Holter monitoring continuous telemetry from an ICD for troubleshooting and improved programming

The authors developed a modified Holter monitoring system for continuously recording the telemetered electrogram or marker channel from a new, tiered therapy implantable cardioverter/defibrillator (ICD) as an aid in ICD programming and to determine the cause of inappropriate therapy. The third generation, tiered therapy ICD, the Medtronic PCD Model 7217(B), can be programmed to transmit, for up to 63 h, either the device´s marker channel, a series of coded pulses which show, among other things, the classification and timing of ventricular depolarizations sensed by the device, or the near-field or far-field electrogram. The new Holter system records the telemetry signal, using a PCD/Holter adapter, together with the surface electrocardiogram (ECG). To evaluate the performance and usefulness of this new system, two series of tests were performed with patients who received a PCD. This new system has been practical to use, flawless in performance, and invaluable in managing the treatment of PCD patients who actually or apparently receive inappropriate ICD therapy. Because the marker channel and the ECG are recorded simultaneously, this new system gives more information than either standard Holter monitoring or the read-out of stored electrograms from the memory of other third generation ICDs