Nonlinear finite element simulation to elucidate the efficacy of slit arteriotomy for end-to-side arterial anastomosis in microsurgery

The slit arteriotomy for end-to-side arterial microanastomosis is a technique used to revascularize free flaps in reconstructive surgery. Does a slit open to a width sufficient for blood supply? How is the slit opening affected by factors, such as arterial wall thickness and material stiffness? To answer these questions we propose a nonlinear finite element procedure to simulate the operation. Through modeling the arteries using hyperelastic shell elements, our simulation reveals that the slit opens up to a width even larger than the original diameter of the donor artery, allowing sufficient blood supply. It also identifies two factors that explain the opening of the slit: blood pressure which is predominant in most cases, and the forces applied to the slit by the donor artery. During simulation, when we increase the donor artery thickness and stiffness, it is found that the contribution of blood pressure to the slit opening decreases while that of the forces applied by the donor artery increases. This result indicates that sometimes the forces applied by the donor artery can play an even more significant role than the blood pressure factor. Our simulation elucidates the efficacy of the slit arteriotomy. It improves our understanding of the interplay between blood pressure and donor vessel factors in keeping the slit open.