Estimation of entrainment response using electrograms from remote sites: validation in animal and computer models of reentrant tachycardia

INTRODUCTION: Studies suggest that entrainment response (ER) of reentrant tachycardia to overdrive pacing can be estimated using signals from sites other than the paced site. METHODS AND RESULTS: A formula for estimation of ER using remote sites against the difference between the postpacing interval (PPI) and tachycardia cycle length (TCL) determined solely from the paced site signal was validated in experimental data and using a simple two-dimensional cellular automata model of reentry. The model also was used to study the behavior and features of entrained surfaces, including the resetting of tachycardia phase by single premature paced stimuli. Experimental results from 1,484 remote sites in 115 pacing sequences showed the average of the median ER estimate error at each pacing site was -2 +/- 5 msec, and the median ER estimate was within 10 msec of PPI-TCL for 94% of pacing sites. From simulation results, ER at the paced site was accurately estimated from >99.8% of 20,764 remote sites during pacing at 24 sites and three paced cycle lengths. Intervals measured from remote electrograms revealed whether the site was activated orthodromically or nonorthodromically during pacing, and results of simulations illustrated that the portion of the surface activated nonorthodromically during pacing increased with distance from the pacing site to the circuit. The phenomenon of nonorthodromic activation of reentrant circuits predicted by modeling was discernible in measurements taken from the animal model of reentrant tachycardia. Results also showed that, for single premature stimuli that penetrated the tachycardia circuit, phase reset of the tachycardia was linearly related to distance between the central obstacle and the paced site. CONCLUSION: The ER is a complex but predictable perturbation of the global activation sequence of reentrant tachycardias. This predictability allows calculations of the response from anywhere on the perturbed surface. These findings suggest new techniques for measurement of the ER, which may lend themselves to computer-based methods for accurate and rapid mapping of reentrant circuits.     

Atrial tachycardia masquerading as atrial flutter following ablation of the subeustachian isthmus

We report a case of atrial tachycardia masquerading as atrial flutter in a man who had previously undergone catheter ablation for atrial flutter. The recurrent arrhythmia was electrocardiographically almost identical to the prior atrial flutter; at repeat electrophysiologic study, although bidirectional conduction block was observed in the tricuspid annulus-inferior vena caval isthmus, the atrial arrhythmia was readily initiated. Activation mapping suggested typical atrial flutter, but entrainment techniques demonstrated intra-atrial reentry not involving the ablated isthmus. This case illustrates the need to apply entrainment techniques even in cases of apparent "typical" atrial flutter to confirm that putative ablation targets are necessary for tachycardia perpetuation.     

An atrial fibrillation rotor,mapped conventionally

This case illustrates that the condition of atrial fibrillation (AF) may harbor site(s) of regular rotational activity, reentry may be an underlying mechanism, high periodicity and wavebreak through areas of the scar may generate fibrillatory conduction, and disintegration of the “rotor” may not abolish AF.     

QEEG Correlates of Auditory-Visual Entrainment Treatment Efficacy of Refractory Depression

Introduction. It is well established that the number of people diagnosed and suffering from depression is on the increase. Many of these patients are not responsive to first-line pharmacological intervention or simply cannot use medications for other reasons. As such, there has been a growing need for nonmedication approaches to treatment. The purpose of this study was to examine the use of auditory-visual EEG entrainment (AVE) at a 14 Hz (beta) frequency to decrease symptoms of depression with corresponding changes in neurophysiology.

Method. Sixteen participants ranged in age from 20 to 67 years and were screened utilizing the Beck Depression Inventory–II (BDI–II) and broken into two groups of 8 (simulated, AVE treatment groups), with a cross-over design. Both groups were given the BDI–II and QEEG testing at baseline, 4 weeks following either AVE or simulated treatment, and then again after an additional 4 weeks and a switch in treatment in the cross-over design.

Results. Results revealed significant reduction of depression only after the 4 weeks on AVE therapy of the BDI–II scores (p > .01). QEEG scores adjusted for normal age deviations demonstrate significant EEG change scores over time in cortical regions associated with mood regulation.

