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TRANSURETHRAL CONTACT NANOPULSE URETEROPYELOLITHOTRIPSY

A. A. Rumyantsev1, V. V. Dutov2, V. V. Belyaev1, A. A. Saakyan1, D. V. Belyaev1, D. M. Popov2.

1 Municipal Institution - Municipal Clinical Hospital, Zhukovskiy, Moscow Region (Head Physician - Professor A. N. Zlobin, Doctor of Medical Sciences), 2Urology Clinic (Head - M. F. Trapeznikova, Academician of the Russian Academy of Medical Sciences), State Institution - M. F. Vladimirskiy Moscow Regional Research and Clinical Institute (Director - G. A. Onoprienko, Corresponding Member of the Russian Academy of Medical Sciences).
Contact author: A. A. Rumyantsev - Candidate of Medical Sciences, Head of the Urology Department; tel.: 8(495)556-98-58

The purpose of the research study is to determine the indications, efficacy and safety of the contact nanopulse lithotripsy method in clinical practice.
The research study included 161 patients ranging frm 18 to 84 years of age (mean age 47 ± 14 years) admitted to the Urology Department of Zhukovskiy Municipal Clinical Hospital during the period frm 2006 to 2009. Female/male ratio was 1.4:1.
Overall efficacy of contact nanopulse ureterolithotripsy (CULT) reached 98%.Total destruction of the concrement was achieved during the first CULT session in the overwhelming majority of observations.Stone disintegration was partial in only 2% of patients. CULT turned out to be technically feasible for all patients provided that the tool reached the stone level.Duration of the treatment term for this type of therapy, conditional on the complete passage of all stone fragments, varied frm 1 to 6 months.
Contact nanopulse ureteral lithotripsy is reasonable to be performed with single pulses, beginning with low-energy pulses of around 0.45 J. Contact nanopulse pyelolithotripsy initially requires a higher level of pulse energy - around 0.6 J.CULT is a highly efficient method for treatment of concrements in upper urinary tracts.The complication rate for this type of therapy is minimal and does not exceed 5%.The long-term existence of a stone in the urinary system increases the risk of intraoperative complications.
Key words: urolithiasis, contact nanopulse lithotripsy

Introduction. In Russia up to 35% of all the persons hospitalized in urology departments are patients with urolithiasis. Due to the variability and unpredictability of the clinical course, and to the high rate of complications and disability, the diagnosis and treatment of urolithiasis are still important issues that need to be urgently addressed [1-4].
The problem of how to treat ureter stones, which are responsible for the development of obstructive pyelonephritis, calculous ureterohydronephrosis, and ureteric strictures, is one such pressing issue. Modern methods for treatment of ureter stones, including extracorporeal shock wave lithotripsy (ESWL), are not always effective, especially for multilevel and bilateral localization of concrements, as well as for localization of stones in the lower third of the ureter. Nowadays, contact endourological methods are increasingly used for treatment of ureter stones. These methods make it possible to increase treatment efficacy, reducing the post-operative period and time of rehabilitation [5-7].

Materials and Methods. Ureteropyeloscopy with contact ureterolithotripsy (CULT) was performed under peridural or spinal anaesthesia in a special X-ray surgery room equipped with the X-ray urology system, Opus II, manufactured by Dornier MedTech (Germany). The research study involved 161 patients ranging frm 18 to 84 years of age (mean age 47 ± 14 years) admitted to the Urology Department of Zhukovskiy Municipal Clinical Hospital during the period frm 2006 to 2009. Female/male ratio was 1.4:1. The majority of patients (118/73%) were hospitalized as scheduled; emergency care was provided to 43 patients (27%). All patients were ranked by age, localization and size of concrements. A general clinical and comprehensive urological assessment, including ultrasonography, plain and excretory urography, was performed in the preoperative period. A small number of patients with X-ray negative concrements were given computed tomography to more accurately locate and determine the size of stones, and to better assess the condition of the upper urinary tracts. The indication for performing contact nanopulse ureterolithotripsy (CULT) was the presence of a concrement up to 20 mm in its maximum dimension, causing urodynamic abnormality, in the absence of a tendency toward spontaneous passage in the setting of treatment and/or after a failed attempt of extracorporeal shock-wave lithotripsy (ESWL). The main screening criteria were the size and shape of a stone, duration of its existence in the ureter, condition of upper urinary tracts, and the anatomic and functional condition of the kidney. The contraindications to contact destruction of a stone were considered to be ureter strictures located more distally than the stone, musculoskeletal system disorders making it unfeasible to accommodate the patient in the chair, and severe concomitant diseases. In total, 114 (70.8%) patients were given CULT; 47 (29.2%) were given contact pyelolithotripsy. All the patients receiving CULT were divided into three age groups.
The first group (18-59 years) turned out be the largest one: 74 (64.9%) patients. The second group was composed of elderly patients (60-75 years) - 31 (27.1%) subjects. The third group (older than 75 years) included the smallest number of patients - 9 (8%) patients.
Depending upon localization and size of concrements, the patients subjected to CULT were distributed as follows: Stones in the upper third of the ureter were localized in 38 (33.3%) patients (not counting patients given contact pyelolithotripsy), in the middle third - in 35 (30.7%), and in the lower third - in 41 (36%). Two stones in the upper and middle thirds of the ureter were localized in 5 patients; 3 concrements in the lower and middle thirds were localized in 4 patients. In 2 patients, concrements of the ureter were localized on both sides, which was considered as an indication to perform bilateral, single-step ureterolithotripsy. X-ray negative stones were observed in 18 patients. The preceding ESWL had proved ineffective in 12 patients with ureter stones. In 8 patients, infravesical obstruction was eliminated in a single-step procedure performed along with CULT. Four elderly patients were given single-step CULT with subsequent transurethral resection (TUR) of the sclerotized neck of the urinary bladder; 4 patients received a TUR of the prostate gland upon completion of CULT.

