The development of the Siena graft

Abstract

The evolution of surgical replacement of the aortic arch has been shaped by advances in surgical techniques and ancillary technologies. From the early pioneering attempts in the 1950s by Ho Ju Lin, Cooley, and DeBakey, which preceded the advent of cardiopulmonary bypass (CPB), the development of perfusion, cerebral protection, and surgical techniques, along with the evolution of prosthetic grafts, has progressively enabled surgeons to address these challenging conditions with greater confidence. Despite these remarkable advancements, aortic arch surgery still remains one of the most technically challenging procedures in cardiac surgery. A major turning point was the introduction of the elephant trunk technique by Borst in 1983. This approach allowed for staged treatment of diffuse aneurysmal disease, including both degenerative and post-dissection cases, and reduced the overall surgical risk across multiple procedures. Initially met with skepticism, the technique has since been universally adopted by centers specializing in aortic pathology. At the same time, numerous modifications to the technique have emerged. Each modification has addressed specific technical challenges or enabled the integration of new technologies. The development of the Siena graft in the early 2000s was driven by the need to harness the growing potential of endovascular devices, which had been evolving since the 1990s, and to address critical technical issues. These included the use of multi-branched prostheses and the introduction of an anastomotic collar to facilitate secure distal anastomoses, even in less-than-ideal anatomical conditions. The design of the Siena graft, now widely adopted by most manufacturers for arch grafts, required close collaboration with industry partners to ensure a reliable product from its inception. Today, the Siena graft remains a highly relevant platform for the treatment of diffuse aneurysmal disease that requires the elephant trunk technique. This paper describes the evolution and design of the graft, the technical approach, including pitfalls and safeguards, and our clinical experience.

Keywords: Aneurysmal disease; aortic arch surgery; collared graft; elephant trunk technique; endovascular surgery; frozen elephant trunk.

Figure 1

Developmental evolution of the Siena graft. (A) Sketching the idea—initial drawings capturing the conceptualization of the graft and its potential future developments. These early sketches laid the foundation for the design process, transitioning from theoretical models to practical prototypes. The image illustrates the evolution from raw ideas to structured design concepts, ultimately shaping the first model of what would become the Siena graft. (B) The first naïve models of the Siena graft, simulating a challenging large-neck anastomosis. On the right, early attempts at manufacturing the collar using a 10 mm Dacron tube, opened longitudinally and sutured to an aortic graft. (C) The final drawing that marked the beginning of industrial production of a certified graft.

Figure 2

Graft preparation and intraoperative implantation strategy. (A) Graft preparation and sizing. The collar is trimmed to the required diameter, and a Teflon felt ring is placed on its distal surface to enhance hemostasis and create a secure, blood-tight anastomosis. The appropriate trunk length remains a subject of debate due to concerns about paraplegia and distal embolization. Since blood flow extends the graft by approximately 10%, the graft should be considered in its non-stretched state. Traditionally, the graft is cut at the last radiopaque marker (10 cm); our approach has evolved over time, favoring longer grafts in chronic dissection cases and shorter ones in extensive aneurysms to minimize the risk of thrombosis at the distal end of the elephant trunk. (B) Once the target temperature for circulatory arrest is reached, the aorta is opened, and the anastomotic neck is prepared in zone 2 or zone 3. The graft’s elephant trunk is inserted into the aortic lumen using a Gooseneck snare catheter, pre-positioned under angiographic or transesophageal guidance. This step is particularly crucial in dissections, where precise positioning and alignment within the true lumen is essential. The snare catheter has proven highly effective in navigating narrow or angulated aortas, facilitating the use of longer grafts even in small true lumens. This technique is now a standard practice in our cases. (C) To reinforce the anastomosis and improve hemostasis, an external Teflon strip is used in combination with a pre-placed Teflon ring beyond the collar. When the aortic tissue is soft and non-calcified, a single continuous 3-0 Prolene suture is typically sufficient. However, in calcified aortas, three semicontinuous 3-0 Ethibond sutures are preferred to prevent suture imbalance and avoid wrinkles in the collar. These sutures are strategically placed at h12:00, h4:00, and h8:00, with h12:00 corresponding to the divided left subclavian artery. The suture is initiated at h12:00, an area that is particularly challenging to inspect for bleeding, especially after reimplantation of the left subclavian artery.

Figure 3

Outcomes following the Siena graft procedure. Results of elephant trunk procedures and subsequent treatments according to our institutional approach to complex aortic pathology. (A) Survival rates were assessed in relation to the underlying pathology (aneurysm vs. dissection). The comparison of survival between the groups, performed using the log-rank test, did not reveal a statistically significant difference. (B) Kaplan-Meier estimates for freedom from further treatment following the elephant trunk procedure. (C) Kaplan-Meier estimates for overall survival following the elephant trunk procedure. This figure compares overall survival across three techniques: endovascular, surgical, and the unstented (“soft”) approach. In the “soft” technique, the elephant trunk is left unstented within the true lumen, a strategy predominantly applied to patients with dissection. The log-rank test did not reveal a statistically significant difference. Endo, endovascular.

Video

The Siena (Dumbo) graft journey.