Arrhythmias originating in the
Atria:
- Sinus arrhythmias: Cyclic changes in the
heart rate during breathing. Common in children and often found in
adults.
- Sinus tachycardia: This sinus node sends
out electrical signal faster than usual, speeding up the heart rate.
- Sick sinus syndrome: The sinus node does
not fire its signals properly, so that the heart rate slows
down. Sometimes the rate changes back and forth between a
slow (bradycardia) and fast (tachycardia) rate.
- Premature supraventricular contractions or
premature atrial contraction (PAC): A beat occur early in
the atria, causing the heart to beat before the next regular
heartbeat.
- Supraventricular tachycardia (SVT), paroxysmal
atrial tachycardia (PAT): A series of early beats in the
atria speed up the heart rate. In paroxysmal tachycardia,
repeated periods of very fast heartbeats begin and end suddenly. Heart
beat is 140-200 beats per minute, and can persist for several minutes
to hours or days.
- Atrial flutter: Rapidly fired signals
cause the muscles in the atria to contract quickly, leading to a very
fast, steady heartbeat. The heart beats 240-350 beats per
minute.
- Atrial fibrillation: Electrical signals
in the atria are fired in a very fast and uncontrolled manner.
Electrical signals arrive in the ventricles in a completely irregular
fashion, so the heart beat is completely irregular. The heart beats at
more than 350 beats a minute.
- Wolff-Parkinson-White syndrome: Abnormal
pathways between the atria and ventricles cause the electrical signal
to arrive at the ventricles too soon and to be transmitted back into
the atria. Very fast heart rates may develop as the electrical
signal ricochets between the atria and ventricles. The heart
beats from 120-240 beats per minute.
Arrhythmias originating in the Ventricles:
- Premature ventricular complexes (PVC): An
electrical signal from the ventricles causes an early heart beat that
generally goes unnoticed. The heart then seems to pause until the next
beat of the ventricle occurs in a regular fashion.
- Ventricular tachycardia: The heart beats
fast due to electrical signals arising from the ventricles (rather
than from the atria). The heart beats is 150-250 beats per
minute.
- Ventricular fibrillation: Electrical
signals in the ventricles are fired in a very fast and uncontrolled
manner, causing the heart to quiver rather than beat and pump
blood. This is very serious and the patient must be treated
within 3 to 4 minutes.
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