Cardiac electrophysiology

An Electrophysiological Study (EP Study) is a procedure to test your heart's electrical system. It is the electrical system of the heart that generates the heartbeat.

The results of the study may help the Electrophysiologist (a specialist in electrical activity in the heart) to determine your further treatment. This could include inserting a pacemaker or defibrillator, or performing Radiofrequency Ablation.

What happens during the electrophysiological study?

A nurse will check your blood pressure, pulse, temperature and oxygen levels. A small sample of blood may be taken to make sure it is not too thin.

A small tube (cannula) will be inserted into a vein in your arm, so that you can be given sedation and other drugs intravenously.

You will be asked to remove any dentures just before the procedure. Please tell us if you have any capped or loose teeth.

You will be taken to the cardiac catheter lab for your procedure.

You will be awake throughout the procedure, so you will be given a local anaesthetic and possibly a mild sedative. You will need to lay flat during the procedure and you will be asked to lie as still and relaxed as possible.

A small plastic catheter (tube) will be inserted through a vein in your arm or leg and advanced until it reaches your heart. Using special x-rays called fluoroscopy to guide the catheter, it will be positioned in the correct area of the heart. Fine wires are then positioned within the heart.

From these wires, electrical activity from specific areas of your heart is able to be recorded. Extra beats are given via a pacemaker, which may bring on your palpitations. You may feel uncomfortable during this part of the procedure. The rhythm can be restored again quite quickly by giving more extra beats.

A pacemaker is an implanted device that monitors your heartbeat and prevents your heart from beating too slowly.

It consists of a box (pulse generator) attached to one or two wires (leads). The pulse generator is usually placed underneath the skin or muscle beneath your collarbone. The lead or leads pass inside the large veins of your chest from the generator to your heart. The leads transmit information about your heartbeat to the generator.

If your heart beats too slowly the pacemaker sends out a tiny electrical impulse to 'pace' the heart, i.e. to make it beat at an appropriate speed. If your heart then speeds up again, this is detected by the pacemaker, which then stops pacing your heart.

If you are a patient with this device, and have a question, you can find out more information at Pacemaker and ICD patients.

Most cases of heart failure occur because the main pumping chamber of the heart (the left ventricle) is not contracting well enough. Normally all parts of the ventricle contract simultaneously. In some patients with heart failure contraction of part of the ventricle is delayed relative to the rest. This is referred to as dys-synchronous contraction. Dys-synchronous contraction makes the heart less effective as a pump.

The aim of cardiac resynchronisation therapy (CRT) is to stimulate the ventricle to contract simultaneously, improving its function.

Radiofrequency Ablation is a procedure to treat some types of rapid heart beating. It is most often used to treat rapid, uncoordinated heartbeats (also known as tachy arrhythmias).

The procedures are performed under local anaesthetic. You may be able to go home the same day or you may need to stay overnight. You will be informed of this at your pre-admission assessment.

What happens during radiofrequency ablation?

During radiofrequency ablation a form of energy will be delivered down a wire to target the area in the heart that has been causing your palpitations. Most commonly the energy used is a heat source, called radiofrequency energy, but other types may be used such as cryo therapy, which freezes the area.

You may stay overnight or you may be discharged the same day. This will depend on the complexity of your procedure.

An Implantable Cardioverter Defibrillator (ICD) acts as a constant heart monitor. An ICD box is implanted under your skin, usually near the collarbone. Leads from the box are attached to your heart. These leads detect the heart's rhythm, and feed this information back to the box.

The ICD is set to detect heart rates above a certain level. This level will be different from person to person. The ICD will continuously monitor the speed of your heart. If your heart starts beating too fast, then the ICD will switch to 'alert'. Then:

If your heart rhythm returns to normal on its own, then the ICD will switch back to 'monitor'.

If your heart continues to beat too fast, then the ICD will start to deliver treatment.

The treatment may be pacing therapy, or shock therapy. It will continue to treat until either the heart rhythm goes back to normal or until all treatments have been delivered.

If you are a patient with this device, and have a question, you can find out more information at Pacemaker and ICD patients.

A TOE is a procedure to take detailed ultrasound images of your heart from the gullet (also known as the oesophagus or food pipe) which lies directly behind your heart.

To do this, a long flexible probe will be passed into your mouth and down the gullet. This provides an excellent view of your heart chambers and valves, and allows us to examine how efficiently they are working. This procedure provides the most accurate information in diagnosing problems with the heart valves such as:

• Infection of the heart valves (endocarditis).
• The need to repair or replace the valve, or whether the valve needs stretching (valvuloplasty).
• A blood clot (thrombus) in the heart chambers.

The procedure is performed as a day case, under sedation. You will be able to go home two to three hours after the procedure.

Arrhythmia is a term used to describe a number of conditions where the muscle contraction of the heart is too slow, too fast or irregular because of a disturbance with the heart's normal electrical activity

What are the different types of arrhythmia?

Ectopic beats are early beats that frequently cause palpitations and are described as missed or extra beats. Ectopic beats are not normally dangerous and don't damage the heart.

Atrial fibrillation (AF) is the most common, sustained, abnormal heart rhythm involving rapid and irregular activity in the heart. It involves very rapid, irregular activity in the atria (the top chambers of the heart). The ventricles (the bottom, main pumping chambers of the heart) try to keep up and are therefore often fast and irregular too. AF can start and stop on its own after seconds, minutes or even hours. This is known as paroxysmal AF. Persistent AF is AF that does not stop on its own but will stop if a doctor treats it; the doctor may use medicines or a small electric shock (cardioversion). Permanent AF is AF which remains even after cardioversion.

Atrial flutter

Atrial flutter involves the top chambers of the heart (the atria) beating very rapidly, as electricity circulates around them. It arises from the upper chamber on the right side of the heart, the right atrium. Electricity circulates around this chamber at a rapid rate and drives the main pumping chambers (ventricles) at a fast rate, often 100 to 150 beats per minute.

Atrial tachycardia

Atrial tachycardia is an uncommon arrhythmia that may result in rapid palpitations. It is often seen in patients with a diseased heart, although it may occur in patients with an otherwise normal heart. Atrial tachycardia arises from a small area (focus) of tissue in the atria of the heart. This focus starts to fire and drive the heart, more rapidly than the heart's natural pacemaker. Usually, the focus fires only intermittently (this is sometimes known as paroxysmal atrial tachycardia) but occasionally it can continue for days or even persist for months at a time.

Ventricular tachycardia (VT) is a fast rhythm that starts in the bottom chambers of the heart (the ventricles) and leads to the heart beating inefficiently. Symptoms including palpitations, breathlessness, chest pain and dizziness are often present. Rapid ventricular tachycardia may lead to loss of consciousness and degenerate into ventricular fibrillation, causing cardiac arrest.

Common causes of VT include coronary disease and cardiomyopathy, but it may also occur in patients with a structurally normal heart. In these patients VT may be associated with a genetic condition such as long QT syndrome or Brugada syndrome. It is commonly seen in patients who have suffered a previous heart attack and in this setting may be life-threatening.

The majority of patients who die suddenly and unexpectedly have coronary artery disease. Often this was previously unknown. In younger patients - typically age less than 35 years, one of a number of less common, although often inherited heart conditions may be the cause. These include hypertrophic cardiomyopathy, long QT syndrome and the recently recognised Brugada syndrome.

This is a condition based on a deterioration in the ability of the heart to pump blood around the body. It is a progressive disorder affecting many organs and systems in the body.

People with heart failure may experience a limitation in exercise capacity with symptoms of breathlessness and fatigue.