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Chapter: Medicine and surgery: Cardiovascular system

Permanent pacemakers: Investigations and procedures

Types of permanent pacemaker , Procedure, Complications.

Permanent pacemakers


Cardiac pacemakers are used to maintain a regular rhythm, by providing an electrical stimulus to the heart through one or more electrodes that are passed to the right atrium and/or ventricle.


Common indications for a permanent pacemaker:


·        Complete heart block.


·        Sick sinus syndrome with symptomatic bradycardia.



Types of permanent pacemaker


There are several types of pacemaker, most pacemakers are programmable through the skin by radio transmission. Pacemakers may be single chamber, i.e. single electrode usually to the right ventricle, or dual chamber, i.e. one electrode to the right ventricle and one to the right atrium. The descriptive code for the most commonly used pacemakers consists of up to four letters (see Table 2.3).


Common types of pacemakers are as follows:


·        VVI is a single chamber pacemaker that senses and paces the ventricle. If it senses a beat, the paced beat is Inhibited. It is often used in patients with atrial fibrillation with AV block.


·        DDD is a dual chamber pacemaker that is capable of sensing and pacing both the atrium and ventricle. It is used in complete heart block in the absence of atrial fibrillation. It can sense if an atrial beat is not followed by a ventricular beat (due to lack of AV node conduction), in which case it will trigger a ventricular beat. It can also trigger an atrial beat followed at a suitable interval by a ventricular beat if the atrium does not contract spontaneously.



The pacemaker is inserted under local anaesthetic normally taking 45 minutes to 1 hour. A small diagonal incision is made a few centimetres below the clavicle and the electrodes are passed transvenously to the heart. The pacemaker box is then attached to the leads and impplanted subcutaneously. The procedure is covered with antibiotics to reduce the risk of infection.




The procedure is generally low-risk. The most important complications are pneumothorax due to the venous access and surgical site infection. As long as aspirin and anti-coagulants are stopped prior to the procedure, significant haematoma or bleeding is unusual.


The pacemaker function is checked within 24 hours of implantation. Annual follow-up is required to ensure that the battery life is adequate and that there has not been lead displacement. Patients are allowed to drive after 1 month (current DVLA rules), i.e. after the 4-week pacemaker check. Most pacemakers last 5–10 years.


In electromagnetic fields such as in airport security most pacemakers are now programmed to go into a default pacing mode so as not to fail. Even so patients are advised to avoid close proximity to strong electromagnetic fields. MRI scanning is contraindicated and pacemakers must be removed postmortem, if the patient is to be cremated.

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Medicine and surgery: Cardiovascular system : Permanent pacemakers: Investigations and procedures |

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