Variable ECG signs of ischemia during controlled occlusion of the left and right coronary artery in humans

Infarct size (IS) increases with vascular occlusion time, area at risk for infarction, lack of collateral supply, absence of preconditioning, and myocardial demand for O2 supply. ECG S-T segment elevation is used as a measure of severity of ischemia and a surrogate for IS. This study in 50 patients with coronary artery disease undergoing a first 120-s balloon occlusion of a stenosis sought to determine whether S-T segment elevation, corrected for the above-mentioned variables, in the left coronary artery (LCA group, n = 36) is different from that in the right coronary artery (RCA group, n = 14) territory. After consideration of all known determinants of IS, particularly mass at risk and collateral supply, the LCA territory is more sensitive than the RCA region to a 2-min period of myocardial ischemia.

Dynamic directed interictal connectivity in left and right temporal lobe epilepsy.

OBJECTIVE There is increasing evidence that epileptic activity involves widespread brain networks rather than single sources and that these networks contribute to interictal brain dysfunction. We investigated the fast-varying behavior of epileptic networks during interictal spikes in right and left temporal lobe epilepsy (RTLE and LTLE) at a whole-brain scale using directed connectivity. METHODS In 16 patients, 8 with LTLE and 8 with RTLE, we estimated the electrical source activity in 82 cortical regions of interest (ROIs) using high-density electroencephalography (EEG), individual head models, and a distributed linear inverse solution. A multivariate, time-varying, and frequency-resolved Granger-causal modeling (weighted Partial Directed Coherence) was applied to the source signal of all ROIs. A nonparametric statistical test assessed differences between spike and baseline epochs. Connectivity results between RTLE and LTLE were compared between RTLE and LTLE and with neuropsychological impairments. RESULTS Ipsilateral anterior temporal structures were identified as key drivers for both groups, concordant with the epileptogenic zone estimated invasively. We observed an increase in outflow from the key driver already before the spike. There were also important temporal and extratemporal ipsilateral drivers in both conditions, and contralateral only in RTLE. A different network pattern between LTLE and RTLE was found: in RTLE there was a much more prominent ipsilateral to contralateral pattern than in LTLE. Half of the RTLE patients but none of the LTLE patients had neuropsychological deficits consistent with contralateral temporal lobe dysfunction, suggesting a relationship between connectivity changes and cognitive deficits. SIGNIFICANCE The different patterns of time-varying connectivity in LTLE and RTLE suggest that they are not symmetrical entities, in line with our neuropsychological results. The highest outflow region was concordant with invasive validation of the epileptogenic zone. This enhanced characterization of dynamic connectivity patterns could better explain cognitive deficits and help the management of epilepsy surgery candidates.

When left becomes right and vice versa: mirrored vision after cerebral hypoxia

The combination of acquired mirror writing and reading is an extremely rare neurological disorder. It is encountered when brain damaged patients prefer horizontally mirrored over normal script in writing and reading. Previous theories have related this pathology to a disinhibition of mirrored engrams in the non-dominant hemisphere, possibly accompanied by a reversal of the preferred scanning direction. Here, we report the experimental investigation of PR, a patient who developed pronounced mirror writing and reading following septic shock that caused hypoxic brain damage. A series of five oculomotor experiments revealed that the patient's preferred scanning direction was indeed reversed. However, PR showed striking scanpath abnormalities and mirror reversals that cannot be explained by previous theories. Considered together with mirror phenomena she displayed in neuropsychological tasks and everyday activities, our findings suggest a horizontal reversal of visual information on a perceptual level. In addition, a systematic manipulation of visual variables within two further experiments had dramatic effects on her mirror phenomena. When confronted with moving, flickering or briefly presented stimuli, PR showed hardly any left-right reversals. Not only do these findings underline the perceptual nature of her disorder, but also allow interpretation of the pathology in terms of a dissociation between visual subsystems. We speculate that early visual cortices are crucially involved in this dissociation. More generally, her mirrored vision may represent an extreme clinical manifestation of the relative instability of the horizontal axis in spatial vision.

