A S Cass

Hennepin County Medical Center, Minneapolis, Minnesota, United States

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Publications (110)304.37 Total impact

  • Alexander S. Cass
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    ABSTRACT: A controversy has arisen as to whether the initial form of therapy for lower pole nephrolithiasis should be extracorporeal shockwave lithotripsy (SWL) or percutaneous nephrolithotomy (PCNL). We reviewed our results with 968 single lower pole stones treated by SWL and reviewed publications comparing SWL and PCNL for lower pole nephrolithiasis. In our cases, the stone-free rate was 71.2%, the rate of repeat treatment and post-treatment secondary procedures was 6.4%, the complication rate was 0.5%, and the hospital stay was less than 24 hours in 99.3% of patients. In published series of PCNL for lower pole nephrolithiasis, the stone free rate was 70.5% to 100%, repeat treatment rates were 4% to 62.5%, the complication rates were 13% to 38%, and the hospital stay was 3.1 to 6.1 days. The rates of recurrent stone disease with PCNL were 11% to 22%, similar to the rates after SWL. The percentage of renal urolithiasis patients with lower pole calculi since we started our unit in late 1986 has remained essentially constant at 38%. Although the stone-free rate with PCNL is higher than with SWL, the lower complication rate, lower repeat treatment/secondary procedure rate, the shorter hospital stay, and the similar recurrent stone rate with SWL make SWL more clinically effective as the primary therapy for lower pole calculi less than 2 cm in diameter.
    No preview · Article · Mar 1996 · Journal of Endourology
  • Alexander S. Cass
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    ABSTRACT: Some reports have shown a decreased effectiveness of extracorporeal shock wave lithotripsy (ESWL*) with newer lithotriptors. We used a first generation unmodified Dornier HM3 lithotriptor to treat 5,698 patients with renal and ureteral calculi and a second generation Medstone STS device to treat 8,166 patients with renal and ureteral calculi. The treatment results were compared using the chi-square test to determine statistical significance. The stone-free rate, retreatment rate and post-ESWL secondary procedure rate were 69.5%, 4.4% and 3.1%, respectively, with the Dornier HM3 device and 72.1%, 4.9% and 2.3%, respectively, with the Medstone lithotriptor for single renal stones, and 81.5%, 5.2% and 5.5%, respectively, with the Dornier HM3 and 83.2%, 5.2% and 5.0%, respectively, with the Medstone device for single ureteral stones. There were no statistically significant different results between a second generation tubless Medstone STS lithotriptor and the gold standard unmodified Dornier HM3 instrument.
    No preview · Article · Apr 1995 · The Journal of Urology
  • Alexander S. Cass
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    ABSTRACT: We studied renal function an average of 44 months after simultaneous bilateral renal SWL in 56 patients. No cases of clinically apparent acute renal failure occurred in the early postoperative period. The glomerular filtration rate (GFR) was calculated using an empiric formula having a significant correlation with measured creatinine clearance, and a change of 20% or greater was considered a clinically significant deterioration in renal function. Of the seven patients with a preoperative serum creatinine concentration of > 1.5 mg/dL, six had an average increase of 35% in postoperative GFR attributable to relief of obstruction, while one had a 30% reduction in GFR. Among 49 patients with a preoperative serum creatinine concentration of 1.5 mg/dL or less, there was an increase in postoperative GFR in 22 patients (45%), no change in 3 (6%), and a decrease in 24 (49%), who had a higher number of multiple renal stones (p < 0.05) and of repeat SWL (p = 0.08). Nine of them (18%) had a clinically significant decrease in GFR of > 20%. A review of the literature showed a long-term reduction of function in the individual human kidney after SWL in some cases of a solitary kidney and in some cases with an untreated contralateral kidney. Because there is no evidence that an untreated contralateral kidney aids the long-term recovery of the function of a treated kidney in all cases, simultaneous or separate bilateral renal SWL would not influence this long-term reduction in renal function, which was felt to occur with multiple renal stones and repeat SWL.
    No preview · Article · Jan 1995 · Journal of Endourology
  • Alexander S. Cass · John E. Heller
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    ABSTRACT: When pull on a stone basket enclosing a distal ureteral stone met marked resistance and endoscopic lithotripsy failed, extracorporeal shock wave lithotripsy was used to fragment the entrapped stone in the ureter and allowed successful removal of the basket with the enclosed fragments.
    No preview · Article · May 1994 · Urology
  • Alexander S. Cass
