Real-Time Detection and Alerting for Acute ST-Segment Elevation Myocardial Ischemia Using an Implantable, High-Fidelity, Intracardiac Electrogram Monitoring System With Long-Range Telemetry in an Ambulatory Porcine Model
Tim A. Fischell, MD, FACC*,*,
David R. Fischell, PhD ,
Robert E. Fischell, DSc,
Renu Virmani, MD ,
Jennifer J. DeVries, LATG, SRS and
Mitchell W. Krucoff, MD, FACC||
* Borgess Heart Institute, Kalamazoo, Michigan
AngelMed Systems, Inc., Tinton Falls, New Jersey
CV Path, Gaithersburg, Maryland
MPI Research, Mattawan, Michigan
|| Duke Clinical Research Institute/Duke University Medical Center, Durham, North Carolina.
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Figure 1 Photographs showing the various components of the implantable ischemia detection system. (A) The implantable medical device, resembling a VVI pacemaker, is shown, attached to the lead adapter and a standard bipolar, screw-in, right ventricular lead. (B) Shows the external alerting device attached to the laptop computer, which is used for programming and data collection, via telemetry to the implantable medical device. The external alerting device has 2 light-emitting diodes: red light for emergency alerts and yellow light for "see your physician" alerts.
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Figure 2 Illustration showing computer-based analysis of ST-segment shift in an animal with acute ST-segment elevation associated with a left circumflex occlusion (Table 1, pig 6). (A) Shows minor ST-segment depression in the baseline QRST, followed the next day by sudden ST-segment elevation. This shows a net 51% ST-segment shift, relative to baseline, and normalized to the QRS height. It should be noted that the programmer, in this example, manually shifted the P-Q segment to precede the actual Q-wave, as detected by the implantable ischemia detection system by approximately 30 ms.
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Figure 3 Illustration of acute ST-segment changes and spontaneous ST-segment elevation myocardial infarction as recorded by implanted medical device. Tracings were obtained from telemetry from implantable cardiac device to external alerting device. (A) Shows stable normal sinus rhythm without ST-segment shift at baseline 30 h after medical device implant. (B) Heart rate-related (heart rate increase from 119 at baseline to 148 beats/min) ST-segment depression sets off a "see your physician" alert 13 h after copper stent implantation in the left anterior descending coronary artery. (C) ST-segment elevation is noted at 59 h after copper stent implantation, resulting in an "emergency" alert. (D and E) There are more frequent ventricular premature beats, leading to ventricular fibrillation 1 h after the initial ST-segment emergency alert (F). The animal passed away with an agonal rhythm 15 min after the initial ventricular fibrillation (G).
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Figure 4 Illustration of acute ST-segment changes and spontaneous ST-segment elevation myocardial infarction as recorded by implanted medical device. Tracings were obtained from telemetry from implantable cardiac device to external alerting device. (A) Shows stable normal sinus rhythm without ST-segment shift at baseline 26 h after medical device implant. (B) ST-segment elevation is noted after 90 s of balloon inflation, during copper stent implantation in the left anterior descending coronary artery. (C) The animal developed ventricular fibrillation at  120 s into the left anterior descending coronary artery stent implant. External cardioversion/defibrillation is performed with 300 J (square wave in C), without deleterious effect on the implanted medical device. After 4 min of recovery, the intracardiac electrogram returns to baseline (D). At 3 h after copper stent implant, the electrogram shows rapid evolution to marked ST-segment elevation (72% vs. QRS amplitude, E) with emergency alert. Within 30 min from onset of ST-segment elevation myocardial infarction, the animal develops spontaneous ventricular fibrillation (F) and then expires, with a flat line tracing (G).
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Figure 5 Illustration of acute ST-segment changes recorded by implanted medical device, and correlation with necropsy findings. (A) Shows stable normal sinus rhythm without ST-segment shift at baseline 30 h after implanted medical device implant. (B) The animal receives an emergency ST-segment shift alert with pronounced ST-segment elevation 77 h after copper stent implantation in the left circumflex coronary artery. (C) The ST-segment resolves at 72 h after the alerting ST-segment elevation event. Angiography immediately after copper stent implants in the proximal left circumflex coronary artery (D) shows patency of left circumflex coronary artery (white arrows). The stents appear totally occluded at 25 days after copper stent implant by both angiography (white arrows, E) and histopathology (black arrows show inflammation around struts of copper stent) (F). The animal survived until sacrifice at 26 days after copper stent implant. Inflammation, with layers of occlusive thrombus with minor recanalization channels, is observed (F). (G) Shows a lateral and posterior transmural myocardial infarction (stained in blue) at 26 days after stent implant (black arrows).
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