Department of Cardiovascular Surgery, Heart Center Brandenburg, University Hospital Brandenburg Medical School (Theodor Fontane), Ladeburger Strasse 17, 16321 Bernau bei Berlin, Germany.
Medicina (Kaunas). 2022 Aug 4;58(8):1055. doi: 10.3390/medicina58081055.
Friable or infected tissue remains a challenge in surgical aortic valve replacement. We recently described the "Caput medusae" method, in which circumferential tourniquets temporarily secure the prosthesis and are then gently knotted. Tourniquets have been shown to develop significantly less force than knots. The current study investigates the critical threshold forces for tissue damage to the aortic annulus. In 14 fresh porcine hearts, the aortic valve leaflets were removed and several pledgeted sutures were placed along the annulus at defined locations. The hearts were mounted in a self-constructed device. Incremental traction force was applied to every suture and continuously recorded. The movement of each Teflon pledget was filmed with a high-speed camera. Forces at the moment of pledget "cut-in" as well as complete "tear-out" were determined from the recordings. The average threshold force was determined 9.31 ± 6.04 N for cut-in and 20.41 ± 10.02 N for tear-out. Detailed analysis showed that the right coronary region had lower threshold forces than the other regions (4.77 ± 3.28 N (range, 1.67-12.75 N) vs. 10.67 ± 6.04 N (1.62-26.00 N) for cut-in and 10.67 ± 4.04 N (5.40-18.64 N) vs. 23.33 ± 9.42 N (9.22-51.23 N) for tear-out). The findings are discussed in conjunction with the knot and tourniquet forces from our previous study. Even in healthy tissue, moderate forces can reach a critical level at which a Teflon pledget will cut into the annulus, while a complete tear-out is unlikely. The right coronary portion is more susceptible to damage than the remaining regions. When compared to previous data, forces during manual knotting may exceed the critical cut-in level, while rubber tourniquets may provide a higher safety margin against tissue rupture.
在主动脉瓣置换手术中，易碎或感染的组织仍然是一个挑战。我们最近描述了“海蛇头”方法，即用环形止血带暂时固定假体，然后轻轻打结。止血带产生的力明显小于结。本研究调查了对主动脉瓣环造成组织损伤的临界阈值力。在 14 个新鲜猪心模型中，去除主动脉瓣叶，并在瓣环的几个特定位置放置几个带垫片的缝线。心脏被安装在一个自制的装置中。对每个缝线施加递增的牵引力，并连续记录。用高速摄像机拍摄每个聚四氟乙烯垫片的运动。从记录中确定垫片“切入”和完全“撕裂”时的力。切入的平均阈值力为 9.31 ± 6.04 N，撕裂的平均阈值力为 20.41 ± 10.02 N。详细分析表明，右冠状动脉区域的阈值力低于其他区域（切入时为 4.77 ± 3.28 N（范围为 1.67-12.75 N），撕裂时为 10.67 ± 6.04 N（范围为 1.62-26.00 N））和 10.67 ± 4.04 N（撕裂时为 5.40-18.64 N），撕裂时为 23.33 ± 9.42 N（范围为 9.22-51.23 N））。结合我们之前的研究中的结和止血带力，对结果进行了讨论。即使在健康组织中，适度的力也可能达到一个临界水平，此时聚四氟乙烯垫片会切入瓣环，而完全撕裂不太可能发生。右冠状动脉区域比其余区域更容易受损。与之前的数据相比，手动打结时的力可能超过临界切入水平，而橡胶止血带可能提供更高的组织破裂安全裕度。
