ECHOCARDIOGRAPHIC CHARACTERISTICS OF BIOPSY-PROVEN CELLULAR REJECTIONIN INFANT HEART-TRANSPLANT RECIPIENTS

Background: Echocardiography has been used as a primary means to detec t cellular rejection in infant heart transplant recipients. There is, however, limited information correlating echocardiography and biopsy-p roven rejection in this age group. Methods: Between September 1989 and July 1994, 32 consecutive heart transplantations were done in infants younger than 20 months old, who were followed up for 2 to 58 months ( mean 28 months) with concurrent endomyocardial biopsy and M-mode echoc ardiography with digitization. M-mode data from all 16 episodes of rej ection (international Society for Heart and Lung Transplantation grade 3A or greater) that occurred in 12 grafts were compared with data fro m the same grafts with histologic resolution of rejection 2 weeks afte r treatment and with data from biopsy-proven nonrejecting control graf ts matched for sex, time after transplantation, donor weight, and dono r age. Results: Left ventricular mass index increased in rejection (86 +/- 9 gm/m(2)) versus resolution (64 +/- 6 gm/m(2)) and versus that i n nonrejecting control grafts (59 +/- 8 gm/m(2)). Left ventricular sho rtening fraction increased in rejection (40% +/- 2%) versus resolution (38% +/- 10%). Septal thickening fraction decreased in rejection (33% +/- 9%) versus nonrejection (68% +/- 16%). These changes became signi ficant only in grafts transplanted more than 1 month before study. Sub stantial overlap of measurements prevented identification of threshold values. Intraobserver and interobserver variabilities for standard M- mode data were 7% to 8% and 12% to 22%, respectively, whereas those fo r digitized parameters were markedly elevated at 37% to 71% and 51% to 81%, respectively. Conclusions: We found (1) left ventricular mass in dex increases in cellular rejection but may be unreliable less than 1 month after transplantation and (2) significant interobserver and intr aobserver variability may limit the applicability of digitized echo pa rameters to the detection of rejection in infant heart transplant reci pients.