Measuring left ventricular function after heart transplantation via digitization of M-mode echocardiograms

The aim of the study was to assess the usefulness of M-mode echocardiography for noninvasive diagnosis of cardiac rejection. For this purpose, 292 M-mode images of 26 heart transplant recipients were analyzed. The echocardiographic images were digitized into an image analysis system. The curves of left ventricular diameter changes were obtained and its first differential calculated. A total of 23 parameters were measured. The most important parameters were: peak velocity of systolic diameter change, peak velocity of diastolic diameter change, time to peak velocity of systolic diameter change, time to peak velocity of diastolic diameter change (TPEAK-D), isovolumetric relaxation time (IVRT), rapid filling time (RFT), shortening fraction (SF), and mean velocity of circumferential fiber shortening (MVCF). The echocardiographic parameters were compared to biopsy results. In 18 patients, 23 biopsy-proven moderate rejections occurred. When rejection occurred, IVRT decreased 23% +/- 6% (P < 0.05), SF decreased 13% +/- 14% (P<0.05), MVCF decreased 18% +/- 18% (P<0.05), and TPEAK-D increased 27% +/- 27% (P<0.05). We concluded that the analysis of digitized M-mode images can identify heart transplant rejection.