Lithotriptor
Encyclopedia
Extracorporeal shock wave lithotripsy (ESWL) is a non-invasive treatment of kidney stone
s (urinary calculosis) and biliary calculi (stones in the gallbladder
or in the liver
) using an acoustic pulse.
It is estimated that more than one million patients are treated annually with ESWL in the USA alone.
Medizintechnik GmbH (now known as Dornier MedTech Systems GmbH)http://www.dornier.com/americas/english_gb/aboutUs.htm, and came into widespread use with the introduction of the HM-3 lithotriptor
in 1983. Within a few years, ESWL became a standard treatment of calculosis.
or anesthetized
patient lies down in the apparatus' bed, with the back supported by a water-filled coupling device placed at the level of kidneys. A fluoroscopic
x-ray
imaging system or an ultrasound imaging system is used to locate the stone and aim the treatment. The first generation lithotriptor known as the HM3, has a half ellipsoid-shaped piece that opens toward the patient. The acoustic pulse is generated at the ellipsoidal focal point
that is furthest from the patient and the stone positioned at the opposite focal point receives the focused shock wave
. The treatment usually starts at the equipment's lowest power level, with a long gap between pulses, in order to accustom the patient to the sensation. The length of gap between pulses is also controlled to allow cavitation bubbles to disperse minimizing tissue damage. Second and later generation machines use an acoustic lens to focus the shock wave. This functions much like an optical lens, focusing the shock wave at the desired loci. The frequency of pulses are currently left at a slow rate for more effective comminution of the stone and to minimize morbidity while the power levels are then gradually increased, so as to break up the stone. The final power level usually depends on the patient's pain threshold and the obsevered success of stone breakage. If the stone is positioned near a bone
(usually a rib
in the case of kidney stones), this treatment may be more uncomfortable because the shock waves can cause a mild resonance
in the bone which can be felt by the patient. The sensation of the treatment is likened to an elastic band twanging off the skin
. Alternately the patient may be sedated during the procedure. This allows the power levels to be brought up more quickly and a much higher pulse frequency, often up to 120 shocks per minute.
The successive shock wave pressure pulses result in direct shearing
forces, as well as cavitation
bubbles surrounding the stone, which fragment the stones into smaller pieces that then can easily pass through the ureter
s or the cystic duct
. The process takes about an hour. A ureteral stent
(a kind of expandable hollow tube) may be used at the discretion of the urologist. The stent allows for easier passage of the stone by relieving obstruction and through passive dilatation of the ureter
.
Extracorporeal
lithotripsy works best with stones between 4 mm and 2 cm in diameter that are still located in the kidney. It can be used to break up stones which are located in a ureter too, but with less success.
The patients undergoing this procedure can, in some cases, see for themselves the progress of their treatment. If allowed to view the ultrasound
or x-ray
monitor, they may be able to see their stones change from a distinct bright point (or dark spot depending on whether the fluoro unit is set up in native or bones white) to a fuzzy cloud as the stone is disintegrated into a fine powder.
ESWL is the least invasive of the commonplace modalities for definitive stone treatment, but provides a lower stone-free rate than other more invasive treatment methods, such as ureteroscopic
manipulation with laser lithotripsy
or percutaneous nephrolithotomy
(PCNL
). The passage of stone fragments may take a few days or a week and may cause mild pain. Patients may be instructed to drink as much water as practical during this time. Patients are also advised to void through a stone screen in order to capture stone fragments for analysis.
ESWL is not without risks. The shock waves themselves, as well as cavitation bubbles formed by the agitation of the urine medium, can lead to capillary damage, renal parenchymal or subcapsular hemorrhage. This can lead to long-term consequences such as renal failure
and hypertension
. Overall complication rates of ESWL range from 5–20%.
Kidney stone
A kidney stone, also known as a renal calculus is a solid concretion or crystal aggregation formed in the kidneys from dietary minerals in the urine...
s (urinary calculosis) and biliary calculi (stones in the gallbladder
Gallbladder
In vertebrates the gallbladder is a small organ that aids mainly in fat digestion and concentrates bile produced by the liver. In humans the loss of the gallbladder is usually easily tolerated....
or in the liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
) using an acoustic pulse.
It is estimated that more than one million patients are treated annually with ESWL in the USA alone.