Conclusion. The findings indicate that AVE therapy may be a viable nonmedication therapeutic intervention.     

No statistical learning advantage in children over adults: Evidence from behaviour and neural entrainment

Explicit recognition measures of statistical learning (SL) suggest that children and adults have similar linguistic SL abilities. However, explicit tasks recruit additional cognitive processes that are not directly relevant for SL and may thus underestimate children’s true SL capacities. In contrast, implicit tasks and neural measures of SL should be less influenced by explicit, higher-level cognitive abilities and thus may be better suited to capturing developmental differences in SL. Here, we assessed SL to six minutes of an artificial language in English-speaking children (n = 56, 24 females, M = 9.98 years) and adults (n = 44; 31 females, M = 22.97 years), using explicit and implicit behavioural measures and an EEG measure of neural entrainment. With few exceptions, children and adults showed largely similar performance on the behavioural explicit and implicit tasks, replicating prior work. Children and adults also demonstrated robust neural entrainment to both words and syllables, with a similar time course of word-level entrainment, reflecting learning of the hidden word structure. These results demonstrate that children and adults have similar linguistic SL abilities, even when learning is assessed through implicit performance-based and neural measures.     

冠状窦呈偏心性激动的不典型房室结折返性心动过速的电生理特征及导管消融

目的 总结冠状窦（coronary sinus, CS）呈偏心性激动的不典型房室结折返性心动过速（atrioventricular nodal reentry tachycardia, AVNRT）的电生理特点、鉴别诊断及消融方法。方法 回顾性收集2014年1月至2018年12月在复旦大学附属中山医院心内科进行射频消融治疗的524例AVNRT患者的临床资料。其中,CS呈偏心性激动的不典型AVNRT患者共16例,男性6例、女性10例,平均年龄（56.6±11.4）岁。分析16例不典型AVNRT患者的体表心电图和腔内心电图特点、诱发方式、鉴别诊断及射频消融策略。结果 16例CS呈偏心性激动的AVNRT患者的心电图均表现为RP间期>PR间期,P波在Ⅱ、Ⅲ、aVF导联中倒置;发作时12例患者房室传导比例为1∶1,4例患者为2∶1或3∶1;13例患者可以轻易通过心室拖带的方式进行鉴别,2例患者需要多次拖带才能成功,1例患者多次拖带下心房-心室（atrioventricular,VA）仍然分离;14例患者在右心房后间隔靠近三尖瓣环处成功消融,3例患者在CS内成功消融。结论 CS呈偏心性激动的...     

Effects of nursing mothers on rPer1 and rPer2 circadian expressions in the neonatal rat suprachiasmatic nuclei vary with developmental stage

The ability of nursing mothers to entrain the circadian pacemaker of rat pups was examined by measuring the rat Per1 (rPer1) and rPer2 expression levels in the suprachiasmatic nuclei (SCN). Newborn rats from mothers under a light-dark cycle (LD) were blinded immediately after birth and reared by foster mothers under either LD (LD blind pups) or reversed light-dark cycle (DL; DL blind pups). At postnatal day (P)6, small but significant phase differences were observed in the circadian gene expression rhythms of the SCN not only between the blind and sighted pups, but also between the two groups of blind pups, indicating the involvement of both free-running and maternal influence in phase-resetting the circadian rhythms of blind pups. However, from P6 to P13 the circadian rhythms of both LD and DL blind pups showed phase delays of similar extent, which suggests that the influence of nursing mothers was lost. From P13 to P20 (the day of weaning), the rPer1 and rPer2 rhythms phase-shifted in a different manner, the rPer2 rhythm being related more closely to the behavioural rhythm than was the rPer1. This finding suggests a differential influence of mothers on the rPer1 and rPer2 rhythms in the third week of life. It is concluded that the ability of nursing mothers to entrain pup circadian oscillation depends on the developmental stage.