Biomedical subjects

S B Streem

Publications and source records attributed to S B Streem.

At least 19 recordsLinked to original sources

PubMed2001

Extracorporeal shock-wave lithotripsy: a comparative study of electrohydraulic and electromagnetic units.

PURPOSE: We determined the results of shock wave lithotripsy with a newer electromagnetic lithotriptor and compared them with those in a contemporary series of cases managed by an electrohydraulic lithotriptor using identical treatment and followup criteria at a single center. MATERIALS AND METHODS: Between 1995 and 1999, 356 patients (375 renal units, 483 upper urinary tract stones) meeting study inclusion criteria were treated with an MFL 5000 electrohydraulic shock wave lithotripsy unit (Dornier Medical Systems, Inc., Marietta, Georgia). From 1999 to 2000, 173 patients (175 renal units; 218 upper urinary tract stones) meeting identical study inclusion criteria were treated using an electromagnetic Modulith SLX shock wave lithotripsy unit (Karl Storz Lithotripsy, Atlanta, Georgia). In each group stone-free results were determined by plain abdominal x-ray and renal ultrasound 1 month after lithotripsy and efficiency quotients were developed. Baseline patient and stone characteristics were compared by the Wilcoxon rank sum and Fisher exact tests. All variables significant at p <0.05 were included in subsequent outcome analysis using multivariate logistic regression. RESULTS: Baseline characteristics were equivalent, including patient age, gender, stone number and location, although patients treated with the electrohydraulic unit had a significantly larger median stone burden (103 versus 71 mm.2, p = 0.015). Multivariate regression analysis demonstrated a higher stone-free rate in the electrohydraulic group (77% versus 67%, p = 0.01) but also a higher rate of total adjunctive measures (56% versus 47%, p = 0.04). Consequently the efficiency quotients were comparable for the electrohydraulic and electromagnetic lithotripsy units (0.45 and 0.42, respectively, p = 0.43). CONCLUSIONS: Electrohydraulic lithotripsy resulted in a higher stone-free rate at 1 month, although it was associated with a higher rate of auxiliary measures. Ultimately the efficiency quotients were equivalent, implying that these 2 contemporary energy sources are acceptable. According to single center treatment and followup criteria they are equally efficacious.

Adolescent↗

PubMed2001

Long-term renal functional effects of shock wave lithotripsy, percutaneous nephrolithotomy and combination therapy: a comparative study of patients with solitary kidney.

PURPOSE: We compared the long-term impact on renal function after shock wave lithotripsy, percutaneous nephrolithotomy or the 2 techniques combined in patients with a solitary kidney. MATERIALS AND METHODS: A total of 45 women and 38 men 15 to 86 years old (mean age 56.1) with a solitary kidney were treated with shock wave lithotripsy (53), percutaneous nephrolithotomy (18) or the 2 techniques combined (12). Before and after treatment serum creatinine, blood pressure and the calculated glomerular filtration rate were determined, and raw and calculated data were compared by the Kruskal-Wallis, Fisher exact and Wilcoxon rank sum tests, and the Spearman correlation coefficient. Followup was 1 to 166.5 months (mean 53.0, median 46.9) overall and statistically equivalent in the 3 treatment arms. RESULTS: Treatment groups were comparable in regard to patient age, sex distribution, weight, blood pressure and pretreatment serum creatinine. There was no significant difference in any evaluated pretreatment or posttreatment parameters and no difference in the change in any parameter after treatment. Stratifying patients to pretreatment serum creatinine less or greater than 2 mg./dl. likewise revealed no significant difference in the impact on long-term renal function. However, pretreatment serum creatinine positively and strongly correlated with a positive change in the glomerular filtration rate after therapy. CONCLUSIONS: In this study there was no evidence that any of these 3 treatment modalities resulted in the deterioration of renal function even at long-term followup. This finding implies that shock wave lithotripsy, percutaneous nephrolithotomy and the 2 therapies combined are equally efficacious for preserving renal function when performed in patients with a solitary kidney.

Adolescent↗

PubMed2001

Contemporary "urologic" intervention in the pancreaticobiliary tree.

