Spinal cord ischemia after endovascular repair of the descending thoracic aorta in a sheep model.

OBJECTIVES: Spinal cord ischemia remains a devastating complication after thoracic aortic surgery. The aim of this study was to investigate the pathophysiology of spinal cord ischemia after thoracic aortic endografting and the role of intercostal artery blood supply for the spinal cord in a standardized animal model. METHODS: Female merino sheep were randomized to either I, open thoracotomy with cross-clamping of the descending aorta for 50 min (n=7), II, endograft implantation (TAG, WL Gore & Ass.), (n=6) or III open thoracotomy with clipping of all intercostal arteries (n=5) . CT-angiography was used to assess completion of surgical protocol and assess the fate of intercostal arteries. Tarloy score was used for daily neurological examination for up to 7 days post-operatively. Histological cross sections of the lumbar, thoracic and cervical spinal cords were scored for ischemic damage after stained with Hematoxylin-Eosin, Klüver-Barrrera and antibodies. Exact Kruskall-Wallis-Test was used for statistical assessment (p<0.05). RESULTS: Incidence of paraplegia was 100% in group I and 0% in group II (p=0.0004). When compared to the endovascular group, there was a higher rate of histological changes associated with spinal cord ischemia in the animals of the control group (p=0.0096). Group III animals showed no permanent neurological deficit and only 20% infarction rate (p=0.0318 compared to group I). CONCLUSIONS: In sheep, incidence of histological and clinical ischemic injury of the spinal cord following endografting was very low. Complete thoracic aortic stent-grafting was feasible without permanent neurologic deficit. Following endovascular coverage or clipping of their origins, there is retrograde filling of the intercostal arteries which remain patent.

[Microsurgical heterotopic ovary transplantation. A preclinical study]. / Mikrochirurgische heterotope Ovartransplantation. Eine präklinische Studie.

Free heterotopic autologous ovary transplantation might be a method to prevent iatrogenic radiocastration in case of Hodgkin's disease. Though first promising clinical case reports have been published, almost no experimental basic data are available. It was the aim of this study to develop a transplantation model in order to evaluate and improve operative technique and perioperative management preclinically. Whereas results in pilot transplantations on minipigs were impaired by the disposition to wound infections on the implantation site, transplantation on Beagle dogs proved to be a suitable model. Eleven transplantations have been performed (five in minipigs, six in Beagle dogs). The success rate of intact preserved transplants was 45% with an observation time of three months for the minipigs and 9 +/- 3.7 months for the dogs.