Impact of Open Surgical Descending Repair on Aortic Stiffness in an Ex Vivo Porcine Model

Background: Previous studies have strongly suggested that stent-graft deployment and acute arch angulation increase aortic stiffness, the impact of surgical interposition grafting remains unclear. We investigated the impact of open surgery on aortic stiffness and compared this with stent-graft induced aortic stiffening, utilising an ex vivo model. Methods: Porcine thoracic aortas were connected to a mock circulatory loop. Baseline characteristics, proximal and distal flow curves (for PWV calculation), and blood pressures were recorded in a type I and III arch configuration. Subsequently, 10 cm proximal descending aorta was excised and replaced with Dacron® (IGK0018-40S). After surgery, all measurements were repeated in both arch configurations. Results: Fifteen aortas were prepared and attached to the circuit. After surgery, with both arch configurations, mean aortic PWV increased (Type I: 3.46 – 3.84 m/s (+10.7%),P < 0.001); Type III: 3.61 – 3.98 m/s (+10.4%),P = 0.001), systolic pressure remained stable (Type I: 121 – 124 mm Hg, P = 0.26; Type III: 124 – 124 mm Hg,P = 0.85), diastolic pressures decreased (Type I: 73 – 65 mm Hg,P < 0.001; Type III: 75 – 66 mm Hg,P < 0.001), and consequently mean arterial pressure decreased (Type I: 89 – 85 mm Hg,P = 0.020; Type III: 92 – 85 mm Hg,P = 0.001). The stable systolic pressure and decreased diastolic pressure, after surgery, led to an increased pulse pressure (Type I: 49 – 59 mm Hg,P < 0.001; Type III: 49 – 58 mm Hg; P < 0.001) Conclusions: Surgical interposition grafting of the proximal descending aorta increases aortic PWV, increases pulse pressure, and decreases diastolic blood pressure. These findings might be important for the long-term results of patients undergoing surgical treatment of aortic diseases.