Impact of high-power and very high-power short-duration radiofrequency ablation on procedure characteristics and first-pass isolation during pulmonary vein isolation

Introduction

High-power short-duration (HPSD) radiofrequency ablation has been proposed as a method for producing rapid and effective lesions for pulmonary vein isolation (PVI). We aimed to evaluate the procedural characteristics and the first-pass isolation (FPI) rate of HPSD and very high-power short-duration (vHPSD) ablation compared to low-power long-duration (LPLD) ablation technique.

Methods

156 patients with atrial fibrillation (AF) were enrolled and assigned to LPLD, HPSD, or vHPSD PVI. The energy setting was 30W, 50W, and 90W in the LPLD, HPSD, and vHPSD groups, respectively.

Results

Bilateral PVI was achieved in all cases. The procedure time was 85 [75–101] min, 79 [65–91] min, and 70 [53–83] min in the LPLD, HPSD, and vHPSD groups, respectively (p<0.0001). Left atrial (LA) dwelling times were also decreased significantly with the increase of RF energy (61 [55–70] min, 53 [41–56] min, and 45 [34–52] min, in the LPLD, HPSD, and vHPSD groups, respectively, p<0.0001). The total RF ablation time was 1567 [1366–1761] sec, 1398 [1021–1711] sec, and 336 [247–386] sec in the LPLD, HPSD, and vHPSD group, respectively (p<0.0001). The bilateral FPI rate was 57%, 78%, and 80% in the LPLD, HPSD, and vHPSD groups, respectively (p=0.0097). On the left side, FPI was achieved in 66% in the LPLD, 92% in the HPSD, and 85% in the vHPSD ablation group (p=0.0015). FPI on the right side was achieved in 72% in the LPLD, 88% in the HPSD, and 88% in the vHPSD ablation group (p=0.0188). The univariate analysis revealed that the use of HPSD (both sides: OR=2.72, 95% CI 1.15–6.44, p=0.023; right side: OR=2.90, 95% CI 1.02–8.20, p=0.045; left side: OR=5.91, 95% CI 1.84–19.04, p=0.003) and vHPSD (both sides: OR=2.90, 95% CI 1.24–6.44, p=0.014; right side: OR=3.09, 95% CI 1.09–8.74, p=0.045; left side: OR=2.89, 95% CI 1.13–7.43, p=0.027) ablation techniques were associated with a higher probability of FPI. The mid-term arrhythmia-free survival was similarly high in all three groups.

Conclusion

Our prospective, observational cohort study showed that both HPSD and vHPSD RF ablation is effective, as it shortens procedure time and RF time and results in a higher rate of FPI compared to LPLD ablation. Moreover, the mid-term arrhythmia-free survival was similarly high in all three groups. In our study, no safety concerns were raised for HPSD or vHPSD ablation.

Funding Acknowledgement

Type of funding sources: None.

[Suicidal behavior in childhood]

The suicidal behaviour in the child is a complex problem, less rare than suggested by epidemiological data which only concern the completed suicide. Implicitly, this subject raises the question of the idea a child has of death. Some risk factors and clinical signs are mentioned in the literature but they remain insufficiently studied. It is based on their knowledge and detection however that a preventive action can be taken, but only on an individual basis.

Reorganization in the visual cortex after retinal and cortical damage

Retinal and cortical lesions are completely different events that trigger visual cortical plasticity. We therefore compared the cortical effects of homonymous lesions of the central retina with effects of cortical lesions. All in vivo experiments were performed in anaesthetized, adult cats. Retinal lesions were made with a Xenon-light photocoagulator, and cortical lesions were induced by focal application of heat or ibotenic acid injection. Both, in cortical regions representing the retinal scotoma and at the border of small focal cortical lesions single neuron activity was initially suppressed and accompanied by a narrow area of increased activity adjacent to the region of functional loss during the first 1-2 weeks. At the same time an increased glutamatergic NMDA response and a reduction of GABA(A) and GABA(B) responses was observed around the cortical lesions in vitro. At an early stage long-term potentiation (LTP) is facilitated in those regions that were characterized by local upregulation of excitation and downregulation of inhibition after cortical lesions. Similarly, at the border of cortical scotomas in area 17 an increased glutamate level was found while inside the scotoma GAD levels were reduced. Shifts in topography of retinal representation as well as increases of receptive field size were detected as signs of lesion-induced neuronal reorganization after retinal and cortical lesions with longer survival times. A common cascade of events is triggered in the visual cortex by retinal as well as cortical lesions: reduced GABAergic inhibition and increased glutamatergic excitation, leading to increased spontaneous activity and visual excitability that is accompanied by facilitated LTP, and appears to initiate local cortical reorganization after functional disturbances in the visual system.

