Holmium laser enucleation of the prostate with Virtual Basket mode: faster and better control on bleeding

HoLEP is a surgical option for the management of BPH and an alternative treatment to TURP, or open prostatectomy, according to EAU Guidelines. One of the main advantages of HoLEP is that it reduces intraoperative and postoperative bleeding, leading to a lower transfusion rate, shorter hospitalization and catheterization [7].

This enucleating technique is performed with the Ho:YAG laser, which emits a pulsed laser beam, with a wavelength of about 2.1 µm, obtaining tissue vaporization, coagulation and necrosis limited to a depth of 0.3–0.4 mm [8]. The Ho:YAG laser is also used for stone lithotripsy, during which, the impact of the energy against the stone can cause its migration from the ureter to the renal cavities or from one calyx to another. To prevent this phenomenon, anti-retropulsion devices have been engineered, like the “Virtual Basket” mode, which is a result of the laser’s pulse modulation: the laser creates an initial bubble with the first part of its energy and discharges the remaining energy once the bubble is formed, so that it can pass through the formed vapor channel. In this study, we report our results on the application of the Virtual Basket mode to HoLEP (VB-HoLEP) compared to the conventional technique, with a 6-month follow-up.

Vizziello et al. firstly reported their in vitro experience regarding the use of the Virtual Basket in stone phantom lithotripsy [9]. The authors concluded that this mode was associated with significantly fewer events of stone migration and better target stability during the procedure. Another study [10] investigated this emission mode in the treatment of ureteral and renal stones. In particular, it was reported that when compared to the regular mode, the Virtual Basket technology was associated with significantly lower retropulsion, fragmentation time and total procedural time, with no significant differences in total emitted energy.

Based on these studies, this mode may grant a smoother effect not only on stones but also on soft tissues, resulting in less trauma and bleeding.

Because of its double pulse pattern, we hypothesized that the use of the Virtual Basket during HoLEP may result in a first energy portion creating an initial separation of the prostatic tissues and the remaining energy being discharged through the incision, expanding it further and clotting bleeding vessels. As the laser’s second pulse travels through the vapor tunnel created by the first pulse, a lower attenuation of the second pulse should occur, resulting in a stronger effect on the tissue (sealing and/or incision). This system, with the emission of two energy pulses fired with a small time gap between one another, seems to allow faster coagulation, reducing the risk of bleeding and, therefore, operative time. Indeed, as reported in our results, compared to HoLEP, the VB-HoLEP was faster (57.33 ± 29.71 vs. 42.99 ± 18.51 min, P = 0.04) and resulted in less hemoglobin decrease (2.54 vs. 1.12 g/dl, P = 0.003). Despite being inferior, compared to older surgical techniques, bleeding risk with HoLEP still remains. Some studies report a risk of severe hemorrhage in 5.2% of patients and a risk of bladder tamponade that required cystoscopy and evacuation of blood clots in 2.3% [11]. In some Centers, to reduce the risk of bleeding in the early post-operative period, surgeons use a bipolar resector to obtain prostatic loggia coagulation. This lengthens the operating time, increasing the risk of anesthesiologic complications. The use of the Virtual Basket could improve coagulation with the laser, allowing to avoid the use of the bipolar resector and reduce morcellation time, thanks to a good endoscopic vision, without residual bleeding.

Moreover, HoLEP has proven to be safe and effective in anticoagulated patients. The hemostatic efficacy of the Ho:YAG laser makes HoLEP more effective and safer than other BPH treatments in patients taking anticoagulant agents. Specifically, the low penetration depth of the holmium laser limits eschar formation, which can contribute to delayed bleeding seen after other BPH procedures [12]. The use of VB-HoLEP, thanks to its observed better coagulation capability, could further reduce the risk of bleeding in patients under anticoagulation therapy [13].

The comparison between HoLEP and VB-HoLEP during the 6-month follow-up did not demonstrate significant differences in Qmax, IPSS, PVR, and QOLS.

