Ventricular Tachycardia Stimulation Test
The normal electrical system of the heart
The heart has its own electrical conduction system. This conduction system sends signals throughout the upper (atria) and lower (ventricles) chambers of the heart to make it beat in a regular, coordinated rhythm. The conduction system consists of two nodes that contain conduction cells and special pathways that transmit the impulse.
The normal heartbeat begins when an electrical impulse is fired from the sinus node (also called sino-atrial or SA node), in the right atrium. The sinus node is responsible for setting the rate and rhythm of the heart and is therefore referred to as the heart's natural "pacemaker”.
The electrical impulse fired from the SA node spreads throughout the atria, causing them to contract and squeeze blood into the ventricles. The electrical impulse then reaches the atrioventricular node (AV node), which acts as a gateway, slowing and regulating the impulses travelling between the atria and the ventricles. As the impulse travels down the pathways into the ventricles the heart contracts and pumps blood around the body. The cycle then begins all over again.
The normal adult heart beats in a regular pattern 60-100 times a minute; this is called sinus rhythm.
Diagram of the Heart’s Electrical System
What is an arrhythmia?
Sometimes, if the conduction pathway is damaged or becomes blocked; or if an extra pathway exists, the heart's rhythm changes. The heart may beat too quickly (tachycardia), too slowly (bradycardia) or irregularly which may affect the heart's ability to pump blood around the body. These abnormal heartbeats are known as arrhythmias. Arrhythmias can occur in the upper chambers of the heart, the atria or in the lower chambers of the heart, the ventricles.
Why do I need a ventricular tachycardia stimulation study?
Your doctor has decided that an abnormal heart rhythm may be the cause of your symptoms. To find out more about your heart rhythm disorder (arrhythmia) and to decide what will be the most effective treatment for you, he has advised you to have a ventricular tachycardia stimulation study.
The type of rhythm disorder you are suspected of having is called ventricular tachycardia (VT), it occurs when the ventricles, the bottom two chambers of the heart start beating at an abnormally fast rate. Because the ventricles are beating rapidly the heart does not work as efficiently, this can cause you to experience feelings of weakness, dizziness, chest pain, shortness of breath or even collapse.
Ventricular tachycardia is often found in people who have previously had a heart attack. The area of the heart muscle damaged by the heart attack forms scar tissue which makes the heart susceptible to abnormal heart rhythms such as VT. Other people who may experience VT are patients with cardiomyopathy or inherited arrhythmias. There is also a small group of people who have VT with a structurally normal heart. Following a number of investigations your doctor will be able to explain the cause of your possible VT to you.
A ventricular tachycardia stimulation test provides your doctor with information about your heart's electrical system, it is done to find out why your heart beats too quickly, this may be due to an extra area of conduction (short circuit) within your heart.
What is ventricular tachycardia stimulation study?
Your doctor will recommend you have an EP study when other tests cannot provide enough information to diagnose your arrhythmia.
An ventricular tachycardia stimulation is a catheter technique whereby the doctor will pass 1 or 2 flexible wires (catheter electrodes) through a vein in your groin and carefully place them at specific positions within your heart, these special wires will record the electrical signals (activity) from inside your heart. A ventricular tachycardia stimulation test records how the ventricles (the bottom chambers) react to extra electrical signals (paced beats) delivered within the heart. This allows your doctor to collect detailed information about the cause of your ventricular tachycardia, where exactly in the ventricle it is coming from, how fast it is, how easy it is to stop and choose the most appropriate treatment for you. This procedure is performed under a local anaesthetic, with sedation, which will help you to relax.
The procedure is undertaken in a special room called the EP lab using X-ray screening; therefore, if you think you may be pregnant you should let us know before the procedure.
Is the ventricular tachycardia stimulation study safe
?
Yes, the VT stimulation study is safe however, with any procedure, there are potential risks. The risks will be fully explained by our doctors before you have your procedure. The ventricular tachycardia stimulation test is performed safely in both children and adults.
Risks of the procedure
Although the majority of patients who undergo VT stim do not experience complications, it is important that you are made aware that on rare occasions there are some risks associated with the procedure that may occur either during, or after the procedure. If you are known to have underlying coronary heart disease the procedural risks are slightly increased.
It is important for you to remember that the risks outlined below can be treated and are rarely life threatening. In our experience complications associated with this procedure are very rare.
