基于神经网络的心电分类器设计

设计了一种基于神经网络的心电分类器,该设计利用前向多层神经网络的反向传播算法,即BP算法,采用Matlab软件建立了用于心电信号分类的BP神经网络,并利用大量的心电图数据训练神经网络,使神经网络能分辨出正常和异常的心电信号。     

二甲苯胺噻唑对绵羊心电图影响的研究

研究了静松灵对绵羊的心脏传导系统的作用，实验结果表明，静松灵对心脏系统产生较生时间的抑制作用，心电图表现为第１，１１度房室传导阻滞、窦性心动徐缓、窦性心律不齐和抑制心室的复极过程等，而对心室内的传导却无明显的影响，静松灵对心脏的抑制作用从给药后５分钟，持续几个小时。     

基于神经网络的心电分类器设计

设计了一种基于神经网络的心电分类器,该设计利用前向多层神经网络的反向传播算法,即BP算法,采用Matlab软件建立了用于心电信号分类的BP神经网络,并利用大量的心电图数据训练神经网络,使神经网络能分辨出正常和异常的心电信号。     

传统SMB、Varicol和Partial-discard工艺分离纯化ECG和EGCG的比较研究

使用B型三带模拟移动床技术,以C₁₈键合硅胶为固定相,乙醇与水（20︰80,V/V）为流动相,分别采取传统SMB工艺、Varicol工艺和Partial-discard工艺分离98%的茶多酚（TP98）。以得到高纯度和高回收率的ECG和EGCG为目标,分别优化柱配置、切换时间、进样流速、冲洗流速。结果表明,采用Varicol工艺能得到纯度为91.33%的ECG,回收率为91.41%;采用Partial-discard工艺能得到纯度为90.12%的EGCG,回收率为97.83%。相对于传统模拟移动床,Varicol工艺具有提高产品纯度和回收率的优点,Partial-discard工艺具有提高收集液浓度和产品纯度的优点。     

Electrocardiography‐guided and retrospective analysis of central venous catheter placement in the dog

Objective To compare the success rates of central venous catheter placement (CVCP) in dogs using electrocardiograph (ECG)‐guided and external landmark (‘blind’) techniques. To report success rates determined retrospectively of CVCPs in dogs using external landmarks at a tertiary referral institution. Study design Prospective blinded comparison of techniques. Retrospective analysis of case records. Animals Adult Beagles weighing 11.9 ± 2.6 kg were used in the experimental group (n = 38). Various breeds of dogs were in the retrospective clinical group (n = 33). Methods Laboratory dogs were anesthetized and CVCPs were placed using a modified Seldinger technique. Catheter tip position was first based on external landmarks and then the catheter was repositioned using an ECG‐guided placement. The ECG‐guided technique used the V‐lead with the positive electrode attached to the guide wire. Catheter placement was determined by moving the catheter cephalad and caudad to the point of maximum p‐wave amplitude and then withdrawing the catheter 1–2 cm from this point. Catheter position with each technique was determined using a lateral thoracic radiograph. Retrospective data were collected from the medical records of dogs that had CVCPs using anatomical landmarks and corresponding thoracic radiographs. Results The number of successful CVCP attempts was the same for both prospective groups (21/38). There was no statistically significant difference in success between the ECG‐guided technique and the blind technique. From the retrospective investigation 10/33 of the cases that fit the criteria had correct CVCPs. Conclusions and clinical relevance The odds of correctly placing a central venous catheter by ECG‐guidance were the same as the external landmark technique. The ECG‐guided technique may be useful in situations where external landmarks are not readily available.     

Postnatal autonomic activity in the preterm lamb

Background

Early postnatal abnormalities of autonomic nervous system (ANS) activity, including at baseline and following cardiorespiratory challenge, are involved in apneas-bradycardias of prematurity, apparent life-threatening events of infancy and sudden infant death syndrome. Literature data suggest that baseline ANS activity does not mature normally after premature birth.