Time courses and quantitative analysis of atrial fibrillation episode number and duration after circular plus linear left atrial lesions: trigger elimination or substrate modification: early or delayed cure?

OBJECTIVES We sought to analyze the time course of atrial fibrillation (AF) episodes before and after circular plus linear left atrial ablation and the percentage of patients with complete freedom from AF after ablation by using serial seven-day electrocardiograms (ECGs). BACKGROUND The curative treatment of AF targets the pathophysiological corner stones of AF (i.e., the initiating triggers and/or the perpetuation of AF). The pathophysiological complexity of both may not result in an "all-or-nothing" response but may modify number and duration of AF episodes. METHODS In patients with highly symptomatic AF, circular plus linear ablation lesions were placed around the left and right pulmonary veins, between the two circles, and from the left circle to the mitral annulus using the electroanatomic mapping system. Repetitive continuous 7-day ECGs administered before and after catheter ablation were used for rhythm follow-up. RESULTS In 100 patients with paroxysmal (n = 80) and persistent (n = 20) AF, relative duration of time spent in AF significantly decreased over time (35 +/- 37% before ablation, 26 +/- 41% directly after ablation, and 10 +/- 22% after 12 months). Freedom from AF stepwise increased in patients with paroxysmal AF and after 12 months measured at 88% or 74% depending on whether 24-h ECG or 7-day ECG was used. Complete pulmonary vein isolation was demonstrated in <20% of the circular lesions. CONCLUSIONS The results obtained in patients with AF treated with circular plus linear left atrial lesions strongly indicate that substrate modification is the main underlying pathophysiologic mechanism and that it results in a delayed cure instead of an immediate cure.

High frequency repetitive transcranial magnetic stimulation (rTMS) of the left dorsolateral cortex: EEG topography during waking and subsequent sleep.

Repetitive transcranial magnetic stimulation (rTMS) is a novel research tool in neurology and psychiatry. It is currently being evaluated as a conceivable alternative to electroconvulsive therapy for the treatment of mood disorders. Eight healthy young (age range 21-25 years) right-handed men without sleep complaints participated in the study. Two sessions at a 1-week interval, each consisting of an adaptation night (sham stimulation) and an experimental night (rTMS in the left dorsolateral prefrontal cortex or sham stimulation; crossover design), were scheduled. In each subject, 40 trains of 2-s duration of rTMS (inter-train interval 28 s) were applied at a frequency of 20 Hz (i.e. 1600 pulses per session) and at an intensity of 90% of the motor threshold. Stimulations were scheduled 80 min before lights off. The waking EEG was recorded for 10-min intervals approximately 30 min prior to and after the 20-min stimulations, and polysomnographic recordings were obtained during the subsequent sleep episode (23.00-07.00 h). The power spectra of two referential derivations, as well as of bipolar derivations along the antero-posterior axis over the left and right hemispheres, were analyzed. rTMS induced a small reduction of sleep stage 1 (in min and percentage of total sleep time) over the whole night and a small enhancement of sleep stage 4 during the first non-REM sleep episode. Other sleep variables were not affected. rTMS of the left dorsolateral cortex did not alter the topography of EEG power spectra in waking following stimulation, in the all-night sleep EEG, or during the first non-REM sleep episode. Our results indicate that a single session of rTMS using parameters like those used in depression treatment protocols has no detectable side effects with respect to sleep in young healthy males.

Outer skull landmark-based coordinates for measurement of cerebral blood flow and intracranial pressure in rabbits

