Visualization of the Stomach's Arterial Networks During Esophageal Surgery Using the HyperEye Medical System

Discussion

Although the short-term outcomes from esophagectomies for esophageal cancer have improved at our Institution with the introduction of LGM, which is a less invasive technique (8, 9), anastomotic leakage remains a problematic complication. Securing a good arterial blood supply and relieving the tension at the anastomosis site are essential. However, a method that enables for evaluation of the arterial blood supply to the anastomosis has not been established. In esophagectomies, the right GEA mainly supplies blood to the GT; however, approximately 30% of patients lack the connection between the right and left GEA (10). In these cases, the blood supply to the anastomosis depends on the ANS; however, identifying this network based on color alone is difficult. Our study suggests that the ICG fluorescence method can visualize the GEA and the ANS.

Some investigators who have not deployed the HEMS have, nevertheless, reported the usefulness of ICG fluorescence for evaluating blood supply to the anastomosis during esophagectomies (11, 12). The key advantage relating to the deployment of the HEMS is that the blood flow can be visualized on a color monitor in a well-lit operating room (13), and it enables for detection of areas of good blood supply through simultaneous comparisons with the actual surgical field. The HEMS does not require the operating room lights to be switched off, and surgery can be performed as the blood flow is evaluated. However, we experienced GT necrosis in a patient in whom the HEMS was deployed after GT creation, which led us to consider the deployment of the HEMS before GT creation to confirm the ANS border. Subsequently, we began to deploy the HEMS-LMM before GT creation. In addition, we could repeat the test using the HEMS during surgery because ICG is washed-out within 20 min of injection (5). We have also undertaken small intestinal surgery in whom the HEMS was used to evaluate the mesenteric blood flows (14).

With respect to cases that experienced leakages, the leakage in case 1 occurred at the tip of the GT, and it appeared that we had cut the tip of the GT on the line that had a lower level of fluorescence. Therefore, surgeons should pay attention to the anastomosis and to the tip of the GT. This patient resumed oral intake 7 days after surgery, because no evidence of a leakage was found, for example, fever or swelling of the neck. The early mechanical pressure applied to the tip of the GT, which had a lower fluorescence intensity, might have additionally contributed to the delayed leakage; therefore, initiation of oral intake should have been postponed. Case 5 involved partial GT necrosis. In this case, the fluorescence intensity in the area of the leakage in the GT was obviously low compared with that seen in the peripheral region. We considered that an interruption of the ANS had led to the low level of fluorescence of the GT. Therefore, surgeons should pay attention to absence of fluorescence in the estimated anastomosis area, at the tip of the GT, and on the ANS boundary. The HEMS-LMM has the advantage of confirming these areas before creating the GT.

The HEMS may be considered safe in clinical practice, because none of the patients in the HEMS group experienced adverse events associated with the ICG injection. However, precise criteria have not yet been established for the HEMS in relation to postponement of oral intake or where the anastomosis of the vessels should be performed. A history of cardiovascular disease might be associated with a risk of leakage (15), and our data suggest that a lower fluorescence intensity in the HEMS images is indicative of a risk of delayed leakage. When the HEMS images show low levels of fluorescence, early necrosis may occur. Furthermore, even when the HEMS images show good levels of fluorescence on the GT, a history of mediastinal radiation therapy might be associated with a risk of leakage after esophageal surgery (16).

The usefulness of early endoscopic assessments following esophagectomies has been previously reported (17). Early endoscopic assessments may contribute to establishment of criteria for the HEMS by comparing the ICG fluorescence with the endoscopic images of the anastomosis. In addition, the HEMS can be used to predict which reconstruction method is the most suitable following esophageal surgery, including the estimated anastomosis and the GT resection line. This is an issue that should be investigated in the future.

The present study was limited by its retrospective nature, involving a small number of patients. Further investigations need to be undertaken in order for the usefulness of the HEMS-LMM for preventing leakages after esophageal surgery to be determined.

The HEMS-LMM is safe and feasible for visualizing the blood supply border associated with the right GEA and the ANS before GT creation during esophageal surgery. It might reduce leakage, but further investigations are required to establish criteria that determine when the HEMS should be deployed to ensure there are no leakages.