Students often get confused which chamber comes first in the coding but the paced chamber is the most important as without a paced chamber it's not a pacemaker so it naturally comes first. True pacemaker malfunction is uncommon, pseudomalfunction is much more common
About pacemaker codes
- A pacemaker consists of a pulse generator and pacing leads. Pacemaker leads are usually inserted into the subclavian vein or its tributaries,
and positioned on the inner surface (endocardium) of the heart. They
are attached to the endocardium by a small screw mechanism, or are held in
place by tines.
- Pacemaker leads may also be placed on the outside of the heart (epicardium)
during a surgical procedure. These leads are either sewn onto the heart, or
fixed in place with a small screw-in mechanism.
- A standard dual-chamber pacemaker has a lead in the right atrium and a
lead in the right ventricle. (A dual-chamber defibrillator has a pacing lead-in
the right atrium and a pacing/defibrillation lead in the right ventricle. The
latter delivers the defibrillation shock, as well as pacing
- Biventricular pacing is a newly developed type of pacing incorporating a third lead, which is positioned to activate the posterolateral wall of the left ventricle. This results in "ventricular resynchronization, which can improve ventricular haemodynamics, and relieve heart failure symptoms in certain patients with heart failure and conduction abnormalities.
- Dual chamber pacemakers can be programmed to sense
activity in one chamber (usually the atrium) and deliver a pacing stimulus in the other chamber (usually the ventricle) after a certain time delay. This is known as triggered pacing
- Hysteresis allows more extensive use of the patient
intrinsic rhythm and saves battery life. Allows heart to have a slower rate at night
Hysteresis rate less than the base rate. Activated by sensing intrinsic electrical activity
- Example. Pacemaker with Base Rate=60. If the patient has NSR at 65, then goes to sleep and the NSR decreases to 55, do we want the pacer to activate and pace at 60. Hysteresis rate set at 50. No pacing until intrinsic rhythm falls below 50,
then the pacer paces at 60
NBG pacemaker codes
- The pacemaker code is written in a five-letter format as in the table below, using no more letters than necessary.
- For example, the DDDR pacemaker is a dual-chamber paced, dual-chamber sensed, dual response, rate modulated device.
- At least one pacemaker mode, the DVIC mode variation, does not conform to the NBG identification code, and may sometimes be written DVI(C).
- In the 1970s and 1980s, before the NBG codes came into being, the Inter-Society Commission for Heart Disease (IHCD) established standardized codes for pacemakers. Information on these older pacemaker codes can be found at NASPE
|V = Ventricle||V = Ventricle||T = Triggered||R = Rate Modulated||O = None|
|A = Atrium||A = Atrium||I = Inhibited||C = Communicating||P = Paced|
|D = Dual (A & V)||D = Dual (A & V)||D = Dual Triggered/Inhibited||M = Multi programmable||S = Shocks|
|O = None||O = None||O = None||P = Simple Programmable||D = Dual (P & S)|
|---||---||---||O = None||---|
Complications of insertion
- Local infection, bleeding, bruising and pain
- Pneumothorax / Tension Pneumothorax usually if Subclavian puncture
- Arrhythmias as lead crosses the RV outflow tract
- Atrial or ventricular wall perforation and tamponade and death
indications for Temporary Pacing
- Asystole and usually some p wave activity, Complete heart block
- Any Severe haemodynamic disturbance due to bradycardia
- Prevent Bradycardia dependent rhythms e.g. Torsades de pointes
- Overdrive termination of VT, A flutter, TDP
- Acute MI and 2nd/3rd-degree heart block
indications for Long term Permanent Pacing
- Chronic Atrio-ventricular block
- Sick sinus syndrome with poor rate responsiveness
- Post AV nodal ablation for arrhythmias
- Long QT syndrome, Heart failure
- Dilated Cardiomyopathy, Hypertrophic cardiomyopathy
- Neurocardiogenic syncope with bradycardia