OBJECTIVES: To evaluate the role of minimally invasive "urologic" interventional techniques for the treatment of pancreaticobiliary calculi in contemporary practice. METHODS: Fourteen patients with retained cystic duct (n = 2), hepatic duct (n = 5), common duct (n = 2), pancreatic duct (n = 4), or gallbladder (n = 1) calculi were treated with 19 procedures, including shock wave lithotripsy (n = 9) and percutaneous flexible endoscopy with electrohydraulic or holmium laser lithotripsy (n = 10). Previous attempts using standard gastroenterologic or radiologic interventions before the urologic referral had failed in all 14 patients. RESULTS: A successful result, defined by the resolution of stones and symptoms, was achieved in 12 patients (86%); 2 patients (14%) had residual calculi that ultimately required an open operative procedure. The hospital stay for each intervention was 0 to 2 nights, and no patients had any significant complications. CONCLUSIONS: Even in this age of advanced gastroenterologic technology, including laparoscopic cholecystectomy, endoscopic retrograde cholangiopancreatoscopy, and percutaneous transhepatic cholangiography, the urologist can play a significant role in the minimally invasive treatment of patients with complicated biliary disease such that the need for open operative "salvage" procedures will be further minimized.

Adult↗

PubMed2001

Medical and surgical therapy of the cystine stone patient.

Cystinuria is an inherited defect in renal tubular and intestinal transport of dibasic amino acids that results in elevated urinary excretion of cystine, ornithine, lysine, and arginine. The only clinical manifestation of this disease is the development of urinary tract cystine calculi. Cystinuric patients suffer recurrent stone episodes, requiring an aggressive multi-modal approach to management. This article reviews the results of medical prevention regimens, the role of minimally invasive urologic intervention, and the recent insights into the complex genetic basis for the varied cystinuric phenotypes.

Cystine↗

PubMed2000

Simplified approach to percutaneous endopyelotomy.

The purpose of this report was to describe a safe, simple, and rapid approach to percutaneous antegrade endopyelotomy. In contrast to standard percutaneous endopyelotomy techniques, in this procedure, the endopyelotomy stent is placed at the outset. The endopyelotomy incision is then made with an acorn-tipped Bugbee electrode directly down onto the stent, in a manner analogous to a ureteral meatotomy in the bladder. The advantage of this approach is twofold. Primary placement of the stent helps to define the appropriate site and direction for the endopyelotomy incision, allowing marsupialization of the proximal ureter into the renal pelvis. Use of this technique also obviates the need to pass a large-caliber stent after the endopyelotomy incision has been made, thereby avoiding a potential risk of ureteropelvic junction disruption. Clinical and radiographic follow-up was available in 29 (76%) of 38 patients who underwent this procedure. Success, defined as a resolution of symptoms and decrease in calicectasis, was achieved in 24 (83%) of the 29 patients. We have found primary placement of an endopyelotomy stent and use of electrocautery as a cutting mode safely facilitates a precise endopyelotomy incision.

Endoscopy↗

PubMed2000

Percutaneous endopyelotomy.

Percutaneous endopyelotomy, introduced over 15 years ago, is a well-established alternative to open operative pyeloplasty for management of ureteropelvic junction (UPJ) obstruction. Although several variations of the technique have been described, the goal in all cases is to develop a full thickness incision though the obstructing proximal uretra that extends out to the peripyeloureteral fat and heals over an internal stent. Though a percutaneous endopyelotomy can be considered for almost any patient with primary or secondary UPJ obstruction, it is particularly valuable in the setting of upper tract stones that can then be managed simultaneously. This article reviews the indications, techniques, and outcomes of percutaneous endopyelotomy.

Humans↗

PubMed2000

Renal transplant complications. Minimally invasive management.

Advancements in endourology, laparoscopic urology, and interventional radiology continue to influence the contemporary management of renal transplant complications. The successful implementation of these minimally invasive therapies significantly relies on careful patient selection; not all renal transplantation complications are suitable or amenable for this form of management--true for transplant ureteral complications and less so for other potential complications. With such a strategy, renal transplant complications can be managed efficiently and effectively with these minimally invasive modalities to minimize further recipient morbidity while also minimizing potential risk to the recipient and for the renal allograft.

Humans↗

PubMed2000

Extracorporeal lithotripsy. Update on technology.