History
Lithotripsy and the lithotriptor were developed in the early 1980s in Germany by DornierDornier
Dornier may refer to:* Claudius Dornier , German aircraft designer and builder** Dornier Flugzeugwerke, German aircraft manufacturer founded in 1914 by Claudius Dornier* Dornier Consulting, international consulting and project management company...
Medizintechnik GmbH (now known as Dornier MedTech Systems GmbH)http://www.dornier.com/americas/english_gb/aboutUs.htm, and came into widespread use with the introduction of the HM-3 lithotriptor
Lithotriptor
Extracorporeal shock wave lithotripsy is a non-invasive treatment of kidney stones and biliary calculi using an acoustic pulse....
in 1983. Within a few years, ESWL became a standard treatment of calculosis.
How it works
The lithotriptor attempts to break up the stone with minimal collateral damage by using an externally-applied, focused, high-intensity acoustic pulse. The sedatedSedation
Sedation is the reduction of irritability or agitation by administration of sedative drugs, generally to facilitate a medical procedure or diagnostic procedure...
or anesthetized
Anesthesia
Anesthesia, or anaesthesia , traditionally meant the condition of having sensation blocked or temporarily taken away...
patient lies down in the apparatus' bed, with the back supported by a water-filled coupling device placed at the level of kidneys. A fluoroscopic
Fluoroscopy
Fluoroscopy is an imaging technique commonly used by physicians to obtain real-time moving images of the internal structures of a patient through the use of a fluoroscope. In its simplest form, a fluoroscope consists of an X-ray source and fluorescent screen between which a patient is placed...
x-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
imaging system or an ultrasound imaging system is used to locate the stone and aim the treatment. The first generation lithotriptor known as the HM3, has a half ellipsoid-shaped piece that opens toward the patient. The acoustic pulse is generated at the ellipsoidal focal point
Focus (geometry)
In geometry, the foci are a pair of special points with reference to which any of a variety of curves is constructed. For example, foci can be used in defining conic sections, the four types of which are the circle, ellipse, parabola, and hyperbola...
that is furthest from the patient and the stone positioned at the opposite focal point receives the focused shock wave
Shock wave
A shock wave is a type of propagating disturbance. Like an ordinary wave, it carries energy and can propagate through a medium or in some cases in the absence of a material medium, through a field such as the electromagnetic field...
. The treatment usually starts at the equipment's lowest power level, with a long gap between pulses, in order to accustom the patient to the sensation. The length of gap between pulses is also controlled to allow cavitation bubbles to disperse minimizing tissue damage. Second and later generation machines use an acoustic lens to focus the shock wave. This functions much like an optical lens, focusing the shock wave at the desired loci. The frequency of pulses are currently left at a slow rate for more effective comminution of the stone and to minimize morbidity while the power levels are then gradually increased, so as to break up the stone. The final power level usually depends on the patient's pain threshold and the obsevered success of stone breakage. If the stone is positioned near a bone
Bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...
(usually a rib
Rib
In vertebrate anatomy, ribs are the long curved bones which form the rib cage. In most vertebrates, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the chest cavity. They serve to protect the lungs, heart, and other internal organs of the thorax...
in the case of kidney stones), this treatment may be more uncomfortable because the shock waves can cause a mild resonance
Resonance
In physics, resonance is the tendency of a system to oscillate at a greater amplitude at some frequencies than at others. These are known as the system's resonant frequencies...
in the bone which can be felt by the patient. The sensation of the treatment is likened to an elastic band twanging off the skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...
. Alternately the patient may be sedated during the procedure. This allows the power levels to be brought up more quickly and a much higher pulse frequency, often up to 120 shocks per minute.
The successive shock wave pressure pulses result in direct shearing
Shearing (physics)
Shearing in continuum mechanics refers to the occurrence of a shear strain, which is a deformation of a material substance in which parallel internal surfaces slide past one another. It is induced by a shear stress in the material...
forces, as well as cavitation
Cavitation
Cavitation is the formation and then immediate implosion of cavities in a liquidi.e. small liquid-free zones that are the consequence of forces acting upon the liquid...
bubbles surrounding the stone, which fragment the stones into smaller pieces that then can easily pass through the ureter
Ureter
In human anatomy, the ureters are muscular tubes that propel urine from the kidneys to the urinary bladder. In the adult, the ureters are usually long and ~3-4 mm in diameter....
s or the cystic duct
Cystic duct
The cystic duct is the short duct that joins the gall bladder to the common bile duct. It usually lies next to the cystic artery. It is of variable length...