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    ABSTRACT: To determine if a ureteral stent or catheter was necessary to achieve satisfactory results with extracorporeal shock-wave lithotripsy (ESWL) for a stone in the ureter. A retrospective review of 1,712 single ureteral stones treated in the ureter by ESWL using Dornier HM3 and Medstone STS lithotriptors was performed, 1,425 with a stent and 287 without a stent (in situ). Statistical analysis was performed using the chi-square test to determine the p value. The stone site, size, and treatment parameters (average shocks, kV, and estimated radiation to the patient) were similar in both groups. The retreatment rate, post-ESWL secondary procedure rate, and stone-free rate were 5 percent, 5 percent, and 79 percent, respectively, with a stent and 6 percent, 9 percent, and 79 percent, respectively, without a stent. The results of ESWL for single ureteral stones were similar with or without a stent, making the presence of a ureteral stent unnecessary.
    No preview · Article · Mar 1994 · Urology
  • Alexander S. Cass
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    ABSTRACT: Studying renal function in patients with a solitary kidney undergoing SWL eliminates the compensatory effects of an untreated contralateral kidney and thus indicates any loss of function in the treated kidney. In 17 patients with a preoperative serum creatinine clearance of 1.5 mg/dl or less who underwent SWL to a solitary kidney, the glomerular filtration rate (GFR) was calculated by the formula of Cockcroft and Gault, which correlates significantly with measured creatinine clearance. A change of > or = 20% in the GFR was considered a clinically significant deterioration of renal function. In 12 patients with < 24 months' follow-up (mean 7.3 months) after SWL, there was no change in the estimated GFR, whereas 5 patients with > 24 months' follow-up (mean 36 months) had an average 22% reduction in the estimated GFR. This long-term effect is similar to the 29% long-term reduction in renal function recorded after percutaneous nephrolithotomy in solitary kidneys. Multiple stones, higher numbers of shock waves, and repeated SWL sessions correlated with decreases in GFR, but none of the differences was statistically significant. Like percutaneous nephrolithotomy, SWL results in a clinically significant long-term reduction in renal function.
    No preview · Article · Feb 1994 · Journal of Endourology
  • Alexander S. Cass
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    ABSTRACT: To compare the results of using Dornier HM3 and Medstone STS lithotriptors to treat a ureteral stone overlying the pelvic bone (mid third of ureter) requiring the patient to be in the prone position. The ease of use with each lithotriptor was evaluated and a retrospective review of the results using a Dornier HM3 in 53 patients and a Medstone STS in 143 patients was performed. The chi-square test was used to determine statistical difference. With single stones, the re-treatment rate, the post-ESWL secondary procedure rate, and the stone-free rate were 6 percent, 13 percent, and 75 percent, respectively, with the Dornier, and 6 percent, 8 percent, and 80 percent, respectively, with the Medstone. There was no statistically significant difference between these outcome results (p > 0.05). The prone position was difficult to achieve with the Dornier HM3, while the Medstone STS, a tubeless lithotriptor, allowed easy positioning of the patient in the prone position on its flat table. Satisfactory results were achieved using either machine.
    No preview · Article · Feb 1994 · Urology
  • Alexander S. Cass · Joe Y. Lee · Carl S. Smith
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    ABSTRACT: Perirenal extravasation of urine with an intact renal parenchyma and with dye visualized in the ureter was seen on an excretory urogram (IVP) and computed tomographic (CT) scan in two patients (bilateral in one) with multiple injuries following blunt trauma. Expectant management with no invasive procedures resulted in disappearance of the extravasation within 3 to 5 days. Traumatic rupture of a calyceal fornix is thought to be the cause of the extravasation similar to the perirenal extravasation seen with renal colic from a ureteral calculus.
    No preview · Article · Aug 1993 · The Journal of trauma
  • Joe Y. Lee · Alexander S. Cass
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    ABSTRACT: One of the most important advances in trauma to the lower urinary and genital tracts has been the increased use of imaging techniques in its diagnosis and treatment. Computed tomography has been used in the diagnosis of bladder rupture and magnetic resonance imaging and ultrasonography in the diagnosis of post-traumatic urethral strictures. The treatment of post-traumatic urethral strictures by endoscopic urethroplasty has been facilitated by ultrasonography and fluoroscopy and ultrasonography has helped with blunt testicular injury in deciding surgery or observation. (C) Lippincott-Raven Publishers.
    No preview · Article · May 1993 · Current Opinion in Urology
  • A S Cass

