Flutter with Paced Tachycardia

Report:

Atrial flutter 250/min 4

Electronic pacemaker, atrial-sensing 5

Ventricular rate approximately 120-130/min 1

Comment:

The flutter can be made out as the underlying rhythm during pacing in the two longer ventricular cycles: there is an obvious negative F wave before the pacing spike and another, 6 mm further back, just before the T wave.

The patient’s atrial flutter, with predominant 4:1 block, is shown below (Fig 33a). Ventricular response is often very difficult to control in flutter; this is one of the reasons for pacemaker insertion. However, an atrial-sensing unit would pace the ventricles to its own upper rate limit, in this case about 130/min. The problem is not solved: the flutter has to be abolished or blocked, or the pacemaker converted to a VVI one. Many pacemakers have the mode switch option, converting automatically to VVI mode in the presence of an atrial tachyarrhythmia.

Fig 33b shows a run of regular broad-complex tachycardia.

Fig 33a.

Fig 33b. Regular broad-complex pacemaker tachycardia resulting from sensing atrial flutter. The unit was eventually changed to VVI mode.

Fig 34. 82 year old lady with periods of (until now) unexplained hypotension.