Arrhythmia: Taming the Troubled Heartbeat

When the heart is functioning normally, electrical impulses originating from special cells in the heart cause it to contract, resulting in a heartbeat. A heart usually beats in a steady rhythm 60-100 times per minute. "I always say that the heart is a peculiar organ. It can be normal except for a single cell or two," says James A. Roth, MD. That might be all it takes to lead to an irregular heartbeat.

Dr. Roth, Medical College of Wisconsin Associate Professor of Cardiovascular Medicine and Director of Electrophysiology, practices at the Froedtert & The Medical College of Wisconsin Cardiovascular Medicine Clinic.

"The heart has a normal rhythm; it beats in a certain order," he notes. "When there is a change in the rhythm of your heartbeat - if it beats too rapidly or too slowly - that's arrhythmia."

An arrhythmia or abnormal heartbeat is not an uncommon condition; it affects millions of people in the United States. Most arrhythmias are harmless, but some can be serious or even deadly.

Timing is Everything
Arrhythmias can be divided into two broad groups: tachyarrhythmias, in which the heart beats faster than normal, and bradyarrhythmias, in which the heart beats slower than normal. They can occur in the two upper chambers of the heart (the atria) or the two lower chambers of the heart (the ventricles).

"Atrial arrhythmias usually are not life-threatening but can cause significant symptoms and disability. Ventricular arrhythmias may be life-threatening, especially in the setting of advanced heart disease such as a prior heart attack or coronary artery disease," Dr. Roth explains. "Significant atrial arrhythmias tend to be more common than significant ventricular arrhythmias."

"The heart needs to beat in an organized fashion. The timing must be coordinated between each chamber. When you lose that rhythm, you might experience symptoms," Dr. Roth says. These symptoms can present in several different ways. "Interestingly, your heart can bump around in your chest hitting other organs and you don't notice it. But when the heart's cadence changes, people notice it immediately, even if it is not uncomfortable. People might feel their heart race, or the beat is so disordered, they may have low blood pressure or fainting spells."

Diagnosis
Minor arrhythmias can be caused by too much caffeine, stress, exercise, or smoking. "A lot of rhythm problems occur in healthy people. These are not life-threatening," Dr. Roth says. A small number of people have dangerous arrhythmias caused by heart disease, particularly coronary artery disease, abnormal heart valve function, and heart failure.

In order to determine what is causing the arrhythmia, a physician must first find out about your medical history. "A prior heart attack or heart problems or a family history of heart disease could mean a life-threatening problem, but cardiac arrest is rare if the heart is working well," Dr. Roth notes. "The first thing we do is to determine if the person's heart is normal, and then treat the symptoms."

That usually means the doctor will run some tests. One of the more common tests is an EKG, or electrocardiogram. During this test, the patient lies down while heart activity is traced via electrodes that are placed on the chest and body. Additional EKGs might be performed while the patient walks on a treadmill during monitoring - this is known as an exercise stress test. The stress test measures how the heart and blood vessels respond to exertion.

Other tests include use of a Holter monitor - a small portable recorder that continuously records the heart's rhythm for 24 hours. "If these tests are reassuring, we know with a high likelihood that the patient will be okay. If not, we will find a way to treat it," Dr. Roth says.

If the tests indicate a more serious problem, the doctor might order additional diagnostic tests called electrophysiologic studies. These are invasive procedures such as a cardiac catheterization. In this procedure, the doctor inserts a very thin tube into a blood vessel in an arm or leg and threads it all the way to the heart. The doctor can then study blood flow to help determine the causes of the arrhythmia.

Treatment Overview
"How we treat cardiac arrhythmias depends on the type of arrhythmia we discover and how serious it is," Dr. Roth says. In fact, some arrhythmias don't require any treatment. A patient might be asked to cut down on caffeine. In other cases, medication may be enough to keep the heart rate in a normal rhythm and at a normal rate.

If these treatments do not work, physicians will try other procedures. "When the heart rate is too slow, we can use an artificial pacemaker. These have been used since the 1960's and they are very effective," Dr. Roth says. "When the heart has advanced disease, we have the option of an implantable defibrillator. The defibrillator delivers an electrical shock to the heart to return the heart beat to normal," he adds.

If an arrhythmia is caused by a certain area of the heart that is damaged or scarred, it might be possible to remove that small area. "If this is the case, we may insert an ablation catheter, a thin tube through the blood vessels to the heart and destroy the electrical pathways causing the over-stimulation. This treatment is 90% percent effective," Dr. Roth notes. Surgical ablation is similar in principle, but it is performed using a probe instead of radio waves to destroy tissue.

Prognosis and Prevention
In the long run, the best way to avoid serious cardiac arrhythmia is to try to keep your heart healthy by maintaining a healthy lifestyle and having regular checkups. Contact your doctor right away if you have any of the following symptoms, especially if you have heart disease or you have had a heart attack: