Pacemaker
From Ganfyd
A group of cells that produce neural or endocrine activity in order to produce a rhythmical biological activity. It may be replaced by an artificial electrical device. Where the organ is not specified this is invariably the heart, but some regard the interstitial cells of Cajal as pacemakers within the gastrointestinal system.
Contents |
Cardiac pacemakers
History
The first successful implantable pacemaker, designed by Wilson Greatbatch, was fitted in 1960 in the veterans hospital in Buffalo. A previous effort in 1958 at the Karolinska Institute had failed quickly.[1]
Physiological
Pathophysiology
Temporary Pacing
- Percussion pacing
Permanent Pacemaker
Types
The main types practically are
- Single lead - as in the classic relatively cheap and cheerful VVI pacemaker often adequate option to treat complete heart block
- Dual lead - necessary for synchrony of atrial and ventricular contraction which increases cardiac output and allows more physiological cardiac function. This can be important in heart failure.
- Defibrillators - Will also have potential pacemaking functionality.
Codes
| Cardiac chamber
paced | Cardiac chamber
sensed | Mode of
response | Programmable
functions | Anti-arrhythmia
functions |
|---|---|---|---|---|
| V≡ventricle | V≡ventricle | T≡triggered | C≡communicating | P≡paced |
| A≡atria | A≡atria | I≡inhibited | R≡rate modulated | S≡shock |
| D≡dual A & V | D≡dual A & V | D≡dual triggered/inhibited | M≡multiprogrammable | D≡dual paced & shock |
| O≡off | O≡off | O≡off | P≡simple programmable | O≡off |
| S≡Special(see note) | S≡Special(see note) | O≡off |
| Primary function
S designation is only valid in manufacturers description of a pacemaker that can use either an atrial or ventricular lead. Once the lead is attached the code becomes A or V. | Secondary function
S designation is only valid in manufacturers description of a pacemaker that can sense using either an atrial or ventricular lead. Once the lead is attached the code becomes A or V. | Magnet application usually temporarily turns off sensing function into an asynchronous mode such as AOO, VOO, DOO. The rare T mode is used to observe the location of sensing of intrinsic events and can be very useful | Only R mode is usually specified as other modes are implicate. P mode is limited to single chamber pacemakers. M mode has usually rate, sensing, output, refractory periods, hysteresis and mode options | Most bradycardia devices are assumed to be ????O devices and a fifth code position is only commonly used in defibrillators |
Post-mortem Removal
Removal is mandatory before cremation as batteries may explode at the temperatures reached.[2] This may damage the crematorium equipment. Usually in the subcutaneous space in right infra-clavicular area, but few may be epigastric. The devices can also migrate laterally or inferiorly.[3]
In the UK, statute suggests you can charge for it, though it appears the 'health authority' (now superceded by PCT) is liable rather than next of kin.[4]
This task may often be performed by the anatomical pathology technicians (colloquially known as the mortuary technicians). If the patient dies at home a GP may be asked by the undertaker to remove the device. Undertakers may be trained to remove pacemakers.
To remove, simply make an incision over the device. Remove the device, cutting the wires to leave them in situ. A GP was on one occasion criticised for using a pocket-knife to do this, which may represent a confusion with operating on the living, but there is clearly scope for upset. Beware the possibility of an implanted defibrillator, which requires switching off by a wireless control box to avoid risk to operators from electric shock.
References
- ↑ Obit: Telegraph: http://www.telegraph.co.uk/news/obituaries/medicine-obituaries/8794961/Wilson-Greatbatch.html</a>
- ↑ Gale CP, Mulley GP. Pacemaker explosions in crematoria: problems and possible solutions. Journal of the Royal Society of Medicine. 2002 Jul; 95(7):353-5.
- ↑ Gale CP, Mulley GP. A migrating pacemaker. Postgraduate medical journal. 2005 Mar; 81(953):198-9.(Link to article – subscription may be required.)
- ↑ http://www.pulsetoday.co.uk/story.asp?storyCode=4001909§ioncode=19>
