Safety pacing

Fig. 3.20 Safety pacing. In the upper and lower panels, the first complex is an AV paced beat. In the upper panel, the second complex is only an atrial paced complex not followed by a ventricular paced complex (asterisk). The electrical stimulus of ths atrial complex is sensed on the ventricular channel, resulting in ventricular inhibition, a phenomenon called crosstalk. In the lower panel, the second complex is an AV paced beat but the AV interval is marked shorter, approximately 110ms (asterisk). This shortened AV represents safety pacing, a feature in which a ventricular paced complex occurs when sensing occurs during the second phase of the AV interval. The first phase of the AV interval is the absolute blanking period. The third phase of the AV interval is the alert period, during which a ventricular sensed event results in ventricular inhibition.

For the past few years, however, there has been a hiatus in the pace of discovery of novel medicinal agents. It has been postulated by some that the field has now slowed down due to the limitations of the almost strictly empirical approach that has been applied to date to drug development. It is possible, too, that the higher standards of efficacy and safety that a new drug must meet today, combined with the enormously increased costs of clinical trials, have acted to keep all but the most promising new drugs off the market. 

Wechsler, J. (2001). Clinical trial safety and oversight top policy agenda. Appl. Clinical Trials, January 2001, pp. 18-21. www.actmagazine.com/articles/act/act0101 jill.pdf Willman, D. (2000). Quickened pace of drug approvals by FDA taking toll. San Jose Mercury News, Dec. 28, 2000. 

While steady improvements in the efficiency of delivery of medical care and prescribing safety will create concomitant improvements in clinical research over time, it is likely that the pace of such advances will not satisfy the demands of sponsors for faster, higher quality and less expensive trials. 

The field of chemical process miniaturization is growing at a rapid pace with promising improvements in process control, product quality, and safety, (1,2). Microreactors typically have fluidic conduits or channels on the order of tens to hundreds of micrometers. With large surface area-to-volume ratios, rapid heat and mass transfer can be accomplished with accompanying improvements in yield and selectivity in reactive systems. Microscale devices are also being examined as a platform for traditional unit operations such as membrane reactors in which a rapid removal of reaction-inhibiting products can significantly boost product yields (3-6). 

The selection of liquid monofunctional monomers for use in EB cure has been a key factor in the slow pace of development of acceptable formulations. These monomers play dominant roles in determining cure speed, viscosity, safety and cost, in addition to significant contributions to the physical properties of the cured films. 

However with due regard for real budget funding of the entire program of complex decommissioning of NSs, MVs and environmental rehabilitation of former naval CMBs, optimal NS decommissioning paces determined by nuclear, radiation and environmental safety, are estimated today at 13-15 NSs per year at the most. 

It has been emphasized already that you should be familiar with the regulations and codes of practice pertaining in your laboratory. We will not discuss safety legislation here but some fundamental rules should be stressed. Never work alone in a laboratory. Always wear suitable safety spectacles and a cotton lab coat, and use other protection such as gloves, face masks, or safety shields if there is a particular hazard. Never eat, drink or smoke in a laboratory. Work at a safe, steady pace, and keep your bench and your lab clean and tidy. Familiarity breeds contempt do not allow yourself to get careless with everyday dangers such as solvent flammability. Familiarize yourself with the location and operation of the safety equipment in your laboratory. 

Krahn AD, Klein GJ, Yee R. A randomized, double-blind, placebo-controlled evaluation of the efficacy and safety of intravenously administered dofetilide in patients with Wolff-Parkinson-White syndrome. Pacing Clin Electrophysiol 2001 24(8 Pt l) 1258-60. 

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