Since the advent of cyclosporin A surface electrocardiograms have been unreliable for diagnosing cardiac allograft rejection. Although several noninvasive methods have been proposed, none have been sufficiently accurate to be considered for clinical use. We have studied the use of the QRS complex amplitude, the unipolar peak-to-peak amplitude, recorded from intramyocardial electrodes for detecting rejection. Ten adult mongrel dogs underwent placement of intramyorardial electrodes on each ventricle. After stabilization of signals the hearts were transplanted heterotopically into unmatched recipients receiving cyclosporin A, azathioprine and methylprednisolone. Endomyocardial biopsies were performed after stabilization of unipolar peak-to-peak amplitude, twice weekly thereafter, and when unipolar peak-topeak amplitude fell significantly. This detected 13 of 14 episodes of rejection. There was one false-positive and one false-negative result. The false-negative study became positive the following day. Thus, analysis of unipolar peak-to-peak amplitude detected all episodes of rejection in a clinically relevant time frame and was able to detect mild forms of rejection and multiple episodes of rejection in the same heart even in the presence of therapeutic levels of cyclosporin A.
Bibliographical noteFunding Information:
We acknowledge financial support provided by Medtronic Inc, who provided partial funding for this work by a Synergy Technology Transfer Award (Medtronic Inc, Minneapolis, MN).