Low blood pressure is not always a sign of a problem. But if you have symptoms of low blood pressure, your doctor can diagnose the condition and uncover the cause. Symptoms of dizziness and lightheadedness when you stand up from sitting or lying down -- with a decrease in your blood pressure -- may indicate a condition called postural hypotension. A wide range of underlying conditions may also cause your symptoms. It's important to identify the cause of low blood pressure so appropriate treatment...
Atrial fibrillation is the most common type of
SVT. It means that the heart's upper chambers (atria) beat irregularly.
Atrial flutter is like atrial fibrillation, because the electrical problem is in the atria. But with atrial flutter, the heart beats very fast in a regular rhythm. Atrial flutter is less common than atrial fibrillation.
Atrioventricular nodal reentrant tachycardia
Atrioventricular nodal reentrant
tachycardia (AVNRT) is a common type of
supraventricular tachycardia. It accounts for many of
the fast heart rates that start in the upper part of the heart (excluding
atrial fibrillation). Atrioventricular (AV) nodal reentrant tachycardia can
cause symptoms at any age. It isn't
generally a result of other forms of heart disease.
Atrioventricular tachycardias are caused by an abnormal or extra
electrical pathway in the heart, a kind of "short circuit." Electrical pathways
in the heart consist of microscopic muscle fibers that conduct electrical
impulses. Normally, a single electrical pathway allows impulses to travel from
the upper to the lower chambers. An extra electrical pathway allows those
impulses to travel backward at the same time, starting another heartbeat.
During AV nodal reentrant tachycardia the electrical impulses continuously go
around the two pathways. This is known as "reentry" and can lead to a very fast
Atrioventricular reciprocating tachycardia
Atrioventricular reciprocating tachycardia (AVRT) occurs when there
is an extra electrical pathway linking the upper (atria) and lower (ventricles)
chambers of the heart.
AV node is the only tissue that conducts electrical
impulses between the upper and lower chambers of the heart: all electrical
impulses must go through the AV node to reach the lower chambers of the heart.
In an atrioventricular reciprocating tachycardia, electrical impulses travel
one direction in the normal manner, down the AV node to the lower chambers
(ventricles), but they then travel back up to the upper chambers (atria)
through an abnormal, extra electrical pathway (accessory pathway) located
outside the AV node.
Symptoms may start
during the teen or young adult years.
Atrial tachycardia is a type of
fast heart rate caused by rapid electrical signals that begin in the upper
chambers of the heart. As a result, the heart can sometimes beat very