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The Twinheads extracorporeal shock wave lithotriptor (THSWL) is composed of 2 identical shock wave generators and reflectors. One reflector is under the table and the other is over the table with a variable angle between the axes of the 2 reflectors. The 2 reflectors share a common second focal point, making it possible to deliver an almost synchro...
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Context 1
... Twinheads lithotriptor is composed of 2 identical shock wave generators and 2 identical shock wave reflectors. The generators are 60 nF with power settings from 7 kV (400 bar at focal point 2 [F2]) to 14 kV (1,100 bar at F2). The power of the 2 generators was adjusted independently, while shock wave emission was synchronous. The twin synchronous shock waves are counted as 1 shock wave and peak pressure at F2 was not significantly different from that of single shock wave when measured by a needle hydrophone with an angle between the reflectors of 90 or greater. This finding requires further evaluation. Each reflector has a focal depth of 12.7 cm (distance between the reflector rim and F2) and a cigar- shaped focal zone of 16 30 mm, as defined using standard plaster of Paris blocks. One reflector is fixed under the table with an angle of 40 degrees over the horizontal plane. The second reflector is mobile and travels over the table. The 2 reflectors share the same F2, while the angle between the axes is variable as a function of changing the position of the reflector over the table. The minimum angle that can be achieved is 67 degrees and the maximum angle is 105 de- grees. At angles greater than 105 degrees the reflectors in- terfere with the x-ray field, largely precluding clinical appli- cation ( fig. ...
Context 2
... Twinheads lithotriptor is composed of 2 identical shock wave generators and 2 identical shock wave reflectors. The generators are 60 nF with power settings from 7 kV (400 bar at focal point 2 [F2]) to 14 kV (1,100 bar at F2). The power of the 2 generators was adjusted independently, while shock wave emission was synchronous. The twin synchronous shock waves are counted as 1 shock wave and peak pressure at F2 was not significantly different from that of single shock wave when measured by a needle hydrophone with an angle between the reflectors of 90 or greater. This finding requires further evaluation. Each reflector has a focal depth of 12.7 cm (distance between the reflector rim and F2) and a cigar- shaped focal zone of 16 30 mm, as defined using standard plaster of Paris blocks. One reflector is fixed under the table with an angle of 40 degrees over the horizontal plane. The second reflector is mobile and travels over the table. The 2 reflectors share the same F2, while the angle between the axes is variable as a function of changing the position of the reflector over the table. The minimum angle that can be achieved is 67 degrees and the maximum angle is 105 de- grees. At angles greater than 105 degrees the reflectors in- terfere with the x-ray field, largely precluding clinical appli- cation ( fig. ...
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The human urinary calculi are mainly formed from calcium oxalate, magnesium ammonium phosphate hexahydrate (MAPH) and uric acid (UA) crystals. It is important for the physician and surgeon to distinguish the two types of hydrates of calcium oxalate, mainly mono- (COM, Whewellite) and dihydrate (COD, Weddelite). This is because COM stones are evacua...
Citations
... The idea was that the two waves would impact on the target yet cancel out peripheral damaging effects. It was found that this technique reduces and localizes the cavitation effects, together with improving the quality and rate of stone disintegration, especially with a right-angle between the axes of the SW reflectors [6,7]. There was minimal tissue damage compared with the standard single-pulse method in an animal study [8]. ...
... The most common clinical indication of renal trauma is gross haematuria from SW-induced renal injury [9,10]. Aiming to limit renal damage, while preserving the effectiveness of ESWL, the bidirectional synchronous twin-pulse technique was developed, and experimental in vitro and in vivo studies conducted to confirm its efficacy and safety [6][7][8]. The aim of the present study was to compare the results with this technique to those of the standard single-pulse technique. ...
