Author:

Published on:

A cardiac arrhythmia refers to any abnormality in the heart's rate or rhythm. There are many different types of arrhythmias, some much more serious than others. A minor arrhythmia may cause you to feel a single "skip" in your heartbeat. Almost all people have felt this type of sensation at some point in their lives and this generally does not need special treatment.

On the other end of the spectrum, much more dangerous arrhythmias may cause cardiac arrest (sudden death). In the United States, more than half of all deaths from heart disease occur suddenly. In total, it is estimated that more than 300,000 Americans die each year from sudden death related to heart disease.
 

Symptoms of an Arrhythmia

The symptoms of cardiac arrhythmias are highly variable from person to person. My patients usually complain about heart palpitations, lightheadedness, and fainting spells. In some cases, there may be no symptoms at all. A palpitation is a sensation of the heart beating within your chest. You may feel palpitations during a normal heart rhythm, particularly when nervous or exercising. They can vary in intensity, speed, and regularity. If palpitations seem unusually fast, frequent, or are accompanied by other symptoms such as dizziness, it is important to mention them to your primary care provider.

Lightheadedness and fainting are symptoms that may or may not be due to an arrhythmia. When the cause is an arrhythmia, these symptoms signify that the heart is not pumping enough blood to the brain. Cardiac arrest is the most severe symptom of any arrhythmia. In general, survival is only possible if someone immediately present knows cardio-pulmonary resuscitation (CPR). Prompt attention of an ambulance (in the United States dialing 911) and transport to a nearby hospital is essential. Even today, the chances of surviving a cardiac arrest is only about two percent in most large American cities.
 

Types of Cardiac Arrhythmias

Abnormalities of heart rate are classified as those that are too fast (called tachycardia) and those that are too slow (called bradycardia). Arrhythmias are also classified by the region of the heart that gives rise to the rhythm. Normally, your heartbeat arises from the sinus node, a tiny area on the upper right side of the heart; therefore, the normal heart rhythm is called normal sinus rhythm. Places where abnormal heart rhythms can start include the atrium (thin chambers at the top of the heart) and the ventricles (muscular chambers at the bottom of the heart).

Several common arrhythmias include:

Premature contractions
The simplest arrhythmia is a single extra heartbeat, called a premature beat (or premature contraction). It may occur in either the atrium (an atrial premature contraction, or APC) or the ventricle (a ventricular premature contraction, or VPC). Premature contractions may be sensed as "skipped beats," but are often not even noticed. Generally, isolated premature contractions are not a serious problem. If one of my patients complains of palpitations due to premature heartbeats, I would prescribe medicines only if the symptoms are extremely bothersome.

Atrial fibrillation
In atrial fibrillation, the atria lose the ability to contract properly, producing an irregular and rapid heartbeat. Atrial fibrillation (also called “a fib”) is a growing problem in the United States. This is because of the aging of the American population, and the increasing incidence of atrial fibrillation in older individuals. In addition, more people are surviving heart attacks and more are living with congestive heart failure; these people are especially prone to have atrial fibrillation. This arrhythmia usually requires medicines to slow the heart rate as well as lifelong treatment with anticoagulants (blood thinners), such as warfarin. Anticoagulants are used to prevent blood clots from forming in the heart, a common problem in atrial fibrillation. These clots can dislodge to cause a stroke. Another treatment option for atrial fibrillation is called cardioversion. Cardioversion refers to the use of small paddles that deliver a small electrical shock through the chest wall to the heart. This procedure can restore your heart's normal rhythm. Your doctor will give you mild anesthesia at the time of a cardioversion so the shock is not felt.

In some cases, your doctor may give you an antiarrhythmic medication during or after a cardioversion. These medicines can decrease the risk of going back into atrial fibrillation. The benefits of keeping you out of atrial fibrillation need to be weighed against the possible side effects of the medication.

Sick sinus syndrome
Sick sinus syndrome is a common arrhythmia, typically seen in older people. If you have sick sinus syndrome, the heart rate alternates between going too fast and too slow. The slow heart rate is usually the main problem, often causing fainting spells or brief periods of lightheadedness. When sick sinus syndrome causes fainting or lightheadedness, a pacemaker may be required.

Heart block
Heart block refers to impaired communication between the top and bottom chambers of the heart. It can result from aging, coronary artery disease, medications, or even Lyme disease. When severe, a pacemaker may be required.

SVT (supraventricular tachycardia)
SVT is a fast heart rhythm arising from the upper chambers of the heart. Most of my patients with SVT describe very rapid and strong palpitations, which may be associated with shortness of breath, chest discomfort, or dizziness. SVT can occur in either young or old people, with or without underlying heart problems. Treatment with medications is usually successful. If the medicines are not effective or are causing side effects, your doctor may be able to cure SVT with an ablation procedure (see description below).