. The process takes about an hour. A ureteral stent
Stent
In the technical vocabulary of medicine, a stent is an artificial 'tube' inserted into a natural passage/conduit in the body to prevent, or counteract, a disease-induced, localized flow constriction. The term may also refer to a tube used to temporarily hold such a natural conduit open to allow...
(a kind of expandable hollow tube) may be used at the discretion of the urologist. The stent allows for easier passage of the stone by relieving obstruction and through passive dilatation of the ureter
Ureter
In human anatomy, the ureters are muscular tubes that propel urine from the kidneys to the urinary bladder. In the adult, the ureters are usually long and ~3-4 mm in diameter....
.
Extracorporeal
Extracorporeal
An extracorporeal medical procedure is a medical procedure which is performed outside the body.-Circulatory procedures:A procedure in which blood is taken from a patient's circulation to have a process applied to it before it is returned to the circulation...
lithotripsy works best with stones between 4 mm and 2 cm in diameter that are still located in the kidney. It can be used to break up stones which are located in a ureter too, but with less success.
The patients undergoing this procedure can, in some cases, see for themselves the progress of their treatment. If allowed to view the ultrasound
Ultrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
or x-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
monitor, they may be able to see their stones change from a distinct bright point (or dark spot depending on whether the fluoro unit is set up in native or bones white) to a fuzzy cloud as the stone is disintegrated into a fine powder.
ESWL is the least invasive of the commonplace modalities for definitive stone treatment, but provides a lower stone-free rate than other more invasive treatment methods, such as ureteroscopic
Ureteroscopy
Ureteroscopy is an examination of the upper urinary tract, usually performed with an endoscope that is passed through the urethra, bladder, and then directly into the ureter...
manipulation with laser lithotripsy
Laser lithotripsy
Laser lithotripsy is a surgical procedure to remove stones from urinary tract, i.e., kidney, ureter, bladder, or urethra.-History:Laser lithotripsy was invented at Wellman Center for Photomedicine in the 1980s to remove impacted stones from the urinary tract. Laser pulses delivered through a fiber...
or percutaneous nephrolithotomy
Percutaneous nephrolithotomy
Percutaneous nephrolithotomy is a surgical procedure to remove stones from the kidney by a small puncture wound through the skin. It is most suitable to remove stones of more than 2 cm in size. It is usually done under general anesthesia or spinal anesthesia.- Procedure :A Retrograde pyelogram is...
(PCNL
Percutaneous nephrolithotomy
Percutaneous nephrolithotomy is a surgical procedure to remove stones from the kidney by a small puncture wound through the skin. It is most suitable to remove stones of more than 2 cm in size. It is usually done under general anesthesia or spinal anesthesia.- Procedure :A Retrograde pyelogram is...
). The passage of stone fragments may take a few days or a week and may cause mild pain. Patients may be instructed to drink as much water as practical during this time. Patients are also advised to void through a stone screen in order to capture stone fragments for analysis.
ESWL is not without risks. The shock waves themselves, as well as cavitation bubbles formed by the agitation of the urine medium, can lead to capillary damage, renal parenchymal or subcapsular hemorrhage. This can lead to long-term consequences such as renal failure
Renal failure
Renal failure or kidney failure describes a medical condition in which the kidneys fail to adequately filter toxins and waste products from the blood...
and hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
. Overall complication rates of ESWL range from 5–20%.
Further reading
- Abe T, Akakura K, Kawaguchi M, Ueda T, Ichikawa T, Ito H, et al. Outcomes of shockwave lithotripsy for upper urinary-tract stones: a large-scale study at a single institution. J Endourol. Sep 2005;19(7):768-73.
- Albala DM, Assimos DG, Clayman RV, Denstedt JD, Grasso M, Gutierrez-Aceves J, Kahn RI, Leveillee RJ, Lingeman JE, Macaluso JN, Munch LC, Nakada SY, Newman RC, Pearle MS, Preminger GM, Teichman J, and Woods JR: Lower pole I: a prospective randomized trial of extracorporeal shock wave lithotripsy and percutaneous nephrostolithotomy for lower pole nephrolithiasis-initial results. The Journal of Urology 166(6):2072-80 2001 Dec
- Anagnostou T, Tolley D. Management of ureteric stones. Eur Urol. Jun 2004;45(6):714-21.
- Auge BK, Preminger GM. Update on shock wave lithotripsy technology. Curr Opin Urol. Jul 2002;12(4):287-90.
