Affecting more than three million Americans, atrial fibrillation (AF) is the leading cause of stroke in the United States. Characterized by a rapid and irregular rhythm, AF causes the upper chambers (atria) of the heart to fibrillate or quiver. When this happens blood can pool in the atria and form a clot, which can potentially result in stroke or heart failure.
WHERE THE BEAT BEGINS
The heart's electrical system is responsible for sending electrical signals to make the heart contract and pump blood. In a healthy heart, the sinoatrial (SA) node located in the right atrium sends the signal for the atria to pump blood into the lower chambers (ventricles) of the heart, and then into the body. However, a heart in AF does not receive electrical signals from the SA node; instead, the pulmonary veins send the signals for the atria to contract. Signals from the pulmonary veins do not travel normally and cause disorganization in the atria, which results in a rapid and irregular heart rhythm.
TYPES OF AF
Brian Kim, MD, board-certified electrophysiologist at
St. Joseph Hospital, explained there are three different types of AF, including:
- Paroxysmal AF that occurs when the rapid rhythm in the atria start and stop suddenly for minutes or days at a time.
- Persistent AF that occurs when the atria beats erratically for more than seven days, requiring medical intervention or drug therapy.
- Permanent AF that occurs when the atria consistently beats erratically at very fast rates (the most severe type).
Common risk factors for AF are heart disease, previous heart attack, high blood pressure, clogged arteries, diabetes, overactive thyroid, emphysema or other lung diseases, viral infections, sleep apnea, stress, fatigue and age.
AF can go unnoticed because symptoms are not always present. It's important to be aware of even the slightest symptoms, including:
- Heart sensations (or palpitations) such as irregular, thumping or pounding heart beats
- Feeling like the heart is racing
- Chest discomfort or pain
- Fainting or lightheadedness
- Fatigue, shortness of breath or weakness
While oral medications are often the first line of treatment for AF, they do not offer all patients relief. Advances in technology such as cryoablation, are proven to restore a normal heart rhythm and greatly reduce the risk of AF-induced stroke, heart failure and death.
Cryoablation is a minimally invasive procedure that uses a catheter that releases refrigerant to freeze tissue in the atria. This technique is used around the pulmonary veins to block electrical signals that trigger irregular heart rhythms.
"The four pulmonary veins are blood vessels that carry blood from the lungs to the left atrium. A narrow band of muscle tissue around each pulmonary vein can cause erratic electrical signals that result in atrial fibrillation. Freezing the targeted tissue prevents the transmission of irregular signals, restoring a normal heart rhythm," said Jay Lee, MD, board-certified electrophysiologist at St. Joseph Hospital.
Compared to traditional cryo technology using a basic cryocatheter, the newest technology uses a cryoballoon catheter to freeze the tissue. "The cryoballoon catheter employs the same technology but offers improved capability to treat patients with a wide variety of vein abnormalities. In fact, the balloon-shaped catheter allows us to more precisely maneuver around the pulmonary vein to create round lesions of frozen tissue in a shorter amount of time," Dr. Lee explained.
During the procedure, the catheter is inserted into a blood vessel in the upper leg and image guided to the heart to access the pulmonary vein. Then, the balloon attached to the catheter is inflated and coolant is released to freeze the affected tissue.
THE BENEFITS OF CRYOABLATION
Cryoablation is a proven safe and effective treatment for AF. Compared with heat-based ablation, Dr. Kim explained there is a low risk associated with cryoablation because freezing the tissue reduces the chances of damaging healthy surrounding tissue.
In addition, cryoablation offers improved outcomes for patients with AF. "Cryoablation for the treatment of AF has shown tremendous success in clinical trials. 80-85 percent of patients treated with cryoablation were free of AF one year after the procedure," Dr. Lee added.
Both Dr. Lee and Dr. Kim remind patients that their personal success with cryoablation depends on other health factors and the type of AF they experience. Patients should talk with their doctor to determine if this treatment option is right for them. For more information about cryoablation or the heart services offered at St. Joseph Hospital, visit sjo.org/heart.
For more information about Dr. Kim, click here. For more information about Dr. Lee, click