DDD pacemaker

Ishikawa T, Sumita S, Kimura K, et al. Prediction of optimal atrioventricular delay in patients with implanted DDD pacemakers, [see comment]. Pacing Clin. Electrophysiol. 1999 22 1365-71. 

Hirschberg J, Ekwall C and Bowald S DDD pacemaker system with single lead (SLDDD) reduces intravascular hardware. Long-term experimental study (Abstract). PACE 1996 19 601. 

Sanders RS, Barold SS. Understanding elective replacement indicators and automatic parameter conversion mechanisms in DDD pacemakers. In Barold SS, Mugica J, eds. New perspectives in cardiac pacing. Mount Kisco, NY Futura Publishing, 1988. 

Halperin JL, Camunas JL, Stem EH, et al. Myopotential interference with DDD pacemakers endocardial electrographic telemetry in the diagnosis of pacemaker-related arrhythmias. Am J Cardiol 1984 54 97-102. 

Ellenbogen KA, Hellkamp AS, WiLkoff BL, et al. Complications arising after implantation of DDD pacemakers the MOST experience. Am J Cardiol... 

Fig. 19.2 Assessment of pacemaker dependency, (a) Totally paced ventricular rhythm when the base rate is reduced to 30 ppm in a nontracking (DDI) mode in a patient who has asystoUc complete heart The P waves that occur during the atrial alert period are identified by event markers as are all the ventricular paced complexes, (b) Underlying 2 1 block rhythm is identified in a patient with a DDD pacemaker whose ventricle is normally totally controlled by the permanent pacemaker. To show this, the mode was temporarily changed to VVI and the pacing rate reduced to 30 ppm. The simultaneously telemetered unipolar atrial electrogram is shown along the bottom demonstrating the atrial activity as well as far-field ventricular signals.

When evaluating the rhythm strip of a patient with a DDD pacemaker, keep several points in mind. 

This rhythm strip shows the effects of a DDD pacemaker. Complexes 1,2, 4, and 7 show the atrial-synchronous mode, set at a rate of 70. The patient has an intrinsic P wave, so the pacemaker only ensures that the ventricles respond. Complexes 3,5,8,10, and 12... 

The DDD upper rate behavior defines the function of the pacemaker at atrial rates above the upper rate limit. When the intrinsic atrial rate exceeds the upper rate limit, the ventricular-paced events are delayed until the upper rate interval is reached (Fig. 3.27). This results in extension of the AVI. After one or more cycles of extension of the AVI, the P wave may occur within the PVARP. When the atrial event falls within the PVARP, it is not sensed and therefore does not result in a ventricular-paced event. The subsequent atrial-sensed event is tracked or followed by a ventricular-paced event. This results in a pattern of progressively prolonging atrial-sensed (P) to ventricular-paced events (V) intervals followed by an atrial event that is not tracked. This pattern... 

Brandt J, Fahraeus T, Schuller H, Ear-field QRS complex sensing via the atrial pacemaker lead, I Mechanism, consequences, differential diagnosis and countermeasures in AAI and VDD/DDD pacing, PACE 1988 11 1432-1438. 

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