- Chacko J, Moore M, Sankey N, Chandhoke PS. Does a slower treatment rate impact the efficacy of extracorporeal shock wave lithotripsy for solitary kidney or ureteral stones?. J Urol. Apr 2006;175(4):1370-3; discussion 1373-4.
- Chaussy CG, Fuchs GJ. Current state and future developments of noninvasive treatment of human urinary stones with extracorporeal shock wave lithotripsy. J Urol. Mar 1989;141(3 Pt 2):782-9.
- Collins JW, Keeley FX. Is there a role for prophylactic shock wave lithotripsy for asymptomatic calyceal stones? Curr Opin Urol. Jul 2002;12(4):281-6.
- Delius M. This month in Investigative Urology: effect of extracorporeal shock waves on the kidney. J Urol. Aug 1988;140(2):390.
- Joshi HB, Obadeyi OO, Rao PN. A comparative analysis of nephrostomy, JJ stent and urgent in situ extracorporeal shock wave lithotripsy for obstructing ureteric stones. BJU Int. Aug 1999;84(3):264-9.
- Kim FJ, Rice KR. Prediction of shockwave failure in patients with urinary tract stones. Curr Opin Urol. Mar 2006;16(2):88-92.
- Krambeck AE, Gettman MT, Rohlinger AL, Lohse CM, Patterson DE, Segura JW. Diabetes mellitus and hypertension associated with shock wave lithotripsy of renal and proximal ureteral stones at 19 years of followup. J Urol. May 2006;175(5):1742-7.
- Lee C, Ugarte R, Best S, Monga M. Impact of renal function on efficacy of extracorporeal shockwave lithotripsy. J Endourol. May 2007;21(5):490-3.
- Lee YH, Tsai JY, Jiaan BP, Wu T, Yu CC. Prospective randomized trial comparing shock wave lithotripsy and ureteroscopic lithotripsy for management of large upper third ureteral stones. Urology. Mar 2006;67(3):480-4; discussion 484.
- Lindqvist K, Holmberg G, Peeker R, Grenabo L. Extracorporeal shock-wave lithotripsy or ureteroscopy as primary treatment for ureteric stones: a retrospective study comparing two different treatment strategies. Scand J Urol Nephrol. 2006;40(2):113-8.
- Lingeman JE, Zafar FS. Lithotripsy systems. In: Smith AD, Badlani GH, Bagley DH, et al. Smith's Textbook of Endourology. St Louis, Mo: Quality Medical Publishing; 1996:553-89.
- Lingeman JE, Kim SC, Kuo RL, McAteer JA, Evan AP. Shockwave lithotripsy: anecdotes and insights. J Endourol. Nov 2003;17(9):687-93.
- Liou LS, Streem SB. Long-term renal functional effects of shock wave lithotripsy, percutaneous nephrolithotomy and combination therapy: a comparative study of patients with solitary kidney. J Urol. Jul 2001;166(1):36; discussion 36-7.
- Macaluso JN and Thomas R: Extracorporeal shock wave lithotripsy: an outpatient procedure. The Journal of urology 146(3):714-7 1991 Sep
- Macaluso JN: Management of stone disease—bearing the burden. The Journal of urology 156(5):1579-80 1996 Nov
- Macaluso JN: Shock Wave Lithotripsy for Stones in the Ureter. Business Briefing: North America Pharmacotherapy; 85-88, April 2004
- Macaluso JN: Editorial Comment: re Incorporation of patient preferences in the treatment of upper urinary tract calculi: a decision analytical view. Journal of Urology, Vol 162, 1913–1919, December 1999
- Madaan S, Joyce AD. Limitations of extracorporeal shock wave lithotripsy. Curr Opin Urol. Mar 2007;17(2):109-13.
- Martin TV, Sosa RE. Shock-wave lithotripsy. In: Walsh PC, Retik AB, Vaughan ED, Wein AJ. Campbell's Urology. Vol 3. 7th ed. Philadelphia, Pa: WB Saunders; 1998:2735-52.
- Micali S, Grande M, Sighinolfi MC, De Stefani S, Bianchi G. Efficacy of expulsive therapy using nifedipine or tamsulosin, both associated with ketoprofene, after shock wave lithotripsy of ureteral stones. Urol Res. Jun 2007;35(3):133-7.
