A pacemaker is a device inserted just underneath the clavicle which paces the heart when the natural heartbeat is too slow. An “artificial pacemaker” is a small, battery-operated device that helps the heart beat in a regular rhythm. Some are permanent (internal) and some are temporary (external). They can replace a defective natural pacemaker or blocked pathway.
- A pacemaker uses batteries to send electrical impulses to the heart to help it pump properly. An electrode is placed next to the heart wall and small electrical charges travel through the wire to the heart.
- Most pacemakers are demand pacemakers. They have a sensing device. It turns the signal off when the heartbeat is above a certain level. It turns the signal back on when the heartbeat is too slow.
INDICATIONS FOR PACEMAKERS:
- Sick sinus syndrome (sinus node dysfunction).
- Advanced heart block (either 2nd degree Mobitz II or 3rd degree).
- Marked sinus bradycardia.
- Black-outs for which heart block is a highly likely cause even though there is no rhythm strip or recording evidence.
- Recurrent episodes of fast and slow heart rates. (Typically fast heart rates are controlled with medications, but slow heart rates need to be backed up with a pacemaker).
TYPES OF PACEMAKERS
There are many types of pacemakers as well as from various medical companies: Medtronic, Boston Scientific, St. Jude, Biotronik etc.
- Brady pacing (single or dual chamber pacemakers)
- Biventricular pacemakers
- Internal defibrillators
- Long-term detection of heart rhythm (REVEAL® implant)
All pacemakers can pace the heart, meaning that they will activate when or if a heart beat falls below a certain pre-determined heart rate. Biventricular pacemakers have additional functions of coordinating the beating of the right AND left-sided heart chambers, these pacemakers are mainly indicated in patients with weak hearts) heart failure. Defibrillators are also capable of shocking the heart from within to restore normal rhythm – especially in patients with a history or at great risk of suffering from sudden cardiac death (ventricular tachycardia or fibrillation). Combinations of all three are also common.
PACEMAKER INSERTION PROCEDURE
Nowadays, pacemaker insertion is performed with local anaesthetic and mild sedation, taking anywhere from 1/2 hour to 3 hours depending on the complexity of the procedure and the various challenging patient cardiac anatomy. An incision is made just beneath the clavicle, and pacemaker leads (wires) are tunneled under X-ray guidance into the right heart chambers. These leads are then connected to the pulse generator (battery and electronics) and the whole assembly is sown underneath the skin. The patient typically stay overnight in hospital and will go home the next day after chest X-ray and pacemaker check is satisfactory.
PACEMAKER CLINIC/FOLLOW-UP
Regular checking of an implanted pacemaker is an integral part of management of pacemakers. Batteries do run down, and regular checks will prevent any untoward incidences. WIres/leads can fracture, and patients can develop differing responses to pacemakers, so all these issues can be managed in a pacemaker clinic. Newer pacemakers now can have remote link functions, where information from a pacemaker can be interrogated in a wireless fashion and transmitted via modem to a central server; this information will then be relayed to the doctor either via email, internet, or even SMS via mobile phone.
Medtronic has released a pacemaker system (ADVISA) – pulse generator (battery) and leads (wires) that are completely MRI-safe. This means that patients who had this system implanted can still undergo scanning with MRI in future. For further news, click here.