Permanent pacing, external pacing and implantable cardiac defibrillator (ICD) Flashcards
Describe how pacemakers are named.
1st letter is the chamber that is paced
2nd letter is the chamber that is sensed
3rd letter e.g.
* I means “inhibited” is added to say that that whatever is sensed inhibits pacing
* D means dual mode
4th letter (R) indicates whether a pacemaker has rate response (all modern pacemakers have this so sometimes not mentioned) - this uses several factors to check whether the pacemaker needs to increase your HR (by sensing acceleration, RR, acid-base levels)
E.g. AAI means pacemaker that senses and paces the atria; pacing is inhibited when the atria activate spontaneously without help from the pacemaker
What is cadiac resynchronisation therapy (CRT)?
A new type of pacemaker which makes different walls of the heart contract at the same time instead of incoordinately e.g. LBBB
This has an atrial lead and 2 ventricular leads so 3 in total
What kind of pacemaker does this patient have implanted?
There is a sharp spike before the P and QRS so dual pacing.
What is the pacemaker doing?
Pacing the ventricle, independent of the atrium (although there are no P waves at all, just fibrillation activity which is at random intervals)
Could be a VVI pacemaker in AF
What has happened with the highlighted beat?
Ventricle activation had already begun so this was sensed and the pacemaker was not activated
What wave on the ECG would make you suspect sinus node disease?
Abnormal P waves means sinus node is malfunctioning
Define pacemaker.
Devices that supply the electrical initiation to contraction - these lie subcutaneously and generally stimulate the atrium/ventricle (endocardial pacing) or the external surface of the heart (epicardial pacing),
What are the indications for a temporary pacemaker?
- Symptomatic/haemodynamically unstable bradycardia - no response to drugs (atropine)
- Onsent of acute conduction disturbance - post anterior-MI type II or complete heart block
- To suppress drug-resistant VT or SVT
- Trifascicular block prior to surgery
What are the indications for a permanent pacemaker?
- 2nd or 3rd degree heart block
- symptomatic bradycardias e.g. sick sinus syndrome
- persistent bifascicular block following MI (controversial)
- supression of resistant tachyarrhythmias (rare)
What is the advice around pacemakers and driving and travel?
After pacemaker implant/box change:
* Group 1 entitlement - must not drive for 1 week and notify DVLA
* Group 2 entitlement - must not drive for 6 weeks and notify DVLA
Must not fly at least 2 days after temporary/permanent pacemaker implantation due to pneumothorax risk
What is meant by class I/II/III indications for pacemakers?
Class I - pacing is definitely beneficial
Class II - pacing may be indicated
Class III - permanent pacing is not indicated and may be harmful
How long do pacemakers last?
7-15yrs
What are some causes of bradyarrhythmias requiring permanent pacing?
Disease within the AV node:
* 1st degree HB
* 2nd degree block - Mobitz I
* Normal QRS
Disease below the AV node:
* Normal PR
* 2nd degree block - Mobitz II
* 3rd degree block
* Widening QRS
Reversible causes:
* Medications - BB, NDHP CCBs, antiarrhythmics
* Toxic, metabolic, electrolyte, disturbances
* Acute MI
* Cardiac trauma e.g. indwelling catheter, post-op, blunt chest trauma
* Lyme disease
Congenital complete heart block
Neuromuscular diseases
Long QT syndrome
Bradycardia induced ventricular arrhythmias
Hypertrophic cardiomyopathy
Heart failure
What are some causes of bradyarrhythmias?
Disease within the AV node:
* 1st degree HB
* 2nd degree block - Mobitz I
* Normal QRS
Disease below the AV node:
* Normal PR
* 2nd degree block - Mobitz II
* 3rd degree block
* Widening QRS
Reversible causes:
* Medications - BB, NDHP CCBs, antiarrhythmics
* Toxic, metabolic, electrolyte, disturbances
* Acute MI
* Cardiac trauma e.g. indwelling catheter, post-op, blunt chest trauma
* Lyme disease
What are the components of a permanent pacemaker?
Pulse generator - provides the electrical impulse for myocardial stimulation
Electrodes - one or more deliver the impulse from the pulse generator to the myocardium; these travel through veins
You can also have leadless systems inserted into the RV
What is external pacing?
Another name for temporary cardiac pacing which is non-invasive and delivers pulses to keep the heart beating at a steady state
Pads connected to a monitor/defibrillator are positioned in front and behind the heart on the patient’s chest and switched on to deliver electrical impulses to maintain heart contractility.
