Jörg P. Ritz

The German Registry for Natural Orifice Translumenal Endoscopic Surgery: Report of the First 551 Patients

Objective:To analyze patient outcome in the first 14 months of the German natural orifice translumenal endoscopic surgery (NOTES) registry (GNR). Summary Background Data:NOTES is a new surgical concept, which permits scarless intra-abdominal operations through natural orifices, such as the mouth, vagina, rectum, or urethra. The GNR was established as a nationwide outcome database to allow the monitoring and safe introduction of this technique in Germany. Methods:The GNR was designed as a voluntary database with online access. All surgeons in Germany who performed NOTES procedures were requested to participate in the registry. The GNR recorded demographical and therapy data as well as data on the postoperative course. Results:A total of 572 target organs were operated in 551 patients. Cholecystectomies accounted for 85.3% of all NOTES procedures. All procedures were performed in female patients using transvaginal hybrid technique. Complications occurred in 3.1% of all patients, conversions to laparoscopy or open surgery in 4.9%. In cholecystectomies, institutional case volume, obesity, and age had substantial effect on conversion rate, operation length, and length of hospital stay, but no effect on complications. Conclusions:Despite the fact that NOTES has just recently been introduced, the technique has already gained considerable clinical application. Transvaginal hybrid NOTES cholecystectomy is a practicable and safe alternative to laparoscopic resection even in obese or older patients.

Laser-Induced Thermotherapy Combined With Hepatic Arterial Embolization in the Treatment of Liver Tumors in a Rat Tumor Model

OBJECTIVEnTo assess the effect of combined laser-induced thermotherapy (LITT) and hepatic arterial embolization with degradable starch microspheres (DSM) on tumor response and intrahepatic temperature distribution in rats with liver tumors.nnnSUMMARY BACKGROUND DATAnLaser-induced thermotherapy is a promising in situ ablation technique for malignant liver tumors. However, clinical use is still limited, mainly because of the small size of the inducible coagulation necroses. This results in insufficient tumor destruction.nnnMETHODSnColon carcinoma CC531 was implanted in 60 WAG rat livers. Fourteen days later, a silicon catheter was implanted in the hepatic artery for DSM administration. Tumors were exposed to 1064 nm Nd:YAG laser light at 2 watts for 10 minutes from a diffuser tip applicator placed in the tumor. The animals were randomized into a sham-operated control (group I) and three test groups. Group II received DSM alone, group III received LITT alone, and group IV received DSM + LITT. Tumor control was examined 1, 7, and 14 days after treatment.nnnRESULTSnA complete tumor remission was achieved in all rats treated with LITT + DSM (group IV). In contrast, tumor progression was seen in animals treated with LITT alone (group III) or DSM alone (group II), as well as in the sham-operated controls (group I).nnnCONCLUSIONSnThe authors results suggest that the combination of LITT and DSM considerably increases the efficacy of LITT in the treatment of liver metastases in the rat.

MR-guided interstitial laser-induced thermotherapy of hepatic metastasis combined with arterial blood flow reduction: technique and first clinical results in an open MR system.

The feasibility and safety of percutaneous laser‐induced thermotherapy (LITT) of liver metastases in an open low‐field magnetic resonance imaging (MRI) system combined with microsphere‐modulated blood flow reduction were tested. Nd:YAG laser therapy with an internally cooled laser applicator was performed under local anesthesia on 20 patients with 34 liver metastases. To increase the effectivenes of LITT, degradable starch microspheres were injected into the proper hepatic artery through an MR‐visible catheter initially inserted under fluoroscopy. Near real‐time imaging was used for positioning the laser applicator. A T1‐weighted gradient‐echo breath‐hold sequence was used for catheter localization and temperature monitoring. The volumes of the liver metastases and the thermonecroses were determined. MRI‐guided LITT could be performed in all patients with no clinically relevant complications. Intraprocedural imaging underestimated the extent of thermonecrosis. In conclusion, percutaneous LITT of liver metastases after injection of starch microspheres is both technically feasible and safe in an open MRI system. J. Magn. Reson. Imaging 2001;13:31–36.

Influence of intrahepatic vessels on volume and shape of percutaneous thermal ablation zones: in vivo evaluation in a porcine model.

