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Dr Wells answers some frequently asked questions

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What is an arrhythmia?

An arrhythmia is any abnormal way for the heart to be excited, that is, not from the sinus node at a rate appropriate for the needs of the body. In general, there are two classes of arrhythmias: bradycardias (too slow) and tachycardias (too fast). Bradycardias that are not reversible usually require a permanent pacemaker. Arrhythmias caused by fast heart rhythm problems may be treated without a permanent pacemaker.

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What causes arrhythmia?

Arrhythmias may be caused in several ways. First, it can be a failure of the normal heart electrical system (that is, the failure of the sinus node, AV node, bundle of His or bundle branches to function normally). The second major cause would be irritable spots taking over and making the heart race. The third cause would be a short circuit allowing continuous excitation and racing of the heart. Some arrhythmias are likely to recur over time, since they are the result of fixed electrical abnormalities in the person’s heart. Others are only temporary and caused by medications, hormone abnormalities, electrolyte disturbances (minerals in the blood like potassium), etc. Once these abnormalities are corrected, the heart rhythm returns to normal. Some arrhythmias are inherited and present from birth; these can be transmitted to children. Others present from birth are a sort of heart electrical birth defect but cannot be passed on to children. Still others are not present from birth but develop as the person gets older.

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Are arrhythmias serious?

Arrhythmias may involve the top or the bottom of the heart. In general, arrhythmias involving the top part of the heart are not serious or life-threatening. In contrast, arrhythmias involving the bottom part of the heart may be life-threatening. Secondly, arrhythmias occurring in hearts with normal plumbing (normal valve function and a strong left ventricle) are seldom life-threatening. In contrast, arrhythmias occurring in people who have a weak left ventricle from a heart attack or any other reason may be life-threatening. Lastly, persons who have one or more family members die suddenly or at home “from a heart attack” (these are seldom actual heart attacks but fatal arrhythmias) may have life-threatening arrhythmias.

Non-threatening arrhythmias may, however, have serious long-term consequences. For example, arrhythmias involving the top part of the heart that are present for at least 90% of the day resulting in an average daily heart rate of at least 130 may lead to weakness of the left ventricle and congestive heart failure – a potentially very serious disorder with a 50% mortality over 5 years. Atrial fibrillation, in certain people, may lead to a stroke if not treated with blood thinners.

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How would I know if I have an arrhythmia?

Some people do not even know that they have an arrhythmia; in these cases, a doctor usually discovers the arrhythmia during a routine visit like the yearly physical examination. However, most people feel bad in some way when an arrhythmia occurs. Some who experience “spells” of arrhythmia may have symptoms of abnormal heart beating (“palpitations”) or outright heart racing. Other symptoms may include chest pain, pulsations in the neck, shortness of breath, light-headedness, fatigue, and sweating. After a spell of arrhythmia, the person may have frequent urination (due to release of a protein from the top heart chambers that stimulates urine formation) or feel fatigued for hours to days. Other arrhythmias may cause the person to pass out with the chance of falling and injuring him- or herself. More serious arrhythmias may result in a cardiac arrest or death. In the United States alone, about 400,000 sudden cardiac deaths occur annually, which approaches the total number of deaths from all forms of cancer! Fortunately, the rhythm problems dealt with here are seldom, if ever, life-threatening.

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How can I tell how long I have been out of rhythm?

Sometimes, it is difficult to tell when the heart went out of rhythm, particularly when the symptoms are not prominent. With other people, it is fairly easy to tell when the arrhythmia started and therefore how long it has been going on.

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How do I find out which arrhythmia I have?

Arrhythmias can be documented by a regular ECG performed when people are having symptoms if they’re in the emergency room or in their doctor’s office. People who have daily episodes of arrhythmia can have a 24-hour Holter monitor placed to document which arrhythmia is present. More commonly, people may have less frequent, for example, monthly episodes, and can use an external event monitor to record their heart rhythm by holding the monitor to their chest and pressing a button. The event monitor records an ECG and stores it in memory. The person can then call a toll-free telephone number, and the device will turn the ECG into sound waves and send them over the phone. The technician on the other end of the phone has a machine that turns the sound waves back into an ECG that can be printed out and faxed to the doctor to see which arrhythmia is present. More rare (for example, yearly) episodes are difficult to document unless the person waits until an episode occurs and then seeks medical attention at an emergency room or physician’s office. Persons who call 911 may have their episode of arrhythmia documented by the paramedics who can perform an ECG en route to the hospital. Persons who are in the hospital wearing a heart rhythm monitor when the arrhythmia hits may have it documented in that way. Internal looped monitors may be deployed to document arrhythmias when other means fail. These devices are implanted under the skin and are capable of automatically recording an ECG if an arrhythmia occurs. Also, the person can activate the device if he or she feels an arrhythmia occurring. The device continuously records the person’s rhythm with a looped memory. If the person activates the device, it freezes the memory buffer, which contains the previous 5 minutes of the person’s rhythm and usually the arrhythmia. The person can then visit his or her doctor’s office, and the nurse can place a communicating wand on the skin over the device and retrieve the rhythm information. All of these methods give the doctor a pretty good idea about what is going on, but the definitive diagnosis may require an invasive study called an electrophysiology (or EP) study to see what arrhythmias can be caused in the person.

