Huifang Huang

BACKGROUND: The inter-patient classification schema and the Association for the Advancement of Medical Instrumentation (AAMI) standards are important to the construction and evaluation of automated heartbeat classification systems. The majority of previously proposed methods that take the above two aspects into consideration use the same features and classification method to classify different classes of heartbeats. The performance of the classification system is often unsatisfactory with respect to the ventricular ectopic beat (VEB) and supraventricular ectopic beat (SVEB). METHODS: Based on the different characteristics of VEB and SVEB, a novel hierarchical heartbeat classification system was constructed. This was done in order to improve the classification performance of these two classes of heartbeats by using different features and classification methods. First, random projection and support vector machine (SVM) ensemble were used to detect VEB. Then, the ratio of the RR interval was compared to a predetermined threshold to detect SVEB. The optimal parameters for the classification models were selected on the training set and used in the independent testing set to assess the final performance of the classification system. Meanwhile, the effect of different lead configurations on the classification results was evaluated. RESULTS: Results showed that the performance of this classification system was notably superior to that of other methods. The VEB detection sensitivity was 93.9% with a positive predictive value of 90.9%, and the SVEB detection sensitivity was 91.1% with a positive predictive value of 42.2%. In addition, this classification process was relatively fast. CONCLUSIONS: A hierarchical heartbeat classification system was proposed based on the inter-patient data division to detect VEB and SVEB. It demonstrated better classification performance than existing methods. It can be regarded as a promising system for detecting VEB and SVEB of unknown patients in clinical practice.

Pyrolysis of waste rubber in thermal plasma is studied for the purpose of producing gaseous fuel and recovering carbon black filler. The plasma reactor has a dc arc nitrogen plasma generator with a maximum electric power input of 62.5 kVA and a reaction chamber of 50 mm inner diameter and 1000 mm height. The results of a series of experiments have shown that the main components of the gaseous product are H2, CO, C2H2, CH4, and C2H4; the heat value of the gas is about 5−9 MJ/Nm3. The solid product contains more than 80 wt % elemental carbon, has a surface area of about 65 m2/g, and is referred to as pyrolytic carbon black (CBp). X-ray photoelectron spectroscopy (XPS) analysis has revealed that the CBp has mainly graphitic carbon structure similar to those of commercial carbon black. The CBp may be used as semireinforcing carbon black in nontire rubber applications, or, after upgrading, as carbon black filler for tire. Thus thermal plasma pyrolysis is potentially a useful way of treating waste rubber for resource recovery.

OBJECTIVE: To report the results of management of intravenous leiomyomatosis with intracaval and intracardiac extension at Peking Union Medial College Hospital. METHODS: We reviewed a cohort of 20 patients with intravenous leiomyomatosis extending to the inferior vena cava and heart, focusing on the clinical characteristics, the results of surgical management, and prognosis. RESULTS: The mean age of the patients was 42.4 ± 7.0 years. The clinical manifestations of intravenous leiomyomatosis are various and nonspecific, including pelvic mass, chest tightness and shortness of breath, swelling in the lower extremity, abdominal distension, palpitation, syncope, hypermenorrhea, and skelalgia. All the patients had history of uterine leiomyoma and 16 patients (80%) had undergone uterine leiomyoma operation. After careful preoperative evaluation, nine patients underwent one-stage operations (cardiac surgery, vascular and gynecologic surgery together) and 11 patients underwent two-stage operations (cardiac surgery first, then vascular and gynecologic surgery). There was no significant difference in the postoperative complication rate (33.3% compared with 27.3%; P>.99) between one-stage and two-stage operations. All operations were performed without severe surgical-related complications or death. Approximately 78% of patients had complete resection of tumor and 22.2% of the patients experienced incomplete resection. Eleven (55%) patients received hormone therapy postoperatively. During mean follow-up time of 20.5 months, recurrence occurred in five patients (27.8%) but all the patients survived. CONCLUSIONS: Precise and full-scale preoperative evaluation, complete tumor resection, and multidisciplinary cooperation are crucial for successful treatment.