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Abstract #1351

In Vivo Temperature Threshold for Myocardial Thermal Damage

Peter Nabil Costandi1, Ramez Emile Necola Shehada1, Neha Bharat Butala1, Ben Anthony Coppola1, Kevin Jurkowski1, Ali Dianaty1

1Cardiac Rhythm Management Division, St. Jude Medical, Sylmar, CA, United States

Current contraindications for pacemaker patients in clinical MR systems stem primarily from RF induced tissue heating hazards. The quantified effect of elevated temperature doses on myocardial tissue remains unknown. Sixteen canines were implanted with a ventricular pacing system capable of monitoring temperature of viable myocardium. Three cumulative one-hour thermal doses to 44C were applied to each chronic canine. Change in capture threshold relative to baseline was measured following each heating cycle and shown to increase by 68%, 81% and 83%, respectively. These findings provide data that may serve as a foundation for proof of safety of pacemaker systems in MRI.