Dr Han Naung @ Henry Han : Electrophysiology and Heart Rhythm : 2017-12-31

Saturday, January 6, 2018

Cardiac Ablation for Arrhythmia

Overview

Cardiac ablation is a procedure that can correct heart rhythm problems (arrhythmias).
Cardiac ablation works by scarring or destroying tissue in your heart that triggers or sustains an abnormal heart rhythm. In some cases, cardiac ablation prevents abnormal electrical signals from entering your heart and, thus, stops the arrhythmia.

Cardiac ablation usually uses long, flexible tubes (catheters) inserted through a vein or artery in your groin and threaded to your heart to deliver energy in the form of heat or extreme cold to modify the tissues in your heart that cause an arrhythmia.
Cardiac ablation is sometimes done through open-heart surgery, but it's often done using catheters, making the procedure less invasive and shortening recovery times.

Types

Atrial flutter ablation
Pulmonary vein isolation
SVT ablation
Ventricular tachycardia ablation

Why it's done

Cardiac ablation is a procedure that's used to correct heart rhythm problems.
When your heart beats, the electrical impulses that cause it to contract must follow a precise pathway through your heart. Any interruption in these impulses can cause an abnormal heartbeat (arrhythmia), which can sometimes be treated with cardiac ablation.
Ablation isn't usually your first treatment option. Ablation is a treatment option for people who:

Have tried medications to treat an arrhythmia without success
Have had serious side effects from medications to treat arrhythmias
Have certain types of arrhythmias that respond well to ablation, such as Wolff-Parkinson-White syndrome and supraventricular tachycardia
Have a high risk of complications from their arrhythmias, such as sudden cardiac arrest

Risks

Cardiac ablation carries a risk of complications, including:

Bleeding or infection at the site where your catheter was inserted
Damage to your blood vessels where the catheter may have scraped as it traveled to your heart
Puncture of your heart
Damage to your heart valves
Damage to your heart's electrical system, which could worsen your arrhythmia and require a pacemaker to correct
Blood clots in your legs or lungs (venous thromboembolism)
Stroke or heart attack
Narrowing of the veins that carry blood between your lungs and heart (pulmonary vein stenosis)
Damage to your kidneys from dye used during the procedure
Death in rare cases

Discuss the risks and benefits of cardiac ablation with your doctor to understand if this procedure is right for you.

How you prepare

Your doctor will evaluate you and may order several tests to evaluate your heart condition. Your doctor will discuss with you the risks and benefits of cardiac ablation.
You'll need to stop eating and drinking the night before your procedure. If you take any medications, ask your doctor if you should continue taking them before your procedure.
Your doctor will let you know if you need to follow any other special instructions before or after your procedure. In some cases, you'll be instructed to stop taking medications to treat a heart arrhythmia several days before your procedure.
If you have an implanted heart device, such as a pacemaker or implantable cardioverter-defibrillator, talk to your doctor to see if you need to take any special precautions.

What you can expect

During cardiac ablation

Catheter ablation is performed in the hospital. Before your procedure begins, a specialist will insert an intravenous line into your forearm or hand, and you'll be given a sedative to help you relax. In some situations, general anesthesia may be used instead to place you in a sleep-like state. What type of anesthesia you receive depends on your particular situation.
After your sedative takes effect, your doctor or another specialist will numb a small area near a vein on your groin, neck or forearm. Your doctor will insert a needle into the vein and place a tube (sheath) through the needle.
Your doctor will thread catheters through the sheath and guide them to several places within your heart. Your doctor may inject dye into the catheter, which helps your care team see your blood vessels and heart using X-ray imaging. The catheters have electrodes at the tips that can be used to send electrical impulses to your heart and record your heart's electrical activity.
This process of using imaging and other tests to determine what's causing your arrhythmia is called an electrophysiology (EP) study. An EP study is usually done before cardiac ablation in order to determine the most effective way to treat your arrhythmia.
Once the abnormal heart tissue that's causing the arrhythmia is identified, your doctor will aim the catheter tips at the area of abnormal heart tissue. Energy will travel through the catheter tips to create a scar or destroy the tissue that triggers your arrhythmia.
In some cases, ablation blocks the electrical signals traveling through your heart to stop the abnormal rhythm and allow signals to travel over a normal pathway instead.
The energy used in your procedure can come from:

