AUA2023: REFLECTIONS Steerable Ureteroscopic Renal Evacuation with CVAC Aspiration System for Fragment Aspiration

By: J. Stuart Wolf Jr, MD, FACS, Dell Medical School, University of Texas at Austin | Posted on: 06 Jul 2023

Figure 1. The CVAC aspiration system.

Figure 2. The CVAC catheter and introducer (*), irrigation tubing and self-filling syringe (+), and suction tubing with collection cannister (x).
Figure 3. Fluoroscopic view of the CVAC in an interpolar calyx outlined by contrast material.
Figure 4. The CVAC is manipulated by the surgeon (white gloves), with the tip directed by the steering control dial (left hand) and suction controlled with the vacuum controller (right hand). The irrigation is performed by an assistant (brown gloves).
Figure 5. Stone fragments in collection canister.
Figure 6. Endoscopic view before and after steerable ureteroscopic renal evacuation in a lower-pole calyx.
Figure 7. Coronal CT images before (left) and 30 days after (right) the procedure.

With the advent of high-power laser lithotripsy, the strategy of “dusting” is applicable even to hard and/or large renal calculi. The technique requires that the patient passes the fragments postoperatively; if this does not occur, then the patient is left with residual stone material. The steerable ureteroscopic renal evacuation (SURE) procedure using the CVAC aspiration system (Figure 1) addresses this problem. The CVAC device is a steerable coaxial catheter that incorporates an outer lumen for irrigation and a 7.5Fr inner lumen for aspiration of fluid and stone fragments. The preliminary experience has been published,1 and an abstract presented at this year’s AUA Annual Meeting demonstrated effectiveness in a cohort of 43 patients with large calculi (mean preoperative stone burden 29±12 mm).2

During SURE, the stone is treated with laser lithotripsy until all fragments are small enough to be aspirated. Even though the inner lumen can accept a fragment up to 2.5 mm in the greatest dimension, in our experience the device works best if the stones are fragmented to particles 1 mm or less. The additional supplies for the procedure include a 12/14Fr ureteral access sheath, an irrigation system with a 10-cc syringe, and suction tubing with a stone collection canister (Figure 2).

Once laser lithotripsy has been completed, the ureteroscope is removed and the CVAC aspiration system (catheter with introducer) is inserted via a 12/14Fr ureteral access sheath over a guidewire. The CVAC catheter can be directed into the desired calyx under spot fluoroscopy, and the placement can be aided by contrast injection (Figure 3). The device can be advanced, turned, and the tip deflected with the steering control dial (Figure 4). Continuous irrigation with a 10-cc syringe is provided by the assistant, and the surgeon activates intermittent suction by closing the vacuum controller (which is a hole on the handle of the device). The large vacuum lumen and open system allows passive drainage even when the vacuum is not activated, such that the intrarenal pressure does not rise above 40 mm Hg unless there is clogging.3 The CVAC is sequentially moved to every calyx bearing stone fragments. We have found that placing the patient in the Trendelenburg position early in the case often will facilitate movement of most fragments to a single upper calyx. Scope inspection in between CVAC sequences can help determine the relative clearance of the calyx and identify any target calyx with residual fragments. After the completion of the procedure, stone fragments are gathered from the collection canister (Figure 5).

At the AUA Annual Meeting, we presented a semi-live surgery session about this technique, demonstrating the use of the CVAC in a 62-year-old man with an 11-mm impacted renal pelvic stone and a 7-mm lower-pole stone. CVAC was used in each of the 4 calyces of a very dilated system that harbored fragments after the laser lithotripsy. Figure 6 illustrates the endoscopic result after SURE in a lower-pole calyx. Figure 7 displays images from the coronal view of a CT scan, before and 30 days after the procedure. There are a few small fragments in the lower pole but, given the preoperative stone burden and the dilation of the intrarenal collecting system, this is thought to be a satisfactory result, albeit not optimally stone-free. The patient had significant flank pain preoperatively and is asymptomatic postoperatively.

In summary, SURE with the CVAC device may lead to a patient outcome that is more favorable than one that depends on the fragments to pass. The optimal application of SURE with CVAC is yet to be determined and further studies are underway.

  1. Sur RL, Agrawal S, Eisner BH, et al. Initial safety and feasibility of steerable ureteroscopic renal evacuation: a novel approach for the treatment of urolithiasis. J Endourol. 2022;36(9):1161-1167.
  2. Stern KL, Borgert B, Wolf JS Jr. MP23-14 Ureteroscopy with CVAC aspiration system for the surgical management of large renal stones. J Urol. 2023;209(supplement):e311-e312.
  3. Unpublished data on file (Calyxo, Inc.)