An 83-year-old man who had undergone implantation of a DDDR pacemaker (Evia DR-T, Biotronik, Berlin, Germany) due to paroxysmal atrioventricular block, had a routine electrocardiogram (Figure 1), that revealed sinus rhythm with premature ventricular contractions in bigeminy and pacemaker spikes superimposed on the QRS of the sinus beats. As a malfunction of the device was suspected, it was subjected to interrogation. All the parameters were normal (atrium/ventricle: P/R wave sensing, 2.3/13mV; impedance, 236/634 Ω, and threshold, 0.3/0.7V at 0.4ms). Figure 2 shows a tracing obtained with the programmer.
In view of these values, is this a case of a real pacemaker malfunction?
- 1.
If the pacing and sensing parameters are normal, there is no malfunction.
- 2.
The pacemaker is functioning perfectly. This is a case of fusion: pacing by the device and the appearance of the conducted QRS occur simultaneously.
- 3.
Despite the fact that the R wave measured during the interrogation was normal, there is a defect in ventricular sensing.
- 4.
This situation could be resolved by increasing the ventricular pacing pulse amplitude.
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