Biomedical subjects

Noel A Armenakas

Publications and source records attributed to Noel A Armenakas.

10 recordsLinked to original sources

PubMed2005

Extracorporeal shock wave lithotripsy success based on body mass index and Hounsfield units.

OBJECTIVES: To determine whether body mass index (BMI) and Hounsfield units (HUs) could be used as independent predictors of stone-free status after extracorporeal shock wave lithotripsy (ESWL). No detailed studies have assessed BMI as an independent predictor of ESWL outcome. Some studies have suggested that HUs of urinary calculi on noncontrast computed tomography may predict the stone-free rate after ESWL. METHODS: We evaluated 100 patients who had undergone ESWL for 5-mm to 10-mm upper urinary tract stones. The BMI was calculated for each patient. HU determination and chemical analysis was performed for each stone. Radiographic assessment at 6 weeks categorized patients into a stone-free (SF) or residual-stone (RS) group. Statistical analysis, using BMI and HUs as predictors, was performed to assess the stone-free rate after ESWL. RESULTS: Of 100 patients, 72 were in the SF and 28 in the RS group. The mean BMI for the SF group was 26.9 +/- 0.5 versus 30.8 +/- 0.9 in the RS group (P <0.05). The difference in the mean HU values for the SF and RS groups was statistically significant (577.8 +/- 182.5 versus 910.4 +/- 190.2, respectively; P <0.05). A successful outcome was significantly related to BMI (odds ratio 1.34, 95% confidence interval 1.09 to 1.65, P <0.01) and HUs (odds ratio 1.01, 95% confidence interval 1.007 to 1.019, P <0.01). The following equation was formulated to compute the probability of treatment failure: 1/1 + 2.7(-z), where z = 0.294 BMI + 0.13 HU - 18.98. CONCLUSIONS: BMI and HUs were statistically significant independent predictors of stone-free rates after ESWL. We believe a predictive model of ESWL outcome may be formulated on the basis of these findings and may be used to select the preferred treatment option for patients with urinary calculi.

Adult↗

PubMed2004

Iatrogenic bladder perforations: longterm followup of 65 patients.

BACKGROUND: We reviewed our experience with bladder perforations to better understand the causes of these injuries and to describe their management and its effect on longterm outcomes. STUDY DESIGN: Our bladder trauma database yielded 65 patients during a 12-year period, followed for a mean of 36 months, who had sustained iatrogenic bladder perforations. Endourologic procedures were excluded. Demographic data, surgical details, mechanism of injury, anatomic location, grading, diagnosis, management, and outcomes were assessed. RESULTS: Gynecologic procedures accounted for 40 perforations (61.5%), general surgical procedures for 17 (26.2%), and urologic procedures for 8 (12.3%). The type of gynecologic surgery included abdominal hysterectomy in 16 (40%), resection of a pelvic mass in 12 (30%), cesarean section in 10 (25%), and diagnostic laparoscopy in 2 (5%). Of the general surgical procedures, eight were for colon cancer (47.1%), six for diverticulitis (35.3%), and three for inflammatory bowel disease (17.6%); of the urologic injuries, six occurred during vaginal surgery and two during laparoscopy. Predisposing factors were identified in 52 patients (80%). Intraoperative urologic consultation was obtained in 63 of 65 patients, with prompt identification and repair. In two cases a concurrent left ureteral injury was identified and managed by reimplantation. The sole complication was a vesicovaginal fistula 2 months postoperatively, so the success rate for repair was 98.4%. CONCLUSIONS: Although infrequent, iatrogenic bladder perforations can occur during any pelvic, abdominal, or vaginal procedure. Prompt intraoperative recognition is paramount to ensure satisfactory outcomes. Adequate repair usually can be achieved simply by vesicorrhaphy, limiting unnecessary extravesical dissection. With this approach, morbidity can be minimized.

Colon↗

PubMed2004

Efficacy of high-energy transurethral microwave thermotherapy in alleviating medically refractory urinary retention due to benign prostatic hyperplasia.