At the time of the procedure
• Occasionally, the catheter electrodes can accidentally damage the blood vessels when being moved into position within the heart. The risk of this happening to you is between 3%-5%. Serious injury to the blood vessels requiring a surgical procedure to repair the damage is extremely rare and occurs in less than 1% of patients.
• Very occasionally, the catheter electrodes can puncture the lung wall. Air leaks out of the lungs and collects in the space between the lung and chest wall, resulting in partial or complete collapse of the lung. This is called a pneumothorax. If this happens the doctor may need to insert a drain to reinflate your lungs. The risk of this happening to you is less than 1%
• Again, very occasionally the catheter electrodes can puncture the lung wall. Blood leaks out of the lungs into the pleural cavity, the space between the lungs and the walls of the chest. This is called a haemothorax. If this happens the doctor will need to insert a drain to reinflate your lungs. The risk of this happening to you is less than 1%
• The risk of developing blood clots that travel to the lungs (pulmonary embolism), brain (stroke) or lower leg (DVT) is extremely rare, less than 1%.
• It is common to experience palpitations (extra heart beats) during the procedure due to the catheter electrodes stimulating your heart. Your heartbeat will usually return to its normal rhythm very quickly without needing further treatment. However, very occasionally extra treatment (cardioversion) is needed to correct your arrhythmia. Cardioversion is a treatment for heart rhythms that are irregular. Before you are cardioverted you will be given a short-acting sedative to make you sleepy. Once you are asleep a special machine called a defibrillator is used to send electrical energy to the heart muscle to restore the normal rhythm and rate.
• During placement the catheters may puncture the heart muscle causing blood to collect around the heart, this is called a cardiac tamponade. If this happens the doctor may need to insert a drain to remove it. The risk of this happening to you is less than 1%
After the procedure
• Bruising and bleeding in the groin is common following the procedure. However, this usually disappears within a week and does not cause a problem.
Before admission
If you are taking medication to control your heart rhythm it is likely that you will be advised to continue taking your tablets until your procedure. Again, if you are taking warfarin (blood thinner) it is very important you check with the EP co-ordinator before your admission, as you may need to stop taking it before you have the procedure. If you have any questions please talk to the EP co-ordinator about the medicines that you are currently taking.
Before The Study
On your arrival to the ward you will be introduced to the nurse who will be looking after you. The nurse will talk to you and your family about your hospital admission and answer any questions you may have. Before the procedure, you will have blood tests taken and an electrocardiogram (ECG) recorded. A doctor will also see you and explain the procedure to you, he will then ask you to sign a consent form; this is to ensure you understand the procedure and the associated risks. If you have any worries or questions please do not be afraid to ask. It is important to tell your nurse or doctor if you have any allergies or have had a previous reaction to drugs or other tests. If you are having the procedure done under a general anaesthetic, you will also talk to an anaesthetist.
Before the procedure a nurse will help to get you ready. The doctor or nurse will need to insert a small needle into a vein in your hand (cannula) this is to allow the doctor to give you drugs during the procedure. You will also be asked to shave your groin and if necessary your upper chest and you will then be given a hospital gown to wear.
You will be asked not to eat or drink anything for 4 hours before your procedure. If you are diabetic, your nurse will discuss your tablets/insulin dose with you, because not eating may affect your blood sugar levels.
Please tell your family that the procedure may take a couple of hours so that they do not worry.
During the procedure
You may feel very anxious during the procedure, however the staff involved in your care are aware of your possible anxieties. Whilst you are in the catheter lab a nurse will stay with you and be there to reassure you throughout the procedure. There is a lot of equipment in the room, which is used to monitor your heart rhythm. You will be awake during the procedure however, to help you relax your doctor will give you a short acting sedative.
The doctor will inject a local anaesthetic into your groin to numb your leg, this may sting a little and you may feel some mild discomfort. When the local anaesthetic has taken effect, the doctor will insert a small tube (sheath) into your groin, you should not feel any pain, if you do, please let your doctor know. Through the sheath the doctor will gently thread several flexible wires (catheter electrodes) into your heart, these special wires will record the electrical signals from inside your heart.
The catheters are about the size of a small drinking straw. The doctor carefully moves the catheters into position within your heart under x-ray screening. You should not feel pain during this part of the procedure.