The development of shock-wave lithotripsy was a serendipitous event. Fortunately, the significance of this accidental discovery was not overlooked by the engineers at Dornier and their medical counterparts. There are many components that make up a lithotripter, but the heart of the lithotripter is its energy source. These machines often are categorized by the type of shock-wave generator used, and each type of generator has its own advantages and disadvantages. Unfortunately, no quantitative value of a shock-wave generator can be correlated to its qualitative effect. Interestingly, each type of energy source delivers its shock-wave energy with such distinctiveness that even the crater pattern it leaves in a stone is unique. New technology and ideas have transformed lithotripters in form and function so that they bear little resemblance to the original HM-1 prototype. Ongoing research is attempting to improve ESWL in several different ways, and advances in shock-wave generation, shock-wave measurement, and stone localization should result in even more efficient lithotripsy. The application of the time-reversal process to lithotripsy ultimately may enable lithotripters to track stones and electronically steer shock waves toward the target. Advances like these herald a time when ESWL, fortunately or unfortunately, will become automated completely.

Equipment Design↗

PubMed2000

Ureteroscopic approach to upper-tract urothelial tumors.

Transitional-cell carcinoma (TCC) of the upper urinary tract has traditionally been managed by nephroureterectomy, whereas nephron-sparing surgery has been reserved for those few patients with solitary kidneys or bilateral lesions. However, with the introduction of improved diagnostic and therapeutic technology, including smaller ureteroscopes and working instruments, and the concomitant ease of surveillance, ureteroscopic treatment of upper-tract urothelial tumors has become a reasonable alternative to open operative intervention in patients requiring conservative management. Furthermore, as preoperative grading and staging have improved, ureteroscopic treatment of upper-tract urothelial tumors is assuming an increasingly important role in the management of some patients who might have otherwise been treated with a nephroureterectomy. The technique of ureteroscopic resection is described in detail.

Carcinoma, Transitional Cell↗

PubMed2000

Nephrolithiasis associated with autosomal dominant polycystic kidney disease: contemporary urological management.

PURPOSE: We evaluate the role of contemporary urological intervention in patients with nephrolithiasis associated with autosomal dominant polycystic kidney disease. MATERIALS AND METHODS: Intervention for upper tract stones associated with autosomal dominant polycystic kidney disease was performed in 5 women and 2 men 29 to 65 years old (mean age 47). Indications for intervention consisted of flank pain in 6 patients and/or hematuria in 2. A total of 12 procedures (mean 1.7 per patient) were performed, including shock wave lithotripsy in 6 patients, percutaneous nephrolithotomy in 2, retrograde endoscopy or manipulation in 3 and extended pyelonephrolithotomy in 1. RESULTS: All patients were rendered stone-free or had only residual "dust." Hospital stay for 5 patients was 1 night or less and there were no complications. Renal function for each patient was stable or improved as measured by serum creatinine. CONCLUSIONS: Most patients with autosomal dominant polycystic kidney disease who require intervention for nephrolithiasis can be safely and effectively treated with essentially any or all contemporary, minimally invasive techniques. The choice of intervention can be based primarily on size and location of the upper tract stones rather than the associated presence of polycystic kidneys.

Adult↗

PubMed2000

Metabolic risk factors in patients with ureteropelvic junction obstruction and renal calculi.

PURPOSE: We performed a prospective study to determine the incidence and spectrum of metabolic abnormalities predisposing to stone formation in patients with ureteropelvic junction obstruction and renal calculi. MATERIALS AND METHODS: A total of 47 consecutive patients with congenital ureteropelvic junction obstruction underwent metabolic evaluation of stone risk factors. Of these patients 21 had associated stones (study group), while 26 did not (control group). Logistical regression, Wilcoxon rank sum and Fisher's exact tests were performed to determine whether there was a significant difference between these groups in regard to the presence of metabolic risk factors. RESULTS: Demographically and symptomatically the 2 groups were equivalent except that the study patients were older. The 24-hour urinary excretion of calcium was significantly higher in study than in the control patients (p = 0.007). While the incidence of hypercalciuria and hyperuricosuria was also higher in the study population, these differences were not significant (p = 0.08 and 0.07, respectively). CONCLUSIONS: Metabolic abnormalities predisposing to stone formation are present more frequently in patients with ureteropelvic junction obstruction who have associated stones compared to those who do not. As such, urinary stasis alone does not explain stone formation in these cases. Rather, the local physiological environment of urine likely has a predisposing role. In addition to restoring unobstructed urinary flow, consideration should be given to metabolic evaluation and prophylactic treatment for affected patients.