OBJECTIVES: To determine the efficacy of high-energy transurethral microwave thermotherapy (HE-TUMT) in treating patients with medically refractory complete urinary retention secondary to benign prostatic hyperplasia (BPH). METHODS: Between April 2000 and July 2003, 39 patients in urinary retention due to BPH were treated with HE-TUMT. A Foley catheter was reinserted after HE-TUMT and removed at 3 weeks for a voiding trial. Patients unable to void were recatheterized, and voiding trials were repeated at 2-week intervals. Patients were evaluated according to history and physical examination, prostate-specific antigen level, prostate volume, cystourethroscopy, International Prostate Symptom Score, quality of life score, peak uroflow, and postvoid residual. Success was defined as the ability to urinate after HE-TUMT without the need for further intervention. RESULTS: The mean (+/- SD) patient age was 72 +/- 9.3 years. Mean follow-up period was 18 +/- 10.2 months. Twenty patients (51%) were characterized as American Society of Anesthesiologists class III or higher. The mean prostate volume was 75.2 +/- 57.6 cm3. The mean length of time that patients were dependent on indwelling Foley catheters before HE-TUMT was 9.6 +/- 14.2 weeks. Thirty-two patients were able to void after HE-TUMT, for an overall success rate of 82%. Patients voiding successfully after HE-TUMT had a mean of 1.6 +/- 0.8 voiding trials and required catheters after HE-TUMT for a mean period of 4.1 +/- 2 weeks. Only 6 (15%) of the patients who were voiding were able to stop their medication for BPH. CONCLUSIONS: We found an encouraging success rate with HE-TUMT in relieving urinary retention in patients with BPH, including those with large prostate volumes. It is an acceptable option for patients who are considered high risk for surgery. Several patients required multiple voiding trials before spontaneous urination, which suggests that improvements in bladder outlet obstruction might require a prolonged period after HE-TUMT. Finally, many patients might require continued use of medications after HE-TUMT.

5-alpha Reductase Inhibitors↗

PubMed2004

Ventral onlay buccal mucosal grafts for anterior urethral strictures: long-term followup.

PURPOSE: We present our long-term experience with buccal mucosal grafts, placed ventrally, for the treatment of anterior urethral strictures. MATERIALS AND METHODS: A total of 23 patients with anterior urethral strictures underwent urethral reconstruction using buccal mucosa as a ventral onlay graft, with 18 grafts placed in the bulbar and 5 in the penile urethra. All operations were performed in 1 stage by a single surgeon (NAA). Mean graft length was 4.9 cm (range 3 to 12). International Prostate Symptom Score and uroflowmetry were obtained preoperatively, at 3, 6 and 12 months postoperatively, and annually thereafter. Urethral imaging was obtained preoperatively, at catheter removal and selectively thereafter. RESULTS: Patients were followed for a mean of 50 months (range 17 to 94). Etiology of the strictures was instrumentation (in 9), idiopathic (in 9), prior hypospadias repair (in 2), urethritis (in 2) and trauma (in 1). Of the 23 patients 21 (91%) were previously treated for urethral stricture with a total of 59 procedures (mean 2.8 procedures per patient). Success, defined as normal voiding without any need for subsequent urethral manipulation, was achieved in 20 of 23 patients (87%). A distal anastomotic stricture developed in the remaining 3 patients, each managed with 1 internal urethrotomy. One of these patients continues to require monthly self-dilations. There were no fistulas or clinically perceptible graft sacculations. CONCLUSIONS: With long-term followup our series confirms the durability of ventrally placed buccal mucosal grafts for the treatment of anterior urethral strictures. This proven procedure results in a high success rate with few complications.

Adult↗

PubMed2004

Urethroplasty in patients older than 65 years: indications, results, outcomes and suggested treatment modifications.

PURPOSE: Despite an aging population, the results of urethroplasty in elderly patients have not been extensively reported. We performed a multi-institutional review of urethroplasty results in 70 elderly males to determine outcomes. MATERIALS AND METHODS: We reviewed all urethroplasties performed on males older than 64 years with at least 6 months of followup at 4 medical centers. Stricture type varied and included anastomotic urethroplasty (44%), penile fasciocutaneous onlay flap (31%), Johanson urethroplasty (stage 1, 6%, stages 1 and 2, 4%), buccal mucosa grafts (7%), foreskin grafts (6%) and meatoplasty (1%). RESULTS: Stricture recurred in 11 (16%) patients, but was managed with a single direct visual internal urethrotomy or dilation in 5 of 11 patients, yielding a final success rate of 91%. Recurrent strictures were more common after fasciocutaneous flaps (7 of 22 cases, 32%) than end-to-end urethroplasty (2 of 31 cases, 6%, p <0.05). Compared to patients younger than 65 years there were more treatment failures, but this was not statistically significant. Perioperative complications were uncommon. Moderate bladder outlet obstructive symptoms developed in 3 patients due to benign prostatic hyperplasia. Notably 6 patients treated previously for post-radiation strictures did well without complications. CONCLUSIONS: Older men tolerate urethroplasty and these data indicate that therapy should not be withheld solely on the basis of age. The potential for impaired flap blood supply in this population is suggested but has not been proven. Benign prostatic hyperplasia must be considered in those patients who have decreased stream after stricture repair.