Once the catheters are in place, your doctor will attempt to start your arrhythmia by giving your heart small electrical impulses (paced beats) to make it beat at different speeds. Sometimes your doctor will also need to give you drugs to bring on your arrhythmia. This allows the doctor to collect detailed information about the cause of your arrhythmia and pinpoint where the area of extra electrical activity responsible for your arrhythmia is within your heart. During this time you may feel your heart speeding up, slowing down or missing a beat; this may cause you some mild discomfort. This is a normal part of the test and in the controlled setting of a VT stim is not a danger to you.
The test will be stopped after your doctors have collected and recorded all the information they need. Your doctors will assess how fast your heart is beating, where about in your heart the arrhythmia is coming from and how easily it can be stopped. Remember, your doctors want to find out what is causing your problem, so that they can treat it. Your arrhythmia should stop by itself, however, if it continues your doctor will need to stop it, he may try to pace your hear into a regular rhythm or give you drugs to slow your heart rate down. Occasionally, it may be necessary to give you electric shock treatment (cardioversion). If you need this treatment your doctor will give you more sedation, as a cardioversion would never be done when you are awake.
If you do have any uncomfortable symptoms during the procedure, for example, chest pain, dizziness, shortness of breath, please tell your nurse or doctor. It is important that your doctor knows how you feel when you have your arrhythmia.
After the procedure is completed the catheter and IV line will then be removed. Firm pressure will be applied to your groin where the catheter was inserted to stop you from bleeding.
After the procedure
After the procedure you will be moved to the recovery area where you will be monitored for a short time before returning to the ward. On return to the ward you will need to rest for a few hours. You may feel a little sleepy until your sedation has worn off. The nurse will record an ECG, check your blood pressure, pulse and feel your foot pulses. The nurse will also check your groin for any bleeding. It is important that you remain in bed for approximately two hours after the catheters have been removed. You should also try to lie still and avoid bending your affected leg; this is to prevent any bleeding from the puncture site. You can however rotate your ankle and flex your foot, this will help your circulation and reduce your risk of developing a blood clot (DVT) in your lower leg (calf). After this time of rest, you will be able to get up. On return to the ward you will be able to eat and drink normally. The nurse will remove the small needle in your hand. If you feel any palpitations or dizziness after the test, please let the nurse know. You will also have a chest x-ray to make sure that you do not have a pneumothorax (pocket of air) in your lung.
When will I know the result of my procedure?
After your procedure your doctor will usually discuss the results and treatment plan with you and your family.
Your discharge
You will normally be able to go home the following day. It is important to ask a family member or friend to collect you and drive you home. Prior to your discharge, your doctor or EP nurse will advise you regarding the medicines you will need to take, or stop and your follow-up care.
Caring for your wound
You will have a small dressing on your puncture site that can be removed the next day. It is important to keep the area clean and dry until it has healed. If you notice any swelling, redness or oozing please let your GP know.
When can I resume my normal activities?
You can resume your normal daily activities (walking, bathing, showering, etc.) upon discharge from hospital. The only restriction is straining or lifting heavy objects for a few days so that the incision site can heal.
When can I go back to work?
Unless your job requires you to lift heavy objects, you can return to work in a day or two.
Will I still need to take medication?
After the procedure all your antiarrhythmic tablets may be stopped.
Warfarin will be continued for 3 months, occasionally longer if you experience a repeat episode of atrial fibrillation. On average, it takes about three months for the heart to fully recover. You may experience atrial fibrillation and palpitations (skipped heartbeats) whilst in hospital and in the first 2 – 3 months after the procedure, this does not mean the abaltion has failed. If this happens your doctor may give you medicines to stop your arrhythmia and keep you anticoagulated on warfarin. If during this period, if you continue to experience atrial fibrillation and feel unwell your doctor may suggest you have a cardioversion to regulate your heart rhythm.
The atrial fibrillation and palpitations will gradually decrease. Three months after the procedure the majority of patients are in normal sinus rhythm and your doctor will ask you to stop taking your medications.
It is important to remember however that approximately two thirds of patients respond to pulmonary vein isolation with one third requiring a repeat procedure.
Driving
The DVLA's guidance is that after a PVI ablation you should not drive a car for 1 week. If you hold a Group PSV 2 licence (lorries/buses), you are not able to drive for 6 weeks.
Will I come back here for follow-up?
Upon discharge from the hospital, you will receive specific follow-up instructions by our Electrophysiology team. Our doctors will write a detailed letter to your GP detailing your hospital stay and treatment.