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What is an EP study?

An electrophysiology (EP) study is a diagnostic test performed to determine the exact nature of the heart racing problem. It is not a surgery since there are no incisions and no stitches. The doctor numbs up the skin in the crease of the leg and/or near the collar bones or the side of the neck. IVs are then placed into the blood vessels: usually just the veins but occasionally the arteries. Through these IVs, long tubes that look like pieces of spaghetti are inserted and using an x-ray camera pushed within the blood vessels until they enter the heart. They are then leaned against the inner lining of the heart at strategic locations to record the spark of electricity that makes the heart beat. The using a special computer pacemaker outside the body, the doctor can speed the heart up and put in extra beats to start as well as stop the heart racing. An EP study gives the doctor the most complete information about why the heart is racing; for example which specific type of heart racing is present. An EP study is nearly always done during the same time as the ablation procedure to give the doctor this invaluable information. However, some people have already had their EP study done somewhere else and then are referred to another doctor for the ablation. An EP study is not very painful, and sometimes people are awake for it. At other times they are put to sleep for it.

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How do I prepare for a catheter ablation?

Most electrophysiologists (heart rhythm doctors) need a few weeks notice to schedule an ablation depending on their schedule and the special equipment needed. Almost all ablations are elective procedures; they can be done anytime when the health of the person is stable. Should the person get, for example, an upper respiratory tract or urinary tract infection, the procedure would be rescheduled, because to forge ahead would increase the risk of the procedure. People should therefore notify their doctor immediately if their health changes in any way before their schedule ablation procedure.

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Do I need to stop taking my medications?

Certain medications may need to be stopped before the ablation. Blood thinning medications such as coumadin/warfarin are usually stopped. In some people, shots of a different blood-thinning medication, lovenox, are given to “bridge” the time period and minimize the risk of a blood-clotting problem. The doctor will make this decision. Heart rhythm medications are stopped days to a few weeks before the procedure. Typical instructions include not drinking or eating after midnight the night before the procedure. Our practice involves asking people to take their normal morning medications with a sip of water except that diabetes pills are not given. Because the patient will not eat breakfast, only one half of the normal dose of insulin is given in people with diabetes.

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What happens at the hospital?

People must show up at the hospital several hours before the procedure. Blood tests are drawn (unless they have already been done before the day of the procedure). An IV is started in a vein of the hand or arm. People are asked to sign consent forms. Next, some pills may be given to make them somewhat sleepy. The person is then transported to the laboratory where the procedure will be done. There he or she is moved onto the bed, and small sticky patches are applied to the skin of the chest, which are connected to the ECG wires. In this way, the rhythm can be monitored throughout the procedure. Larger sticky patches are applied to the chest wall in case a shock might be required to restore normal rhythm during the procedure. In some patients a catheter is inserted into the bladder to drain the urine so that kidney function can be monitored during the procedure. Next, the groin and/or collarbone areas where the doctor will be working are shaved and prepped. Sterile drapes are applied to the skin areas.

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Will I be awake for the ablation procedure?

The average ablation procedure at our institution takes 3 hours. Some ablations are completed in less than 2 hours while others last 6 hours or longer. The only discomfort from an ablation is local anesthesia numbing the skin for insertion of the IV tubes. Minor discomfort sometimes occurs if radiofrequency energy is used as the ablation source. Cryo energy causes no discomfort at all. Because it is very difficult to ask a person who is awake to hold still, we use an anesthesia provider who provides deep sedation or general anesthesia for the procedure. Usually, the person undergoing ablation stays asleep for the entire procedure, but occasionally during sleep, the arrhythmia cannot be induced, and he or she must then be allowed to wake up partially. Most people do not remember the procedure and have therefore an acceptable experience.

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What are the risks of ablation?

Minor complications include fluid around the heart or lung, breathing problems, nerve injury, pneumonia, and low blood pressure, bleeding or infection. Major complications include death, stroke, accidental damage to the normal pathway (the AV node) requiring a permanent pacemaker, perforation of the heart, heart attack, collapsed lung and blood-clot formation. Since almost all ablations involve a fluoroscope to see where the catheters are inside the heart, there is some exposure to x-rays and the risks related to that exposure.

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What happens during the procedure?

If he or she hasn’t already done so, the doctor will now perform an EP study to assess the heart electrical system and find out about all possible heart rhythm problems. With an EP study, the person’s heart racing condition can be induced in over 95% of cases.

If the problem is on the right side of the heart, it can be reached through the IV tubes in the veins. If the problem is on the left side of the heart, it can be reached in two ways. The first involves putting an IV into the artery in the groin area. Then the ablation catheter tube can be pushed upstream through the aorta (the main artery carrying clean blood away from the heart to all the body) and then down through the aortic valve into the left ventricle. The second way is called trans-septal catheterization. With this technique, a needle is used to go from the right top chamber across the thin wall dividing it from the top left chamber.

