Understanding heart rhythm disorders

The electrical system of a normal heart begins with signals that start in the top chambers (atria) and then move to the bottom chambers (ventricles) in a steady rhythmic pattern. This normal heartbeat is called “sinus rhythm.” Abnormal heart rhythms called arrhythmias are caused by a change in the electrical impulses that regulate a steady heartbeat. Many times, arrhythmias are harmless and can occur in healthy people without heart disease; however, some of these rhythms can be serious and require special treatment.

Atrial Fibrillation (A-fib) is the most common abnormal heart rhythm. In A-fib, the electrical impulses do not follow the normal order. Many impulses begin in the atria, and these extra impulses compete to move down to the ventricles. This can result in the heart beating irregularly and sometimes very fast. This abnormality results from the normal electrical pathway or structure of the heart changing over time. This happens more often as we get older.

More than 2 million people in the United States have A-fib. Though A-fib is not life-threatening, it can lead to other problems — most importantly a stroke. Symptoms may include skipping, fluttering or racing heart beats. Some people describe dizziness, lightheadedness, shortness of breath, chest pain or pressure, fatigue or swelling of the feet, ankles or legs. The symptoms are different for each person. Some people with A-fib have no warning signs or symptoms — this could be worse because those with A-fib are five times more likely to have a stroke compared to those without this diagnosis.

Strokes may occur because blood can pool in the atria during A-fib, which can allow a blood clot to form. These blood clots can break loose and lodge in blood vessels in the brain, which leads to an ischemic stroke. One out of every four strokes is due to a A-fib. Physicians often prescribe blood thinners called anticoagulants, which are highly effective at lowering the likelihood of a stroke.

There are several anticoagulant medications approved for use in patients with atrial fibrillation. They target different parts of the coagulation cascade to keep blood clots from forming. When taken as prescribed, they can reduce the risk of ischemic stroke, but these blood thinners may cause abnormal bleeding. Each type of anticoagulant has its own benefits and risks, which should be discussed between the patient and physician. Remember, stroke prevention is the primary goal of A-fib treatment.

Atrial fibrillation is diagnosed by an electrocardiogram (EKG). Sometimes patients have mobile monitors or implanted monitors that monitor the EKG over a long period of time, allowing the physician to capture episodes of A-fib. Once a diagnosis is made, A-fib can be treated with a variety of antiarrhythmic medications to control the frequency or rate of the rhythm. Other treatments may include procedures such as a cardioversion or catheter ablation. Cardioversion is a controlled delivered low level of shock to the heart to “reset” it to normal rhythm. Catheter ablation is another option for treating some patients in whom medicines and or cardioversion are not effective.

Catheter ablation is procedure in which some form of energy is delivered to the electrical pathways in the heart that are responsible for the A-fib. The tissue becomes scarred and no longer has the ability to send these abnormal signals. The energy used may be in the form of radiofrequency, which uses heat, or cryoablation, which uses cold. Both result in the formation of scar tissue. This minimally invasive procedure can be performed in an electrophysiology lab by a specially trained physician called an electrophysiologist, and highly skilled nurses and technicians who work alongside. Catheters (narrow, flexible wires) are inserted into blood vessels in the groin or neck and advanced into the heart to locate the pathway of the abnormal electrical signals. This procedure is not for all patients with arrhythmias but is a treatment option that can be discussed with your physician.

Sometimes an artificial pacemaker is needed if the heart rhythm becomes too slow. A slow heart rhythm is called bradycardia. These abnormal rhythms can occur for several reasons, but those with A-fib could develop a syndrome in which their hearts beat too slow or too fast. Pacemakers are implanted into the right or left side of the chest just under the collarbone. They weigh about an ounce. Leads (flexible wires) are placed in the heart’s chambers (atria, ventricle or both) and are connected to the pacemaker. This small device then sends signals to the heart through the leads to help it beat at a certain rate when needed.

Settings on a pacemaker can be changed by a physician or practitioner trained in this technology. Routine monitoring is done — even remotely by phone or wireless transmission to make sure the pacemaker is working properly. Pacemakers can also store diagnostic information for your physician, and they often reveal when patients are having atrial fibrillation — including how long it lasts and when it occurs. This can help your physician to make sure you’re protected with anticoagulants and if needed to determine the effectiveness of your medications. Although pacemakers are not a standalone treatment for A-Fib, they could be used in conjunction with medications or catheter ablation.

Atrial fibrillation is increasing in prevalence, and more complex treatment options are becoming available. It is important to know your treatment options and to understand the disease process. There are many misconceptions regarding anticoagulants and antiarrhythmic medications. Fear and anxiety are reduced through knowledge and an understanding of the treatment plan, because this results in patients having a better sense of control over their health and overall well-being.