Georgi Vassilev

Dr. Georgi Vassilev


Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 May 2020 in Obesity Surgery
Verified
Journal Article
Open access
PDF file
IKIoannis Karampinis
Ioannis Karampinis
ELEliette Lion
Eliette Lion
SHSvetlana Hetjens
Svetlana Hetjens
GVGeorgi Vassilev
Georgi Vassilev
CGChristian Galata
Christian Galata
MOMirko Otto
Mirko Otto
Background: The exact prevalence of trocar site hernias after bariatric procedures is not yet known. Recent metaanalysis data indicated concerning rates of up to 25%. We conducted a prospective cohort study to estimate the prevalence and analyze the role of fascia closure in the development of trocar hernias. Method: A total of 365 patients who were operated for obesity in our department between 2009 and 2018 were included. All patients were invited for a follow-up ultrasonography scan in order to detect abdominal wall defects. The role of intraoperative fascia closure in the development of trocar site hernias was evaluated, and a logistic regression analysis was performed to detect potential risk factors. Results: The overall prevalence of trocar hernias detected by ultrasonography was 34%. The prevalence of abdominal wall defects in patients who received a fascia closure was 37% compared with 34% in patients who did not receive a fascia closure (p = 0.37). The only factor that was associated with a higher risk for trocar site hernias was high excessive weight loss (p = 0.05). Conclusion: Trocar site hernias are an underestimated complication of minimally invasive, multiportal bariatric surgery, and the prevalence of asymptomatic hernias is probably higher than initially expected. In this study, fascia closure did not protect against trocar hernias. However, opposing evidence from similar trials suggests closing the fascia. This clinical problem should therefore be further assessed in a prospective randomized setting.

Verified
Journal Article
Open access
PDF file
GVGeorgi Vassilev
Georgi Vassilev
CGChristian Galata
Christian Galata
AFAlida Finze
Alida Finze
CWChristel Weiss
Christel Weiss
MOMirko Otto
Mirko Otto
SBSusanne Blank
Susanne Blank
Background: In sarcopenic patients the skeletal muscle reduction is the primary symptom of age- or disease-related malnutrition, which is linked to postoperative morbidity and mortality. The skeletal muscle mass index (SMI) from magnet resonance imaging (MRI) is increasingly used as a prognostic factor in oncologic and surgical patients, but under-represented in the field of obesity surgery. The bioelectrical impedance analysis (BIA), on the other hand is a commonly used method for the estimation of the body composition of bariatric patients, but still believed to be inaccurate, because of patient-related and environmental factors. The aim of this study was to compare the postoperative SMI values as a direct, imaging measured indicator for muscle mass with the BIA results in patients undergoing Roux-en-Y gastric bypass (RYGB). Methods: We performed a prospective single-center trial. Patients undergoing RYGB between January 2010 and December 2011 at our institution were eligible for this study. MRI and BIA measurements were obtained 1 day before surgery and at 6, 12 and 24 weeks after surgery. Results: A total of 17 patients (four male, 13 female, average age of 41.9 years) were included. SMI values decreased significantly during the postoperative course (p < 0.001). Comparing preoperative and postoperative measurements at 24 weeks after surgery, increasing correlations of SMI values with body weight (r = 0.240 vs. r = 0.628), phase angle (r = 0.225 vs. r = 0.720) and body cell mass (BCM, r = 0.388 vs. r = 0.764) were observed. Conclusions: SMI decreases significantly after RYGB and is correlated to distinct parameters of body composition. These findings show the applicability of the SMI as direct imaging parameter for the measurement of the muscle mass in patients after RYGB, but also underline the important role of the BIA, as a precise tool for the estimation of patients’ body composition at low costs. BIA allows a good overview of patients’ status post bariatric surgery, including an estimation of sarcopenia.

