page forward page back  Table of Contents Index
Ventricular Pacing example four



Note the regular native P-waves, with an atrial rate of 95 beats per minute (the P-P interval is 0.63 seconds).  Some of these P-waves are buried in the paced QRSTs.  Note how the waveform changes when the two waves are superimposed.  The pacer is set at 70 beats per minute (the interval between pacer spikes is 0.84 seconds).  There is never a native QRS following a P-wave, even though periods as long as 0.52 seconds pass between P-waves and pacer spikes.   The absence of ventricular response to atrial activity indicates the underlying rhythm is third degree block or ventricular standstill.  The pacer is probably in VVI mode, but for all we can tell, with no native ventricular activity seen, it could be in VOO.