Extreme cold (cryoablation)
Heat (radiofrequency)
Lasers

Cardiac ablation usually takes three to six hours to complete, but complicated procedures may take longer.
During the procedure, it's possible you'll feel some minor discomfort when the catheter is moved in your heart and when energy is being delivered. If you experience any type of severe pain or shortness of breath, let your doctor know.

After cardiac ablation

Following your procedure, you'll be moved to a recovery area to rest quietly for four to six hours to prevent bleeding at your catheter site. Your heartbeat and blood pressure will be monitored continuously to check for complications of the procedure.
Depending on your condition, you may be able to go home the same day as your procedure, or you may need to stay in the hospital. If you go home the same day, plan to have someone else drive you home after your procedure.
You may feel a little sore after your procedure, but the soreness shouldn't last more than a week. You'll usually be able to return to your normal activities within a few days after having cardiac ablation.

Results

Although cardiac ablation can be successful, some people need repeat procedures. You may also need to take medications, even after you've had ablation.
To keep your heart healthy, you may need to make lifestyle changes that improve the overall health of your heart, especially to prevent or treat conditions that can cause or worsen arrhythmias, such as high blood pressure. Your doctor may suggest that you:

Use less salt, which can help lower blood pressure
Increase your physical activity
Quit smoking
Avoid drinking alcohol
Eat heart-healthy foods
Maintain a healthy weight
Manage strong emotions, such as anger

Clinical trials

Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this disease.

Interventional Electrophysiology and Cardiac Resynchronization Therapy Delivering Electrical Therapies for Heart Failure

Balloon occlusive coronary sinus venography in the left anterior oblique projection with the branches identified.

Right atrial anatomy and relationship to coronary sinus. OS indicates ostium. Reproduced from Ellenbogen KA et al. Clinical Cardiac Pacing, Defibrillation and Resynchronization Therapy. 3rd ed. Philadelphia, Pa: Elsevier, Inc; 2006:685, with permission from Elsevier, Inc. Copyright 2006.

A, the image was obtained from Cardio-Optic catheter placed in the coronary sinus. The image reveals the takeoff of a side branch on the right and the main coronary sinus on the left. B, The left anterior oblique fluoroscopic position of the catheter. Venography confirms the location of the branch vessel

The remote magnetic navigation workstation screen shows the venography and roadmap in the lower 2 panels. B, The same workstation reveals the final lead position.

The top ECG demonstrates right ventricular pacing, and the bottom ECG demonstrates biventricular pacing. Note that with biventricular pacing, an R wave is present in V1 and S wave in lead 1.

Transmitral Doppler flow reveals the E and A waves.

CRT (Cardiac resynchronization therapy)

Cardiac resynchronization therapy

Cardiac resynchronization therapy is a procedure to implant a device in your chest to make your heart's chambers contract in a more organized and efficient way.
Cardiac resynchronization therapy uses a device called a biventricular pacemaker that delivers electrical signals to both of the lower chambers of your heart (ventricles). The signals tell your ventricles to contract at the same time, maximizing the amount of blood that's pumped out of your heart.

Sometimes the device also contains an implantable cardioverter-defibrillator (ICD), which can deliver stronger electrical shocks if your heart rhythm becomes dangerously erratic.

Why it's done

Cardiac resynchronization therapy is a treatment for heart failure in people whose ventricles don't contract at the same time.
If you have heart failure, your heart muscle is weakened and may not be able to pump out enough blood to support your body. This can be worsened if your heart's chambers aren't in sync with each other.
Cardiac resynchronization therapy delivers electrical signals that cause your heart to beat in a way that maximizes the amount of blood that's pumped out of your heart. This treatment may reduce your symptoms of heart failure and reduce your risk of heart failure complications, including death.

