![]() ![]() On an ECG, the pacemaker produces a jolt of electricity and a spike on the ECG, but no complex follows the spike. Our experience has shown that the variable nature of this type of pacing can even cause a different chamber to be stimulated by the bipolar electrode in the atrium (Figure 3).A pacemaker produces a stimulus, but the heart fails to respond to the pacemakerâs impulse. The pacemaker was triggered by the absence of an inherent heartbeat (the heart did not beat on its own), and fired, as it should. However, four spikes do not produce a ventricular complex. Asynchronous stimulation can also be produced by other types of pacing. The pacing spikes the follow-up period, and in accordance with the standard procedure for evaluating this type of pacemaker, atrial stimulation using OLBIs was started.Äuring a subsequent routine check-up, intermittent failure of atrial capture was observed during atrial stimulation using AAI pacing at a near-threshold voltage. The pacemaker was programmed to function in a VDD mode just after implantation and performed without problems. Electrocardiogram shows atrial sensed ventricular paced rhythm with a very wide complex tachycardia (QRS duration of 240 milliseconds) at 115 beats per minute with group beating due to intermittent failure to capture. ![]() Use of a Holter monitor prior to pacemaker implantation confirmed the existence of severe paroxysmal atrioventricular block but there was no evidence of concomitant sinus node dysfunction. In 1997, a permanent VDD pacemaker (Eikos SLD, Biotronik, with an Intermedics UniPass electrode) was implanted. Our patient was an 85-year-old ex-smoker with a history of trifascicular block and episodic syncope of cardiogenic origin. ![]() This mode of stimulation involves the generation of two broad large-amplitude unipolar impulses of opposite polarity. 2,3 During 19, at the Hospital ClÃnico in Zaragoza, Spain, we implanted a number of VDD pacemakers that were also able to provide atrial stimulation by means of overlapping biphasic impulses (OLBIs) from "floating" electrodes. 1įor a number of years, there has been an interest in developing single-lead DDD pacing. The principal advantages of these pacemakers are the simplified implantation procedure and reduced overload of the venous system. The use of single-lead VDD pacemakers enables atrioventricular synchrony to be maintained in patients who have impaired atrioventricular conduction with preserved sinus node function. ![]()
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