Investigation of high-frequency ultrasound biomicroscopy for examining arteriopathy in hand transplant patients.

Abstract

The fourth hand transplant recipient in Louisville lost his graft at nine months post transplant from ischemia due to severe graft arteriopathy. Conventional imaging techniques and clinical measurements, including CT angiography and measurements of brachial indices via ultrasound, did not indicate that the patient was in such a severe condition in the days prior to amputation. Histological analysis of tissue from the amputated graft revealed massive intimal hyperplasia, a hallmark of chronic rejection. The purpose of this study was to describe a method to allow non-invasive monitoring of wall thicknesses in the radial, ulnar, palmar arch, and digital arteries of the transplanted hand. A novel ultrasound biomicroscopy unit (Vevo 2100) was used to image the blood vessels of the transplanted and native hands in four hand transplant recipients, ranging from 16 months to 11 years post transplant. The unit has a potential resolution of 30 µm, which allowed measurement of the intima and media layers of the arteries. The intima, media, and lumen measurements were compared in the native and transplanted hand in all four patients. Significant increases in intima thickness were found in the transplanted hands. In addition, the transplanted hand had significantly higher intima to lumen diameter ratios. From Doppler waveforms, it was found that that peak velocities were lower in the transplanted hand. Finally, hoop stress calculations revealed that the hoop stress seen in the arterial walls was lower in the transplanted hand. The ultrasound biomicroscopy unit provided an accurate, repeatable, and realtime method to investigate the arteriopathy of hand transplant patients. In the future, it vi will provide a way for clinicians to monitor the progression of arteriopathy in the hand, including intimal hyperplasia. vii