Ablation of Complex Fractionated Atrial Electrograms in Catheter Ablation for AF; Where have we been and where are we going?

Catheter ablation for persistent AF remains a challenge to the ablator as the disease is now outside the veins and cannot be tackled by pulmonary vein isolation alone. In this article we describe targeting complex fractionated atrial electrograms (CFAE) as a method to guide atrial substrate modification.     

Susceptibility to ischemia-induced ventricular fibrillation in isolated female rat hearts varies moderately with estrous cycle stage

IntroductionThe vast majority of studies employing the isolated perfused rat heart model to study ischemic arrhythmias have used male rats only. The objective of this study was to determine the susceptibility to ischemia-induced ventricular fibrillation (VF) in isolated female rat hearts in each stage of the estrous cycle that corresponds with a different endogenous reproductive hormonal environment.MethodsHearts were isolated from female rats under pentobarbital anesthesia and perfused with modified Krebs solution containing 3 mM K⁺. Experiments were grouped according to estrous cycle stage that was determined by prior vaginal lavage (n = 10–13 per group). A group of male rat hearts was used as the control. Regional ischemia was induced by coronary ligation and maintained for 30 min. The incidence of VF was determined from the ECG.ResultsThe incidence of VF in male hearts was 100%, while the incidence of VF in female hearts was also high but varied moderately with stage of the estrous cycle (diestrus 70%, metestrus 100%, proestrus 90%, estrus 69%; P > 0.05). Compared to male hearts, the onset of VF was similar in all groups except for hearts excised from rats in proestrus, in which it was delayed. There was no difference between groups in an arrhythmia score, ischemic zone size, or baseline electrocardiographic or hemodynamic variables.DiscussionIn conclusion, the susceptibility of isolated female rat hearts to ischemic VF is comparable to that of male rat hearts, meaning that isolated female rat hearts can be used as controls in studies to assess antiarrhythmic drug efficacy. Since female rats can be used for isolated heart studies of ischemic VF, the need to cull female rats is reduced. However, the variation in VF susceptibility in female rat hearts that is associated with the different stages of the estrous cycle may affect statistical power that could potentially lead to Type II statistical errors. This problem can be prevented with careful randomization.     

Current Strategic Thinking for the Development of a Trivalent Alphavirus Vaccine for Human Use

Vaccinations against the encephalitic alphaviruses (western, eastern, and Venezuelan equine encephalitis virus) are of significant interest to biological defense, public health, and agricultural communities alike. Although vaccines licensed for veterinary applications are used in the Western Hemisphere and attenuated or inactivated viruses have been used under Investigational New Drug status to protect at-risk personnel, there are currently no licensed vaccines for use in humans. Here, we will discuss the need for a trivalent vaccine that can protect humans against all three viruses, recent progress to such a vaccine, and a strategy to continue development to Food and Drug Administration licensure.