    No preview · Article · May 1993 · British Journal of Urology
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    ABSTRACT: Calcification of a ureteral stent has been an unusual complication of long-term stent use for bypassing ureteral obstruction or after surgical repair. Open or percutaneous procedures have usually been required to remove the calcification before the stent can be extracted. We report six cases of calcified ureteral stents successfully managed by extracorporeal shock wave lithotripsy (SWL) followed by cystoscopic extraction, thus avoiding open or percutaneous procedures.
    No preview · Article · Mar 1993 · Journal of Endourology
  • Alexander S. Cass
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    ABSTRACT: A case report of an acute severe genital infection simulating Fournier's gangrene was subsequently found to be caused by chickenpox.
    No preview · Article · Feb 1993 · Urology
  • J.Y. Lee · A.S. Cass · J.M. Streitz
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    ABSTRACT: Traumatic dislocation of the testes with bladder rupture occurred in 2 multiply injured patients with pelvic fracture. One had a history of retractile testes and the other of previous testicular dislocation. Surgical correction was performed after closed reduction failed. These injuries must be recognized and treated promptly to maximize the likelihood of testicular salvage. If early intervention is not possible, duplex ultrasonography and pulsed Doppler analysis are the optional valuative studies.
    No preview · Article · Jan 1993 · Urology
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    ABSTRACT: Of 6765 patients having extracorporeal shock wave lithotripsy (SWL) with either a Dornier HM3 or a Medstone STS lithotripter to 7381 kidneys, 7 (0.1 %) developed clinically significant renal hemorrhage diagnosed by persistent pain, increasing hematuria, or a drop in hemoglobin in excess of 2 g/ml and confirmed by retrograde pyelography or ultrasound or CT scanning. Blood transfusion was required in one patient, and all seven patients were managed expectantly, with one patient having an unsuccessful attempt at percutaneous drainage of suspected infection of the hematoma at 4 weeks post-SWL. Pre-existing hypertension was present in three patients. Aspirin intake was present in four patients, and abnormal platelet aggregation studies were present in one of these patients 7 days after ceasing aspirin intake. It is important that patients be specifically questioned regarding aspirin intake, as some patients do not regard aspirin as a medication. Shock wave lithotripsy should be performed no earlier than 2 weeks after cessation of aspirin intake.
    No preview · Article · Dec 1992 · Journal of Endourology
  • ALEXANDER S. CASS
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    ABSTRACT: Concerns have been expressed by some in the United States that extracorporeal shock wave lithotripsy (SWL) for mid and lower ureteral stones could damage ovarian reproductive function, is difficult to perform with a Dornier HM3, and is not as effective as ureteroscopy. Seventy-nine patients with midureteral stones and 45 patients with lower ureteral stones were treated using Dornier HM3 and Medstone STS lithotripters. With the latter machine, the head and foot angle radiographs, the absence of the water-filled tub, and the easy prone positioning of the patient made the visualization and treatment of the mid and lower ureteral stones easier to perform. With single stones, the stone-free rate at 3 months was 77%, the retreatment rate was 2%, and the post-SWL secondary procedure rate was 15%. However, stone retrieval by ureteroscopy in the lower third of the ureter is a single procedure without the need for secondary or repeat treatments and, with reported stone-free rates of 83% to 93%, it is more efficient and less expensive than ESWL.
    No preview · Article · Oct 1992 · Journal of Endourology
  • A S Cass · JY Lee · H Aliabadi
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    ABSTRACT: A total of 12 patients with urinary diversions had calculi in 15 kidneys managed initially by extracorporeal shock wave lithotripsy (ESWL) in 12 kidneys and percutaneous nephrolithotripsy in 3. After 15 treatments with ESWL only 3 of the 12 kidneys (25%) became stone-free. Endoscopic procedures were used in 5 kidneys with fragments remaining after ESWL, and comprised percutaneous ultrasound lithotripsy in 2 and transstomal retrograde manipulations in 3. The 3 initial and 5 subsequent endoscopic procedures resulted in 6 of the 8 kidneys (75%) being stone-free. The poor results with ESWL are due to preexisting dilated upper urinary tracts and to immobility in obese myelomeningocele patients. Endoscopic procedures are the preferred method of treatment in these patients.
    No preview · Article · Oct 1992 · The Journal of Urology
  • ALEXANDER S. CASS
