Diagnosis of Implantable Pacemaker Failure and Analysis of Its Causes

From February,1973 to August,1979,85 pacemakers were implanted on patients with complete A-V block,sick sinus syndrome,etc.,Thirteen instances of pacemaker failure took place during a 2 year follow-up.The attributable causes of the failure and their diagnostic features are as follows:
1.Battery exhaustion:Decrease in pacing rate and impulse amplitude,and prolongation of the pulse width are its characteristic points.
2.Fracture of the electrode:It causes sudden interruption of stimulation and a decrease in impulse slope S on wave form analysis.The fracture site may or may not be observed on the X-ray film.
3.Breakage in insulation:This may create a short circuit which makes the impulse slope S steeper.
4.Electrode displacement:It may cause intermittent pacing and interruption of the pacing.On X-ray film,the tip of the electrode may be in the right ventricular outflow tract or in the right atrium.
5.Impulse generator failure:Its diagnostic points are:interruption of stimulation, loss of sensing function and decrease or increase in impulse frequency and duration.It may result in pacemaker tachycardia.
6.Rise in threshold:The effective resistance in the electrode circuit is increased.
In order to prevent sudden pacemaker failure and its serious consequences,the patients with implanted pacemaker should be regularly checked both clinically and radiologically.The wave form analysis makes accurate prediction of impending cardiac pacemaker failure possible.