The aim of this study was to assess the role of MRI as a single modality for anatomical and functional evaluation of obstructed kidneys in patients with compromised renal function. The study included 96 adults with unilateral or bilateral chronic obstructive hydronephrosis and compromised renal function (serum creatinine >1.8 mg dl –1). Patients were subjected to gadolinium-enhanced MRI (Gd-MRI), which determined the anatomy of both renoureteral units, as well as their function, through selective calculation of the glomerular filtration rate (GFR) of each kidney. All patients underwent a technetium-99m diethylenetriamine-pentaacetic acid renal scan. Moreover, a correlation was made between the GFR determined by Gd-MRI and the isotope GFR. The study comprised 59 males and 37 females. A comprehensive MRI study detected the cause of obstruction in all kidneys with non-calcular obstruction (sensitivity of 100%) and in 21 kidneys with calcular obstruction (sensitivity of 70%). The overall sensitivity of MRI combined with plain X-ray of the abdomen and ultrasound in the detection of various causes of obstruction was 97%. A comparison between the isotope GFR of the obstructed kidneys and the corresponding magnetic resonance urography (MRU) GFR showed perfect correlation. In conclusion, combined static and dynamic MRU is a promising technique that allows anatomical and functional evaluation of obstructed kidneys in patients with impaired renal function but, owing to the possible risk of nephrogenic systemic fibrosis in patients with a GFR ,30 ml min –1 , the lowest possible dose of the most stable Gd-macrocyclic chelates should be used if a functional MRI study is required.
... The idea was that the two waves would impact on the target yet cancel out peripheral damaging effects. It was found that this technique reduces and localizes the cavitation effects, together with improving the quality and rate of stone disintegration, especially with a right-angle between the axes of the SW reflectors [6,7]. There was minimal tissue damage compared with the standard single-pulse method in an animal study [8]. ...
... The most common clinical indication of renal trauma is gross haematuria from SW-induced renal injury [9,10]. Aiming to limit renal damage, while preserving the effectiveness of ESWL, the bidirectional synchronous twin-pulse technique was developed, and experimental in vitro and in vivo studies conducted to confirm its efficacy and safety [6][7][8]. The aim of the present study was to compare the results with this technique to those of the standard single-pulse technique. ...
To asses the efficacy and safety of bidirectional synchronous twin-pulse extracorporeal shock wave lithotripsy (ESWL) compared with standard ESWL.
Between March 2003 and December 2006, 240 patients with a radio-opaque single renal stone of <or=25 mm were randomized to treatment either by the Twinheads (TH) lithotripter (FMD, Lorton, Virginia, USA) or the Dornier Lithotripter S (DLS, Dornier MedTech Europe GmbH, Germering, Germany). Before and after ESWL, urinary N-acetyl-B-glucosaminidase (NAG) levels were assessed and patients were evaluated with dynamic MRI. The efficacy and complications were compared, with success defined as no residual fragments.
For stones of >10 mm the rate for the failure of disintegration was 13.3% for the DLS vs 1.4% for the TH (P = 0.009). For stones of <or=10 mm the stone-free rate was 74.4% for the TH vs 67.7% for the DLS (P = 0.6), while for stones of >10 mm it was 78.1% and 66.7%, respectively (P = 0.14). The median (range) number of sessions in both groups was 2 (1-5). After ESWL urinary NAG levels were increased significantly in both groups; in the TH group it declined below the level before ESWL after 2 days, while in the DLS group it remained high after 7 days. In the DLS group four patients developed subcapsular or parenchymal haematoma after ESWL, vs none in the TH group. There was loss of corticomedullary differentiation after ESWL in three patients in the DLS group and only one in the TH group. In the DLS group there was a statistically significantly decrease in bilateral renal perfusion after ESWL, but no changes in the TH group.
Synchronous twin-pulse ESWL has clinical advantages over standard ESWL in terms of safety and efficacy.
... This device (TwinHeads, FMD Corp.) employs two electrohydraulic shock sources, one in fixed position under the treatment table, the other movable. Although several reports have been published describing in vitro stone breakage, assessment of renal injury and initial clinical experience with this lithotripter operated in synchronous (simultaneous) mode [26][27][28][29], it has recently been disclosed by the manufacturer that dual pulses with the TwinHeads are actually separated by a lengthy delay (~23 milliseconds) [U.S. Patent 6780161]. The influence of pulse timing on stone breakage and tissue injury in dual head lithotripsy has yet to be adequately defined, and it may be that a certain delay time is advantageous-but this needs to be determined with rigorous systematic testing. ...
To assess the effect of dual-head lithotripsy on renal function and morphology in a pig model of shockwave (SW) injury, as lithotripters with two shock heads are now available for treating patients, but little information is available with which to judge the safety of treatment with dual pulses.