What you can expect

Cardiac resynchronization therapy requires a minor surgical procedure to implant a device in your chest.
You'll likely be awake during the procedure, though the area where the pacemaker is implanted is numbed and you'll receive medication to help you relax (conscious sedation). The procedure typically takes a few hours.
During surgery, insulated wires (leads, or electrodes) are inserted into a major vein under or near your collarbone and guided to your heart with the help of X-ray images. One end of each wire is secured to the appropriate position in your heart, while the other end is attached to a pulse generator, which is usually implanted under the skin beneath your collarbone.
Types of cardiac resynchronization therapy devices include:

Cardiac resynchronization therapy with a pacemaker (CRT-P). The device used for cardiac resynchronization therapy has three leads that connect the pacemaker to the right upper chamber of your heart (right atria) and both lower chambers (ventricles).
Cardiac resynchronization therapy with a pacemaker and an ICD (CRT-D). People with heart failure who also have a risk of sudden cardiac death may benefit from an ICD that can detect dangerous heart rhythms and deliver a stronger correcting shock of energy than a pacemaker can deliver. In these cases, a cardiac resynchronization therapy device that works as both a pacemaker and an ICD may be recommended.

You'll usually stay overnight in the hospital after cardiac resynchronization therapy. Your doctor will test your device to make sure it's programmed correctly before you leave the hospital. Most people can return to their usual activities after a few days.

Pacemaker

Overview

A pacemaker is a small device with two parts — a generator and wires (leads, or electrodes) — that's placed under the skin in your chest to help control your heartbeat.
People may need a pacemaker for a variety of reasons — mostly due to one of a group of conditions called arrhythmias, in which the heart's rhythm is abnormal.

Normal aging of the heart may disrupt your heart rate, making it beat too slowly. Heart muscle damage resulting from a heart attack is another common cause of disruptions of your heartbeat.
Some medications can affect your heart rate as well. For some, genetic conditions cause an abnormal heart rate. Regardless of the underlying cause of an abnormal heart rate, a pacemaker may fix it.
A pacemaker can often be implanted in your chest with a minor surgery. You may need to take some precautions in your daily life after your pacemaker is installed.
Mayo Clinic's approach

Types

Cardiac resynchronization therapy

Why it's done

Pacemakers are implanted to help control your heartbeat. They can be implanted temporarily to treat a slow heartbeat after a heart attack, surgery or overdose of medication.
Pacemakers can also be implanted permanently to correct a slow heartbeat (bradycardia) or, in some cases, to help treat heart failure.
Smaller pacemakers about the size of a pill have been developed and are currently undergoing clinical trials. This new, leadless device can be implanted directly into the heart, where it emits an electrical impulse to control the heartbeat. Because a lead isn't required, this device can minimize the risk of infection and speed recovery time.

How your heart beats

To understand how a pacemaker works, it helps to know how your heart beats.
The heart is a muscular, fist-sized pump with four chambers, two on the left side and two on the right. The upper chambers are the right and left atria. The lower chambers are the right and left ventricles.
For your heart to function properly, the heart's chambers must work in a coordinated fashion. Your heart must also beat at an appropriate rate — normally from 60 to 100 beats a minute in resting adults. If your heart beats too slowly or too rapidly, not enough blood flows through your body, leading to fatigue, fainting, shortness of breath, confusion, and other signs and symptoms.
Your heart's electrical system controls the chambers' pumping action. A normal heartbeat begins in your right atrium, in the sinus node. This cluster of cells — your natural pacemaker — acts like a spark plug, generating regular electrical impulses that travel through specialized muscle fibers.
When an electrical impulse reaches both the right and left atria, they contract and squeeze blood into the ventricles. After a split-second delay to allow the ventricles to fill, the impulse reaches the ventricles, making them contract and pump blood to the rest of your body.

