The term cardiac rhythm refers to the pace at which the heart contracts and pumps blood throughout the body. The heart is equipped with a natural pacemaker called the Sinoatrial (SA) node, which is located in the right atrium. The SA node generates electrical impulses that cause the heart muscle in the atria to contract and pump blood into the ventricles. The atrioventricular (AV) node, which is located on the lower left side of the right atrium, then relays the electrical impulses to the ventricles causing them to contract.

An arrhythmia occurs when the electrical impulses occur irregularly and interrupt the sinus rhythm (or normal rhythm of the heart). Over the long term, an arrhythmia can create a heart rhythm that is too fast (tachycardia or more than 100 beats per minute) or too slow (bradycardia or less than 60 beats per minute).

The most common type of arrhythmia occurs when premature beats arise either from the atrial tissue (premature atrial contractions or PACs) or from the ventricular tissue (premature ventricular contractions or PVCs). These 'extra beats' interrupt the normal pulse and can often be felt. They commonly cause a pounding sensation in the chest and can transiently take away one's breath.

Another common arrhythmia is atrial fibrillation (AF), which occurs when the electrical impulses in the atria (or upper chambers of the heart) cause the atria to beat rapidly and irregularly. This arrhythmia is particularly more prevalent as one ages. Roughly 10% of people above the age of 70 will experience this form of arrhythmia. Complications of AF include congestive heart failure, fatigue, additional rhythm problems and most seriously stroke. In fact, people diagnosed with AF are five times more likely to suffer from a stroke, which is why proper treatment is especially important.

Arrhythmias can also occur in the ventricles. The most common ventricular arrhythmias include premature ventricular contractions, ventricular tachycardia and ventricular fibrillation.

The causes of arrhythmias like AF vary between patients. Common causes include:

• Coronary artery disease
• High blood pressure
• Congenital heart defect
• Increasing age
• Pulmonary embolism
• Electrolyte disturbances

Symptoms of an arrhythmia may include:

• Consistently irregular heartbeats
• Regular chest palpitations, fast heartbeat, fluttering
• Dizziness, faintness, weakness

To diagnose an arrhythmia, your cardiologist may order one or more of the following tests:

• Resting EKG
• Holter monitor (a small EKG that you wear over a long period of time that records your heart rate throughout the day or days)
• Echocardiogram
• Electrophysiology study (EP)

Therapy of arrhythmia varies considerably. This treatment may vary from no medicine at all to suppression of the irregular heartbeat. Elimination of the arrhythmia is done for two basic reasons. If the arrhythmia is too bothersome, even after reassurance and proper evaluation, then medicine is required. Also, if the arrhythmia is dangerous and considered life threatening, then an appropriate drug is prescribed. Allowing your physician to complete an evaluation is important so that an appropriate treatment plan can be formulated. This plan will be tailored to ultimately include the best-tolerated and most effective medication for the particular arrhythmia. Consistently following the treatment plan is very important, as adverse consequences are especially common if one deviates too much from the plan.

Treatment options for an arrhythmia may include:

• Drug therapy (including antiarrhythmic drugs, blood thinners (also known as anticoagulants), calcium channel blockers, beta blockers)
• Pacemaker implant*
• Defibrillator implant*
• Ablation
• Cardioversion*
• Cardiac resynchronization therapy*

Atrial fibrillation & stroke

People diagnosed with atrial fibrillation (AF) are five times more likely to suffer from a stroke because this condition causes the blood to pool in the atria of the heart. When the blood pools in the left atrium, the chances of a blood clot forming are increased. If a clot forms, part of or the entire clot may travel to the brain. In the brain, the clot may block the flow of blood and cause a stroke, a potentially debilitating and even fatal condition.

For this reason, most patients with AF are proactively prescribed blood thinners or anticoagulants to prevent a stroke. Depending upon your condition, the anticoagulant may range from over-the-counter aspirin to prescription warfarin therapy. Anticoagulants are very serious medications that require careful monitoring and a complete understanding of potential side effects. If you're placed on an anticoagulant, make sure you thoroughly discuss this medication with your physician.