Perivascular vital cells in the ablation center after multibipolar radiofrequency ablation in an in vivo porcine model

Multibipolar radiofrequency ablation (RFA) is an advanced ablation technique for early stage hepatocellular carcinoma and liver metastases. Vessel cooling in multibipolar RFA has not been systematically investigated. The objective of this study was to evaluate the presence of perivascular vital cells within the ablation zone after multibipolar RFA. Multibipolar RFA were performed in domestic pigs in vivo. Three internally cooled bipolar RFA applicators were used simultaneously. Three experimental settings were planned: (1) inter-applicator-distance: 15 mm; (2) inter-applicator-distance: 20 mm; (3) inter-applicator-distance: 20 mm with hepatic inflow occlusion (Pringle maneuver). A vitality staining was used to analyze liver cell vitality around all vessels in the ablation center with a diameter > 0.5 mm histologically. 771 vessels were identified. No vital tissue was seen around 423 out of 429 vessels (98.6%) situated within the central white zone. Vital cells could be observed around major hepatic vessels situated adjacent to the ablation center. Vessel diameter (> 3.0 mm; p < 0.05) and low vessel-to-ablation-center distance (< 0.2 mm; p < 0.05) were identified as risk factors for incomplete ablation adjacent to hepatic vessels. The vast majority of vessels, which were localized in the clinically relevant white zone, showed no vital perivascular cells, regardless of vessel diameter and vessel type. However, there was a risk of incomplete ablation around major hepatic vessels situated directly within the ablation center. A Pringle maneuver could avoid incomplete ablations.

Sacral nerve stimulation in patients with ileal pouch-anal anastomosis

PURPOSE

Functional results after proctocolectomy and ileal pouch-anal anastomosis (IPAA) are generally good. However, some patients suffer from high stool frequency or fecal incontinence. Sacral nerve stimulation (SNS) may represent a therapeutic alternative in these patients, but little is known about indication and results. The aim of this study was to evaluate incontinence after IPAA and demonstrate SNS feasibility in these patients.

METHODS

This retrospective study includes patients who received a SNS between 1993 and 2020 for increased stool frequency or fecal incontinence after proctocolectomy with IPAA for ulcerative colitis. Proctocolectomy was performed in a two- or three-step approach with ileostomy closure as the last step. Demographic, follow-up data and functional results were obtained from the hospital database.

RESULTS

SNS was performed in 23 patients. Median follow-up time after SNS was 6.5 years (min. 4.2-max. 8.8). Two patients were lost to follow-up. The median time from ileostomy closure to SNS implantation was 6 years (min. 0.5-max. 14.5). Continence after SNS improved in 16 patients (69%) with a median St. Marks score for anal incontinence of 19 (min. 4-max. 22) before SNS compared to 4 (0-10) after SNS placement (p = 0.012). In seven patients, SNS therapy was not successful.

CONCLUSION

SNS implantation improves symptoms in over two-thirds of patients suffering from high stool frequency or fecal incontinence after proctocolectomy with IPAA. Awareness of the beneficial effects of SNS should be increased in physicians involved in the management of these patients.

[Natural orifice transluminal endoscopic surgery in Germany: Data from the German NOTES registry]

BACKGROUND

The German NOTES registry (GNR) was initiated by the German Society for General and Visceral Surgery (DGAV) as a treatment and outcome database for natural orifice transluminal endoscopic surgery (NOTES).

AIM

The aim of this study was the descriptive analysis of all GNR data collected over a 5-year period since its start in 2008 with more than 3000 interventions.

MATERIAL AND METHODS

The GNR is an online database with voluntary participation available to all German-speaking clinics. Demographic data, therapy details, complications and data on the postoperative course of patients are recorded. All cases in the GNR between March 2008 and November 2013 were included in the analysis.

RESULTS

From a total of 3150 data sets 2992 (95 %) were valid and suited for the analysis. Hybrid transvaginal cholecystectomy was the most frequently used procedure (88.7 %), followed by hybrid transvaginal/transgastric appendectomy (6.1 %) and hybrid transvaginal/transrectal colon procedures (5.1 %). Intraoperative complications occurred in 1.6 %, postoperative complications in 3.7 % and conversions were reported in 1.5 %. Intraoperative bladder injuries and postoperative urinary tract infections were identified as method-specific complications of transvaginal procedures. Bowel injuries occurred as a rare (0.2 %) but potentially serious complication of transvaginal operations.

CONCLUSION

The German surgical community ensures a safe and responsible introduction of the new NOTES operation techniques with its active participation in the GNR. Despite an overall low complication rate, the high number of procedures in the GNR permitted the identification of method-specific complications. This knowledge can be used to further increase the safety of NOTES in practice.

[Stump closure in laparoscopic appendectomy. Influence of endoloop or linear stapler on patient outcome]

BACKGROUND

Even though laparoscopic appendectomy is one of the most frequent procedures in abdominal surgery, the technique of appendiceal stump closure is still not standardized. The aim of this retrospective study was to analyze the effect of the use of endoloops or linear staplers for appendiceal stump closure concerning surgical site infections (SSI) and intra-abdominal abscesses (IAA).

