Successive Shock Waves Research Articles

SHOCK WAVE LITHOTRIPSY DURING PREGNANCY: A SUCCESSFUL CLINICAL EXPERIMENT

During the last 15 years extracorporeal shock wave lithotripsy (ESWL*) has been used in the treatment of urolithiasis with pregnancy considered a strict contraindication.' There is lack of knowledge concerning the possible effects of shock wave therapy on the development of a human embryo or fetus. We report a case of successful experimental piezoelectric shock wave lithotripsy of an obstructing ureteral stone in an advanced pregnancy. CASE REPORT A 28-year-old multigravid woman presented with severe left flank pain during week 25 of gestation. Ultrasound demonstrated dilatation of the left renal collecting system, including the proximal ureter, due to a 16 x 5 mm. ureteral calculus obstructing the upper ureter (part A of figure). Since pushing or passing the stone by ureteral stents was not successful and recurrent attacks of colic were not relieved by parenteral narcotics, percutaneous nephrostomy was recommended. However, when the patient was confronted with the risks of bleeding, infection, tube displacement and occlusion, and the prospect of urinary diversion with an external appliance for the remainder of the pregnancy, she specifically requested shock wave treatment modalities. After consideration of what is known about the physical properties and biological effects of shock wave application, we ascertained that there was sufficient distance (11 cm.) between the stone./ focus and the uterus, and extracorporeal piezoelectric shock wave lithotripsy was performed. The patient was fully informed about the experimental nature of the treatment modality and gave written, informed consent. Lithotripsy was performed with an ultrasound guided Piezolith 2300,t which provides a small focal zone of 6 mm. in radial and 10 mm. in axial diameter (part B of figure). We delivered 1,600 impulses (focal energy 750 bar) with simultaneous monitoring of the fetus by a second ultrasound scanner and intermittent cardiotocography. No drugs were administered. Alterations of cardiotocography were not seen and no unusual fetal movements were registered. The stone was disintegrated and fragments were discharged spontaneously without further colic. To avoid a steinstrasse, we inserted without difficulty a Double-JS ureteral stent for 3 weeks. X-ray diffraction analysis of the fragments revealed a mixture of two-thirds apatite and one-third struvite. Despite the latter component, no urinary tract infection occurred during gestation. The patient recovered promptly after lithotripsy, and the remainder of the pregnancy and childbirth were free of complications. The female newborn was mature, normally developed, and showed normal size and Apgar score. There have been no adverse sequelae from the intrauterine ESWL at 6-year followup.

“Mirror Pain” as an Unusual Presentation of Renal Colic

Although most patients suffering from pain related to upper urinary tract stones feel the discomfort on the same side as the stone, rarely it is perceived on the opposite side. We sought to identify the prevalence of this clinical scenario and to review possible explanations. The charts and x-rays of all patients with unilateral, symptomatic, radiologically identifiable upper urinary tract stones, seen at an outpatient clinic between June 1993 and August 1996, were reviewed retrospectively in terms of the side of the discomfort in comparison to the side of the stone. Three of 631 patients presented with contralateral or “mirror pain” secondary to a renal or ureteric calculus. In each case the symptoms resolved completely following successful extracorporeal shock wave lithotripsy or spontaneous passage of the stone.

Gallstone recurrence after shock-wave therapy

The long-term outcome of nonoperative gallstone therapy depends on both absence of stones and absence of biliary pain. The aim of the present study was to determine the rate of stone recurrence and the rate of symptoms within 5 years after successful shock wave lithotripsy combined with bile acid therapy. One hundred consecutive patients (single stones, n = 89; 2 or 3 stones, n = 11) were followed up for a median of 4.3 years after stone disappearance and discontinuation of bile acids. Twenty-three of the 100 patients developed recurrent stones. Calculated by actuarial analysis, the recurrence rate was 7% +/- 3%, 11% +/- 3%, 13% +/- 4%, 20% +/- 5%, and 31% +/- 7% (mean +/- SD) at 1, 2, 3, 4, and 5 years, respectively. The recurrent stones were small (6 +/- 5 mm) and were associated with recurrent biliary pain in 14 (61%) of the 23 patients. Repeated shock wave lithotripsy and/or bile acid medication resulted in stone disappearance in only 10 of 20 patients with recurrence. The long-term rate of stone recurrence after lithotripsy of primarily solitary gallbladder calculi is lower than expected from post-bile acid dissolution trials. Recurrence of stones frequently is associated with recurrence of biliary pain.

