Efficiency analysis of bipolar and multipolar radiofrequency ablation in an in vivo porcine kidney model using three-dimensional reconstruction of histologic section series.

BACKGROUND AND PURPOSE: Radiofrequency ablation (RFA) was established for minimally invasive treatment of small kidney tumors in multimorbid patients. Bipolar and multipolar RFA may allow the treatment of larger tumors. Safe tumor coagulation depends on total energy supplied and proper electrode placing. To investigate the influence of energy on ablation size and shape in intact kidneys, we used cooled bipolar and multipolar RFA in an in vivo pig model. MATERIALS AND METHODS: Twenty-five male pigs were treated with percutaneous bipolar (one electrode) or multipolar (two electrodes) RFA with various energy transfer under laparoscopic visual control. The animals were sacrificed 4 to 5 hours after RFA. Volume and shape of the coagulation zone was analyzed by three-dimensional reconstruction of hematoxylin and eosin and diaminobenzidine stained paraffin serial sections. Heat-induced cellular activation was addressed by immunohistologic detection of apoptosis marker proteins heat shock protein 70 (Hsp70) and caspase-3 (Casp3). RESULTS: Multipolar RFA led to significant larger tissue ablation than bipolar RFA. Increasing energy, however, did not result in significant enlargement of the coagulation volume. Shape control was better in bipolar RFA. Hsp70 and activated Casp3 immunoreactivity were increased close to the central coagulation zone and occasionally in the caliceal system. CONCLUSIONS: RFA causes minimal tissue damage beyond the primary coagulation zone, indicating that RFA is a safe, minimally invasive method for treatment of renal tumors. The ablation of larger volumes necessitates further improvement of multipolar RFA. These findings may be of general interest, because treatment failure correlates with mass size in monopolar RFA and cryoablative techniques as well.

A new vagal anchor electrode for real-time monitoring of the recurrent laryngeal nerve.

BACKGROUND: Despite conventional neuromonitoring, the recurrent laryngeal nerve (RLN) is still at risk for damage during thyroid surgery. The feasibility of continuous RLN monitoring by vagal nerve (VN) stimulation with a new anchor electrode should be shown, and electromyographic signal alterations of stressed RLN were analyzed to be alerted to imminent nerve failure whereby the nerve damage becomes reversible. METHODS: VN stimulation was achieved in 23 pigs. Sensed signals were analyzed and stored as real-time audio/video feedback EMG system. RLN was stressed by mechanical and thermal injury; signal alterations were evaluated. RESULTS: VNs were successfully real-time stimulated by using the anchor electrode. No complications or side effects during stimulation were detected. RLN injury led to an alteration of signal amplitude and latency period but signal restitution after injury. CONCLUSIONS: Real-time monitoring of the RLN is technically feasible to perceive imminent nerve failure. The anchor electrode was safely and easy to handle. Its implementation is being tested in an ongoing clinical trial.

The endoscopic extraperitoneal radical prostatectomy (EERPE): technique and initial experience.

Using the experiences of the extraperitoneal (endoscopic pelvic lymphadenectomy and inguinal hernia repair) and the transperitoneal approach (laparoscopic radical prostatectomy), we developed a totally extraperitoneal approach to endoscopic radical prostatectomy. In view of the favourable short-term outcome, we describe the technique of totally extraperitoneal endoscopic radical prostatectomy (EERPE) as a now standardised procedure. After creating the preperitoneal space by balloon dissection, five trocars were placed in the hypogastrium, allowing immediate access to the space of Retzius. The surgical technique of EERPE replicates the steps of the classical retropubic descending radical prostatectomy with slight modifications. The procedure starts with exposing the Retzius space and pelvic lymph node dissection. After that, the endopelvic fascia and the puboprostatic ligaments are incised, followed by ligating the Santorini plexus. The actual prostate dissection is similar to the open descending approach: bladder neck dissection, freeing of the seminal vesicles, transsectioning of the prostatic vesicles (with or without preserving the neurovascular bundles) and, finally, apical dissection. A water-tight urethrovesical anastomosis is performed with interrupted sutures. There were 20 patients who underwent EERPE. Mean operating time was 170 min with no conversion. No major complications occurred. Only one patient required a blood transfusion. The catheter could be removed on postoperative day 6 (n = 17) or on postoperative day 12 (n = 3). Final pathologic evaluations were 4 stage pT2a, 10 stage pT2b, 5 stage pT3a, and 1 pT3b. Surgical margins were negative in 17 patients. By avoiding entry into the peritoneal cavity, therefore, obviating intra-abdominal complications, such as bowel injury, ileus, or intestinal adhesions, the extraperitoneal endoscopic access provides a safe and minimally invasive approach to the prostate, combining the advantages of minimally invasive laparoscopy and retropubic open prostatectomy.