THE HEART The main function of the heart is to pump blood and oxygen around your body to all of your vital organs. It has four chambers, two at the top (the right and left atria) and two at the bottom (the right and left ventricles).
THE ELECTRICAL SYSTEM OF THE HEART The conduction system carries electrical impulses throughout your heart, causing it to beat. The conduction system permits the electrical impulse to reach all parts of your heart at the right time, so that the heartbeat is coordinated and occurs at a normal rate.
Problems with the rhythm of your heart
There are many kinds. Some of the most common are:
Early heartbeats start from the upper chambers of the heart. Usually, no medicine treatment is needed.
Congenital Heart Defect Correction can be employed to correct atrial septal and ventricular septal defects, closure of a patent ductus arteriosus and angioplasty of the great vessels.
Sinus tachycardia occurs when your heart speeds up when you are exercising, being active, feeling anxious or afraid and when you have a fever. This is normal.
If your heart rate stays at this fast rate for a long period of time, you may feel pounding in your chest (palpitations), lightheadedness, weakness, shortness of breath or other symptoms
Atrial fibrillation occurs when electrical impulses travel through the atria (top part of your heart) in a random or disorganized way. This causes the atria to beat (or contract) many times for each one time that the ventricles contract. When your atria are fibrillating, they are not able to pump blood effectively.
If you have atrial fibrillation, your risk of stroke is up to five times greater than people who have a normal rhythm. Sometimes atrial fibrillation occurs in healthy people, but usually it happens if you also have high blood pressure, a history of valve or heart disease, coronary artery disease or hyperthyroidism.
Ventricular tachycardiaoccurs when you have consecutive episodes of premature (early) ventricular contractions. Some people tolerate this, while others may faint. This condition can be life-threatening. An electrophysiology study can tell your doctor if you have this rhythm, or one that looks similar. Sometimes, it is found on an ECG (electrocardiogram).
Ventricular fibrillation occurs when electrical impulses in your heart travel through the ventricles (bottom chambers of your heart) in a disorganized way. This prevents your ventricles from contracting correctly. When the ventricles are fibrillating, they are not able to pump blood to your body. You will pass out or lose consciousness. An electrical shock or defibrillation can put your heart back into a normal rhythm.
Bradycardia occurs when your heart beats slower than normal – fewer than 60 beats a minute. A normal sinus rhythm (or heart rate) is 60 to 100 beats per minute. A slow heart rate may be caused by medicines and is not a problem, unless it causes symptoms such as fatigue, shortness of breath, or lightheadedness.
Heart block is the blocking of electrical impulses through the heart. Some heart blocks do not need to be treated. It becomes serious when your heart beats too slowly to maintain good circulation. Heart block is caused by certain medicines, disease or wear on the electrical conduction path.
Heart block may cause your heart to beat out of rhythm. If it worsens into complete heart block, impulses from the heart’s atria don’t reach the ventricle. The ventricles beat independently at a very slow rate. You’ll become weak, dizzy or lightheaded. If you have complete heart block, you will need a permanent pacemaker.
Heart rhythm disorders are managed in a number of ways, including medications, pacemakers, implantable defibrillators, invasive electrophysiologic procedures and biventricular pacemakers.
During ablation, a catheter delivers radio frequency energy to the area of the heart that is causing an abnormal rhythm. This area, which is quite small, is cauterized which stops abnormal rhythm. Ablation has more than a 90 percent success rate, meaning that patients no longer have to take medication or have follow-up treatments for their abnormal rhythms.
This technology is used to treat patients who have congestive heart failure. In a normal heart, the regions of the left ventricle pump in sync. The electrical system can be impaired enough to make the regions of the left ventricle pump out of sync in a person with congestive heart failure, so not enough blood gets pumped to the body, which intensifies heart failure symptoms such as shortness of breath and fatigue. To remedy this, physicians resynchronize the timing of the electrical impulses in the heart with biventricular pacemakers that help the regions of the left ventricle pump in time to increase efficiency of contraction.
A defibrillator device is implanted to monitor the regularity of the heartbeat and deliver an electric shock should the heart begin fibrillation (fast or slow twitching of cardiac muscle fibers).
A pacemaker is an electrical system that reads and delivers cardiac electrical impulses. By “reading” these signals, the pacemaker is able to monitor the heart’s activity and respond appropriately. A pacemaker helps to pace the heart when the natural rate is too slow (bradycardia) to pump enough blood to the body.
There are several reasons why people have pacemakers implanted; most people have an abnormality in the electrical conduction system of the heart. This can cause the heart to beat too slowly, too quickly or irregularly and may cause symptoms such as dizziness, shortness of breath, extreme fatigue, fainting.
These rhythm disturbances have many causes – the most common being
A Pacemaker consists of two major parts: the generator and the lead.
The generator is a tiny, sealed box containing electronic circuitry and a battery. The battery life of most pacemaker generators today is 3 – 8 years.
The lead is a flexible insulated electrical wire. One end is attached to the generator and the other end is passed via a vein into your heart. You may have one, two or three leads depending on the type of pacemaker being implanted.
Single chamber pacemaker – this will pace the right atrium or right ventricle. Only one pacing lead is used.
Dual chamber pacemaker – both the right atrium and right ventricle of the heart are paced. This requires two pacing leads.
Bi-ventricular pacemaker – Both ventricles are pacedusing a bi-ventricular pacemaker. This improves the ability of the heart to pump and improves cardiac output. This requires three pacing leads.
The type of pacemaker chosen to treat your condition will be dependent on your heart condition.
As with any procedure there are some small risks associated with having a pacemaker fitted. Generally the most common risks are:
Infection to the wound – You will be given antibiotics after your pacemaker is fitted to reduce this risk.
Lead displacement – there is a very slight risk that the wire may move from its original position (become displaced).
Pneumothorax – On very rare occasions the lung may be perforated during the implant, this causes air to leak from the lungs into the chest. The follow-up chest X-ray after your implant would pick this up.
Pain / discomfort / bruising – Some bruising can occur, as the skin has been stretched to accommodate the pacemaker. You may also feel some discomfort around the wound site.
Electrophysiological studies (EPS) are investigations which look at the electrical conduction system within the heart. The conduction system controls the heart’s rate and rhythm.
Who benefits from having EPS?
What does EPS and Ablation involve?
EPS involves passing long fine wires up into the heart via a blood vessel in the groin area (commonly the right groin), and a second wire is inserted into a vessel underneath the collar bone (the left hand side). This is undertaken using a combination of local anaesthetic and intravenous sedation. No general anaesthetic is required.
Once inside the heart, the wires are used to seek out abnormal tissue which may be responsible for causing electrical abnormalities. Then, using radio-frequencies, the wires are used to ‘burn’ this abnormal tissue and prevent it from being able to conduct any abnormal rhythm.
The radio waves that are used can cause localised heat generation which destroys the abnormal tissue. Sometimes, the tissue can be a little resistant to a single burn, so several burns may be necessary in order to achieve the desired effect of getting rid of all abnormal conducting tissue. This process of finding the abnormal tissue and then delivering several burns can take anything from 2 – 4 hours.