A dual-head electrohydraulic lithotripter (Duet, Direx Corp., Natick, MA, USA) was used to treat the lower renal pole of anaesthetized pigs with a clinical dose of SWs (2400 dual SWs; 10 kidneys) delivered in synchronous mode, i.e. both heads fired simultaneously. For comparison, pigs were treated with either 2400 SWs (12 kidneys) or 4800 SWs (eight) with a conventional electrohydraulic lithotripter (HM3, Dornier, Wessling, Germany).
Dual-pulse SW treatment with the Duet lithotripter caused a decline in the mean (sd) glomerular filtration rate (GFR) of 4.1 (1.9) mL/min, with a trend for the effective renal plasma flow (RPF), at 31 (19) mL/min, to also decrease. These changes in renal haemodynamics were similar to the decreases in GFR and RPF in response to treatment with the HM3 lithotripter with 2400 SWs, at 4.8 (0.8) and 32 (10) mL/min, respectively, or 4800 SWs, at 5.4 (1.0) and 68 (14) mL/min, respectively. Linear association analysis showed that the functional response to dual-pulse SWs was more variable than with conventional SWs. Morphological quantification of kidney damage (expressed as a percentage of functional renal volume, FRV) showed that tissue injury with 2400 paired SWs with the Duet, at 0.96 (0.39)% FRV, was similar to injury produced by either 2400 single SWs, at 1.08 (0.38)% FRV, or 4800 single SWs, at 2.71 (1.02)% FRV, with the HM3. However, morphological damage was less consistent with the Duet (measurable in only five of eight kidneys) than that with the HM3 (measurable in all 12 kidneys). Acoustic output and the timing of dual SWs in synchronous mode increased in variability as the electrodes aged, affecting the amplitude and targeting of focal pressures.
With the caveat that variability in the timing of dual SWs will unpredictably alter the distribution of SW energy within the kidney, this study shows that a clinical dose of dual-head SWs delivered in synchronous mode elicits a renal response similar to, but more variable than, that with a clinical dose of SWs from a conventional electrohydraulic lithotripter.
... On 1999 we developed the bidirectional synchronous twin-pulse technique with variable angles between the shock wave reflectors, and found that it improved the quality and rate of stone disintegration in vitro (especially with a right angle between the reflectors) [8]. The disintegrative efficacy for both artificial and human stones was improved as the number of shock waves and the power were increased [9,10]. Bidirectional synchronous 90∞ twin-pulse-induced tissue damage (acutely) appeared to be minimal when compared with a single pulse [11]. ...
... This technique intensifies and localizes the cavitation effects by the interacting focal zones of both reflectors, resulting in a better quality and rate of stone disintegration, especially with a right angle between the axes of the reflectors [8,9]. This device had good in vitro disintegrative efficacy for both artificial (Bon(n)-stones, and plaster of Paris) and human stones (COM, brushite and cystine) with better efficacy as the number of shock waves and the power were increased [10]. ...
To present the results of the first clinical study of a synchronous twin-pulse technique for extracorporeal shock-wave lithotripsy (ESWL), which is effective for in vitro stone fragmentation and safe when assessed in vivo on animal tissue.
Fifty patients with urinary stones (35 men and 15 women) were enrolled and treated with the TWINHEADS lithotripter. The entry criteria were: age > or = 18 years, with a radio-opaque single stone in the kidney or upper ureter, a normal laboratory profile (serum creatinine, liver function, blood, bleeding and clotting times, and prothrombin concentration). The exclusion criteria included lower ureteric stones, patients with urinary tract infection, obstructed urinary tract distal to the stones, or congenital abnormalities. All patients received one session and were evaluated by ultrasonography (US), urinary tract plain X-ray, and complete laboratory investigations before and immediately after treatment, and after 2, 14 and 30 days. Patients requiring re-treatment at the 14-day visit received a second session and were re-evaluated after 7 and 14 days.
The mean (sd, range) stone size (longest diameter) was 12.3 (2.6, 9-18) mm. Intravenous sedation was used in 30 patients. There was mild haematuria in 25 patients on the day of treatment. During the follow-up there was no evidence of haematoma, gross renal injury, upper urinary tract obstruction or significant changes in the laboratory investigations. After 14 days, 17 patients (34%) were free of stones, with residual stones of < or = 5 mm in 20 (40%); they were free of stones at the 1-month follow-up. Thirteen patients (26%) had residual stones of 6-9 mm, but the stones were half or less of the original size. Patients with residual stones of > 5 mm had another ESWL session and were free of stones within 14 days. Thus all patients were rendered stone-free within 1 month.