         Efficacy of Lithotripsy Depending on Method of Shock Pulse Generation

 

Method of stone destruction

Specific energy, J/mm3

Pulse energy, J

Efficacy

Advantages

Disadvantages

Pulsed kinetic

0.2–0.65

0.1

Up to 90% [7–9], 60% according to the authors’ data

It does not affect living tissue

Rigid probe, frequent proximal migration of fragments

Laser

At least 5

0.5–3

Up to 80-100%

[7.9]

Flexible probe, “vaporization” of any type of stones is possible

Damage to endoscope and surrounding tissues (burn, perforation) is possible

Electrohydraulic

0.5–0.6

0.25–2.5

Approx. 67-100% [8]

High efficacy with use of thin and flexible probes

High-voltage pulses of microsecond and millisecond duration. Pulse energy is relatively high (up to 2.5 J); ureterodialysis is possible at maximum energy levels. Electrical injury is possible.

Ultrasound

0.1

More than 50% [5]

Easy to use, high fragmentation rate

Rigid probe of large diameter, method does not allow destroying all types of stones and exerts a pathologic thermal exposure on tissues.

Rigid ureterorenoscopes manufactured by Karl Storz and Sholly (Germany) of 10 Fr and 9.5 Fr in diameter, respectively, were used as endoscopic tools. Operating channels were of 5 Fr in diameter and equipped with 6° optics. Contact nanopulse lithotripsy was performed using the Urolit-105M nanopulse lithotripter manufactured by MedLine, Ltd. (Russia). Probes with working tips of 3.6 Fr in diameter and 1300 mm in length were used for fragmentation of ureteral and renal concrements. In most of the observations, CULT of ureter stones was performed with single pulses at an energy level of 0.45-0.6 J. On average, 68 ± 44 pulses were required for stone destruction throughout the ureter. Fragmentation was generally performed with the patient under spinal and peridural anaesthesia. In a number of clinical cases, elderly and older patients were given endotracheal anaesthesia because bone changes in the spine made it impossible to perform spinal puncture. Whenever a concrement was found, it was caught in a Nitinol basket in order to prevent it frm proximal migration. Then, under direct vision, the lithotripter probe was advanced to the stone through the operating channel of the ureterorenoscope until the working tip of the probe made complete contact with the stone. Depending upon the size and estimated composition of the stone, the energy level and pulse generation rate were set individually. Stone disintegration during its close contact with the probe was performed through the transfer of nanopulse energy to the concrement. Stone fragments were removed partially with forceps, partially with the Nitinol basket. All patients were given internal drainage of the upper urinary tracts. Stents were used in the overwhelming majority of observations. The time frame for stent removal varied frm 5 to 30 days, depending on the prior clinical situation. A follow-up examination of the patients was conducted within the first month after the surgery.

