lightheadedness include hyperventilation, panic or anxiety attacks, prolonged standing, and excessive fluid loss caused by problems such as vomiting or diarrhea.
Many of the medicines used to treat heart conditions, such as
beta-blockers, calcium channel blockers, angiotensin-converting enzyme (ACE)
inhibitors, and diuretics, can lower the blood pressure excessively and result
in lightheadedness. In general, medicine-induced lightheadedness frequently
occurs soon after you stand up because of a drop in blood pressure that happens
when you stand (orthostatic hypotension). In contrast, lightheadedness due to
an arrhythmia can occur even when you are sitting or reclining.
Syncope (say "SING-kuh-pee") refers to a sudden loss of
consciousness that doesn't last long. Syncope may be the first sign that you
have an arrhythmia. And it is a very worrisome symptom for several
- Fainting can result in a serious injury (for
example, if you faint while climbing stairs or driving).
- You faint
because your brain did not get enough oxygen to function, which may be a
warning sign that you have a serious medical condition.
An arrhythmia can cause syncope in the same way that it causes
lightheadedness (presyncope). Your heart cannot pump blood effectively during
excessively fast or slow heart rates, reducing the amount of blood that reaches
your brain. With syncope, though, the arrhythmia causes such a dramatic drop
in the blood pressure that the brain doesn't receive enough blood to keep you
awake. So you lose consciousness. For an arrhythmia to
cause syncope, your heart rate must be extremely fast or extremely slow, or you
must also have some other heart condition.
How long does syncope last?
It is important to recognize that syncope is transient, meaning
that you wake up soon after fainting. Consciousness may return because the
arrhythmia spontaneously stops and a normal heart rhythm and blood pressure
return. Even if the arrhythmia persists, you may still regain consciousness.
When you have an episode of syncope due to an arrhythmia, it typically happens
while you are standing or sitting, and the loss of consciousness causes you to
fall to the floor. After you are lying down, blood flow returns to your brain,
even though your blood pressure may remain low. When adequate blood flow
returns to your brain, you will likely wake up.
What are the risks associated with passing out from an arrhythmia?
Fast or slow arrhythmias may cause you to pass out.
Depending on your position and activity at the time of the episode, you may
seriously injure yourself. If you are standing up at the time of the
arrhythmia, you may pass out and fall. The fall may cause you to injure your head,
break an arm or leg, or receive other injuries. If you are driving, you may
crash, causing severe injury to yourself and anyone else involved.