ABILITY OF ACTIVATION RECOVERY INTERVALS TO ASSESS ACTION-POTENTIAL DURATION DURING ACUTE NO-FLOW ISCHEMIA IN THE IN-SITU PORCINE HEART

Activation Recovery Intervals During No-Plow Ischemia, Introduction: T he ability to assess transmural changes in action potential duration d uring acute no-flow ischemia is essential to an understanding of the t achyarrhythmias that occur in this setting. The purpose of this study was to determine if activation recovery intervals determined from unip olar electrograms would provide this information. Methods and Results: We recorded simultaneously transmembrane action potentials and unipol ar electrograms from sites located as closely together as possible in the center and at the lateral margin of the ischemic zone during acute no-flow ischemia and correlated the changes in activation recovery in tervals obtained from the unipolar electrograms to the changes in acti on potential duration. We found that the activation recovery intervals provided an accurate measure of the changes in action potential durat ion during acute no-flow ischemia provided the electrograms had a well -defined, single negative component to the QRS complex with a maximum negative dV/dt > 10 V/sec and a single positive component to the T wav e having a maximum positive dV/dt > 1.6 V/sec. Electrograms meeting th ese criteria comprised 90% of the electrograms recorded at the margin of the ischemic zone throughout 60 minutes of no-flow ischemia, In the center of the ischemic zone, 75% of the recorded electrograms met the se criteria for the first 20 minutes of no-flow ischemia, Thereafter, the percentage declined and after 40 minutes of no-flow ischemia, none of the electrograms recorded in the center of the ischemic zone met t hese criteria. Conclusion: Activation recovery intervals obtained from unipolar electrograms provide an accurate assessment of changes in ac tion potential duration throughout the ischemic zone during acute no-f low ischemia, provided the characteristics of the electrograms meet sp ecific predetermined criteria.