The doctor must now find out exactly where the heart racing is coming from. This requires a mapping procedure to find the site. There are several ways to do this. This first way is for the doctor to move the catheter around inside the heart until the earliest timing is found. This so called activation mapping identifies the spot of the heart racing. Sometimes activation mapping is aided by computers. This so-called 3D mapping is a more expedient and accurate method in some cases. For other cases, the doctor may use special pacing techniques (pace mapping, entrainment mapping) to identify the origin of the heart racing. For other cases, a special intracardiac ultrasound catheter is used to see tiny structures inside the heart.

Once the doctor in convinced that the catheter is right on the origin of the heart racing, the ablation energy is delivered. The energy kills the part of the heart which the catheter is touching producing what is called a “lesion.” The typical lesion is about the size of a kernel of corn and is too small to weaken the heart in any way. If the ablation catheter was positioned properly then the irritable focus or short circuit that caused the heart racing will no longer function. This could be because it is dead or just stunned. Therefore the doctor waits a period of time (usually 30 minutes or so) and tries again to get the heart to race to see if the irritable focus/short circuit has awakened or not. If it wakes up again or if a second focus/short circuit is seen, the mapping and ablation procedure is repeated. Usually, by the end of the procedure, no further heart racing can be caused and the procedure then is considered successful. Rarely, other causes of fast heart racing are found, but if the doctor does not think that these have ever occurred in the patient, he or she may elect not to ablate them.

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What happens after the procedure?

At the completion of the procedure, the catheters are pulled out and the IV tubes are removed with pressure applied until bleeding is controlled and a band-aid applied to the site(s). No stitches are required since no incisions are made. The person goes to the recovery unit for a while and then back to the hospital room for a few hours of observation. Most people from the Dallas area do not spend the night in the hospital but go home in the early evening. People who come from a long distance away usually spend the night and then begin their journey home early in the afternoon of the next day. If the ablation is favorable, the heart-rhythm medications are stopped when the person leaves the hospital. If coumadin/warfarin was stopped, the doctor will tell the person whether to give themselves  blood thinning shots or not.

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How will I feel after the procedure?

People may have some soreness where the IVs were removed as well as some bruising. Depending on where the ablation was inside the heart, they may also have some minor soreness in the chest. They should not have severe chest pain or shortness of breath. If such symptoms occur, they should notify their doctor immediately. The heart racing should also not recur. However, after some ablations, the normal heart rhythm is faster than normal for days to weeks. Sometimes this can lead the person to believe that the ablation procedure did not work. The easiest way to distinguish this condition from the original heart rhythm problem is that this new condition involves fast heart beating usually in response to exertion and starts and stops gradually. Most heart-racing conditions that lead to the ablation procedure start and stop suddenly and are not consistently caused by exercise. However, sometimes the doctor must help figure out which it is.

The other thing that frequently confuses people is that they still have extra heartbeats or skips as they had before the ablation. In fact, before the ablation, it was these skips that started the heart racing. Seldom does the ablation address the spots that produce these extra/skipped beats, so they will continue to occur. However, the mark of a successful ablation procedure is that these beats no longer start the heart racing. We encourage people to feel their pulse after these skips to ensure that the heart is not racing. Every time this happens, it is a very good sign that the procedure was a success.

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What should I do when I go home?

The doctor will give specific instructions about what the person should and should not do at home. Our usual recommendation is not to engage in exercise until 24 hours after the procedure. However, going home and just lying around the house all day is not advised either. When the IV catheters are removed, small blood clots must form or the person would bleed to death. However, small blood clots can become large ones that can cause problems if they do not get up and move around. We recommend doing normal activities at home.

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When can I get back to work?

Motivated people with sedentary jobs can return to work within 48 hours of the ablation procedure. Those with strenuous jobs or those who had an IV placed in their artery should probably wait a few days. The doctor will advise on this.

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When do I need to see the doctor again?

Sometimes the doctor will ask the person to come back to the office for a visit in 1 to 2 months. For others, no follow-up is required since there is nothing that can be tested in the office to prove that the ablation has succeeded. Ultimately, the passage of time without any more heart racing in a person who is no longer taking heart rhythm medications strongly suggests that the procedure was a success.

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What if the arrhythmia comes back?

Heart racing may recur in about 2-15% of people. Early recurrences (less than 6-12 months) usually mean a recurrence of the original cause of the racing whereas later recurrences may signal the appearance of a new form of racing. The exception to this is for people having ablation for atrial fibrillation in which recurrences in the first 2 or 3 months do not necessarily mean that the ablation procedure did not work. Options for people with recurrence include the four original options:

  1. Doing nothing to prevent or cure SVT
  2. Taking medications
  3. Having another ablation either with the same doctor or referral to another doctor
  4. Having open-heart surgery

The doctor should discuss which of these options are best.