The device was not returned to zoll medical corporation for evaluation.Instead, the data file of the customer's report was provided.Review of the data file shows the device performed to specification.Implanted pacemakers generate voltages that exceed those that are being generated by the heart.Because of this, monitors incorporate a blanking/refractory period starting at the point of the detected pacemaker/stimulus for a duration of up to 180 milliseconds.During the blanking period, qrs detection is inhibited.In this instance, the blanking period goes over the r wave and therefore they are not counted as beats.The qrs detectors found the next peaks and determined it was the onset of an r wave every time a paced beat occurred; the r wave was not being synced.Per the r series operator's guide: "verify that markers are clearly visible on the monitor and their location is appropriate and consistent from beat to beat.If necessary, use the lead and size buttons to establish settings that yield the most consistent sync marker pattern." additionally, the operator's guide states, "inappropriate defibrillation or cardioversion of a patient (for example, with no malignant arrhythmia) may precipitate ventricular fibrillation, asystole, or other dangerous arrhythmias.".
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