In order to enhance the position accuracy of ablation catheter in heart electrophysiology operation, signals of respiration and heartbeat must be removed for subsequent data processing. Based on locating principle of electrical field with low frequency, synchronous detector with MC1496 has been developed in this study. In the present research, several methods are utilized to optimize the circuit performance, such as coupling and stopping direct current, low-pass filtering, as well as limiting ripple voltage etc. Through simulation results, it showed that the demodulation performance of the circuit was fine. Through simulation platform of thorax electric field and animal experiment, the circuit feasibility were further proved good for extracting signals of respiration and heartbeat.
Atrial Fibrillation ; surgery ; Catheter Ablation ; methods ; Computer Simulation ; Electromagnetic Fields ; Heart ; anatomy & histology ; physiology ; Humans ; Models, Biological ; Signal Processing, Computer-Assisted ; Thorax

Objective: To establish a scoring system to predict the risk of anastomotic leakage in patients with rectal cancer older than 60 years. Methods: The study included 995 patients (≥ 60 years) with rectal cancer locating 3-12 cm from the anal verge who underwent anterior resection or intersphincteric resection at the Department of General Surgery, Henan Cancer Hospital from January 2012 to December 2016. Potential risk factors for leakage were subjected to univariate analysis. Multivariate logistic regression analysis was used to identify the independent risk factors for anastomotic leakage. The scoring system was developed based on regression coefficient for each significant risk factor. One point was allocated to the risk factor with a regression coefficient β < 1, and two points were allocated to the risk factor with β > 1. The proposed scoring system was tested by the area under curve (AUC) of the receiver operating characteristic curve (ROC) . Results: Surgery was successfully performed in all 995 patients. The incidence of anastomotic fistula was 4.6% (46/995) . Among these 46 patients, 31 recovered after conventional treatment, and 13 patients underwent transverse colostomy, and 2 died of multiple organ failure. Independent risk factors included age (β = 0.643, OR = 1.902, 95%CI: 1.020 - 3.614, P = 0.048) , body mass index (BMI) (β = 1.218, OR = 3.379, 95%CI: 1.607 - 7.105, P = 0.001) , albumin levels (β = 0.986, OR = 2.681, 95%CI: 1.432-5.021, P = 0.002) , and level of anastomosis from the anal verge (β = 1.395, OR = 4.034, 95%CI: 2.086-7.801, P = 0.000) . The scoring system was created base on coefficient β of the independent risk factors (age≥70 years for 1, BMI≥25 kg/m² for 2, albumin levels < 35 g/L for 1, level of anastomosis from anal verge < 4.0 cm for 2) . All the scores were added up, and all patients were divided into the high-risk group (4-6 points, n=71) and intermediate-low-risk group (0-3 points, n=924) based on the scoring system. The incidence of anastomotic leakage in the two groups was 23.9% (17/71) and 3.1% (29/924) , respectively (χ² = 60.092, P = 0.000) . The AUC of age, BMI, albumin levels, and level of anastomosis from the anal verge were 0.598, 0.591, 0.622, and 0.635 respectively. The AUC of the scoring system was 0.656, which was higher than above parameters with a sensitivety of 0.37 and specificity of 0.94. Conclusions The scoring system is effective and accurate for identifying a subgroup at high risk for postoperative anastomotic leakage in rectal cancer patients over 60 years old.

Objective To explore the clinical effects of pedicled ligamentum teres hepatis in preventing duodenum stump fistula after resection of gastric cancer.Methods The clinicopathological data of 563 patients with gastic cancer who underwent resection from Jan.2013 to Dec.2016 were analyzed.Results Fourteen patients in the control group developed duodenum stump fistula.Four patients in the experimental group developed duodenum stump fistula.The incidence of duodenum stump fistula in the control group was 4.6％,while that in the experimental group was 1.5％ (x2 =4.356,P =0.037).All the 14 patients in the control group had high fever and 2 died of multiple organ failure,8 were cured with conservative treatment,and 4 received reoperation.For patients in the experimental group,moderate fever was observed in 2 patients and all were cured by conservative treatment.Conclusion Pedicled ligamentum teres hepatis was safe and effective to prevent duodenum stump fistula after resection of gastric cancer.