Age Factors↗

PubMed2003

The effect of finasteride on the expression of vascular endothelial growth factor and microvessel density: a possible mechanism for decreased prostatic bleeding in treated patients.

PURPOSE: Several studies have confirmed the benefit of finasteride in limiting hematuria from benign prostatic hyperplasia. Vascular endothelial growth factor (VEGF), a potent stimulator of angiogenesis, and microvessel density have been independently evaluated in the mechanism of decreased bleeding observed in patients treated with finasteride. We evaluated the expression of VEGF and suburethral prostatic microvessel density in patients with benign prostatic hyperplasia treated with finasteride. MATERIALS AND METHODS: The study included 24 patients undergoing prostatic surgery for benign disease, of whom 12 were given finasteride for a minimum of 6 weeks before surgery and the remaining 12 served as controls. Sections from the prostatic urothelium and hyperplastic prostate were individually stained for CD34 specific for nascent blood vessels and VEGF. Analysis of each specimen was performed in a blinded fashion. Microvessel density was calculated by counting the number of positively stained blood vessels on 10 consecutive, nonoverlapping, high power fields within the suburethral and hyperplastic prostate compartments. VEGF expression was examined by immunohistochemistry. Statistical analysis of the results was performed using Student's t test. RESULTS: Prostatic suburethral VEGF expression and microvessel density were significantly lower in the finasteride group compared to controls (p <0.05). Differences in VEGF expression and microvessel density at the level of the hyperplastic prostate were not found to be significantly different between the 2 groups. CONCLUSIONS Decreased expression of VEGF by finasteride inhibits angiogenesis and significantly decreases microvessel density in prostatic suburethral tissue. This sequential relationship provides histochemical insight into the mechanism by which finasteride reduces prostatic urethral bleeding.

Aged↗

PubMed2003

Influence of prostate volume in the detection of prostate cancer.

OBJECTIVES: To assess the influence of prostate volume on prostate cancer (CaP) detection in men who underwent repeated sextant transrectal ultrasound biopsy of the prostate. METHODS: Between September 1991 and September 2000, 4376 men underwent sextant transrectal ultrasound-guided biopsy of the prostate. Of the 4376 men, 556 underwent repeat biopsy because of persistent prostate-specific antigen elevation (greater than 4 ng/mL) and/or an abnormal digital rectal examination or suspicious pathologic findings. The percentage of CaP missed on the initial biopsy and detected on the repeat biopsy between arbitrary prostate volumes of less than 50 and 50 cm3 or greater and between less than 37.5 and 37.5 cm3 or greater, the median prostate volumes of men with CaP, were compared. Patient age, prostate-specific antigen level, digital rectal examination findings, and Gleason score in each volumetric cutoff group were also compared. RESULTS: CaP was detected in 22% of men who underwent a repeat biopsy. The percentage of CaP missed on the initial biopsy but subsequently detected on the repeat biopsy consistently increased as the volume increased. A statistically significant difference in the percentage of CaP not detected on the initial biopsy was found between prostate volumes of less than 50 and 50 cm3 or greater and between less than 37.5 and 37.5 cm3 or greater (P <0.05). No statistically significant difference in prostate-specific antigen, age, digital rectal examination, or Gleason score was found between each volumetric cutoff group. CONCLUSIONS: A significant percentage of men are diagnosed with CaP after a repeat biopsy. We have demonstrated that the percentage of CaP missed on the initial biopsy and detected on the repeat biopsy increases as the prostate volume increases. The results of our study suggest that in men with large prostates, traditional sextant biopsies may not be adequate to detect CaP.

Age Factors↗

PubMed2003

Hounsfield units on computerized tomography predict stone-free rates after extracorporeal shock wave lithotripsy.