What a pacemaker does

An implanted electronic pacemaker mimics the action of your natural pacemaker. An implanted pacemaker consists of two parts:

The pulse generator. This small metal container houses a battery and the electrical circuitry that regulates the rate of electrical pulses sent to your heart.
Leads (electrodes). One to three flexible, insulated wires are each placed in a chamber, or chambers, of your heart and deliver the electrical pulses to adjust your heart rate.

Pacemakers monitor your heartbeat and, if it's too slow, the pacemaker will speed up your heart rate by sending electrical signals to your heart. In addition, most pacemakers have sensors that detect body motion or breathing rate, which signals the pacemaker to increase your heart rate during exercise to meet your body's increased need for blood and oxygen.

Single chamber pacemaker

This type of pacemaker usually carries electrical impulses from the pulse generator to the right ventricle of your heart.

Dual chamber pacemaker

A dual chamber pacemaker carries electrical impulses from the pulse generator to both the right ventricle and the right atrium of your heart. The impulses help control the timing of contractions between the two chambers.

Biventricular pacemaker

A biventricular pacemaker is a treatment option for people with heart failure whose hearts' electrical systems have been damaged. Unlike a regular pacemaker, a biventricular pacemaker stimulates both of the lower chambers of the heart (the right and left ventricles) to make the heart beat more efficiently.
A biventricular pacemaker paces both ventricles so that all or most of the ventricular muscle pumps together. This allows your heart to pump blood more effectively. Because this treatment resets the ventricles' pumping mechanism, it's also referred to as cardiac resynchronization therapy (CRT).

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Risks

Complications from having surgery to implant your pacemaker are uncommon, but could include:

Infection where the pacemaker was implanted
Allergic reaction to the dye or anesthesia used during your procedure
Swelling, bruising or bleeding at the generator site, especially if you are taking blood thinners
Damage to your blood vessels or nerves near the pacemaker
Collapsed lung

Life-threatening complications of pacemaker implantation are rare.

How you prepare

Before your doctor decides if you need a pacemaker, you'll have several tests done to find out the cause of your irregular heartbeat. These could include:

Electrocardiogram. In this noninvasive test, sensor pads with wires attached, called electrodes, are placed on your chest and sometimes your limbs to measure your heart's electrical impulses. Your heart's beating pattern can offer clues to the type of irregular heartbeat you have.
Holter monitoring. Also known as an ambulatory monitor, a Holter monitor records your heart rhythms for an entire 24-hour period. Wires from electrodes on your chest go to a battery-operated recording device carried in your pocket or worn on a belt or shoulder strap.
While you're wearing the monitor, you'll keep a diary of your activities and symptoms. Your doctor will compare the diary with the electrical recordings to try to figure out the cause of your symptoms.
Echocardiogram. This noninvasive test uses harmless sound waves that allow your doctor to see your heart without making an incision. During the procedure, a small instrument called a transducer is placed on your chest. It collects reflected sound waves (echoes) from your heart and transmits them to a machine that uses the sound wave patterns to compose images of your beating heart on a monitor.
These images show how well your heart is functioning, and recorded pictures allow your doctor to measure the size and thickness of your heart muscle.
Stress test. Some heart problems occur only during exercise. For a stress test, an electrocardiogram is taken before and immediately after walking on a treadmill or riding a stationary bike. In some cases, an echocardiogram or nuclear imaging may be done.
Other types of treadmill exercise tests also can be done to evaluate your heart, including an oxygen consumption test that measures how much oxygen your body is using.

What you can expect

Before the procedure

Surgery to implant the pacemaker is usually performed while you're awake and typically takes a few hours. Before the procedure, you are taken to a special room (called a preparation room or holding area) to start an intravenous (IV) line.
Most pacemaker implantations are done using local anesthesia to numb the area of any incisions. You may receive additional IV medication to help you relax. The implantation is done in a room with special X-ray equipment. Your chest is cleaned with an antibacterial soap, and an IV line is placed in your arm on the same side as the pacemaker.