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    ABSTRACT: De novo extracorporeal shock wave lithotripsy (SWL) for ureteral stones is appealing because no instrumentation is used and stone-free rates of 90%+ are reported with low-power lithotripters using minimal or no anesthesia. This makes SWL an attractive alternative to ureteroscopic stone extraction and to ureteral stent/SWL, which give similar stone-free rates but require instrumentation and major anesthesia. De novo SWL using high-power lithotripters (Dornier HM3 and Mestone STS) and general anesthesia was used on 100 patients with impacted ureteral stones of 2 weeks' duration or longer (upper ureter 80, mid 6, lower 14). There were 78 single stones and 22 multiple stones. The retreatment and post-SWL secondary procedure rates with single stones were 6% and 14%, respectively, and with multiple stones were 9% and 18%, respectively. The stone-free rate at 3 months was 78% with single stones and 73% with multiple stones. The difference in stone-free rates between low- and high-power lithotripters performing de novo SWL for ureteral stones is difficult to explain except for the theory that low-power machines fragment stones into smaller particles that are more readily passed down the ureter or the fact that low-power lithotripters are used by some urologists for the immediate treatment of acute renal colic caused by small ureteral stones that would have passed spontaneously with a short period of observation.
    No preview · Article · Oct 1992 · Journal of Endourology
  • Alexander S. Cass
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    ABSTRACT: We reviewed the results of ureteral stent use with extracorporeal shock-wave lithotripsy (ESWL) in 3,096 patients with renal calculi less than 3 cm in diameter. The 2,595 patients with indwelling ureteral stents required lower total power (shocks x voltage) and less radiation and had a lower secondary procedure rate but a higher retreatment rate than the 501 patients without stents. However, the only statistically significant difference was in the average radiation dose in patients with or without stents and single stones no larger than 10 mm (16 vs. 18 rad). The hospital stay was one day or less in 98 percent of the patients in both groups. With an 80 percent follow-up rate at three months indwelling ureteral stents were associated with a higher stone-free rate in patients with a single stone but a lower stone-free rate in patients with multiple stones, compared with those treated without a stent. An indwelling ureteral stent may result in urinary frequency and bladder discomfort in some patients, and with no statistical difference in the results with or without a ureteral stent it is questionable whether or not the high use of an indwelling ureteral stent is justified in patients admitted for one day or less.
    No preview · Article · Jun 1992 · Urology
  • A S Cass · P B Kavaney · C L Smith
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    ABSTRACT: Multiple large cystine stones formed on an indwelling ureteral stent used in the medical management of a 12-year-old boy with obstructing renal stones and cystinuria. Extracorporeal shock wave lithotripsy fragmented the cystine stones and allowed for extraction of the stent by cystoscopy.
    No preview · Article · May 1992 · The Journal of Urology
  • A S Cass
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    ABSTRACT: Although mobile renal lithotripsy appears to be a cost-efficient method for a urologist to treat patients at the local hospital the quality issue has been raised with occasional use of a mobile lithotriptor. We reviewed 4,278 kidneys in 3,900 patients treated by 129 urologists using a mobile Dornier HM3 and a mobile Medstone lithotriptor at 21 mobile sites in 6 upper midwest states during 3 1/2 years. These results were compared with those in 524 kidneys in 480 patients treated by our fixed Medstone lithotriptor. After the procedure auxiliary treatments were needed in 3% of the patients treated with the mobile units and 2% of those treated with the fixed unit. The rate in 2 large published series was approximately 9%. The retreatment rates were 5% with the mobile lithotriptors and 6% with the fixed (reported average 16%), and the over-all stone-free rates at 3 months were 69% and 68% (versus 66%). Of note, the mobile units were as effective as the fixed unit against difficult stones. A mobile lithotriptor with a constant support staff that is used 1 or 2 times per month by many trained urologist will perform as well as fixed lithotriptor used regularly by a small unvarying staff of trained urologists.
    No preview · Article · Sep 1991 · The Journal of Urology

Publication Stats

2k Citations
304.37 Total Impact Points

Institutions

  • 1978-1996
    • Hennepin County Medical Center
      • Department of Emergency Medicine
      Minneapolis, Minnesota, United States
  • 1994
    • Abbott Northwestern Hospital
      Minneapolis, Minnesota, United States
  • 1976-1985
    • St. Joseph's Hospital, St. Paul, Minnesota
      Minneapolis, Minnesota, United States
    • Gillette Children's Specialty Healthcare
      Saint Paul, Minnesota, United States

Disciplines