Objectives:Aim of the study was to evaluate the precise influence of different intrahepatic vessels, vessel sizes, and distances from the applicator on volume and shape of hepatic laser ablation zones in an in vivo porcine model. Materials and Methods:The study was approved by the institutional animal care and use committee. Eighteen computed tomography-guided Nd:YAG laser ablations were performed in the livers of 10 pigs at varying distances from hepatic veins and portal fields. After hepatectomy the livers were cut into 2-mm slices perpendicular to the laser applicator axes. For each ablation zone the maximum achievable (ideal) volume, the segmented (real) volume, the maximum radius, and the radius at the position of adjacent hepatic vessels were determined. The shapes of the ablation zones were evaluated qualitatively. Comparative statistics using the unpaired t test and a multiple linear regression analysis were performed. Results:Ideal and real ablation zone volumes differed by 27.3% (8.6 ± 1.5 mL vs. 6.4 ± 1.1 mL; P < 0.0001). Thirty-eight of 60 (63%) hepatic veins versus 28 of 31 (90%) portal veins within the central slices of the 18 ablation zones led to a reduction of the ablation zones radius, depending on the distance between the vessel and the applicator and the vessel type. Portal fields revealed stronger effects than hepatic veins. The vessel diameter showed no independent effect (P > 0.05). When influencing, all hepatic veins showed a focal indentation whereas portal fields always showed broad flattening of the ablation zone. Conclusions:Portal fields lead to more heat sink than hepatic veins. The effects decreased with the distance between vessel and applicator tip, but less so for portal fields. The 2 vessel types induced considerably different shape alterations of the ablation zones. These results were not dependent on vessel size. This should be considered in the planning of thermal tumor ablations.

Total Extraperitoneal Hernioplasty: Does the Long-Term Clinical Course Depend on the Type of Mesh?

INTRODUCTIONnImplantation of alloplastic material has become a standard surgical procedure in inguinal hernia repair. The properties of different meshes are discussed as determinants of postoperative outcome. The aim of this study was to comparatively evaluate long-term results after total extraperitoneal hernioplasty (TEP) with a heavyweight polypropylene mesh (PP) and a lightweight polypropylene-polyglactin composite mesh (PP-PG) in a large patient population.nnnMATERIALS AND METHODSnThe study included patients who underwent TEP for elective repair of uni- or bilateral inguinal hernias between June 1997 and October 2004. We used a heavyweight PP mesh from June 1997 to February 2001 and a lightweight PP-PG mesh from March 2001 to October 2004. Patient data were evaluated by a prospective online registry, and long-term results were assessed by standardized ad hoc questionnaires after a minimum follow-up of 12 (12-103) months.nnnRESULTSnFive hundred twenty-two patients aged 18-87 years underwent surgical repair of 655 inguinal hernias, and 370 (70.8%) were evaluated. TEP was performed with PP mesh in 192 cases and with PP-PG mesh in 169 cases. Nine patients died during follow-up; 14.6% (PP) versus 20.1% (PP-PG) patients complained of mild pain, and 8.9% (PP) versus 5.3% (PP-PG) patients reported moderate to severe pain (P > 0.05). Mild dysesthesias occurred in 13.5% of the PP group and 11.8% of the PP-PG group (P = 0.63). Moderate to severe dysesthesias were reported by 6.8% with a heavyweight mesh and by 3.0% with a lightweight mesh (P = 0.10). There were no significant differences with regard to the patients postoperative return to normal daily activities. The recurrence rate was 5.2% with a PP mesh and 1.8% with a PP-PG mesh (P = 0.08).nnnCONCLUSIONSnThe long-term results after TEP showed no difference between PP and PP-PG meshes with regard to chronic pain, chronic dysesthesias, postoperative daily activities, and recurrence rates.

Minimal vascular flows cause strong heat sink effects in hepatic radiofrequency ablation ex vivo.

The present paper aims to assess the lower threshold of vascular flow rate on the heat sink effect in bipolar radiofrequency ablation (RFA) ex vivo.

Finding Optimal Ablation Parameters for Multipolar Radiofrequency Ablation

Purpose. Radiofrequency ablation (RFA) for primary liver tumors and liver metastases is restricted by a limited ablation size. Multipolar RFA is a technical advancement of RFA, which is able to achieve larger ablations. The aim of this ex vivo study was to determine optimal ablation parameters for multipolar RFA depending on applicator distance and energy input. Methods. RFA was carried out ex vivo in porcine livers with three internally cooled, bipolar applicators in multipolar ablation mode. Three different applicator distances were used and five different energy inputs were examined. Ablation zones were sliced along the cross-sectional area at the largest ablation diameter, orthogonally to the applicators. These slices were digitally measured and analyzed. Results. Sixty RFA were carried out. A limited growth of ablation area was seen in all test series. This increase was dependent on ablation time, but not on applicator distance. A steady state between energy input and energy loss was not observed. A saturation of the minimum radius of the ablation zone was reached. Differences in ablation radius between the three test series were seen for lowest and highest energy input (P < .05). No differences were seen for medium amounts of energy (P > .05). Conclusions. The ablation parameters applicator distance and energy input can be chosen in such a way, that minor deviations of the preplanned ablation parameters have no influence on the size of the ablation area.