Ventricular arrhythmias
The two most important ventricular arrhythmias are ventricular tachycardia and ventricular fibrillation. Both are fast heart rhythms that arise from the lower muscular chambers of the heart. These rhythms are very dangerous, accounting for most cases of sudden death from heart disease. When I see these ventricular arrhythmias, it is usually (but not always) in patients who have had heart attacks or congestive heart failure. Treatment with either medications or an implantable cardioverter defibrillator (called an ICD, see below) is often helpful.
 

Diagnosis of Arrhythmias

Many arrhythmias are detected during a routine physical examination. If you have symptoms or physical exam findings that suggest an arrhythmia, your doctor will do additional testing to evaluate the heart's rhythm. The first test is almost always an electrocardiogram (also called an ECG or EKG). This will catch some, but not all, arrhythmias. Special monitors can be used to detect arrhythmias that are only present occasionally. A Holter monitor is a small portable tape recorder (like a Walkman) that is worn for 24 hours and provides your doctor with a recording of every heartbeat during an entire day. A small button can be pushed to mark when you experience symptoms. You should then write a brief description of the symptoms in a diary, which is provided along with the monitor.

In evaluating less frequent symptoms, I use monitors called loop recorders. They are smaller than Holter monitors and can be worn for several months. When you feel a symptom, you press a button, which causes a recording of the heart rhythm to be transmitted by telephone to the physician.

Finally, some arrhythmias are diagnosed during an EP (electrophysiology) study. An EP study is a procedure where catheters, inserted through a large vein in the leg or the neck, are positioned inside of the heart. A very specialized cardiologist uses these catheters to provoke the onset of your arrhythmia. Careful measurements can be made, which will give your doctor detailed information about the nature of your arrhythmia. EP studies can be combined with ablation procedures (see below) to improve or cure some arrhythmias.
 

Treatment of Arrhythmia

There are several treatments that may help your arrhythmia. First, I always search for underlying causes, especially those that can be corrected easily. Some examples of reversible causes of arrhythmias include alcohol, caffeine, illicit drugs, prescription and over-the-counter medications, and abnormal blood levels of salts, such as magnesium and potassium. For many of my patients, simply stopping a medication or avoiding caffeine may be enough treatment. Frequently, other medical conditions may cause arrhythmias. These conditions can be problems arising from the heart, such as coronary artery disease or diseases in other parts of the body, such as the lungs or thyroid. It is important to make sure that these other conditions are being treated fully. Recently, one of my patients had an arrhythmia that was caused by hyperthyroidism. Following treatment of her thyroid disease, her arrhythmia became much easier to control. Still, other arrhythmias may be present from birth, possibly arising from a gene passed to you from your parents. Finally, even after a careful investigation, I still may not be sure of the exact cause of some arrhythmias.

Medications
After your doctor has excluded this list of underlying causes and decided that treatment is needed, there are a number of possibilities. For many of my patients, medications are very effective in treating their arrhythmias. Several of the most effective medicines are the same pills used to treat high blood pressure, such as beta-blockers or calcium channel blockers. I recently started caring for a 45-year-old gentleman with SVT. Following treatment with verapamil (a calcium channel blocker), he has had no symptoms for more than a year. In certain cases, however, more powerful medicines are needed. Some examples are amiodarone, sotalol, quinidine, and procainamide. These medications can have dangerous side effects and, therefore, treatment usually is guided by a cardiologist with a special knowledge of their use.

Ablation procedure
A growing number of arrhythmias can be improved or even cured with a procedure called an ablation. Similar to the EP study, this is a procedure where catheters are placed inside of the heart and a specialized doctor makes a map of the electrical activity of the heart. When the source of the arrhythmia is found, high-energy radio waves are used to literally burn out the abnormal tissues.

Pacemakers
Finally, some arrhythmias are best treated with implanted devices. Pacemakers are commonly used to treat slow heart rhythms. Pacemakers are small devices that are placed under the skin of the upper chest. Thin wires extend from the pacemaker into the heart and stimulate it to beat whenever the heart rate becomes too slow. Certain fast heart rhythms also may be treated with a device called an implantable defibrillator (ICD). ICDs are a little larger than pacemakers in appearance, but they have the ability to provide an electrical shock to the heart if a dangerous heart rhythm is detected.
 

Conclusion

There are many types of cardiac arrhythmias. Symptoms usually involved palpitations, shortness of breath, or dizziness. Fainting and sudden death can result from more serious arrhythmias. If you think you have symptoms of an arrhythmia, I recommend that you discuss this with your doctor. In some cases, your doctor may reassure you that your heart rhythm is normal. In other cases, you may discover that you have an arrhythmia. Knowing this is important, as many beneficial treatments are available. Getting proper treatment for your arrhythmia will likely improve your symptoms and, in some cases, even be life-saving.