ObjectiveTo explore the difference between minimally invasive direct and conventional thoracotomy off-pump coronary artery bypass surgery (CABG). MethodsWe selected 276 patients underwent off-pump CABG surgery in our hospital from June 2005 through June 2014. There were 55 patients with minimally invasive off-pump CABG surgery and 221 patients conventional thoracotomy surgery. By using the method of peopensity score matching, we selected 55 conventional thoracotomy patients as a control group in our study. There were 41 males and 14 females at age of 60.8±10.5 years with minimally invasive off-pump CABG surgery, 44 males and 11 females at age of 60.6±12.5 years with conventional thoracotomy. ResultsThere was no statistical difference in surgery time, stay in the intensive care unit (ICU) time between conventional thoracotomy surgery and minimally invasive off-pump CABG. Compared with conventional thoracotomy surgery, minimally invasive off-pump CABG patients had statistical improvement in post-operative hospital stay time (7.3±3.1 d vs. 8.8±3.9 d, P=0.01), postoperative drainage (684(0-2 790)ml vs. 739(50-4 460)ml, P=0.03), perioperative blood transfusion (1.91(0-20)U vs. 6.62(0-20)U, P=0.00), surgery incision length (5.6±1.1 cm vs. 26.3±4.5 cm, P=0.00). ConclusionOverlooking the learning curve, minimally invasive direct off-pump CABG surgery has more advantages than conventional thoracotomy surgery. It is a safe and effective procedure.
External support stent is a potential means for restricting the deformation and reducing wall stress of the vein graft, thereby improving the long-term patency of the graft in coronary artery bypass surgery. However, there still lacks a theoretical reference for choosing the size of stent based on the diameter of graft. Taking the VEST (venous external support) stent currently used in the clinical practice as the object of study, we constructed three models of VEST stents with different diameters and coupled them respectively to a model of the great saphenous vein graft, and numerically simulated the expansion-contraction process of the vein graft under the constraint of the stents to quantitatively evaluate the influence of stent size on the radial deformation and wall stress of the vein graft. The results showed that while the stent with a small diameter had a high restrictive effect in comparison with larger stents, it led to more severe concentration of wall stress and sharper changes in radial deformation along the axis of the graft, which may have adverse influence on the graft. In order to solve the aforementioned problems, we ameliorated the design of the stent by means of changing the cross-sectional shape of the thick and thin alloy wires from circle into rectangle and square, respectively, while keeping the cross-sectional areas of alloy wires and stent topology unchanged. Further numerical simulations demonstrated that the ameliorated stent evidently reduced the degrees of wall stress concentration and abrupt changes in radial deformation, which may help improve the biomechanical environment of the graft while maintaining the restrictive role of the stent.