Pathogenic factors in early recurrence of cholesterol gallstones

Supersaturation of bile with cholesterol, rapid nucleation of cholesterol crystals, and/or incomplete emptying of the gallbladder are believed to be required for gallstone formation. The importance of these factors for the recurrence of gallbladder stones was studied. Twenty patients, untreated after successful shock wave therapy, were studied in a matched case-control design for bile acid turnover, composition of duodenal bile, and gallbladder emptying. In 10 of them, gallstones had recurred within 12 +/- 2 months (X +/- SEM); the other 10 had been free of stones since 22 +/- 3 months. In each group, duodenal bile was supersaturated with cholesterol in 8 of 10 patients and showed abnormal nucleation time of cholesterol crystals in half of the patients. Patients with recurrent stones had smaller pool sizes of cholic acid (-43%) and enhanced conversion of cholic acid to deoxycholic acid. The odds for stone recurrence were ninefold increased in the presence of excessive deoxycholic acid (exceeding cholic acid) in the bile acid pool or incomplete emptying of the gallbladder (residual volume > 5 mL) in response to cholecystokinin. The odds ratio was over 20-fold increased when incomplete emptying of the gallbladder coincided with supersaturated bile or with excessive deoxycholic acid. Enhanced conversion of cholic acid to deoxycholic acid and incomplete emptying of the gallbladder could be important cofactors for the recurrence of gallstones.

Sound waves and shock waves in high-density deuterium

The possibility of compressing the cryogenic hollow pellet of inertial confinement nuclear fusion with multiple adiabatic shock waves is discussed, on the basis of the estimation of the properties of a high-density deuterium plasma (1024−1027 cm−3, 10−1−104 eV), such as the velocity and the attenuation constant of the adiabatic sound wave, the width of the shock wave, and the surface tension.It is found that in the course of compression the wavelength of the adiabatic sound wave and the width of the weak shock wave sometimes become comparable to or exceed the fuel shell width of the pellet, and that the surface tension is negative. These results show that it is rather difficult to compress stably the hollow pellet with successive weak shock waves.

Treatment Options for Proximal Ureteral Urolithiasis: Review and Recommendations

The treatment of proximal ureteral calculi has been altered markedly by recent developments in shock wave lithotripsy (bypass, pushback and in situ), ureterorenoscopy and percutaneous stone removal. In an effort to discern the proper role of these newer treatment options with respect to ureterolithotomy (flank approach or dorsal lumbotomy), we completed a multicentered study in which 142 upper ureteral stone patients in 7 different treatment categories were reviewed retrospectively and contacted for convalescence data. From these data we conclude that before extracorporeal shock wave lithotripsy an upper ureteral stone should be manipulated until it is either pushed back to the kidney or bypassed with a stent. This maneuver should result in successful extracorporeal shock wave lithotripsy in more than 90 per cent of the patients. For those few patients with an impacted upper ureteral calculus ureterorenoscopy is recommended. Given the presently available treatment modalities we conclude that less than 3 per cent of all upper ureteral calculi will require ureterolithotomy. In this last circumstance a dorsal lumbotomy incision appears to be less morbid and yet as effective as anterior ureterolithotomy.

Flow structure on the windward side of V-wings with separation of the turbulent boundary layer

The qualitative characteristics of shock-layer flow associated with separation of the turbulent boundary layer under the influence of one or several successive shock waves are explored with reference to a number of examples typical of conical flows.

Extracorporeal Shock Wave Lithotripsy and its Effect on Renal Function

Extracorporeal shock wave lithotripsy has become a major treatment modality for symptomatic upper tract renal stone disease. Although proved to be effective in disintegrating stones the short-term and long-term effects on renal function are not yet known.We evaluated several basic physiological parameters, namely creatinine clearance, fractional sodium excretion, protein excretion and urine osmolality before and after extracorporeal shock wave lithotripsy in 26 consecutive patients in an attempt to quantitate changes in renal function. In addition, a 3 to 6-month followup study of patients showing excessive protein excretion with extracorporeal shock wave lithotripsy also is reported.Our data suggest that with extracorporeal shock wave lithotripsy transient nephrotic range proteinuria occurs immediately after treatment, returning to normal values within 3 to 6 months after treatment without a change in the glomerular filtration rate. The glomerular filtration rate increases after successful extracorporeal shock wave lithotripsy in patients with kidneys obstructed by the treated stone before the start of the procedure, and the kidney appears to maintain its ability to dilute urine and to conserve sodium after treatment.