During the procedure

During surgery, one or more flexible, insulated wires (leads, or electrodes) are inserted into a major vein under or near your collarbone and guided to your heart with the help of X-ray images. One end of each wire is secured to the appropriate position in your heart, while the other end is attached to the pulse generator, which is usually implanted under the skin beneath your collarbone.

After the procedure

You'll usually stay in the hospital for one day after having a pacemaker implanted. Before you leave, your pacemaker is programmed to fit your particular pacing needs. A return visit is often scheduled to make sure your pacemaker's settings are correct.
After that, most pacemakers can be checked remotely using wireless technology. Using your cellphone or radiofrequency signals, your pacemaker transmits and receives information between you and your doctor's office, where your doctor can access the data — including your heart rate and rhythm, how your pacemaker is functioning, and remaining battery life.
Remote transmissions can be made at scheduled intervals or at unscheduled times if your pacemaker sends an alert, or you can send a transmission if you have a concern. Remote technology means fewer trips to the doctor's office, but you'll still need to be seen by your doctor in person for scheduled checkups.
After your procedure to implant your pacemaker, your doctor may recommend that you avoid vigorous exercise or heavy lifting for about a month. You may have some aches and pains near the area where your pacemaker was implanted. These pains can be relieved with over-the-counter medicines, such as acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin IB, others), but talk to your doctor before taking any pain relievers.

Special precautions

It's unlikely that your pacemaker would stop working properly because of electrical interference. Still, you'll need to take a few precautions:

Cellphones. It's safe to talk on a cellphone, but avoid placing your cellphone directly over your pacemaker implantation site when the phone is turned on. Although unlikely, your pacemaker could misinterpret the cellphone signal as a heartbeat and withhold pacing, producing symptoms, such as sudden fatigue.
Security systems. Passing through an airport metal detector won't interfere with your pacemaker, although the metal in it may sound the alarm. But avoid lingering near or leaning against a metal-detection system.
If security personnel insist on using a hand-held metal detector, ask them not to hold the device near your pacemaker any longer than necessary or ask for an alternative form of personal search. To avoid potential problems, carry an ID card stating that you have a pacemaker.
Medical equipment. If a doctor is considering any medical procedure that involves intensive exposure to electromagnetic energy, tell him or her that you have a pacemaker. Such procedures include magnetic resonance imaging, therapeutic radiation for cancer treatment and shock wave lithotripsy, which uses shock waves to break up large kidney stones or gallstones.
If you're having surgery, a procedure to control bleeding (electrocautery) also can interfere with pacemaker function.
Power-generating equipment. Stand at least 2 feet (60 centimeters) from welding equipment, high-voltage transformers or motor-generator systems. If you work around such equipment, your doctor can arrange a test in your workplace to determine whether it affects your pacemaker.

Devices that are unlikely to interfere with your pacemaker include microwave ovens, televisions and remote controls, radios, toasters, electric blankets, electric shavers, and electric drills.

Results

Once your pacemaker is implanted, the battery should last five to 15 years, which is the average battery life. When a pacemaker's battery wears out, the pacemaker's pulse generator is replaced. The leads of your pacemaker can be left in place — though they may need to be replaced eventually — and the procedure to change your pacemaker's battery is often quicker and requires less recovery time than the procedure to first implant your pacemaker.
Pacemakers are a standard treatment for many conditions affecting your heart's electrical system. By preventing a slow heart rate, pacemakers can treat symptoms, such as fatigue, lightheadedness and fainting. Because most of today's pacemakers automatically adjust your heart rate to match your level of physical activity, they can allow you to resume a more active lifestyle.

Pacemakers and end-of-life issues

If you have a pacemaker and become terminally ill with a condition unrelated to your heart, such as cancer, it's possible that your pacemaker could prolong the process of dying. Doctors and researchers have varied opinions on turning off a pacemaker in end-of-life situations.
Talk to your doctor if you have a pacemaker and are concerned about turning it off. You may also want to talk to family members or another person designated to make medical decisions for you about what you'd like to do in end-of-life care situations.