Pacemaker spikes

Main functions Pacemaker Spike Transmitter release Transmitter release Transmitter release... 

Fig. 19.16 The Medtronic 9790 programmer generates a uniform amplitude pacemaker spike in response to any high-frequency transient. Although the paced rhythm can be seen in the background, the multiple pacing stimuli are arising from an unknown source extrinsic to the pacemaker and distorted the recording markedly impeding the pacing system evaluation.

The pacemaker spikes caused significant undersensing and delayed recognition of the VF. In fact it took almost 16 seconds from the time of induction until the 21 J shock was delivered. 

Pacemaker impulses— the stimuli that travel from the pacemaker to the heart—appear as spikes on an ECG tracing. Whether large or small, pacemaker spikes appear above or below the isoelectric line. This illustration shows an atrial pacemaker spike and a ventricular pacemaker spike. 

ECG shows pacemaker spikes anywhere in the cycle (the pacemaker fires, but at the wrong times or for the wrong reasons). 

Fig. 8.5 Dual chamber pacemaker (spikes before both P and QRS)...

The most prominent electrocardiogram (ECG) characteristic produced by a pacemaker is known as a pacemaker spike. The spike occurs when the pacemaker sends an electrical impulse to the heart muscle. 

If you see an intrinsic P wave followed by a ventricular pacemaker spike, the pacemaker is tracking the atrial rate and assuring a ventricular response. 

If you see a pacemaker spike before a P wave, followed by an intrinsic ventricular QRS complex, the atrial rate is falling below the lower rate limit causing the atrial channel to fire. Normal conduction to the ventricles follows. 

Select a monitoring lead that clearly shows the pacemaker spikes and compare at least two leads to verify what you observe. 

Knowing whether your patient has an artificial pacemaker will help you avoid mistaking a ventricular paced beat for a premature venticular contraction (PVC). If your facility uses a monitoring system that eliminates artifact, make sure the monitor is set up correctly for a patient with a pacemaker. Otherwise, the pacemaker spikes may be eliminated as well. 

If your patient has intermittent ventricular pacing, the paced ventricular complex will have a pacemaker spike preceding it, as shown in the shaded area of the top electrocardiogram... 

ECC) strip. You may need to look in different leads for a bipolar pacemaker spike because it s small and may be difficult to see. What s more, the paced ventricular complex of a properly functioning pacemaker won t occur early or prematurely it will occur only when the patient s own ventricular rate falls below the rate set for the pacemaker. 

If your patient is having PVCs, they ll occur prematurely and won t have pacemaker spikes preceding them. Examples are shown in the shaded areas of the bottom ECC strip. 

ECG shows a pacemaker spike without the appropriate atrial or ventricular response (spike without a complex), as shown below. 

A pacemaker spike may appear where intrinsic cardiac activity is already present. 

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