ESWL: Past, Present, and Future

ESWL: Past, Present, and Future

Successful Extracorporeal Shock Wave Lithotripsy of Stones in Ectopic Pelvic Kidneys

We present two cases of calculi in ectopic pelvic kidneys that were removed by extracorporeal shock wave lithotripsy (ESWL). Gantry alterations of the HM3 Model Dornier Lithotripter and repositioning of the patient are necessary to allow adequate placement and imaging of the stone. These changes broaden the clinical usefulness of ESWL to include patients with anomalous kidneys or unusual body habitus.

The Role of the Church in the Modern World

The publication of the Pastoral Constitution on the Church in the Modern World or Gaudium et Spes (1965) by the Second Vatican Council marked the definitive opening of the Catholic Church to the challenge of the modern world. It represented a decisive reformulation of the Church's relationship to the social and historical context in which it now fulfills its mission. While almost a century of Catholic reflection on social issues had prepared the way, nothing previously had matched the depth and comprehensiveness of the Council's examination of the meaning of modern civilization as a whole. Having weathered the successive shock waves of the modernist critique, from Protestantism, to scientism, to historicism, to materialism, the Church seemed to have attained a new-found confidence to confront and contemplate the true nature of the adversary that now simultaneously opposed it and stood in need of its ministry. The eternal light of Christ's love was turned toward the condition of modern man, and the result was an illumination of the spiritual core of the contemporary civilizational crisis that henceforth was intended to define the mission of the Church in the modern world.

Multiple transonic shock-wave/turbulent boundary-layer interaction in a circular duct

An experimental study is described in which detailed pitot, static, and wall pressure measurements have been obtained for multiple transonic shock-wave/turbulent boundary-layer interactions in a circular duct at a freestream Mach number of 1.49, a unit Reynolds number of 4.90xl0/m, and a blockage of 5.15%. The details of the flowfield show the formation of a series of normal shock waves with successively decreasing strength and decreasing distance between the successive shock waves up to the point where a terminal shock occurs. A one-dimensional flow model based on the boundary-layer displacement thickness is postulated to explain the formation of the series of normal shock waves. A comparison with the results from our previous study involving a single shock interaction suggests that the effect of increased blockage is to promote multiple shock interactions and produce a lower pressure recovery, a less retarded boundary-layer flow, and an increase in the overall length of the interaction.

Tensile stresses in copper and aluminum under dynamic tension

The behavior of copper and aluminum slabs under tension, resulting from the detonation of a slab of explosive in contact with them, was studied. A new technique, based on microwave interferometry, was employed for continuous observation of the free-surface velocity. Retrieved metal discs were scanned for microfractures. Tensile stresses, especially in regions where no observable damage occurred, were studied. They were found to be significantly lower than the negative pressures calculated by the common codes, already at early times of tension. This discrepancy increases in a gradual fashion with increased duration of tension. Observable damage appears only after a considerable reduction in the tensile stresses has already taken place. Elastic behavior of copper was studied by observing successive shock wave reverberations in the metal.

Compression and rarefaction waves in shock-compressed metals

The behavior of duralumin and copper is studied under conditions of specimen loading by two successive shock waves and during unloading after the shock compression. The amplitude of the first shock wave was 150–250 kbar. Direct measurements were performed of the difference in main stresses behind the shock front in duralumin. The results obtained do not agree with existing concepts of the behavior of solids under dynamic loading. Possible causes of this divergence are considered.

On the acceleration of cosmic rays

The intensive acceleration of energetic charged particles in perpendicular shock waves which has been known to take place in the interplanetary medium has been utilized in this work in order to account for the energization of cosmic rays. It is proposed that cosmic rays can be accelerated up to 1014–1015 eV in successive perpendicular shock waves which appear inside supernova shells in our Galaxy.