Adolescent↗

PubMed2000

Laparoscopic retroperitoneal live donor right nephrectomy for purposes of allotransplantation and autotransplantation.

PURPOSE: We report the technique of and initial experience with retroperitoneal laparoscopic live donor right nephrectomy for purposes of renal allotransplantation and autotransplantation. MATERIALS AND METHODS: A total of 5 patients underwent retroperitoneoscopic live donor nephrectomy of the right kidney for autotransplantation in 4 and living related renal donation in 1. Indications for autotransplantation included a large proximal ureteral tumor, a long distal ureteral stricture and 2 cases of the loin pain hematuria syndrome. In all cases a 3-port retroperitoneal laparoscopic approach and a pelvic muscle splitting Gibson incision for kidney extraction were used. In patients undergoing autotransplantation the same incision was used for subsequent transplantation. RESULTS: All procedures were successfully accomplished without technical or surgical complications. Total mean operating time was 5.8 hours and average laparoscopic donor nephrectomy time was 3.1 hours. Mean renal warm ischemia time, including endoscopic cross clamping of the renal artery to ex vivo cold perfusion, was 4 minutes. Average blood loss for the entire procedure was 400 cc. Radionuclide scan on postoperative day 1 confirmed good blood flow and function in all transplanted kidneys. Mean analgesic requirement was 58 mg. fentanyl. Mean hospital stay was 4 days (range 2 to 8), and convalescence was completed in 3 to 4 weeks. CONCLUSIONS: In the occasional patient requiring renal autotransplantation live donor nephrectomy can be performed laparoscopically with renal extraction and subsequent transplantation through a single standard extraperitoneal Gibson incision, thus, minimizing the overall operative morbidity. Furthermore, these data demonstrate that live donor nephrectomy of the right kidney can be performed safely using a retroperitoneal approach with an adequate length of the right renal vein obtained for allotransplantation or autotransplantation.

Adult↗

PubMed1999

Ammonium acid urate calculi: a reevaluation of risk factors.

PURPOSE: We reevaluate the demographic and metabolic risk factors for ammonium acid urate stones. MATERIALS AND METHODS: Since 1986, 23 women and 21 men ranging in age from 20 to 81 years (mean 48.7) were treated for stones partly composed of ammonium acid urate. Stone composition ranged from 2 to 60% ammonium acid urate (mean 24.1) of the total stone mass. No patient had a pure ammonium acid urate stone, although 11 (25%) had stones with ammonium acid urate as the predominant crystal. RESULTS: In the 44 patients 1 or more potential risk factors for ammonium acid urate were identified. Of the patients 11 (25%) had a history of inflammatory bowel disease with 10 (22.7%) having undergone ileostomy diversion, 6 (13.6%) admitted to a history of significant laxative use or abuse, 18 (40.9%) were morbidly obese, 16 (36.4%) had a history of recurrent urinary tract infections and 9 (20.5%) had a history of recurrent uric acid stones. CONCLUSIONS: Patients clearly at risk for stones with an ammonium acid urate component include those with a history of inflammatory bowel disease and ileostomy diversion or laxative abuse. Other factors that may potentially enhance ammonium acid urate stone formation include morbid obesity, recurrent uric acid calculi and recurrent urinary tract infection. A careful history followed by further metabolic evaluation is warranted in these patients.

Adult↗

PubMed1999

Endopyelotomy outcome as a function of high versus dependent ureteral insertion.

OBJECTIVES: To determine whether a high versus a dependent ureteral insertion significantly affects the outcome of endopyelotomy for management of ureteropelvic junction (UPJ) obstruction. METHODS: Sixty patients with UPJ obstruction were treated with an endopyelotomy by way of either an antegrade percutaneous approach (n = 36) or a retrograde hot-wire balloon incision (n = 24). In these 60 patients, the ureteral insertion was high on the renal pelvis in 19 (32%), dependent in 25 (42%), and indeterminate in 16 (26%). Intravenous urography was performed 4 to 6 weeks after stent removal (8 to 12 weeks after endopyelotomy) and then at 6 to 12-month intervals. Success of the procedure was defined as resolution of symptoms and decrease in hydronephrosis compared with pre-endopyelotomy studies. RESULTS: With a follow-up range of 2 to 41 months (mean 10.3), the overall success rate was 80%. This rate was independent of whether the procedure was performed in an antegrade or retrograde fashion. A successful result was achieved in 15 (78.9%) of those with a high insertion, 19 (76%) of those with a dependent insertion, and 14 (87.5%) of those with an equivocal insertion; these differences were not statistically significant (P = 0.72). CONCLUSIONS: The type of ureteral insertion (ie, high versus dependent) had no significant impact on the outcome of endopyelotomy by way of either a percutaneous or retrograde approach. As such, these anatomic variations need not play a role in a decision-making algorithm for contemporary management of UPJ obstruction.

