Endovascular creation and validation of acute in vivo animal model for type A aortic dissection.

BACKGROUND: Animal modeling is a prerequisite for clinical transfer of new therapies. This study targets an acute in vivo animal model of type A dissection using endovascular approach with a view to test future stent grafts dedicated to this aortic segment. METHODS: Experiments were conducted on 13 swine. Two arterial accesses, femoral and percutaneous transapical, were required. Entry tear was created by endovascular instrumental means inserted through transapical access with either Outback catheter (group 1, n = 3) or EchoTip Endoscopic Ultrasound Needle (group 2, n = 10). Afterward, dissection extension was obtained in antegrade direction by looped guidewire technique, and, as often as possible, re-entry tear was created with either looped guidewire or Outback catheter. Finally, entry tear, dissected space, and re-entry tear when existing were dilated with 8-mm balloon. In our acute model, animals were euthanized at the end of the experiment day, and aortas were explanted for macroscopic and histologic examination. RESULTS: The model was successfully created in 10 out of 13 animals. In group 1, dissection was limited to arch with 23 mm average length and no possibility of achieving re-entry tear. One aortic perforation was observed. In group 2, dissection was extended up to descending thoracic or thoracoabdominal aorta, with 110 mm average length (range 40-165 mm), and re-entry tear was created in seven cases. Histologic examination confirmed the presence of intimo-medial flap. CONCLUSIONS: The present experiment validates a new type A dissection animal model, which morphologically reproduces human aortic dissection features. As such, it provides an advantageous basis for testing future stent grafts.