Generally, during the procedure of IVCTE for Mayo II IVCTT that closed to the hepatic vein or Mayo III IVCTT, it is necessary to clamp the contralateral renal vascular, subrenal IVC, the first hepatic portal and supra-hepatic IVC. However, this blocking process is complex and time-consuming even for experienced surgeons, and the liver may be damaged during the process of clamping the first porta hepatis. Thus, we modified the IVC clamping technique, that only the IVC below the inferior margin of TT and the contralateral renal vascular were clamped when the TT was resecting; while the cephalic IVC was left to be clamped below the liver margin immediately after the TT was pulled out.
The critical point of this method is how to control the intraoperative bleeding and avoid air embolism. Our experience is that the pneumoperitoneum pressure can be elevated to around 20 mmHg before the incision of IVC to ensure that there is blood flow through the vena cava, but no blood outflow. Though reversal flow of blood in the cephalic IVC at the time of IVC incision is inevitable, this blood flow is so small that the bleeding caused by reversal blood flow can be reduced to a certain extent by increased pneumoperitoneum pressure, which is consistent with K. Eiriksson’s results . However, E. Eiriksson also pointed out that high pneumoperitoneum pressure is more likely to cause air embolism. So, the duration of the high pneumoperitoneum pressure should not be too long. In addition, in the process of thrombectomy, the use of aspirator is not recommended unless necessary, because it can easily lead to bleeding. For the 3 patients who received transperitoneal laparoscopic IVCTE using this modified IVC clamping technique in our study, the pneumoperitoneum pressure was elevated to 20 mmHg before the incision of IVC and quickly restored to 12 mmHg after the TT was removed. The surgery were successful with no intraoperative complications, and the intraoperative blood loss was 600 ml, 300 ml and 50 ml, respectively.
For another 5 patients who received transperitoeneal open IVCTE, the Foley catheter-assisted technique was used to remove the TT. It has been reported that some invasive and complicated process such as thoracotomy, median sternotomy and extracorporeal circulation can be avoided by using Foley catheter in patients with Mayo III-IV IVCTT . Conventionally, during the procedure of IVCTE for Mayo II IVCTT that closed to the hepatic vein or Mayo III IVCTT by using transperitoneal open approach, it is necessary to fully isolate the retro-hepatic IVC and hepatic vein, to incise the ligamentum teres hepatis, the left and right triangular ligament and the sagittal and coronary ligament, and to isolate and retract the liver to the left. These processes are so complicated that it would cause big trauma. In our series, the aforementioned complicated procedures were successfully avoided due to the use of Foley catheter. Therefore, Foley catheter-assisted technique combined with the modified IVC clamping technique can greatly simplify the procedure and reduce the difficulty of operation.
Although it can simplify the operation steps and reduce the surgical trauma, this modified IVC clamping technique cannot be routinely used without caveats—it is not recommended in cases when the friable thrombus is presented, or in cases of intra- or supra-hepatic IVC wall infiltration by TT. At present, there is no standard definition of tumor textures. Roberto Bertini, et al. pointed out that in a friable thrombus, the pseudocapsule is lacking and the tumor cells are intermingled with abundant necrosis and fibrin . This kind of TT is easy to fall off and thus lead to pulmonary embolism during the process that it is pulled out of the IVC lumen. While when the intra- or supra-hepatic IVC was invaded by the TT, it is essential to fully isolate the TT to make it separated from the IVC wall, so that it can be entirely pulled out of the IVC lumen. However, this process is extremely complicated and dangerous. Therefore, in addition to preoperative CT/MRI, intraoperative TEE is recommended in order to determine whether this technique is feasible. Preoperative CT/MRI can preliminarily evaluate the texture of TT and the relationship between TT and IVC wall, while intraoperative TEE is helpful not only to further clarify this, but also to guide the removal of TT in real time. For the 8 patients here, the TT were en bloc extracted under the real-time guidance of the TEE, without shedding and residue.
Complete resection is one of the principles for treatment of malignant tumor. It is reported that for the non-metastatic RCC patients with IVCTT, the 5-year overall survival is 56% if the tumor and thrombus were en bloc resected, versus only 25% if the tumor and thrombus were not entirely resected . Therefore, in order to resect the tumor entirely, segmental IVC resection was performed in 2 patients in whom the IVC wall were extensively invaded by the TT. For these 2 cases, IVC was left in discontinuity without reconstruction, but the circumfluence channel of the right renal vein was ensured (Fig. 3 and Fig. 4). During the follow-up period, no lower extremity edema was found. It is considered that this may be associated with the well-developed collateral circulation due to a long time growth of the tumor.
Perioperative complications is up to 22%-70% for the RN and IVCTE [3, 21]. In our series, early postoperative complications occurred in 2 cases, one is ATN, another is incomplete intestinal obstruction, pleural effusion and pulmonary atelectasis. ATN occurred in a middle-aged man (no. 2), of whom the preoperative SCr was 123 µmol /L [reference range: 53–130 µmol /L], while one week after the operation it went up to 813 µmol /L, with normal serum potassium. Conservative therapy with no dialysis was performed, and the renal function gradually returned to normal, with the SCr 130 µmol /L one month after the operation. It is analyzed that the ATN may be associated with ischemia-reperfusion injury induced by blocking of the contralateral renal vascular, and renal hypoperfusion caused by the intraoperative blood loss. It is reported that damage of renal function can be reduced if the WIT time is controlled within 30 min. The WIT time is only 21 min for this patient, individual differences may be the reason that lead to ATN, but also may be associated with a relatively high value of preoperative SCr. Incomplete intestinal obstruction, pleural effusion and pulmonary atelectasis occurred in patient no.3, and the long operation time may be the reason. So, improving surgical technique to shorten the operation time is critical to prevent these complications. Interestingly, of the 8 patients, one experienced CRF preoperatively, with SCr 958 µmol /L, which reduced to 130 µmol /L one week after the operation. And this patient received segmental resection of the IVC. It is considered that preoperative high value of SCr may be related with the obstruction of the renal vein return, which caused by too fast growth of the tumor. After the TT was removed, the obstruction of renal venous reflux disappeared, blocked renal vein return was removed, so the postoperative renal function gradually returned to normal.
There are some limitations in our study. First, the cases included are limited, especially the cases with Mayo III IVCTT; second, our study is only a single-center experience summary. Therefore, although it is technically feasible and safe to treat the Mayo II-III IVCTT with the aforementioned technique used in our study, its repeatability should be confirmed by other surgeons before its widespread acceptance.