Early recognition of heart transplant rejection by backscatter analysis from serial 2D ECHOs in a heterotopic...

The acute phase of heart transplant rejection was evaluated with two-dimensional echocardiographic (2D ECHO) image analysis in a modified Mann's cervical heterotopic transplant. Serial 2D ECHO images were obtained daily, and myocardial biopsies were obtained on the day of transplant, on day 3 after transplant, and after total rejection. Brightness of serial 2D myocardial ECHO images significantly increased to day 3 after transplant, indicating increased backscatter during hyperacute rejection. Histologically this was associated with myocardial edema. These results suggest a potential noninvasive means of recognizing acute cardiac rejection. Heart transplant rejection is characterized by myocardial edema during the early stages. Myocardial edema resulting from ischemia increases the backscatter of ultrasound, which is seen as increased brightness on 2D ECHOs. Hence we hypothesized that myocardial edema observed histologically during a hyperacute rejection process can be seen on serial 2D ECHOs of the transplanted heart. Serial 2D ECHOs were obtained in five goats that had undergone a modified Mann's cervical heterotopic transplant. Image parameters were kept constant throughout each experiment. After each experiment, 2D ECHOs of a soft-tissue phantom were also recorded with the same image parameters and were used for normalizing the myocardial brightness estimated from 2D ECHO images. Visually, brightness of 2D ECHO images of all transplanted myocardia increased to day 3 after transplantation; thereafter, the brightness decreased but was still greater than on the day of transplantation. The measured mean (+/- SD) relative integrated brightness increased from 0.60 +/- 0.38 on the day of transplantation to 1.05 +/- 0.43 (p less than 0.005) on day 3 after transplantation and decreased to 0.70 +/- 0.33 (p less than 0.05) on day 7 after transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)