Urinary incontinence (UI) is one of the most worrying postoperative complications. Postoperative UI occurres in about 20 % of patients and most of them recover within the first year. Long operative time is the first risk factor: the longer the resectoscope remains in the urethra, the higher the possibility of sphincter damage. Some studies stated that high prostate volume, a conspicuous reduction in postoperative PSA and diabetes mellitus are significant risk factors for stress UI [14]. Various authors have suggested that postoperative incontinence could be related to either thermal injury to the pericapsular structures, resulting in urge incontinence, or linked to the presence of a urinary tract infection, or BPH-related detrusor instability [15]. Another risk factor for UI is the presence of a large prostatic fossa, created after the removal of adenoma, which leads to urine entrapment and leakage with stress maneuvers [16]. VB-HoLEP could reduce the risk of UI thanks to a better cut on the tissue, resulting in reduced traction and stress on the urethra and external sphincter.

The long learning curve is the major negative factor that hinders widespread use of this procedure to date [17]. The inexperience of the surgeon elevates the risk of bleeding and UI after HoLEP because of long operative time, frequent intraoperative complications and inadequate enucleation.

As the use of VB-HoLEP proved to reduce operative time in our study, the risk of UI may be reduced with this technique. Moreover, as the use of the Virtual Basket reduced bleeding, improving the quality of the endoscopic vision, the use of VB-HoLEP may help to reduce the learning curve. These aspects may be verified in future multicentric studies.

Together with the long learning curve associated with the enucleation technique, the cost associated with the purchase of high power laser platforms has probably represented another factor hindering the spread of laser enucleation. However, the possibility to use the VB technology, with reusable fibers and on medium power platforms might help to foster the adoption of HoLEP in upcoming years. Indeed, the non-inferiority of low-power HoLEP with respect to high power HoLEP has been investigated [18, 19]. For instance, Elshal et al. compared 50 W and 100 W HoLEP techniques, reaching comparable improvement in IPSS, Qmax and median PSA reduction, with similar perioperative and late postoperative complications [18].

There is growing interest for new pulse modulation technologies which can potentially enhance lithotripsy effectiveness and which have been recently launched on the market [9, 20, 21]. However, so far the potential advantages of these modulations have been mainly explored for stone application, whereas little has been reported regarding the effect of these pulse modulations on soft tissue treatments. One exception consists in the study performed by Large et al., who shared their experience with the Moses™ technology for HoLEP [22]; Large et al. reported that the use of this modality resulted in increased OR efficiency and hemostasis, regardless of prostate size, when compared to standard HoLEP. Both his study and ours suggest that advanced pulse modulation of the Ho:YAG laser results in increased hemostatic effect. Nevertheless, there are differences between these two technologies. First, the second pulse of Virtual Basket is emitted when the vapor bubble, originated by the first pulse, is at the maximum expansion; instead, the second pulse of the Moses is emitted during the collapse of the bubble originated by the first pulse. Moreover, another difference is in the fiber compatibility with these pulse modulations: Virtual Basket, unlike the Moses, is pulse modulation which is compatible with any standard fiber, without the need of a “special” fiber in order to enable this pulse modulation.

To our knowledge, this is the first study describing the use of the Virtual Basket mode for HoLEP and one of a small group of papers reporting the use of advanced Ho:YAG pulse modulation for soft tissue applications, such as the Moses™ technology, which has been used since 2017. Further investigations by other centers are needed in order to corroborate the findings of our study.

Limitations of this study are linked to the fact that all the procedures were not performed by only one skilled surgeon. Another limitation is that hemostasis effectiveness was judged only by measuring hemoglobin drop. Potentially, recording of the time spent on hemostasis (for example the time with the right pedal pushed) may have represented an additional comparison term to corroborate our outcomes regarding hemostatic properties. Furthermore, only a single emission setting was tested in this study for both groups.