The VAC stent is a fully covered nitinol stent that integrates a polyurethane (PU) sponge into its structure, thus combining the advantages of SEMS and EVT. Although the data on its application are still preliminary, interest in the VAC stent is growing as it promises a more comprehensive approach to sealing leaks in the upper gastrointestinal tract. (1,3,7,12,13,19))
Previous studies demonstrate the effectiveness of the VAC stent in treating leaks and suture insufficiencies even after bariatric surgery in the upper gastrointestinal tract. Additionally, the stent has proven to be a salvage therapy in complex cases where other methods have failed. Moreover, the incidence of adverse events is remarkably low. (1,2,5,7,10,17,19)
The VAC stent controls the septic focus, promotes wound healing, serves as a drainage system for cavities associated with leaks and anastomotic insufficiencies, allows for an open passage for rapid enteral nutrition, and ensures endoscopic access distal to the leak. (2,5,10,13,19)
Prophylactic Application
Data show that the VAC stent should be used as early as possible, ideally at the time of diagnosis, to prevent the formation of larger wound cavities and chronic fistulas. Particularly, the immediate application in fresh endoscopic or surgical lesions leads to healing within a few days. (2,5,10,12)
This observation, along with the wound healing-promoting effect of EVT, led to the concept of prophylactic intraoperative EVT after esophagectomy, which can also be realized through the use of the VAC stent. (4,5,6,12)
Duration of Application and Success Rate
The duration of the required VAC stent treatment depends on the size of the dehiscence, the possible presence of an abscess or a larger extraluminal cavity, and the time between the initial diagnosis and the sealing of the leak. (2,8)
In general, clinical studies and case reports show that VAC stents have a high success rate. Healing rates range between 70–90%, depending on patient selection and early intervention. Thus, the healing rates of the VAC stent are comparable to those of EVT using a PU sponge. (2,5,8,9.10,16,19)
Clinical studies report that the average dwell time of a single VAC stent is about 5 to 5.2 days, with a range of 2 to 8 days. (2,8,10,19)
The average dwell time of the VAC stent in the body (including multiple stent changes) depends on the indication and the healing process. In clinical studies, it ranges between 7 and 14 days. (2,8,19)
Comparison with EVT
EVT has become established for the treatment of anastomotic leakages. In comparison, the VAC stent allows for even more effective application of vacuum than a sponge. It creates a closed zone with negative pressure over the entire circumference of the esophagus. Thus, the VAC stent ensures continuous drainage while simultaneously exerting radial force, which may reduce the risk of luminal stenosis—a complication associated with longer-term use of conventional PU sponges. (1,2,8,18,19)
Furthermore, the nutritional status and quality of life of patients with a VAC stent should be better compared to patients with pure sponge therapy, as the esophageal passage is maintained and oral nutrition is possible. With a lying PU sponge, it can be complicated to place a feeding tube at all. Additionally, the presence of a feeding tube, especially with an intraluminal sponge, may impair the effectiveness of vacuum therapy. (1,2,8,18,19)
Despite its advantages, the VAC stent has the significant disadvantage that large, contaminated dehiscences and wound cavities cannot be treated initially. A contaminated cavity only heals if it is optimally drained. In the case of a large and/or contaminated cavity, endoscopic vacuum therapy should be considered first. (10,11,18)
After the initial application of an intracavitary sponge, in several described cases, once the wound cavity had become smaller, treatment with a VAC stent was transitioned to. The gradual combination of these two therapy forms seems advantageous. (2,3)
The VAC stent can remain in the body for up to 7 days. Compared to EVT, the extended exchange interval reduces the frequency of interventions and the associated patient burden and lowers the workload for medical staff. Additionally, the risk of adverse events associated with sedation and local complications (such as mucosal erosions, bleeding, and difficulties in removing the sponge) is lower. Finally, the VAC stent does not exert direct negative pressure in the mediastinum, which could theoretically have unpredictable consequences for adjacent organs. (2,12,15,18,19)
Comparison with SEMS
Self-expanding metal stents are associated with inherent disadvantages. They have a migration rate of 50% or more, and they exert expansion pressure on the intestinal wall, which can impair microcirculation and complicate wound healing at the leak site. (1,8,10,15,18,19)
Although direct comparative studies are lacking, the VAC stent appears to be associated with a significantly lower migration rate than conventional SEMS. This stability is due to several factors: First, the stent adheres firmly to the esophageal wall along its entire length due to the negative pressure of EVT. The suctioned drainage tube acts as a stabilizing anchor that mechanically holds the stent in position and provides additional resistance against movements caused by normal peristalsis or external physical influences. The 30 mm wide, dumbbell-shaped stent ends provide additional protection against dislocation and migration. (1,2,8,14,19)
The main advantage of the VAC stent over conventional SEMS lies in the integration of vacuum therapy, which allows for the drainage and suction of fluid accumulations in anastomotic insufficiencies. This is particularly valuable for managing infected fluids, as it enables microbiological analysis and targeted antibiotic therapy. In this situation, an SEMS would typically require an additional percutaneously placed drainage. (1,10,14,19)
SEMS are less adaptable to the anatomy of the esophagus. Due to this characteristic and their size, they have been associated with the development of mucosal erosions and ulcers, which occur more frequently in patients undergoing neoadjuvant radiochemotherapy or with prolonged SEMS treatment. There have also been reported cases where SEMS have grown into large vessels such as the aorta or pulmonary artery, leading to fatal events. The VAC stent offers similar protection of the defect site but is better adapted to the anatomical conditions due to its size and design, making such adverse events less common. (2,9,15,18,19)
However, there are also disadvantages. Unlike SEMS, the VAC stent requires hospitalization with a stent change interval of 5–7 days. The multiple exchanges of the stent and the necessary hospitalization increase costs and also lead to increased patient burden and a higher risk of complications related to the endoscopic procedure and sedation. (2,18,19)
Another advantage of SEMS is that patients do not need a nasal tube and can be treated quickly on an outpatient basis, contributing to a better quality of life for patients treated with SEMS. (18,19)
Another limitation of the VAC stent is its availability in only a single size, whereas SEMS are available in various lengths. (2,18)