PATIENTS AND METHODS

All laparoscopic appendectomies between January 1st 2007 and May 31st 2010 were split into an endoloop group (ELG) and a linear stapler group (LSG). The groups were compared with respect to the outcome parameters SSI and IAA.

RESULTS

A total of 430 appendectomies were performed in the study period of which 105 operations were conducted laparoscopically. In this study 47.6 % (n = 50) were alloted to the LSG and 52.4 % (n = 55) to ELG. In LSG 3.1 % (n = 1) developed an SSI versus 10.0 % (n = 4, p = 0.254) in ELG. No IAAs occurred in LSG compared to 2 (5.1 %, p = 0.499) in ELG.

CONCLUSION

The use of EL for appendiceal stump closure is safe and cost effective for low-grade appendicitis but high-grade appendicitis should be treated with LS.

[Safety of resection of symptomatic and asymptomatic Meckel's diverticulum and literature review]

BACKGROUND

Meckel's diverticulum (MD) is the most common diverticulum of the small bowel and an important finding in surgical practice. The aim of this study was to assess the safety of the resection of symptomatic and asymptomatic MD concerning postoperative complications. As MD are relatively rare, an overview of the literature is given.

PATIENTS AND METHODS

All patients with MD at the department at general surgery of the Charité - Campus Benjamin Franklin between 1996 and 2010 were assessed. An analysis for symptomatic and incidental MD was performed for incidence, indication, intraoperative findings, histology and postoperative outcome.

RESULTS

An MD was intraoperatively found in 71 of 29 682 patients (0.2 %). Of these, a symptomatic MD occurred in 26 patients (37 %). A symptomatic MD was causal in 6 of 7 patients with gastrointestinal bleeding (GIB, p = 0.005). All symptomatic MD and 30 (67 %) asymptomatic MD were resected. Ectopic gastric mucosa was found significantly more frequently in patients with symptomatic MD (p = 0.001). Patients with asymptomatic MD and resection had less complications as a trend (p = 0.057).

CONCLUSION

Ectopic mucosa is more frequent in symptomatic MD, especially in bleeding MD. MD should always be considered in GIB of unknown origin. Resection of incidental MD can be recommended in patients without contraindications such as peritonitis, cancer, ascites or immunosuppression.

[Simulation training in surgical education - application of virtual reality laparoscopic simulators in a surgical skills course]

BACKGROUND

Training and simulation are gaining importance in surgical education. Today, virtual reality surgery simulators provide sophisticated laparoscopic training scenarios and offer detailed assessment methods. This also makes simulators interesting for the application in surgical skills courses. The aim of the current study was to assess the suitability of a virtual surgery simulator for training and assessment in an established surgical training course.

MATERIALS AND METHODS

The study was conducted during the annual "Practical Course for Visceral Surgery" (Warnemuende, Germany). 36 of 108 course participants were assigned at random for the study. Training was conducted in 15 sessions over 5 days with 4 identical virtual surgery simulators (LapSim) and 2 standardised training tasks. The simulator measured 16 individual parameters and calculated 2 scores. Questionnaires were used to assess the test persons' laparoscopic experience, their training situation and the acceptance of the simulator training. Data were analysed with non-parametric tests. A subgroup analysis for laparoscopic experience was conducted in order to assess the simulator's construct validity and assessment capabilities.

RESULTS

Median age was 32 (27 - 41) years; median professional experience was 3 (1 - 11) years. Typical laparoscopic learning curves with initial significant improvements and a subsequent plateau phase were measured over 5 days. The individual training sessions exhibited a rhythmic variability in the training results. A shorter night's sleep led to a marked drop in performance. The participants' different experience levels could clearly be discriminated ( ≤ 20 vs. > 20 laparoscopic operations; p ≤ 0.001). The questionnaire showed that the majority of the participants had limited training opportunities in their hospitals. The simulator training was very well accepted. However, the participants severely misjudged the real costs of the simulators that were used.

CONCLUSIONS

The learning curve on the simulator was successfully mastered during the course. Construct validity could be demonstrated within the course setting. The simulator's assessment system can be of value for the assessment of laparoscopic training performance within surgical skills courses. Acceptance of the simulator training is high. However, simulators are currently too expensive to be used within a large training course.

Fast Estimation of the Vascular Cooling in RFA Based on Numerical Simulation

We present a novel technique to predict the outcome of an RF ablation, including the vascular cooling effect. The main idea is to separate the problem into a patient independent part, which has to be performed only once for every applicator model and generator setting, and a patient dependent part, which can be performed very fast. The patient independent part fills a look-up table of the cooling effects of blood vessels, depending on the vessel radius and the distance of the RF applicator from the vessel, using a numerical simulation of the ablation process. The patient dependent part, on the other hand, only consists of a number of table look-up processes. The paper presents this main idea, along with the required steps for its implementation. First results of the computation and the related ex-vivo evaluation are presented and discussed. The paper concludes with future extensions and improvements of the approach.