Despite the increased use of intracranial neuromonitoring during experimental subarachnoid hemorrhage (SAH), coordinates for probe placement in rabbits are lacking. This study evaluates the safety and reliability of using outer skull landmarks to identify locations for placement of cerebral blood flow (CBF) and intraparenchymal intracranial pressure (ICP) probes. Experimental SAH was performed in 17 rabbits using an extracranial-intracranial shunt model. ICP probes were placed in the frontal lobe and compared to measurements recorded from the olfactory bulb. CBF probes were placed in various locations in the frontal cortex anterior to the coronary suture. Insertion depth, relation to the ventricular system, and ideal placement location were determined by post-mortem examination. ICP recordings at the time of SAH from the frontal lobe did not differ significantly from those obtained from the right olfactory bulb. Ideal coordinates for intraparenchymal CBF probes in the left and right frontal lobe were found to be located 4.6±0.9 and 4.5±1.2 anterior to the bregma, 4.7±0.7mm and 4.7±0.5mm parasagittal, and at depths of 4±0.5mm and 3.9±0.5mm, respectively. The results demonstrate that the presented coordinates based on skull landmarks allow reliable placement of intraparenchymal ICP and CBF probes in rabbit brains without the use of a stereotactic frame.

Comparison of pro-atrial natriuretic peptide and atrial remodeling in marathon versus non-marathon runners

Long-term endurance sports are associated with atrial remodeling and an increased risk for atrial fibrillation (AF) and atrial flutter. Pro-atrial natriuretic peptide (pro-ANP) is a marker of atrial wall tension and elevated in patients with AF. The aim of this study was to test the hypothesis that atrial remodeling would be perpetuated by repetitive episodes of atrial stretching during strenuous competitions, reflected by elevated levels of pro-ANP. A cross-sectional study was performed on nonelite runners scheduled to participate in the 2010 Grand Prix of Bern, a 10-mile race. Four hundred ninety-two marathon and nonmarathon runners applied for participation, 70 were randomly selected, and 56 entered the final analysis. Subjects were stratified according to former marathon participations: a control group (nonmarathon runners, n = 22), group 1 (1 to 4 marathons, n = 16), and group 2 (≥5 marathons, n = 18). Results were adjusted for age, training years, and average weekly endurance training hours. The mean age was 42 ± 7 years. Compared to the control group, marathon runners in groups 1 and 2 had larger left atria (25 ± 6 vs 30 ± 6 vs 34 ± 7 ml/m(2), p = 0.002) and larger right atria (27 ± 7 vs 31 ± 8 vs 35 ± 5 ml/m(2), p = 0.024). Pro-ANP levels at baseline were higher in marathon runners (1.04 ± 0.38 vs 1.42 ± 0.74 vs 1.67 ± 0.69 nmol/L, p = 0.006). Pro-ANP increased significantly in all groups after the race. In multiple linear regression analysis, marathon participation was an independent predictor of left atrial (β = 0.427, p <0.001) and right atrial (β = 0.395, p = 0.006) remodeling. In conclusion, marathon running was associated with progressive left and right atrial remodeling, possibly induced by repetitive episodes of atrial stretching. The altered left and right atrial substrate may facilitate atrial arrhythmias.

Measurement of ventilation and cardiac related impedance changes with electrical impedance tomography

Introduction Electrical impedance tomography (EIT) has been shown to be able to distinguish both ventilation and perfusion. With adequate filtering the regional distributions of both ventilation and perfusion and their relationships could be analysed. Several methods of separation have been suggested previously, including breath holding, electrocardiograph (ECG) gating and frequency filtering. Many of these methods require interventions inappropriate in a clinical setting. This study therefore aims to extend a previously reported frequency filtering technique to a spontaneously breathing cohort and assess the regional distributions of ventilation and perfusion and their relationship. Methods Ten healthy adults were measured during a breath hold and while spontaneously breathing in supine, prone, left and right lateral positions. EIT data were analysed with and without filtering at the respiratory and heart rate. Profiles of ventilation, perfusion and ventilation/perfusion related impedance change were generated and regions of ventilation and pulmonary perfusion were identified and compared. Results Analysis of the filtration technique demonstrated its ability to separate the ventilation and cardiac related impedance signals without negative impact. It was, therefore, deemed suitable for use in this spontaneously breathing cohort. Regional distributions of ventilation, perfusion and the combined ΔZV/ΔZQ were calculated along the gravity axis and anatomically in each position. Along the gravity axis, gravity dependence was seen only in the lateral positions in ventilation distribution, with the dependent lung being better ventilated regardless of position. This gravity dependence was not seen in perfusion. When looking anatomically, differences were only apparent in the lateral positions. The lateral position ventilation distributions showed a difference in the left lung, with the right lung maintaining a similar distribution in both lateral positions. This is likely caused by more pronounced anatomical changes in the left lung when changing positions. Conclusions The modified filtration technique was demonstrated to be effective in separating the ventilation and perfusion signals in spontaneously breathing subjects. Gravity dependence was seen only in ventilation distribution in the left lung in lateral positions, suggesting gravity based shifts in anatomical structures. Gravity dependence was not seen in any perfusion distributions.

