A pacemaker is a small device which is implanted beneath the skin below the collarbone. This is a simple procedure usually performed under local anaesthesia, and/or with minimal sedation, and is typically completed within one hour. The pacemaker is connected to a pacing wire placed inside the heart. The pacemaker delivers a small electrical impulse to stimulate the hear t to beat when it is going too slowly. Typically, pacemakers are rate-responsive and have sensors that automatically adjust to changes in a person’s physical activity. If you have a slow heart rate your doctor may recommend you have pacemaker.
Pacemakers may be recommended for a number of conditions, including:
- Atrial fibrillation
- Heart failure
There are three basic types of pacemaker:
- Single-Chamber Pacemakers –only one wire (pacing lead) is placed into a chamber of the heart.
- Dual-Chamber Pacemakers – wires are placed in two chambers of the heart. One lead paces the atrium and one paces the ventricle. This approach more closely matches the natural pacing of the heart.
- Cardiac resynchronisation therapy pacemakers (CRT-P; see cardiac resynchronisation therapy)
Implantable Cardioverter Defibrillator
For those who are at high risk of the lethal heart rhythm disturbances – ventricular tachycardia and ventricular fibrillation – an internal “shocking”device, known as an implantable cardioverter defibrillator (ICD), may provide the best protection against sudden cardiac arrest. Survival following an out-of-hospital arrest is substantially affected by the time to restoration of a normal heart rhythm. The response time in the community for a paramedic ambulance may reach 4-8 minutes, where as an ICD can deliver a shock within 30 seconds with a successful conversion rate >90%.
Implantable cardioverter defibrillators (ICDs) are small devices, about the size of a pager, that are placed below the collarbone. Wires or leads connect these these devices to the heart in order that they can continuously monitor the heart’s rhythm. If potentially letha heart rhythm disturbances occur the ICD issues a life saving of electric shock to restore theheart’s normal rhythm and prevent sudden cardiac death. Sometimes the ICD can beprogrammed to “pace” the heart to restore its natural rhythm and avoidthe need for a shock from the ICD ICDs also can act as pacemakers when a heart beat that is too slow(bradycardia) is detected.
Cardiac Resynchronisation Therapy
Cardiac resynchronization therapy (CRT) is an innovative new therapy that can relieve CHF symptoms and improve survival by improving the coordination of the heart’s contractions.
Many patients with heart failure have incoordinated contraction of the lower cardiac chambers (ventricles) leading to inefficient cardiac pumping. However, these devices do not work for all types of hear t failure The electrocardiogram or echocardiogram can help to identify incoordination in patients with heart failure. CRT uses the technology used in pacemakers and implantable cardioverter devices. In addition to the two leads (right atrium and right ventricle) used by a common pacemaker, the CRT device has a third lead that is positioned in a vein on the surface of the left ventricle. This allows the CRT device to simultaneously stimulate the left and right ventricles and restore a coordinated, or “synchronous,” squeezing pattern. This is sometimes referred to as “bi-ventricular pacing” because both ventricles are electrically stimulated (paced) at the same time. This restores a more coordinated and effective heart beat.
Percutaneous Radiofrequency catheter ablation of arrhythmias
Catheter ablation aims to cure the abnormal heart rhythm by destroying the pathway, or area of extra cells, causing the palpitations. Catheter ablation is a relatively non-invasive procedure that involves inserting catheters –narrow, flexible wires – into a blood vessel, often through a site in the leg or neck, and winding the wire up into the heart.
Once the catheter reaches the heart, electrodes at the tip of the catheter gather data and a variety of electrical measurements are made to pinpoint the location of the faulty electrical site. Once the site is confirmed a targeted lesion is produced by cauterizing the tissue, or delivering intense cold, which freezes, or cryoablates the tissue. The procedures has no adverse effect on the heart pump function. Most people recover quickly from the procedure and feel well enough to carry on with normal activities the following day.
Non-drug treatments for atrial fibrillation
In some individuals the episodes of atrial fibrillation are both severe and frequent,
affecting their quality of life. If drug treatments do not work or cause unpleasant
side effects, it may be necessary to offer a different solution.
Cardioversion is a way of converting the heart back to its normal rhythm. It can sometimes be achieve during intravenous or oral medication. Alternately, an electrical shock can be delivered to the chest wall to convert atrial fibrillation back to a normal rhythm.
AV nodal ablation (“pace-ablate”)
This involves implantation of a permanent pacemaker followed by a subsequent procedure to ablate the AV node or junction box. This does not cure the atrial fibrillation but in abolishes the fast and irregular heart beat caused by it, and regularises the heart rhythm.
Left Atrial Ablation
Also called a left atrial circumferential ablation or pulmonary vein isolation ablation (PVI). It is not suitable for all patients with AF, but may be considered if your symptoms do not respond to other treatment. In recent years it has been found that AF can originate from areas around the pulmonary veins (blood vessels linking the heart with the lungs), which are situated in the left atrium (upper chamber). The technique involves passing a wire into the left side of the hear t. This is done by passing a wire through the vein in the groin, into the right side of the hear t and making a small hole in the muscle, which separates the right and left upper chambers. Once the wire is in place, tiny burns or freezes are delivered around the pulmonary veins. The advantage of having this procedure is that the majority of suitable patients have a dramatic improvement in their symptoms and some are completely cured of AF.