Synchronous twin-pulse ESWL is promising, seems safe and effective for treating patients with renal and upper ureteric lithiasis.
... Using established phantom systems we have demonstrated in vitro that stone comminution and safety of the upgraded system are significantly improved from the original HM-3 lithotriptor, the current gold standard in SWL. Compared to other proposed technical improvements (Twinheads lithotriptor 18 and dual-pulse lithotriptor 10 ), our technologies are much easier and less expensive to implement under clinical SWL conditions. ...
We developed innovations in shock wave lithotripsy (SWL) technology.
Two technical upgrades were implemented in an original unmodified HM-3 lithotriptor (Dornier Medical Systems, Inc., Kennesaw, Georgia). First, a single unit ellipsoidal reflector insert was used to modify the profile of lithotriptor shock wave (LSW) to decrease the propensity of tissue injury in SWL. Second, a piezoelectric annular array (PEAA) generator (f = 230 kHz and F = 150 mm) was used to produce an auxiliary shock wave of approximately 13 MPa in peak pressure (at 4 kV output voltage) to intensify the collapse of LSW induced bubbles near the target stone for improved comminution efficiency.
Consistent rupture of a vessel phantom made of single cellulose hollow fiber (i.d. = 0.2 mm) was produced after 30 shocks by the original HM-3 reflector at 20 kV. In comparison no vessel rupture could be produced after 200 shocks using the upgraded reflector at 22 kV or the PEAA generator at 4 kV. Using cylindrical BegoStone phantoms (Bego USA, Smithfield, Rhode Island) stone comminution efficiencies (mean +/- sd) after 1,500 shocks produced by the original and upgraded HM-3 reflectors, and the combined PEAA/upgraded HM-3 system, were 81.3% +/- 3.5%, 90.1% +/- 4.3% and 95.2% +/- 3.3%, respectively (p<0.05).
Optimization of the pulse profile and sequence of LSW can significantly improve stone comminution while simultaneously decreasing the propensity of tissue injury during in vitro SWL. This novel concept and associated technologies may be used to upgrade other existing lithotriptors and to design new shock wave lithotriptors for improved performance and safety.
... On 1999 we developed the bidirectional synchronous twin-pulse technique with variable angles between the shock wave reflectors, and found that it improved the quality and rate of stone disintegration in vitro (especially with a right angle between the reflectors) [8]. The disintegrative efficacy for both artificial and human stones was improved as the number of shock waves and the power were increased [9,10]. Bidirectional synchronous 90∞ twin-pulse-induced tissue damage (acutely) appeared to be minimal when compared with a single pulse [11]. ...
... This technique intensifies and localizes the cavitation effects by the interacting focal zones of both reflectors, resulting in a better quality and rate of stone disintegration, especially with a right angle between the axes of the reflectors [8,9]. This device had good in vitro disintegrative efficacy for both artificial (Bon(n)-stones, and plaster of Paris) and human stones (COM, brushite and cystine) with better efficacy as the number of shock waves and the power were increased [10]. ...
The first extracorporeal shock‐wave lithotripsy was performed on a stone‐bearing patient by Christian Chaussy on 7 February 1980, and this event thoroughly revolutionized modern stone management. The construction of second‐ and third‐generation lithotripters lead to a rapid propagation of the technique with an expansion of indications. According to international guidelines modern stone management is based on a combination of shock‐wave lithotripsy and endourologic techniques. Consequently, in the past three decades lithotripters have undergone an evolution from “dedicated” shock‐wave‐generating devices to multifunctional urologic workstations.
This chapter describes the fundamentals of shock wave lithotripsy (SWL), the instrumentation for SWL, shock wave generation, rate of delivery and focusing, coupling of the shock wave, and stone localization. The process of fragmentation through spallation, cavitation, and comminution is described. The contemporary indications and contraindications to SWL for renal and ureteral calculi, large and staghorn calculi, and calculi in calyceal diverticula are discussed. Lithotripsy advances in the form of changes to the lithotripter, modifications to treatment strategy, and adjuncts that improve SWL safety and efficacy are described. Future technological advances are explored.
