Francisco M. Sánchez

Transarterial Prostatic Embolization: Initial Experience in a Canine Model

OBJECTIVE The purpose of this study was to prospectively evaluate pathologic responses to transarterial prostatic embolization and its technical safety in a canine model. MATERIALS AND METHODS Ten adult male beagle dogs were surgically castrated and given hormonal therapy for 4 months to induce prostatic hyperplasia. After three months of hormonal therapy, the dogs were randomly assigned to a transarterial prostatic embolization group (n = 7) or a control group (n = 3). Dogs in the transarterial prostatic embolization group were subjected to embolization with microspheres 300-500 μm in diameter. Four months after the study was begun, all dogs were sacrificed for pathologic study. Transrectal ultrasound and MRI were performed to evaluate pathologic responses. The data on prostate size acquired with transrectal ultrasound were processed for statistical analysis by paired Student t test. RESULTS The canine prostatic hyperplasia model was successfully established in 10 dogs. The increase in mean prostate size being as great as 572% after 3 months of hormonal therapy. An intraprostatic cavity was detected 1 month after transarterial prostatic embolization in all seven dogs. Four dogs had significant shrinkage of the prostate, and the other three had an increase in prostate size. Imaging examinations and necropsy revealed a huge cavity occupying almost the entire prostate in the three dogs with increased prostate size. No complications associated with transarterial prostatic embolization were encountered. CONCLUSION Transarterial prostatic embolization is a safe procedure that can induce prostatic infarction and ablate the prostate. The findings suggest the procedure has potential clinical applications in the care of patients with benign prostatic hyperplasia.

Effectiveness of three-dimensional fluoroscopy in percutaneous nephrostomy: an animal model study.

OBJECTIVES To present, in an experimental study, an assessment of innovative digital fluoroscopy systems with three-dimensional (3D) reconstruction for use in endourologic applications. METHODS The experiment was performed in a pig model. We used 5 pigs. An obstructive uropathy model was created in the right kidney to dilate the urinary tract for group 1. Group 2 consisted of the nondilated left kidney. After selecting the tract on the 3D image, the lower caliceal group was punctured in the 2 kidneys under fluoroscopic control, to assess the efficiency of the 3D reconstruction when selecting the renal calix to be punctured. RESULTS The 3D reconstruction system allowed us to obtain reconstruct the pelvis in three dimensions, isolated as the pelvis and renal parenchyma, as well as the adjacent bony relationships. In this study, the success rate was 100% for locating the selected renal calix. CONCLUSIONS With this 3D reconstruction system, we were able to obtain a series of images that allowed for the study of the volume of the kidney, perfectly determining its renal calix distribution in the operating room. This enabled us to determine the precise delineation of the target calix. We, therefore, consider this new urologic application of fluoroscopy very useful in surgical planning for antegrade access of the upper urinary tract.

Prostatic Artery Embolization (PAE) for Symptomatic Benign Prostatic Hyperplasia (BPH): Part 2, Insights into the Technical Rationale

Rationale of prostatic artery embolization (PAE) in the treatment of symptomatic benign prostatic hyperplasia is conventionally believed to include two parts: shrinkage of the enlarged prostate gland as a result of PAE-induced ischemic infarction and potential effects to relax the increased prostatic smooth muscle tone by reducing the number and density of α1-adrenergic receptor in the prostate stroma. This review describes new insights into the likely mechanisms behind PAE, such as ischemia-induced apoptosis, apoptosis enhanced by blockage of androgens circulation to the embolized prostate, secondary denervation following PAE, and potential effect of nitric oxide pathway immediately after embolization. Studies on therapeutic mechanisms in PAE may shed light on potentially new treatment strategies and development of novel techniques.

Prostatic Artery Embolization (PAE) for Symptomatic Benign Prostatic Hyperplasia (BPH): Part 1, Pathological Background and Clinical Implications.