Adolescent↗

PubMed1999

Contemporary management of cystinuria.

Cystinuria is an autosomal recessive disorder characterized by a defect in intestinal and renal tubular transport of dibasic amino acids which results in excessive urinary excretion of cystine. Because of the relative insolubility of cystine in urine, patients with this condition are prone to recurrent stone formation. Medical therapy aims both to decrease the urinary concentration of cystine and to increase its solubility. Standard prevention and treatment regimens include hydration, moderate salt and protein restriction, oral alkalinization, and thiol derivatives. Despite aggressive medical management, however, cystinuric patients are likely to suffer frequent recurrent episodes of stones necessitating urologic intervention. Fortunately, the application of safe and efficacious minimally invasive modalities, including advancements in shockwave lithotripsy, ureteroscopic lithotripsy, and percutaneous nephrolithotomy, have obviated open operative intervention in nearly all cases.

Acetylcysteine↗

PubMed1999

Contemporary diagnosis of retrocaval ureter.

PURPOSE: We describe a noninvasive radiologic evaluation of a retrocaval ureter using currently available technology. MATERIALS AND METHODS: Three-dimensional volume-rendered CT and diuretic renography were performed for evaluation of a possible retrocaval ureter. RESULTS: The 3D CT scan definitively diagnosed the retrocaval ureter, while diuretic renography showed no evidence of clinically significant obstruction. No invasive procedures were required. CONCLUSION: A 3D volume-rendered CT scan in the excretory phase combined with diuretic renography is the radiologic evaluation of choice for patients with a suspected retrocaval ureter, as it is noninvasive yet highly accurate in its anatomic delineation.

Adult↗

PubMed1999

Effects of extracorporeal shock wave lithotripsy on tiered therapy implantable cardioverter defibrillators.

The effects of extracorporeal shock wave lithotripsy (ESWL) were tested on four advanced generation implantable cardioverter-defibrillators (ICDs) in vitro and in vivo in two patients. During in vitro testing, advancement of nonsustained episode counters occurred in one device, and a set screw and power source cell loosened in another, which was connected to an external power source. No arrhythmias occurred during in vivo procedures, but programmed parameters were reset and elective replacement indicated after one procedure. ESWL can be performed safely in selected patients with ICDs, but testing should be performed afterwards to confirm satisfactory function and component continuity.

Defibrillators, Implantable↗

PubMed1999

Triphasic helical CT of the kidneys: contribution of vascular phase scanning in patients before urologic surgery.

OBJECTIVE: The purpose of this study was to evaluate the potential benefits of performing vascular phase scanning of the kidneys in addition to unenhanced and parenchymal phase contrast-enhanced CT in patients being examined for urologic surgery. MATERIALS AND METHODS: Parenchymal and vascular phase images from triphasic renal helical CT of 50 patients were sequentially evaluated in a randomized, retrospective fashion by two independent observers. The number of renal arteries and veins and the presence of vein or collecting system anomalies were recorded for each scan phase along with a subjective 10-point-scale score of the visibility of the vasculature and collecting system. Correlation of these findings was made with surgical or angiographic findings in 67 of the 87 kidneys and was made by consensus review in the remaining 20 kidneys. RESULTS: Accessory renal arteries were seen significantly more often (p < .05, chi-square test) on the vascular phase scans. The subjective scores for the visibility of the renal arteries and renal veins were significantly higher on the vascular phase scans (p < .0001, Wilcoxon's rank sum test). The subjective scores for the visibility of the filling of the collecting system and renal pelvis were significantly higher for the parenchymal phase scans, despite the use of a small contrast bolus before each scan (p < .0001, Wilcoxon's rank sum test). CONCLUSION; Triphasic renal CT better reveals the artery and vein anatomy of the kidney than does parenchymal phase imaging only. Triphasic helical CT is indicated in patients undergoing planning for urologic surgery when vascular anatomy is clinically important.

Adult↗