“Oh, my heart skips a beat
When you walk down the street
I feel a trembling in my knees
And just to know you're mine
Until the end of time
Makes my heart skip a beat” (Buck Owens)

Ahhh… amore! What a great mental picture! Unfortunately, when your heart skips a beat (or beats too fast or too slow) in real life, it bears little reality to the singer’s reaction upon encountering his love.

Heart arrhythmias are fairly common and occur when the electrical system that tells your heart when (and where) to beat malfunctions. They come in several flavors and varieties: too fast, too slow, or simply irregular.

There are two basic types of arrhythmias - tachycardia (faster than normal heartbeat) and bradycardia (slower than normal heartbeat). If you’re diagnosed with an arrhythmia, it’s important to take time to understand the type of arrhythmia that you have. Most of the time, arrhythmias are fairly harmless, although in some instances they can be life threatening.

The types of arrhythmias include:

Tachycardia:
• Atrial fibrillation - risk increases after age 60, high blood pressure or other heart problems increase the risk, heartbeat may beat as fast as 350-600 beats a minute, may last a few minutes to an hour, may lead to stoke or other conditions.
• Atrial flutter: similar to atrial fibrillation but more rhythmic, serious condition which can become life-threatening.
• Supraventricular tachycardia (SVT): bursts of very rapid heartbeats as high as 160-200 beats per minute, originates in ventricles, more common in younger individuals, underlying heart condition often present, non-life threatening.
• Wolff-Parkinson-White syndrome: may cause SVT, rapid heartbeats.
• Ventricular tachycardia (VT): more common in those with other heart conditions, frequently result of scar tissue from a heart attack, originates in ventricles, heart may exceed 200 beats per minute, may become serious if condition is sustained.
• Ventricular fibrillation: very rapid beats to the point ventricles don’t pump blood, results in low blood pressure, loss of blood supply to organs, extremely serious and can be fatal without immediate intervention, may be caused by heart attack.
• Long QT syndrome (LQTS): extremely serious and may cause fainting and lead to death, rapid heartbeats, caused by gene mutation, congenital heart defects, and certain medications.

Bradycardia:
• Sick Sinus: caused by scarring of sinus node or disruption of sinus node impulses, causes slower heart beat.
• Conduction block: malfunction of atrioventricular node impulses, may cause slow or skipped heart beats.

In addition to tachycardia and bradycardia, some people experience premature heartbeats. A premature heartbeat is simply an extra little heartbeat that occurs in-between normal heartbeats. Common causes for premature heartbeats include caffeine and some medications.

Source:
Heart Arrhythmias, The Mayo Clinic, 14 Feb 2009, http://www.mayoclinic.com/health/heart-arrhythmias/DS00290