Objectives

This study performed in preterm lambs was aimed at assessing ANS maturation at baseline and following laryngeal chemoreflexes (LCR), a group of reflexes triggered by the contact of liquids with the laryngeal mucosa.

Methods

Heart rate variability (HRV) and baroreflex sensitivity (BRs) were measured at baseline and after LCR during polysomnographic recordings performed in five non-sedated lambs born 15 days prematurely. Laryngeal chemoreflexes were induced by distilled water or acid (pH 2) during sleep and wakefulness on postnatal days 7 (D7) and 14 (D14, full-term equivalence).

Results

While the life-threatening cardiorespiratory events of the LCR observed at D7 were no longer present at D14, baseline and post-LCR HRV and BRs indices were significantly lower at D14 compared to D7 (up to p < 0.001). These results suggest that an initial autonomic overactivity was present at D7 and normalized at D14.

Conclusion

The autonomic cardiac and baroreflex control appears to follow a specific evolution in the preterm compared to the full-term newborn lamb, with an important initial autonomic stress, which normalizes at an age equivalent to full-term. Potential relevance of these findings in relation to anomalies of cardiac control in the early postnatal period, such as apneas-bradycardias of prematurity, apparent life-threatening events of infancy and sudden infant death syndrome, awaits further studies.     

Morphology of ventricular arrhythmias in the boxer as measured by 12-lead electrocardiography with pace-mapping comparison

The QRS amplitude and polarity were determined in 12-lead electrocardiograms recorded from 22 Boxers with ventricular arrhythmias. Eighty-one percent (18/22) of dogs displayed a positive QRS morphology in the caudoventral leads (II, III, and aVF) and 77% (17/22) of dogs displayed a positive QRS morphology in the left precordial leads (V2-V6). In leads I and V1, the polarity of the QRS complex was variable (positive or negative). To determine if these morphologic features were suggestive of ventricular complexes arising from the right or left ventricle, a comparison was made to the QRS complexes in a pace-mapping study performed in 7 healthy mixed-breed dogs. A total of 3 right and 4 left ventricular sites were paced. None of the left ventricular paced sites resulted in a QRS morphology similar to the most common spontaneous ventricular arrhythmia in the Boxers. In contrast, QRS morphology in each of the 3 right ventricular sites was similar to that observed in the Boxers (P < .033). Each of these produced positive deflections in the caudoventral and left precordial leads, but both positive and negative QRS complexes were observed in leads I and V1 only when the right ventricular septum was paced. This finding suggested that the right ventricular septum might be a site of origin for the ventricular rhythm observed in the Boxers because in the Boxers the polarity of leads I and V1 also varied. Pacing the right ventricular outflow tract always resulted in a negative QRS complex in lead 1, whereas pacing the right ventricular apex always resulted in a positive QRS complex in lead I and a negative QRS complex in V1. However, these locations cannot be excluded as possible sites of origin for the spontaneous ventricular arrhythmias in the Boxers because the arrhythmias could be originating from both of these locations. The spontaneous ventricular arrhythmia of the Boxer is most similar to that of paced ventricular rhythms arising from the right ventricle. More precise localization to a region of the right ventricle such as outflow tract, septal, or apical could not be made.     

Development of Embedded ECG Monitor Based on Linux

Presently, ECG monitor encounters the trend of miniaturizing, intelligentizing and networking. Short distance and limited channels are shortcomings of the existed telemetric ECG (Electrocardiograph) monitoring system, while the existed remote monitoring system has the disadvantages of high cost and low Data Transfer Rate. Furthermore, neither of these two systems can implement real-time monitoring on the spot. So, an embedded ECG Monitor based on Linux, which successfully solves these problems, is introduced. With embedded system technique, this embedded monitor, which can not only realize real-time monitoring on the spot, but also analyse the ECG data, has the advantages of low cost, small volume, light weight, low power, high stability, powerful networking function and so on. And by communicating through Internet, which has the features of low cost, high data transfer rate and good expandability, it can also send ECG data to monitoring center in order to achieve long-term monitoring. The development of this monitor provides a new solution for medical instruments' implementation and networking, and is of certain reference value.