In Vitro Evaluation of Upstream and Downstream Influences on Blood Pressure of the Hybrid Treatment of Thoracoabdominal Aortic Aneurysms

BACKGROUND: The aim of our study was to assess, by means of an experimental model, whether different geometries in retrograde bypass and stent-graft deployment may affect upstream and downstream blood pressure in hybrid treatment. METHODS: An in vitro model of the arterial circulation has been prepared, which consists of a peristaltic pump, silicon tubes with geometrical and mechanical properties close to realistic arteries, a terminal reservoir kept at constant pressure, and a sequence of pressure transducers. The system allows us to study the pressure wave propagation in physiological conditions and simulate the patient's conditions as a result of debranching in 2 different configurations. RESULTS: In configuration 1, the mean pressure value (Kpa) was 4.72 in silicone tube before stent graft and debranching, 4.59 in visceral and renal bypass, and 4.38 in silicone tube after stent graft and debranching. In configuration 2, the mean pressure value (Kpa) was 5.22 in silicone tube before stent graft and debranching, 4.48 in visceral and renal bypass, and 4.99 in silicone tube after stent graft and debranching. CONCLUSION: The experimental data suggest that the debranching geometry and the material of the grafts and stent grafts change significantly the physiological arterial pressure possibly leading to an augmented pressure upstream of the stent grafts, owing to retrograde pressure waves toward the heart, and a decreased pressure downstream visceral and renal arteries.