Pathological features of benign prostatic hyperplasia (BPH) dictate various responses to prostatic artery embolization (PAE). Typically, BPH originates in the transition zone and periurethral region, where should be considered the primary target area in PAE procedures. Given that histological heterogeneity of components in hyperplasia nodules, epithelial or stromal, identifying the more responsive nodules to PAE will have clinical implications. Since some lower urinary tract symptoms (LUTS) in patients with BPH are usually related to bladder outlet obstruction-induced changes in bladder function rather than to outflow obstruction directly, proper selection of candidate patients prior to PAE is of great clinical importance. BPH is a typical chronic progressive condition, suggesting PAE could aim not only to relieve LUTS but also to delay or prevent the clinical progression. Awareness of the pathological background of BPH is essential for interventional radiologists to improve clinical outcomes and develop new treatment strategies in clinical practice of PAE.

Carbon dioxide insufflation safety in double-balloon enteroscopy: an experimental animal study.

The aim of the present study was to assess the safety and efficacy of CO2 during double‐balloon enteroscopy (DBE) in an experimental animal model study. In this study, insufflation with room air and with CO2 was compared.

Experimental laparoscopic evaluation of double balloon versus spiral enteroscopy in an animal model.

Four pigs were subjected to enteroscopic exploration and divided into two groups: Double Balloon Enteroscopy (DBE group) and Spiral Enteroscopy (SE group). The explored length from the pylorus, the feed rate and the time of withdrawal were measured. Simultaneous laparoscopic view allowed evaluation of the enteroscopy maneuvers. During laparoscopy control it was easy to see air trapped in the intestine bent over the overtube, mainly in the DBE group, whereas vascular stress of the bowel wall was higher in the SE group, which was probably related with the spiral torsion observed in the jejunal vessels and the root of the mesentery (Fig. 1). This was not observed in the DBE group. Nevertheless, subperitoneal ecchymosis was observed in both groups, but with higher significance in the SE group. Furthermore, a small tear in the visceral peritoneum appeared in one pig (Fig. 2). The small bowel examined was 219.6 12.7 and 180.0 14.1 cm long, the feed rate was 4.05 and 5.62 cm/min and the time of withdrawal was 67 and 138 s, for the DBE and SE groups, respectively. The vascular supply to the bowel was apparently more altered in the SE group, which is likely determined by a compressive effect of the DSB overtube on the intestinal wall and intense rotation of the root of the mesentery. Akerman et al. indicate that small-bowel pleating is accomplished without apparent twisting of the small bowel because the mesentery attachment to the small bowel resists its rotation; however the laparoscopic visualization in the porcine model suggested that this process could be more iatrogenic than expected. The clockwise rotation of the DSB overtube mimics the motion of a corkscrew and pleats the small bowel onto the overtube, hence twisting the bowel and the mesenteric vessels in a more compressive way. The longer time of withdrawal in the SE could represent a clinical problem.

Metallic ureteral stents versus endoureterotomy as a therapeutic approach for experimental ureteral stricture.

PURPOSE To determine if the deployment of metallic ureteral stents in benign ureteral stricture is more effective than endoureterotomy. MATERIALS AND METHODS Twenty pigs were randomly divided in two groups to be treated with endoureterotomy or metallic stents. The internal ureteral diameter 2 cm distal to the ureteropelvic junction, histopathologic changes, ultrasonographic and fluoroscopic studies, urine culture, and serum urea and creatinine levels were analyzed during the phases of the study. The study was divided into three phases. The first included premodel documentation of normal urinary tract and laparoscopic ureteral stricture induction. In the second phase 1 month later, diagnosis and endoureteral treatment were carried out. Twelve weeks after stricture treatment, follow-up imaging studies and postmortem evaluation of all animals were performed. RESULTS The success rates were 80% for endoureterotomy and 70% for metallic stent implantation. In all animals in the latter group, a ureteral hyperplasic reaction took place that affected the zone of stent implantation. One difference between the groups was the presence of urinary infection in 30% of animals in the endoureterotomy group and in no animals treated with metallic stents. Statistically significant differences in ureteral diameter between the first and second study phases were found within both groups (P < .0001), but not between groups (P = .021). Results from pathologic analysis revealed statistically significant differences between groups (P = .0029). CONCLUSIONS The interaction among the distal end of the metallic stent, the urothelium, and peristalsis might be the origin of the failure of these devices. Although the deployment of metallic stents is attractive compared with other endourologic techniques like endoureterotomy in cases of benign strictures, certain problems must be resolved to prevent hyperplasia. Until then, this technique will not be a fully reliable therapeutic option for ureteral disorders.

