![]() ![]() The ekg strip below shows the first two spikes pacing, then the pacemaker fails to pace. Its absence will result in the underlying rhythm running (if any). It may be the pacemaker battery, the leads or it could be an over sensing problem. In general, you will have no pacing spikes where they need to be. It could be an intermittent problem or failure altogether. There is no particular rhythm to define this. Somehow, the electrodes have no current flowing through them. Spikes are sensing correctly and pace the ventricles.įailure to output (failure to pace) simply means there is no output signal being generated from the pacemaker. (undersensing) shows the first two spikes fire out of place. Sensing issues are identified when there are pacemaker spikes showing up where they do not belong. Which occurs when a foreign signal (non-cardiac) such as a muscle twitch, are mistaken for real cardiac activity. Sensing problems include “undersensing” where the pacemaker fails to sense the native cardiac rhythm. In most cases, sensing problems are less threatening and can be corrected by performing a pacemaker interrogation. The example below shows the first two ventricular paced beats capture, then the next ![]() This is identified by having pacing spikes present with no resulting QRS, (capture). With false capture, you will generally see a near-vertical upstroke or down-stroke to the “phantom” QRS complex (which is actually electrical artifact created by the current passing between the pacing pads).Failure to capture is when the pacemaker signal fires but there is no response. ![]() You can see another example where an echo was used to verify capture here. The patient’s blood pressure subsequently increased to 90 mmHg.” The current was gradually increased to 110 mA, and the heart began to contract in unison with the pacer shocks. These heart contractions did not correspond with the surrounding thoracic muscle contractions generated by the pacer. “Initially, the ultrasound demonstrated ventricular contractions at a rate of 30-40 beats per minute. With the etiology of the patient’s hypotension unclear, the decision was made to use transthoracic ultrasonography to assess the adequacy of her ventricular contractions.” The patient appeared to have palpable pulses however, the rhythm contractions of the patient’s body from the pacer shocks made this assessment difficult. The EKG monitor continued to demonstrate adequate ventricular capture by the pacer. “Shortly after cardiac pacing was initiated, the patient’s systolic blood pressure dropped to 50 mmHg. ![]() Consider this excerpt from the Journal of Emergency Medicine where Douglas Ettin, M.D. There are many reasons why medical professionals often fail to achieve true electrical and mechanical capture. The problem of false capture (also known as echo distortion) is under-recognized and under-reported in the medical literature. Transcutaneous pacing (TCP) is a difficult skill that is often performed incorrectly. The patient eventually expires from multiple-system organ failure.
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