Results and Discussion. At the current stage of urology development, lithotripters for CULT and ESWL are divided into mechanical, electrohydraulic, pneumatic, ultrasound, laser and nanopulse types, depending upon the type of energy generated (see the Table). Each of these energy generation methods has its own advantages and disadvantages. Electrohydraulic ureterolithotripsy often causes intraoperative complications, since high energy and a large number of impact pulses are required for this method. Laser treatment methods have high cost and a longer treatment procedure time compared with other methods. Pneumatic kinetic lithotripsy is an effective method; due to the rigidity of the probes, however, technical restrictions frequently arise when concrements are located in the upper third of the ureter. ESWL is not indicated for all types of stones; a high rate of "steinstrasse" formation is typical for this method. Specific energy for ESWL varies within 1-2 J/mm3. Open surgical intervention is not required, but damage to tissues around the stone is typical, which is an especially relevant issue when the stone is located in a kidney.
Elderly and older patients have broader indications for endoscopic stone destruction in connection with concomitant somatic diseases. This type of treatment ensures the highest level of stone disintegration at lower invasiveness as compared with open surgeries and at a smaller number of therapy sessions as compared with ESWL. CULT was accompanied with ureterolith extraction in 111 (97.3%) patients. In total, the efficacy rate of contact nanopulse fragmentation reached 98%. Complete destruction of the concrement was achieved during the first CULT session in the overwhelming majority of observations. Only in 2% of patients was the calculus disintegration partial in nature. CULT turned out to be technically feasible for all patients provided that the tool reached the stone level. We think that clinical efficacy of any treatment method makes no sense without its safety to a patient. All patients were given 24-hour drainage of the bladder using a Foley catheter. The overwhelming majority of the patients received α-adrenoceptor blocking agents in order to prevent acute retention of urine and to improve discharge of remaining small fragments of concrements. It should be noted that CULT sessions ended with the removal of all visible stone fragments in the majority of observations. Spontaneous passage of small stone fragments (up to 2 mm) was documented in 83% of patients. The passage of stone fragments occurred spontaneously and required no additional intervention. No cases of macrohematuria and dysuria in the early and late post-operative period were registered. No delayed post-operative complications were observed within the first year of follow-up monitoring. Average duration of the surgery was 58 ± 34 minutes; average time of a patient's hospitalization was 9 ± 5.4 days. Thirty percent of patients were discharged frm the hospital on the 3rd day; another 45% of patients were discharged by the end of the 5th day.
Insrtion of the ureterorenoscope into the ureteric orifice is a complex technical aspect. At sufficient diameter of the orifice, it is technically feasible to insrt the tool without its dilatation. In 14 patients the orifice was dilated using two strings. After insrtion of the ureteropyeloscope the strings were removed. We did not use sheaths for the ureterorenoscope in view of the fact that no equipment for intraoperative X-ray control was available. We think that use of the sheath is not an essential condition for CULT, but it certainly does facilitate the surgical procedure.
During the CULT session, perforation of the ureter in the lower third was documented in 2 patients. This required placement of a stent and antibacterial therapy, which made it possible to arrest this complication. Proximal migration of the stone to the kidney was found in 3 patients, which predetermined the indications for stent placement and subsequent ESWL. An acute aggravation of pyelonephritis was registered in 2 patients. It was stopped with the conservative antibacterial therapy. The tool failed to be insrted in 2 patients in connection with a cicatricial deviation of the intramural section of the ureter due to bladder ruptures in the medical history. The problem of contact pyelolithotripsy, which proved to be required in all age groups, deserves to be discussed in detail. Indications for contact pyelolithotripsy in 47 (29.2%) patients included a stone of more than 20 mm in maximum linear dimension, a somatic status, especially in elderly and old patients, that did not permit open operative interventions, and ineffective prior ESWL [6, 10, 11]. In the case of contact pyelolithotripsy, the average sizes of kidney stones were equal to 24 ± 5 mm. Fragmentation of concrements was performed with single or dual pulses at an energy level of 0.6-0.7 J. The average number of pulses required for stone fragmentation was 40 ± 17pulses. During calculus fragmentation, the largest fragments were removed with forceps or the Nitinol basket. In all observations, the operation was completed with internal drainage of the kidney established through the placement of a stent. The remaining fragments of the stone were destroyed using ESWL. Duration of the treatment term for this type of therapy varied frm 1 to 6 months provided that the kidney was completely cleared of stone fragments. This type of therapy proved effective in 69% patients. It should be noted that, in spite of these results, it is advisable to use a ureteral sheath when performing contact lithotripsy of the upper urinary tracts, which facilitates the fragmentation process and evacuation of concrement fragments [6, 11].

Conclusion. CULT is a highly effective and safe method of concrement destruction in urinary tracts, and ensures a positive result in 98% of treated patients. Contact nanopulse fragmentation of ureter stones should be performed with single pulses, beginning with low-energy pulses of around 0.45 J. Contact nanopulse pyelolithotripsy initially requires a higher level of pulse energy - around 0.6 J. The long-term existence of a stone in the urinary system increases the risk of intraoperative complications. CULT is a relatively safe method for the treatment of uroliths, having complication rate of less than 5%.

REFERENCES
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