Objective To study the feasibility and safety of coronary sinus (CS) ventricular pacing comparing with traditional right ventricular (RV) pacing in ordinary pacing treatment.Methods Sixty-one patients with an indication of pacemaker implantation were randomized into traditional RV pacing group and CS ventricular pacing group.The success rate,complications,preoperative and postoperative QRS wave duration and pacemaker parameters were compared between the two groups.Results (1) The instant success rate in traditional RV pacing and the CS pacing groups were 100％ and 68.97％ (P＜0.01);the surgical success rate was significantly higher by using left ventricular electrode than the ventricle tined electrode in CS pacing group (85.71％ and 25％,P＜0.05).There was no significant difference in the incidence of complications between the two groups (P＞0.05);(2) The increase of QRS complex width at postoperative 1 month in CS pacing group is significantly less than the RV pacing group (P＜0.05);(3) Although the pacing threshold and electrode impedance during operation,postoperative 1 month and 3 months in CS pacing group were higher than RV pacing group (P＜0.05),the CS pacing was effective.Conclusion The CS ventricular pacing is as safe and effective as traditional RV pacing,and is more consistent with physiological ventricular activation sequence.Using left ventricular electrode can significantly improve the success rate of CS ventricular pacing.

Objective To verify the feasibility and safety of stomach tumor marker localization based on magnetic tracer technique in dogs.Methods Six male Beagle dogs were examined by gastroscopy.Then tracer magnets were sent to the "tumor" locations assumed in advance and fixed near the "tumors" by endoscopic soft tissue clamp.Laparoscopic gastric tumor localization was performed under general anesthesia 24 hours later.The tracer magnet was placed near the tumor on the surface of the stomach through the operating hole after the conventional establishment of laparoscope puncture parallel mirror to explore the tracer magnet.After the two magnets were attracted,the location of the tracer magnet seen under the laparoscope was the location of the gastric tumor,so as to complete the labeling and positioning of the lesion.Results All the 6 Beagle dogs were successfully implanted with tracer magnets under gastroscopy.Twenty-four hours after the gastroscopy,the pursuit magnet was successfully implanted during laparoscopic surgery.The two magnets automatically attracted each other and formed a sandwich structure of "tracer magnet-gastric wall-pursuit magnet ",which completed the location and identification of gastric tumor under the laparoscopy.Conclusion Gastroscopy combined with laparoscopy based on magnetic tracer technique is simple,accurate,safe and feasible.

Objective:To design magnets to locate colorectal neoplasms based on magnetic tracer technology, and to test its feasibility and safety by animal experiments.Methods:The magnets used for endoscopic localization of colorectal tumors consist of a tracer magnet and a pursuit magnet, both of which are ring-shaped Nd-Fe-B magnets. Eight healthy Beagle dogs were used as animal models. Tumor locations were assumed in the different parts of the colon and rectum under colonoscopy. The tracer magnet was sent to the hypothetical tumors by endoscopic soft tissue clamp and fixed near the tumors. After 24 hours, laparoscopic surgery was performed under general anesthesia. The pursuit magnet was inserted near the resected colon or rectum through the main operating hole. The tracer magnet was absorbed to the pursuit magnet to identify the location of tumors.Results:The tracer magnet and pursuit magnet were successfully designed and processed. The suction force between the tracer magnet and the pursuit magnet at zero distance was 16 N. All the 8 Beagle dogs successfully received indwelling of magnets under colonoscopy, and no magnets fell off after 24 hours. After the placement of pursuit magnet under laparoscopy, the two magnets attracted each other rapidly and accurately, and successfully completed localization of tumor site without any damage during the operation.Conclusion:Colonoscopy combined with laparoscopy for colorectal neoplasms localization based on magnetic tracer technique is simple, accurate, safe and feasible.