Compression of matter to superhigh densities by an accelerating heat wave

A one-dimensional analytical model is presented for the compression of matter (e.g., thermonuclear fusion fuel to densities of more than 103 times the solid density) by an accelerating subsonic heat wave. The heat wave, driven possibly by the absorption of a temporally tailored laser pulse, launches a large number of successive weak shock waves which compress and heat the target quasiadiabatically in order to keep the energy expenditure at a minimum. The net power to drive this heat wave must have a stepwise increase in time approximated by W = 98ρ0c03K2/τ2, where K = Dfρf/D0ρ0 is the fraction of the initial target mass (of density ρ0 and thickness Df) which reaches the final state (of ρf and Df. The adiabaticondition sets the requirement that K should be much smaller than one. The time t is scaled as τ = 1 − t/t8, where t8 = D0/c0 and c0 is the initial sound speed. The sound speed in the compressed matter, from which pressure and density can be obtained using the adiabatic equations of state, will increase approximately as c0(K/τ)1/4. Half of the total driving energy is expended by the time tf[τf = (Df/D0) (ρ0/ρf)1/3], from which time the power has to be held constant at Wf = 98(ρf/ρ0)8/3ρ0c03 until time t8.

Shock loading on a submerged structure

The problem of propagation of a two-dimensional shock wave in water over a submerged rigid structure (semicylinder) due to a nearby underwater explosion has been solved numerically using a method of characteristics based upon a curvilinear co-ordinate system fixed in successive shock wave positions. Maximum surface pressures occur at the transition from regular to irregular reflection, and nonlinear theory appears essential there, even for shocks of Mach number close to unity. Results are given for a range of explosive strengths, distances from the structure, and structural dimensions.

Prediction of the Spectral Content of Combination Tone Noise

Combination tone noise is generated by a pattern of rotating shock waves in the inlet of turbofan engines when the relative tip speed of the fan blades is supersonic. A method is presented for determining the expected distribution of sound power among the harmonics of engine rotation frequency, based on the spectral analysis of an almost periodic succession of pulses. The spectral distribution of combination tone noise is found to depend on two statistical — crfl, the standard deviations of the sequence of shock wave amplitudes; and cr£, the standard deviation of the sequence of time intervals between successive shock waves. The spectral distribution of sound power is found to depend more critically on <jc than on aa. A method of estimating the expected cr£ for an important type of blade geometry is developed. It is found that blades with straight entrance regions produce higher cre and hence more sound power in the subharmonics of blade passage frequency at the expense of the sound power in the fundamental of blade passage frequency than do blades with curved entrance regions. Typical results of the analytical model and comparisons with experimental data are presented.

Regularization in optimal trajectory problems.

Fig. 3b Oscilloscope trace from the pressure gage in the surface of the 9° cone model. 20^5 Mach reflection theory. There is a kink in the reflected shock wave, downstream from the Mach stem. The kink suggests some further shock reflections in the flow behind the Mach stem. The pressure gage trace corresponding to the 41° indicident angle adds evidence that something more than classical Mach reflection is occurring. The trace, Fig. 2b, shows a step in the gage's initial response as if the gage had been struck by two successive shock waves, one close behind the other. The pressure rise associated with the first step is exactly what we would expect to get from the Mach stem alone. The additional pressure rise from the step to the peak brings the pressure up to a level very close to that attained by regular reflection at 39°. So the large drop in pressure from regular to Mach reflection predicted by simple theory does not really exist. The additional compression that we expected to follow the Mach stem does take place, and it appears as though the mechanism for this additional compression is a second reflected shock wave. Further proof of the existence of a second shock wave behind the Mach stem was found by looking at incident angles much larger than the limiting angle. Figure 3a shows a case where the incident angle is 54°. The second reflected shock wave is now clearly visible. The pressure gage trace, Fig. 3b, shows a well-defined step. The time between the two shock waves, as measured from the pressure gage trace, corresponds exactly to the separation distance between the Mach stem and the second shock wave. Again, the second shock wave compressed the gas behind the Mach stem to a level well above that predicted by simple Mach reflection theory. Conclusions

Transitions through two successive oblique hydromagnetic shocks

Landau andLifshitz (1959) mentioned the following result:If two (or more) successive shock waves take a gas from state 1to state 2and from there to state 3,the transition of flow from state 1to state 3cannot, in general, be effected by the passage of only one shock wave. The object of this paper is to obtain thenecessary andsufficient condition under which the transition of flow from state 1 to state 3 in steady flows of conducting gases can be effected by the passage of a single magneto-gasdynamic shock. Furthermore, the condition is obtained under which the stream-line, which passes through two successive oblique hydromagnetic shocks at a pointP, will remain unaffected if the transition of flow from state 1 to state 3 is effected by the passage of a single oblique hydromagnetic shock.