The Heart’s Electrical System

The heart’s pumping action is controlled by an electrical system that sends out impulses, or signals.

An electrical signal starts in the right atrium in the sinus node. The sinus node tells the top of the heart (atria) when and how fast to pump. It is the “pacemaker” of the heart. The signal then is sent to the AV node in the middle of the heart. The AV node holds the signal until the bottom chambers of the heart (ventricles) are filled with blood. It then sends the signal to the ventricles and tells them when to pump the blood out to the body.

Irregular Heartbeat (Cardiac Arrhythmia)

Irregular heartbeat, or cardiac arrhythmia, is a problem with your heart rhythm. The heart may beat too fast or too slowly, or may skip beats. You may feel palpitations: a rapid heart rate, skipped beats, thumping or pounding in your chest. Cardiac arrhythmias may make you feel anxious, nervous, dizzy, faint or short of breath.

Cardiac arrhythmias often are controlled with medications. Your doctor may want to do tests, however, to determine other treatments.

Premature Ventricular Beats (PVCs)
Premature ventricular beats, or PVCs, is a problem where the heart has extra beats. PVCs can occur after a heart attack or may have no known cause.

PVCs occur in the ventricles, the lower chambers of the heart, and may feel like skipped beats or extra beats. After a heart attack, PVCs may stop after the heart begins to heal. If the PVCs continue or are causing problems, your doctor may prescribe medication.

Ventricular Fibrillation (V-fib)
Ventricular fibrillation, or V-fib, is a lifethreatening arrhythmia. It comes on suddenly with chest pressure, shortness of breath and fainting. It also is known as “sudden death,” because it is often fatal. V-fib requires rapid defibrillation or shock treatment within minutes to restore a normal heart rhythm. You may have noticed automatic external defibrillators (AED) in public places. They are used to administer shock treatment. If you are at risk for V-fib, your doctor may recommend an internal cardiac defibrillator (ICD) and/or medication.

Atrial Fibrillation (A-fib)
Atrial fibrillation, or A-fib, is a problem with your heart rhythm. Symptoms of A-fib include palpitations, weakness, tiredness, shortness of breath, chest pain or tightness, dizziness or fainting.

A-fib is rarely life-threatening. It can occur following a heart attack or heart surgery, with high blood pressure or thyroid problems, or it may have no known cause. A-fib is very common, affecting people of all ages. It can lead to other problems such as stroke or heart failure. However, these problems can be avoided if the condition is managed.

A-fib occurs in the upper chambers (atria) of the heart. The cells in the atria send out extra signals, making the atria beat very quickly and unevenly. Sometimes the atria beat so fast that they may quiver instead of contracting. If the atria don’t contract, they can’t move enough blood into the ventricles. Blood that isn’t moving can easily form into clots. These clots can then move to other parts of the body causing serious health problems such as stroke.

Your doctor may prescribe tests that will help diagnose your A-fib. These tests may include EKG, echocardiogram or electrophysiology studies (EPS).

A-fib often is controlled with medications. The three most common medications that are used to slow down the speed of the heart rate are digoxin, calcium channel blockers and beta blockers. You also may be given medication to prevent clots from forming in the atria. These medications are called anticoagulants. The most common anticoagulant is called Coumadin® (warfarin). When medications don’t work sometimes the abnormal tissue is ablated or destroyed with heat or cold. This can be done with a catheter or doing heart surgery.