PURPOSE: Studies suggest that HU values on non-contrast computerized tomography may predict the ability to fragment urinary calculi. We determined whether the HUs of in vivo urinary stones could be used to predict the stone-free rates after extracorporeal shock wave lithotripsy. MATERIALS AND METHODS: We evaluated 50 patients who underwent extracorporeal shock wave lithotripsy for 5 to 10 mm. upper urinary tract stones. Chemical analyses and HU calculations were performed for each stone and posttreatment radiographic assessment categorized patients into a stone-free or a residual stone group. Statistical analysis was performed using the Student t test to compare mean HU values in the 2 groups. RESULTS: Of the patients 32 (64%) were stone-free and 18 (36%) had residual stones. Mean values +/- SEM for the stone-free and residual stone groups were significantly different (551.20 +/- 46.66 versus 926.20 +/- 51.42 HU, p <0.0001). A total of 30 calculi (60%) were located in the ureter, including 21 in the stone-free group and 9 in the residual stone group with a mean value of 505.10 +/- 46.66 and 888.70 +/- 102.00 HU, respectively, which was significantly different (p = 0.0005). A total of 20 calculi (40%) were located in the kidney, including 11 in the stone-free group and 9 in the residual stone group with a mean value of 558.40 +/- 62.38 and 905.10 +/- 61.49 HU, respectively, which was significantly different (p = 0.001). CONCLUSIONS: These findings suggest that HU measurement of urinary calculi on pretreatment non-contrast computerized tomography may predict the stone-free rate. This information may be beneficial for selecting the preferred treatment option for patients with urinary calculi.

Female↗

PubMed2002

Management of fossa navicularis strictures.

The correction of strictures involving the fossa navicularis poses a distinct reconstructive challenge. Unlike surgical repair of strictures involving other urethral segments where the primary concern is restoration of urethral patency, management of fossa navicularis strictures also requires particular attention to cosmesis. Paramount to the success of any of the described procedures is the careful selection of nondiseased tissue for substitution. If the penile skin is healthy, the preferred urethral substitute is the fasciocutaneous ventral transverse island flap. The inherent characteristics of this versatile flap (i.e., well-vascularized predictable pedicle, nonhair bearing, negligible contraction) provide for an excellent time-tested glandular urethral substitute. In rare cases in which there is a suggestion of penile skin inflammation or scarring, extragenital tissue transfer techniques should be considered. Equally important is the need to substitute the entire length of diseased urethra, preferably as an onlay, preserving the dorsal urethral wall. Persistent proximal urethral disease will eventually result in further stricture formation. Finally, the choice of glanduloplasty is particularly important in achieving a cosmetically appealing outcome. A glans-cap repair is preferred because of the limited dissection required with this relatively simple and bloodless technique. Careful selection of the most appropriate combined urethral substitution and glans reconstruction techniques, as well as meticulous attention to surgical details, are mandatory for achieving a satisfactory functional and cosmetic outcome with fossa navicularis strictures.

Balanitis↗

PubMed2002

Decreased suburethral prostatic microvessel density in finasteride treated prostates: a possible mechanism for reduced bleeding in benign prostatic hyperplasia.

PURPOSE: We evaluated the influence of finasteride on prostatic microvessel density to elucidate a mechanism of decreased bleeding in finasteride treated patients with hematuria secondary to benign prostatic hyperplasia (BPH). MATERIALS AND METHODS: A total of 22 patients with clinical BPH and gross hematuria who underwent prostate reductive surgery between 1998 and 2000 were prospectively evaluated. The prostate from 10 finasteride treated and 12 untreated patients was immunohistochemically stained for CD-34. Microvessel density analysis was performed by quantifying positive stained blood vessels located within the stroma of hyperplastic nodules as well as in the suburethral portion of the prostate. RESULTS: Mean microvessel density plus or minus standard deviation in finasteride treated patients was significantly lower in the suburethral portion of the prostate versus untreated controls (14.0 +/- 2.8 versus 20.2 +/- 5.3 vessels per high power field, p <0.05). In the nodular hyperplasia there was no statistically significant difference in the treatment and control groups (mean 17.5 +/- 2.8 and 16.7 +/- 4.6 vessels per high power field, respectively). CONCLUSIONS: Finasteride significantly decreases suburethral prostatic microvessel density in patients with BPH, which may explain its efficacy for decreasing BPH associated bleeding.

Aged↗