Practising orientation identification improves orientation coding in V1 neurons

The adult brain shows remarkable plasticity, as demonstrated by the improvement in fine sensorial discriminations after intensive practice. The behavioural aspects of such perceptual learning are well documented, especially in the visual system. Specificity for stimulus attributes clearly implicates an early cortical site, where receptive fields retain fine selectivity for these attributes; however, the neuronal correlates of a simple visual discrimination task remained unidentified. Here we report electrophysiological correlates in the primary visual cortex (V1) of monkeys for learning orientation identification. We link the behavioural improvement in this type of learning to an improved neuronal performance of trained compared to naive neurons. Improved long-term neuronal performance resulted from changes in the characteristics of orientation tuning of individual neurons. More particularly, the slope of the orientation tuning curve that was measured at the trained orientation increased only for the subgroup of trained neurons most likely to code the orientation identified by the monkey. No modifications of the tuning curve were observed for orientations for which the monkey had not been trained. Thus training induces a specific and efficient increase in neuronal sensitivity in V1.

The role of lateral occipitotemporal junction and area MT/V5 in the visual analysis of upper-limb postures

Humans, like numerous other species, strongly rely on the observation of gestures of other individuals in their everyday life. It is hypothesized that the visual processing of human gestures is sustained by a specific functional architecture, even at an early prelexical cognitive stage, different from that required for the processing of other visual entities. In the present PET study, the neural basis of visual gesture analysis was investigated with functional neuroimaging of brain activity during naming and orientation tasks performed on pictures of either static gestures (upper-limb postures) or tridimensional objects. To prevent automatic object-related cerebral activation during the visual processing of postures, only intransitive postures were selected, i. e., symbolic or meaningless postures which do not imply the handling of objects. Conversely, only intransitive objects which cannot be handled were selected to prevent gesture-related activation during their visual processing. Results clearly demonstrate a significant functional segregation between the processing of static intransitive postures and the processing of intransitive tridimensional objects. Visual processing of objects elicited mainly occipital and fusiform gyrus activity, while visual processing of postures strongly activated the lateral occipitotemporal junction, encroaching upon area MT/V5, involved in motion analysis. These findings suggest that the lateral occipitotemporal junction, working in association with area MT/V5, plays a prominent role in the high-level perceptual analysis of gesture, namely the construction of its visual representation, available for subsequent recognition or imitation.

The 'ecological' probability density function for linear optic flow: implications for neurophysiology

A theoretical analysis of the recovery of shape from optic flow highlights the importance of the deformation components; however, pure deforming stimuli elicit few responses from flow-sensitive neurons in the medial superior temporal (MST) area of the cerebral cortex. This finding has prompted the conclusion that MST cells are not involved in shape recovery. However, this conclusion may be unjustified in view of the emerging consensus that MST cells perform nonlinear pattern matching, rather than linear projection as implicitly assumed in many neurophysiological studies. Artificial neural models suggest that the input probability density function (PDF) is crucial in determining the distribution of responses shown by pattern-matching cells. This paper therefore describes a Monte-Carlo study of the joint PDF for linear optic-flow components produced by ego-motion in a simulated planar environment. The recent search for deformation-selective cells in MST is then used to illustrate the importance of the input PDF in determining cell characteristics. The results are consistent with the finding that MST cells exhibit a continuum of responses to translation, rotation, and divergence. In addition, there are negative correlations between the deformation and conformal components of optic flow. Consequently, if cells responsible for shape analysis are present in the MST area, they should respond best to combinations of deformation with other first-order flow components, rather than to the pure stimuli used in previous neurophysiological studies.

Blood flow in human anterior temporal cortex decreases with stimulus familiarity

In this positron emission tomography investigation of human nonverbal visual memory, we determined the anatomical distribution of changes in regional cerebral blood flow (rCBF) reflecting familiarity of visual shapes. All stimuli consisted of relatively simple, abstract outlines generated by Fourier expansions. Subjects performed the same task twice, once using unfamiliar and once using familiar stimuli. The task was a modified version of delayed nonmatching-to-sample, consisting of one sample presentation prior to tracer injection and a sequence of test trials during which images were acquired. When this task was performed with familiar instead of unfamiliar stimuli, only decreases in rCBF were observed, which were localized to the left lateral anterior temporal neocortex, the left medial temporal pole, and the rostral anterior cingulate. The correlates of familiarity measured in this human brain mapping experiment may correspond with what has been measured in single neurons in monkeys. This correspondence holds both for the type and for the localization of changes.

Illusory, motion, and luminance-defined contours interact in the human visual system

Psychophysical studies of interactions between contours defined by different image attributes report that luminance-defined and illusory contours show little if any interaction. Because the contours defined by these attributes may vary in perceptual saliency, we employed the tilt aftereffect (TAE) and a cross-adaptation procedure to evaluate interaction effects between luminance-defined and illusory contours under varying saliency conditions as well as to explore the interaction between illusory and motion-defined contours. When contour salience of the adaptation or test stimuli was modified by the addition of various amounts of static noise, we observed a TAE for all combinations of contour types including the novel motion-illusory and illusory-motion pairs. The interactions demonstrated between the contour classes in this as well as other studies suggests contour invariance in the orientation domain.