At the Hoffman Heart and Vascular Institute of Connecticut, patients with atrial fibrillation and other more complex arrhythmias are treated in two, high-tech electrophysiology labs located on the main campus of Saint Francis Hospital and Medical Center. The labs are staffed by electrophysiologists, physicians who specialize in the care and treatment of patients with arrhythmias.
What is an Electrophysiology Study?
An electrophysiology study (also known as an EP test) is a study of the heart’s conduction system to determine whether the electrical system is functioning properly. This test can help determine if an abnormality in the heart's electrical system is causing a rapid heartbeat. In some patients who have experienced heart attacks, this test may help to assess whether or not an implantable defibrillator is needed to prevent sudden death. During an EP test, special wires, called catheters, are placed into the veins (usually from the groin) and positioned into the heart. The wires are placed using special intravenous lines known as sheaths. Patients receive local anesthetic to make the procedure more comfortable. In addition, medications are given to make the patient feel sleepy. In fact, many patients sleep through their EP test. It is important to let your electrophysiologist know if you have had any reactions or allergies to medications used for sedation or anesthesia.
The EP test enables doctors to:
- Diagnose the source of arrhythmias
- Evaluate the effectiveness of specific medications in controlling the arrhythmia
- Assess the need for a pacemaker, implantable defibrillator or another corrective procedure
- Predict the risk of sudden cardiac death
What to Expect
On the evening before your test, you should not eat anything after midnight. When you arrive, you will be admitted to a hospital room. You will return to this room after your test. When it is time to go for your test, you will be taken to the Electrophysiology Lab on a stretcher. There you will be positioned on an X-ray table. The area where the catheters will be placed (usually the right groin) will be thoroughly cleaned and shaved if necessary. You will be covered with sterile sheets. Your electrophysiologist and the nurse will be wearing masks, sterile gowns and gloves to prevent infections. You will be given some medications to relax you and help you sleep. Your doctor will also inject a local anesthetic to numb the areas where the catheters will be inserted.
Once the catheters are positioned in the heart, the electrophysiologist will record your heart’s electrical activity and take measurements. You may feel your heart skipping beats and racing at times. This is to be expected, because part of the test involves pacing your heart and causing extra beats. This part of the test is not painful. If a rapid heart rhythm is started, the electrophysiologist can stop it either by using the catheters in your heart or by delivering an electric shock to your chest. In most cases, you won’t feel this because of the sedatives given during the test.
After the test is completed, the catheters and intravenous sheaths are removed. You will be instructed not to move your leg for about four hours to let the area heal. This prevents bleeding.
What are the Risks?
An EP study is an invasive heart test and carries some risk. In general, the risks are low compared to the benefits of performing the test. Your electrophysiologist will discuss the risks with you in detail. One of the most common risks is mild bleeding or bruising where the catheters were inserted. To prevent this, it is important that you try not to move your legs for four hours after the study. Other rare, but serious complications can include: damage to the heart, lungs or blood vessels; formation of blood clots; and infections. A heart attack, stroke or death is an extremely rare complication of an EP study (less than 1 in 1000).
Some arrhythmias can be treated during the EP test. Sometimes, patients must return for treatment so that special equipment can be set up. To ensure the best possible results, The Hoffman Heart and Vascular Institute of Connecticut was the first in the Greater Hartford area to equip its EP labs with Stereotaxis, a navigational system that uses magnetic fields to move the catheter within the heart. This advanced technology allows physicians to safely treat more complex heart rhythm cases such as atrial fibrillation. Read about Stereotaxis in the Winter 2012 edition of BestCare Magazine.
Atrial Fibrillation (AFib)
If left untreated, AFib may cause discomfort. In the worst case, it can lead to a stroke. It can also lead to a weakening of the heart muscle or a worsening of congestive heart failure. Because atrial fibrillation causes so many different problems in many different people, treatment strategies vary for each person. The major focus is to prevent a stroke. The only proven way to prevent a stroke caused by atrial fibrillation is to use a blood thinner called Coumadin (also called warfarin). Patients with the following conditions should discuss Coumadin with the doctor:
- Congestive heart failure
- Hypertension (high blood pressure)
- Age 75 or older
- Previous stroke or TIA ("mini-stroke")
Once we have determined your risk of having a stroke, we focus on keeping the heart from beating too quickly. A rapid heartbeat, if left untreated, can lead to a weakening of the heart muscle.