["Practical course for visceral surgery in Warnemünde" 10 years on. Significance and benefits of a surgical training course]

BACKGROUND

Skill courses for surgery offer a good but cost and personnel-intensive possibility to obtain practical and theoretical knowledge by the employment of a close teacher-pupil contact of a large group of surgeons. The goal of the study presented here was to evaluate the satisfaction and benefits of the practical course for visceral surgery in Warnemünde after 10 years of course experience.

MATERIAL AND METHODS

All participants in the annual course for visceral surgery were included since 1999. During this 1-week course conventional and laparoscopic exercises are performed under direct guidance of an experienced tutor. The participants are divided into 3 groups based on their surgical experience (e.g. <3 years, 3-5 years, >5 years). All participants received a standardised questionnaire before and after successful course completion for the collection of relevant data (e.g. demography, training, surgical experience and course evaluation).

RESULTS

A total of 1,062 participants (435 female, 627 male, mean age 37 years) participated in the course. The average surgical experience of the participants was 5 years. Of the participants 489 came from a hospital of basic medical care, 499 from a hospital of maximum medical care and 74 from a university hospital. Of the participants 96% had no or only little experience with skill courses (1,020 out of 1,065) and 827 participants had no or only few possibilities for training outside of the operation room (78%). The conventional part of the course was evaluated by 77% of the participants as very good and by 50% as very good for the laparoscopic part. Only 8.3% of the participants were willing to finance the costs of the course by themselves.

CONCLUSIONS

The practical course for visceral surgery leads to a subjective success in learning. Participation in the course leads to a high satisfaction and offers a cost-intensive possibility for a standardised surgical training. But there are too few experiences with skill courses and possibilities for surgical training outside the operation room so far.

Improving laser-induced thermotherapy of liver metastases--effects of arterial microembolization and complete blood flow occlusion

INTRODUCTION

A prerequisite for an oncologically curative application of laser-induced thermotherapy (LITT) of liver metastases is complete tumor destruction. This increased effectiveness was achieved experimentally by combining LITT with interrupted hepatic perfusion. The aim of this study was to evaluate whether an interventional selective arterial microembolization might be as effective as complete blood flow occlusion using an open Pringle's maneuver.

PATIENTS AND METHODS

We included patients with unresectable colorectal liver metastases. LITT was performed without interrupted hepatic perfusion (control group) compared to LITT in combination with interrupted perfusion either by embolization of intraarterial degradable starch microspheres (DSM) (percutaneous access) or by complete hepatic inflow occlusion (Pringle's maneuver; open access). Online monitoring was performed using intraoperative ultrasound or MRI. Volumetric techniques were used to assess metastases and postinterventional lesions.

RESULTS

Fifty-six patients with 104 metastases (control group (25), DSM (37), and Pringle (42)) were treated. The preinterventional tumor volumes were significantly smaller than the postinterventional lesion volumes (control group: 9.8 vs. 25.3 cm3; DSM: 9.5 vs. 65.4 cm3; Pringle: 12.9 vs. 76.5 cm3). The morbidity rate was 21.4% without treatment-related mortalities. After 6 months follow-up, tumor recurrence was diagnosed in 6 patients (control group (4), LITT with DSM (1), and Pringle (1)).

CONCLUSIONS

Combining LITT with blood flow occlusion leads to a significant increase in lesion size. The application of DSM offers a safe and effective alternative to the open access with Pringle's maneuver. Compared to LITT-monotherapy, this modality achieves significantly larger thermal lesions with the need of fewer applications.

Laser-induced thermotherapy: intra- and extralesionary recurrence after incomplete destruction of experimental liver metastasis

PURPOSE

The aim of this study was to determine the energy (J/mm3 tumor volume) and temperature required for a complete laser-induced thermotherapy (LITT) of experimental liver tumors, and to find out causes and areas of local recurrence followed by incomplete treatment.

METHODS

In VX-2 tumor-bearing rabbits LITT was performed using neodymium:yttrium-aluminum-garnet (Nd:YAG) laser (1064 nm) with a diffuser-tip applicator and a temperature feedback system. The animals were randomized into four groups (n = 20) that differed in the target temperature at the tumor border as follows: 45 degrees C, 50 degrees C, 55 degrees C and 60 degrees C. The target temperature was held for 10 min constant. Histologic examination (hematoxylin and eosin [H and E], nicotinamide adenine dinucleotide phosphate [NADPH]-dehydrogenase) was performed at 0 h, 24 h, 96 h, and 14 days after LITT.

RESULTS

The pretreatment tumor volume of 2191 +/- 61 mm3 was the same for all groups (p > 0.05). Energy up to target temperature and total energy required, lesion size, and the rate of incomplete tumor ablation (recurrences) are listed below (ap < 0.05, Kruskal-Wallis test). Histologically, two forms of local recurrences could be differentiated intralesionary and extralesionary.

CONCLUSIONS

To achieve complete in situ ablation under the given conditions, it is necessary to apply laser energy of 3 J/mm3 tumor volume. A minimum temperature of 60 degrees C on the tumor border presumed an application of 10 min. Recurrence was found outside the coagulation zone (extralesionary) and in high vascularized areas within the coagulation zone (intralesionary).