- Moody JA, Evans AP, Lingeman JE. Extracorporeal shockwave lithotripsy. In: Weiss RM, George NJR, O'Reilly PH, eds. Comprehensive Urology. Mosby International Limited; 2001:623-36.
- Pareek G, Armenakas NA, Fracchia JA. Hounsfield units on computerized tomography predict stone-free rates after extracorporeal shock wave lithotripsy. J Urol. May 2003;169(5):1679-81.
- Pearle MS, Lingeman JE, Leveillee R, Kuo R, Preminger GM, Nadler RB, Macaluso JN, Monga M, Kumar U, Dushinski J, Albala DM, Wolf JS, Assimos D, Fabrizio M, Munch LC, Nakada SY, Auge B, Honey J, Ogan K, Pattaras J, McDougall EM, Averch TD, Turk T, Pietrow P, and Watkins S: Prospective, randomized trial comparing shock wave lithotripsy and ureteroscopy for lower pole caliceal calculi 1 cm or less. The Journal of urology 173(6):2005-9 2005 Jun
- Putman SS, Hamilton BD, Johnson DB. The use of shock wave lithotripsy for renal calculi. Curr Opin Urol. Mar 2004;14(2):117-21.
- Sayed MA, el-Taher AM, Aboul-Ella HA, Shaker SE. Steinstrasse after extracorporeal shockwave lithotripsy: aetiology, prevention and management. BJU Int. Nov 2001;88(7):675-8.
- Segura JW, Preminger GM, Assimos DG, Dretler SP, Kahn RI, Lingeman JE, Macaluso JN, et al. Nephrolithiasis Clinical Guidelines Panel summary report on the management of staghorn calculi. The American Urological Association Nephrolithiasis Clinical Guidelines Panel. J Urol. Jun 1994;151(6):1648-51.
- Segura JW, Preminger GM, Assimos DG, Dretler SP, Kahn RI, Lingeman JE, and Macaluso JN: Ureteral Stones Clinical Guidelines Panel summary report on the management of ureteral calculi. The American Urological AssociationAmerican Urological AssociationThe American Urological Association is a professional association in the United States for urology professionals.-Awards:*Hugh Hampton Young Award. Presented annually to an individual for outstanding contributions to the study of genitourinary tract disease. This award is sponsored by Karl Storz...
. The Journal of urology 158(5):1915-21 1997 Nov
- Sheir KZ, Madbouly K, Elsobky E, Abdelkhalek M. Extracorporeal shock wave lithotripsy in anomalous kidneys: 11-year experience with two second-generation lithotripters. Urology. Jul 2003;62(1):10-5; discussion 15-6.
- Sheir KZ, El-Diasty TA, Ismail AM. Evaluation of a synchronous twin-pulse technique for shock wave lithotripsy: the first prospective clinical study. BJU Int. Feb 2005;95(3):389-93.
- Skolarikos A, Alivizatos G, de la Rosette J. Extracorporeal shock wave lithotripsy 25 years later: complications and their prevention. Eur Urol. Nov 2006;50(5):981-90; discussion 990.
- Tan EC, Tung KH, Foo KT. Comparative studies of extracorporeal shock wave lithotripsy by Dornier HM3, EDAP LT 01 and Sonolith 2000 devices. J Urol. Aug 1991;146(2):294-7.
- Thomas R, Macaluso JN, Vandenberg T, Salvatore F: An innovative approach to management of lower third ureteral calculi. Journal of Urology, Volume 149, #6, 1427–1430, June 1993.
- Unal B, Kara S, Bilgili Y, Basar H, Yilmaz E, Batislam E. Giant abdominal wall abscess dissecting into thorax as a complication of ESWL. Urology. Feb 2005;65(2):389.
- Weiland D, Lee C, Ugarte R, Monga M. Impact of shockwave coupling on efficacy of extracorporeal shockwave lithotripsy. J Endourol. Feb 2007;21(2):137-40.
- Winters JC, Macaluso JN: Ungated Medstone Outpatient Lithotripsy. Journal of Urology, Volume 153, #3 part 1, 593-595, March 1995
External links
- Patient Guide To Kidney Stone Diagnosis, Treatment and Prevention. By Dr. R. Ari Rabenou, a kidney stone specialist at the New York University School of Medicine.
- International Kidney Stone Institute
- Electromagnetic Technology
- How ESWL works
- Shock wave therapy for kidney stones linked to increased risk of diabetes, hypertension