Possibility of lead displacement has to be considered, which is more likely with temporary pacing. In the setting of evolved inferior wall infarction, it is likely that temporary pacing was done for complete heart block, which has now resolved into first degree AV block. Inhibited mode means that a sensed impulse will inhibit the pacing. On the surface ECG, pacing spikes are present, but they are not followed by a QRS complex in the event of ventricular noncapture or by the lack of P waves in the event of atrial noncapture (Fig. Usually demand pacemaker waits for a pause in the basic rhythm before firing as it senses the spontaneous rhythm and works in inhibited mode. Capture failure occurs when the generated pacing stimulus does not initiate myocardial depolarization. Early occurrence again indicates sensing failure. Failure to sense, also called undersensing, occurs when a previous electric potential is not detected by the pacemaker. Rhythm strip shows two additional pacing spikes with ventricular captures, also occurring fairly early after the previous QRS complex. Check for electrical capture by the presence of a pacing spike followed by a widened QRS complex (response to the stimuli), the loss of any underlying. Though it has not captured the ventricles, it does not mean capture failure as it has occurred within the QT interval of the previous QRS complex when we expect the ventricles to be refractory. The premature occurrence indicates sensing failure. The pacing artefact marked by red arrow has occurred prematurely and has failed to capture the ventricles. The premature occurrence of the pacing spike would indicate a sensing failure of the pacemaker. The spike marked with blue arrow has come a short while after the preceding QRS complex and has captured the ventricles causing a wide QRS complex. Multiple pacemaker spikes or pacing artefacts are visible. Electrical stimuli delivered by the electronic pacemaker to the endocardium are seen as a spike on the surface ECG. They are not followed by a paced QRS complex, however. The pacer spikes, for the most part, track the P waves, which is how this pacemaker is programmed. The interesting part is evident in the rhythm strip. This explains why the patient had a pacemaker implanted. What are the findings in this ECG and possible explanations?ĮCG shows PR interval prolongation, Q and ST elevation with T inversion in lead III, small q and T inversion in aVF along with lateral ST depression and T wave inversion indicating an inferolateral myocardial infarction with first degree AV block.
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