Biological response of laser macrostructured and oxidized titanium alloy: an in vitro and in vivo study.

PURPOSE To assess both the in vitro and in vivo biological response of a laser modified surface in an integrated manner. A combined innovative approach applies lasers to macrostructure as well as to oxidize the surface of titanium alloy implants. MATERIALS AND METHODS A Nd:YAG marking and ArF excimer lasers were used for macrostructuring and UV-oxidizing the surface of Ti6Al4V discs, respectively. Human fetal osteoblastic cell culture and a sheep tibia model were used to assess the cell response and the osseogeneration capability of as-machined, laser macrostructured and laser macrostructured and oxidized surfaces. RESULTS In vitro: Laser macrostructuration alone did not promote cell response. Cellular proliferation was enhanced by the additional UV laser oxidation. In vivo: A greater significant percentage of bone-implant contact was obtained for both laser treated surfaces compared to machine-turned control samples, three months after implantation, in spite of the low cellular response for macrostructured samples. The use of sheep model for six months appears to be less adequate for a comparison because of the high level of bone integration in all samples. In spite of the often reported positive effect of titanium oxidation on the triggering of faster osseointegration, in this experiment the additional UV laser oxidation did not lead to a significant in vivo improvement. CONCLUSIONS Laser macrostructuration of titanium alloy surfaces appears to promote bone apposition and may therefore constitute a promising surface modification strategy. In animal models, the natural process of titanium surface oxidation, because of physiologic fluids, alters properties observed in vitro with cells.

Continuous Vagus Nerve Stimulation Effects on the Gut-Brain Axis in Swine

Objectives.  This study was designed to assess vagus nerve stimulation effects on the food intake pattern in swine and determine the electrical stimulus direction.

New combined approach in metallic ureteral stenting to avoid urothelial hyperplasia: study in swine model.

PURPOSE We assessed the therapeutic value of a new treatment option for ureteral strictures that may avoid urothelial hyperplasia, which is the main cause of metallic stent failure. MATERIALS AND METHODS We used 24 pigs in this study. An experimental model of ureteral stricture was induced in all animals. Obstruction was confirmed by ultrasound and retrograde ureteropyelogram 6 weeks after model creation. The pigs were then randomly allocated to 2 experimental groups. Therapy involved placement of a 6 × 30 mm metallic ureteral covered stent in the ureteral stricture in group 1 and subsequent endoureterotomy at the ureteral segments adjacent to the 2 ends of the stent in group 2. A double pigtail stent was then deployed for 3 weeks. Completion studies 6 months after therapy included retrograde ureteropyelogram, endoluminal ultrasound and ureteroscopy to assess urothelial hyperplasia formation. RESULTS At the end of the study evidence of urothelial hyperplasia was seen in 50% of the pigs in group 1 and in 29% in group 2. Four and 2 cases of cranial stent migration in groups 1 and 2, respectively, were seen at 6 months. Hyperplasia and renal involvement were statistically significantly different between the groups with more damage in group 1 than in group 2. CONCLUSIONS Hyperplasia was markedly reduced when ureteral peristalsis was inhibited by endoureterotomy at the area of interaction between the stent and the ureter.