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Dual Chamber Pacing example three



This strip shows some other things a DDD pacer can do (or fail to do).  Beats 1 and 2 are atrially paced, with good capture of the atria by the pacer, and native conduction from the atria to the ventricles.   Beat 3 shows a pacer impulse stimulating the atria, failure to capture the atria, a pause as the pacer waits for ventricular systole (the pacer has been set to wait for 0.21 second, which is just above the upper limit of normal for a P-R interval), then a ventricular pacer impulse, which has good capture.  Note the difference in QRS shape: this beat is not coordinated by the specialized conduction system of the heart.  It is wider and slurred, resembling a PVC.  Beat 4 is like beats 1 and 2; beat 5 is like beat 3.  Beats 6 through 9 are atrially paced, beat 10 is ventricularly paced, and beat 11 is atrially paced.  The pacer is maintaining an adequate heart rate, but the frequent failure to capture the atria is troubling.  Atrial lead parameters need to be checked.  Failure of ventricular capture would be even more worrisome.