Looking after your heart


Why do I need a ventricular 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 likely suspected of having is called ventricular tachycardia (VT). This occurs when the ventricles start beating at an abnormally fast rate. When the ventricles are beating rapidly the heart does not work efficiently. This can cause you to experience feelings of weakness, dizziness, chest pain, shortness of breath or even collapse.

VT 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.

The test provides your doctor with information about your heart’s electrical system and is done to find out why your heart beats too quickly.


The procedure

Your doctor will recommend you have a ventricular tachycardia stimulation (VT stim) when other tests cannot provide enough information to diagnose your arrhythmia.

A VT stim test is a catheter technique where one or two flexible wires (catheter electrodes) are passed through a vein in your groin and carefully placed at specific positions within your heart to record the electrical signals (activity). A VT stim test records how the ventricles react to extra electrical signals (paced beats) delivered within the heart. This allows your doctor to collect detailed information about the cause of your VT, where exactly in the ventricle it is coming from, how fast it is and how easy it is to stop. The most appropriate treatment can then be chosen for you. This procedure is performed under a local anaesthetic, with sedation, which will help you to relax.

X-ray screening is used during the procedure so if you think you may be pregnant you should let us know before the procedure.


Risks of the procedure

The VT stimulation study is safe however, as with any procedure, there are potential risks. The risks will be fully explained by our doctors before you have your procedure. The VT stim test is performed safely in both children and adults.

If you are known to have underlying coronary heart disease the procedural risks are slightly increased.

All the risks outlined below can be treated and are rarely life threatening

  • Blood vessel damage: 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% and 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.
  • Pneumothorax: 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. If this happens the doctor may need to insert a drain to re-inflate your lungs. The risk of this happening to you is less than 1%.
  • Haemothorax: 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. If this happens the doctor will need to insert a drain to re-inflate your lungs. The risk of this happening to you is less than 1%.
  • Pulmonary embolism or stroke: the risk of developing blood clots that travel to the lungs (pulmonary embolism) or brain (stroke) is extremely rare, less than 1%.
  • Palpitations: 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. You will be given a short-acting sedative to make you sleepy. Once you are asleep a defibrillator is used to send electrical energy to the heart muscle to restore the normal rhythm and rate.
  • Cardiac tamponade: during placement the catheters may puncture the heart muscle causing blood to collect around the heart. 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%.
  • Bruising and bleeding: this is common in the groin 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. If you are taking warfarin (blood thinner) it must be continued as advised. We ask that you keep your INR between 2.0 and 3.0. We also request you check your INR three days before your admission to confirm it is in this range to enable the procedure to go ahead.

If you are taking alternatives to warfarin, such as apixaban, dabigatran, edoxaban or rivaroxaban, your Consultant will advise you with specific instructions about continuing these medications leading up to the procedure.


Before the procedure

When you arrive on the ward a 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 see you to explain the procedure to you and 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.

A doctor or nurse will insert a small needle into a vein in your hand (cannula) in order to give you drugs during the procedure. You will be asked to shave your groin and if necessary your upper chest and you will then be given a hospital gown to wear.

You must not eat or drink anything for four 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.

The procedure could take a couple of hours. You may wish to let your family know so that they do not worry.


During the procedure

You will be taken to the catheter lab where 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, but 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, but 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 and ablate (destroy) the extra electrical signals from within 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 test.

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 study 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 in your heart the arrhythmia is coming from and how easily it can be stopped. Your arrhythmia should stop by itself, but if it continues your doctor will need to stop it. 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 is not 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

After the procedure is completed the catheter and IV line will be removed. Firm pressure will be applied to your groin where the catheter was inserted to stop you from bleeding.

You will be moved to the recovery area where you will be monitored for a short time. On returning to the ward you will need to rest for a few hours. You may feel a little sleepy until your sedative 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 and avoid bending your affected leg for approximately two hours after the catheters have been removed. This is to prevent any bleeding from the puncture site. After this time you will be able to get up if there are no complications. You will be able to eat and drink normally as soon as you return to the ward. 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 may also have a chest x-ray to make sure that you do not have a pneumothorax (pocket of air) in your lung.



Your doctor will usually discuss the results and ongoing treatment plan with you and your family after the procedure.

Going home

You will normally be able to go home the same day. It is important to ask a family member or friend to collect you and drive you home. We would advise you to have someone stay with you for the night. Before going home, consultant 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.

Resuming normal activities

You can resume your normal daily activities upon discharge from hospital. You should not strain or lift heavy objects for a few days so that the incision site can heal.  

Unless your job requires you to lift heavy objects, you can return to work in a day or two.

You should not drive a car for one week. If you hold a Group 2 PSV licence (lorries/buses) you are not allowed to drive for six weeks.

Follow-up care

The cardiac rhythm management team will give you specific follow-up instructions when you leave hospital. . The doctors will write a detailed letter to your GP describing your hospital stay and treatment.


Further information

The following websites also provide useful information:




Our specialist doctors are here to guide you through every part of your procedure


Learn more about the treatment or procedure you are about to have


Without a doubt you will have questions, check out this handy resource


Heart Rhythm Clinic is based at Spire Southampton Hospital but also consults in Lymington, Sarum Road (Winchester) and the Nuffield Hospital, Southampton.