30 August 2021 in Obesity Surgery
Verified
Journal Article
Closed access
PDF file
CYCui Yang
Cui Yang
JBJulia Brecht
Julia Brecht
CWChristel Weiß
Christel Weiß
CRChristoph Reissfelder
Christoph Reissfelder
MOMirko Otto
Mirko Otto
GVGeorgi Vassilev
Georgi Vassilev

24 October 2021 in Journal of Clinical Medicine
Verified
Journal Article
Open access
PDF file
CYCui Yang
Cui Yang
Christoph ReissfelderChristoph Reissfelder
Christoph Reissfelder
Christoph ReissfelderChristoph Reissfelder
Christoph Reissfelder
GVGeorgi Vassilev
Georgi Vassilev
GVGeorgi Vassilev
Georgi Vassilev
Obese patients are at risk of dental erosion due to micronutrient deficiency, consumption of soft drinks, gastric reflux disease and vomiting. The present study evaluates the presence of dental erosion in obese patients before and after bariatric surgery using the BEWE (basic erosive wear examination) scoring system. A total of 62 patients with severe obesity were included in the analysis, 31 in the control group (without bariatric surgery) and 31 in the surgery group (after bariatric surgery). BEWE scores did not vary between groups. Vitamin D deficiency was detected in 19 patients in the control group and three in the surgery group (p < 0.001). The serum calcium and vitamin D values were significantly higher in the surgery group (p = 0.003, p < 0.001 consecutively). All patients after bariatric surgery showed compliance with supplements, including vitamin D and calcium daily. Patients after bariatric surgery were less likely to drink soft drinks regularly (p = 0.026). Obese patients, before or after bariatric surgery, are at risk for erosive dental wear. However, with sufficient education prior to surgery and consistent intake of vitamin and mineral supplements, significant erosive dental wear after bariatric surgery could be avoided. Regular dental examination should be included in the check-up and follow-up program.

21 April 2020 in Obesity Surgery
Verified
Journal Article
Open access
PDF file
IKIoannis Karampinis
Ioannis Karampinis
ELEliette Lion
Eliette Lion
MGMaurizio Grilli
Maurizio Grilli
SHSvetlana Hetjens
Svetlana Hetjens
CWChristel Weiss
Christel Weiss
MOMirko Otto
Mirko Otto
The review was not registered for systematic reviews and meta-analyses, and should be disregarded.

31 July 2025 in medRxiv
Verified
Preprint
Open access
PDF file
CLCheng-Peng Li
Cheng-Peng Li
YCYuan Chu
Yuan Chu
DLDao-Ning Liu
Dao-Ning Liu
EGErfan Ghanad
Erfan Ghanad
SASchaima Abdelhadi
Schaima Abdelhadi
CYCui Yang
Cui Yang
Background: This study aimed to evaluate the effectiveness of ChatGPT-4o and OpenAI o1-preview in responding to pancreatic ductal adenocarcinoma (PDAC)-related queries. The study assessed both LLMs’ accuracy, comprehensiveness, and safety when answering clinical questions, based on the National Comprehensive Cancer Network® (NCCN) Clinical Practice Guidelines for PDAC. Methods: The study used a 20-question dataset derived from clinical scenarios related to PDAC. Two board-certified surgeons independently evaluated the responses by ChatGPT-4o and OpenAI o1-preview for their accuracy, comprehensiveness, and safety using a Likert scale. Statistical analyses were conducted to compare the performances of the two models. We also analyzed the impact of OpenAI o1-preview’s Chain of Thought (CoT) technology. Results: Both models demonstrated high median scores across all dimensions (5 out of 5). OpenAI o1-preview outperformed ChatGPT-4o in comprehensiveness (p = 0.026) and demonstrated superior reasoning ability, with a higher accuracy rate of 75% compared to 60% for ChatGPT-4o. OpenAI o1-preview generated more concise responses (median 64 vs. 82 words, p < 0.001). The CoT method in OpenAI o1-preview appeared to enhance its reasoning capabilities, particularly in complex treatment decisions. However, both models made critical errors in some complex clinical scenarios. Conclusion: OpenAI o1-preview, with its CoT technology, demonstrates higher comprehensiveness than ChatGPT-4.0 and showed a tendency of improved accuracy. However, both models still make critical errors and cause some harm to patients. Even the most advanced models are not suitable for offering reliable medical information and cannot function as an assistant for decision-making.