Sometimes the heart can beat too fast, too slow, or it can beat irregularly or skip beats. When the heart beats in any of these ways, a person is said to have an arrhythmia.

Normally the heart beats in a coordinated and regular manner, efficiently pumping blood throughout the body. The electrical impulse that initiates this pumping originates in your sinoatrial (SA) node, located in the upper right chamber (right atrium) of the heart. The SA node is known as the “natural pacemaker” of the heart. This impulse then travels through the atria to the atrioventricular node and on to the ventricles. As the impulses pass through the heart chambers, they cause them to contract, allowing the heart to pump the blood through the heart and to the body. When the electrical signals do not fire in a regular pattern or when they are blocked, the heart beats in an abnormal or arrhythmic pattern. This in turn disrupts the flow of the blood through the body. There are several types of arrhythmias, due to the electrical impulses firing too fast or too slow.

Bradycardias are arrhythmias in which your heart beats abnormally slow. This occurs when your SA node does not send the electrical impulses fast enough or when the conduction system of your body prevents the electrical impulses from reaching your ventricles. When this happens, your ventricles may not receive enough charge to contract. Therefore they cannot pump the blood effectively to the rest of your body.

Because your heart beats slower if you have a bradycardia, you may feel symptoms of heart palpitations, which feels like your heart is fluttering and pounding. In addition, if there is not enough blood pumped to your brain, you may feel dizzy or faint.

Tachycardias are arrhythmias in which your heart beats too fast because electrical signals are sent more rapidly than normal. When this happens, the ventricles of the heart do not have enough time to fill with blood before they contract again. Therefore, they cannot pump a sufficient amount of blood to the body.

There are several types of tachycardias, some originating in the atria and others originating in the ventricles.