Finally, the symptoms of AFib are treated either by slowing the heart rate or restoring the normal heart rhythm. Several approaches are used including:
- Medications to slow down the rapid heart rate
- Electrical cardioversion to help restore a normal heart rhythm using an electric shock delivered under anesthesia
- Radiofrequency Ablation
- Open heart surgery
- Pacemakers implanted to help produce a more normal heart rhythm
Because atrial fibrillation is so common, new treatments are frequently introduced. New medications are being developed which may be more effective with fewer side effects. Special pacemakers help to record recurrences of atrial fibrillation and can even help to prevent them. Another promising procedure is called pulmonary vein isolation. During this procedure, we try to isolate the abnormal signals that initiate the atrial fibrillation. To do this, we use an advanced mapping system which allows us to reproduce a computerized picture of the heart. This allows us to "see" our catheters on the computer model as we move them around and destroy the abnormal tissue causing the arrhythmia. This procedure can sometimes cure atrial fibrillation.
Options for AFib and Other Arrhythmias
Ablation is a technique designed to cure certain arrhythmias. During an EP test, it is possible to find areas of the heart that are causing rapid or irregular heart rhythms. Some arrhythmias are caused by extra groups of cells that can cause “short circuits” in the heart. During an EP test, these areas can be mapped. During an ablation, a special catheter is placed into the heart, which is used to burn away the region where the trouble originates. If successful, an ablation can cure certain arrhythmias. Ablation is most successful in patients with supraventricular tachycardia (SVT), Wolff-Parkinson-White Syndrome (WPW), or atrial flutter. However, ablations may also be used to help patients with other, more complex arrhythmias, such as ventricular tachycardia and atrial fibrillation.
In general, an ablation has a 90% success rate. This means that most ablations cure the arrhythmia. However, even if initially successful, some arrhythmias may return. The recurrence rate is between 5% and 10%, and tends to happen within the first several months. Most recurrences may be successfully treated with another ablation. Risks are similar to those for an EP test. But because part of an ablation involves cauterizing (burning) cells inside the heart, there is a small chance that the ablation catheter will destroy some of the normal tissue inside the heart. With the Stereotaxis technology, softer, more flexible catheters are precisely guided to targeted areas, providing for improved safety and better success rates. If part of the normal conducting system is destroyed accidentally, the patient will need a permanent pacemaker. This is a rare complication and happens in less than 1% of cases.
Pacemakers are surgically implanted under the skin, usually near your collar bone, in patients with brachycardia (slow heartbeat). One or two wires are inserted through the veins and placed into the heart. A pacemaker monitors the heartbeat and sends out an electrical signal to cause a heartbeat when needed. A pacemaker therefore keeps the heart from beating too slowly.
Implantable Cardioverter/Defibrillator (ICD) is also surgically implanted under the skin near the clavicle. Like a pacemaker, one or two wires are implanted in the heart. The ICD has a backup pacemaker built in, but its primary function is to prevent sudden cardiac death. It does this by monitoring every heartbeat. If it notices a dangerous heart rhythm such as ventricular fibrillation, it delivers a high voltage electrical shock to restore the normal rhythm and to "restart" the heart.
What are the Risks?
Surgery is required to implant a pacemaker or an ICD, so there are some risks. In general, the risks are low compared to the benefits derived from performing the surgery. Your doctor will discuss the risks with you in detail prior to surgery. The more common risks include bleeding or bruising where the device is inserted. There is a chance of more serious complications, including damage to the heart, lungs or blood vessels, formation of blood clots, and infections. These generally occur less than 1 in 100 cases (less than 1%). Heart attack, stroke or death are extremely rare complications of pacemaker or ICD surgery, occurring in fewer than 1 in 1000 cases.