Objectives
Left atrium (LA) plays an important role in left ventricular filling. It is well known that right ventricular apical pacing has unfavorable effects on ventricular systolic and diastolic performance. The aim of this study is to evaluate the LA mechanical functions with 2D echocardiography in patients with a permanent pacemaker after short time ventricular pacing.Design
Echocardiographic examination was performed in 38 patients (mean age 63.0± 10.9, 18 female) with dual chamber pacemakers or defibrillators (< 20% ventricular pacing within previous 6 months, all of them on sinus rhythm) before and after 4 hours > 90% ventricular pacing at 70 beats per minute in DDD mode with an optimal AV interval. Left atrial volumes (LAV) including at the time of mitral valve opening (Vmax), at closure (Vmin), and at the onset of atrial systole (Volp) were measured. The passive emptying, conduit, active emptying and total emptying volume, stroke volumes were also calculated.Results
No significant differences were noted at baseline and after pacing for absolute Vmax, Volp, passive emptying, conduit, active emptying, total emptying volumes as well as the volumes indexed to body surface area (p >0.05).Conclusions
Short - time RV pacing seems to have no acute effects on left atrial mechanical functions. 相似文献Boron is an important element for plants, humans, and animals in limited amounts. However, excess amounts can cause adverse effects in both humans and plants, necessitating its removal from certain systems. Boron compounds are used in many industrial applications, including in developing sectors like alternative energy technology; as a result, the need for this element is increasing and industries are looking towards boron recovery for the sustained use of this element in their products. While the literature on boron removal strategies is abundant, there is a relative lack of studies on boron recovery, with no review papers having yet addressed this topic. In this review, both boron removal and recovery techniques involving conventional approaches and membrane processes are examined to juxtapose the states of the science in these two related—and increasingly important—processes.
Graphical abstract 相似文献