**7. Indications and strategies of intraoperative IVC interruption**

With regard to dealing with the IVC intraoperatively is one of the difficulties of IVC thrombectomy. There necessity of reconstruction after IVC resection is still controversial.

Indications for vena caval interruption include invasion of the venous walls, severe adhesion of the tumor to the vascular endothelium, complete occlusion of the vena cava, and the presence of distal thrombus [21, 39, 40]. In addition, the texture of the cancer thrombus is one of the influencing factors. With regard to preoperative imaging, the IVC in line with the indications of interruption and accompanied by sufficient collateral circulation, meanwhile, without serious cardiac, hepatic, and renal insufficiencies can be completely cut off. IVC venography and intraoperative ultrasound can help determine the disjointed lumina, which enables protection of the established collateral circulation trunk. IVC interruptions include complete and partial vena caval resections with reconstruction. Based on our experience, for right tumors, the height of the tumor thrombus, which is below the secondary hepatic portal, linear cutters are used to successively cut off the proximal, distal, and left renal veins of the tumor thrombus (**Figure 1I**). With regard to right tumor thrombus above the secondary hepatic portal, or left tumor thrombus above the level of the right renal vein and combined with distal thrombus, the vena cava can be resected partially. Methods for right thrombectomy include cutting off the lumina of the IVC below the secondary hepatic portal and reconstructing the lumina of the IVC above the secondary hepatic portal. The left thrombectomy procedure is resecting the lumina of the IVC below the level of the right renal vein and reconstructing the lumina of the IVC above the level of the renal vein.

Meanwhile, IVC interruption is safe and feasible during vena caval thrombectomy [39, 40], and the establishment of collateral circulation can avoid severe hemodynamic disorders. Different strategies of interruption ought to be generated preoperatively based on the height of tumor thrombus, tumor side, degree of vena caval obstruction and invasion, and establishment of collateral circulation.