Moving along the mental number line: Interactions between whole-body motion and numerical cognition

Active head turns to the left and right have recently been shown to influence numerical cognition by shifting attention along the mental number line. In the present study, we found that passive whole-body motion influences numerical cognition. In a random-number generation task (Experiment 1), leftward and downward displacement of participants facilitated small number generation, whereas rightward and upward displacement facilitated the generation of large numbers. Influences of leftward and rightward motion were also found for the processing of auditorily presented numbers in a magnitude-judgment task (Experiment 2). Additionally, we investigated the reverse effect of the number-space association (Experiment 3). Participants were displaced leftward or rightward and asked to detect motion direction as fast as possible while small or large numbers were auditorily presented. When motion detection was difficult, leftward motion was detected faster when hearing small number and rightward motion when hearing large number. We provide new evidence that bottom-up vestibular activation is sufficient to interact with the higher-order spatial representation underlying numerical cognition. The results show that action planning or motor activity is not necessary to influence spatial attention. Moreover, our results suggest that self-motion perception and numerical cognition can mutually influence each other.

Inflammation and atrial remodeling after a mountain marathon

Endurance athletes have an increased risk of atrial fibrillation. We performed a longitudinal study on elite runners of the 2010 Jungfrau Marathon, a Swiss mountain marathon, to determine acute effects of long-distance running on the atrial myocardium. Ten healthy male athletes were included and examined 9 to 1 week prior to the race, immediately after, and 1, 5, and 8 days after the race. Mean age was 34.9 ± 4.2 years, and maximum oxygen consumption was 66.8 ± 5.8 mL/kg*min. Mean race time was 243.9 ± 17.7 min. Electrocardiographic-determined signal-averaged P-wave duration (SAPWD) increased significantly after the race and returned to baseline levels during follow-up (128.7 ± 10.9 vs. 137.6 ± 9.8 vs. 131.5 ± 8.6 ms; P < 0.001). Left and right atrial volumes showed no significant differences over time, and there were no correlations of atrial volumes and SAPWD. Prolongation of the SAPWD was accompanied by a transient increase in levels of high-sensitivity C-reactive protein, proinflammatory cytokines, total leucocytes, neutrophil granulocytes, pro atrial natriuretic peptide and high-sensitivity troponin. In conclusion, marathon running was associated with a transient conduction delay in the atria, acute inflammation and increased atrial wall tension. This may reflect exercise-induced atrial myocardial edema and may contribute to atrial remodeling over time, generating a substrate for atrial arrhythmias.

Auditory motion direction encoding in auditory cortex and high-level visual cortex

The aim of this functional magnetic resonance imaging (fMRI) study was to identify human brain areas that are sensitive to the direction of auditory motion. Such directional sensitivity was assessed in a hypothesis-free manner by analyzing fMRI response patterns across the entire brain volume using a spherical-searchlight approach. In addition, we assessed directional sensitivity in three predefined brain areas that have been associated with auditory motion perception in previous neuroimaging studies. These were the primary auditory cortex, the planum temporale and the visual motion complex (hMT/V5+). Our whole-brain analysis revealed that the direction of sound-source movement could be decoded from fMRI response patterns in the right auditory cortex and in a high-level visual area located in the right lateral occipital cortex. Our region-of-interest-based analysis showed that the decoding of the direction of auditory motion was most reliable with activation patterns of the left and right planum temporale. Auditory motion direction could not be decoded from activation patterns in hMT/V5+. These findings provide further evidence for the planum temporale playing a central role in supporting auditory motion perception. In addition, our findings suggest a cross-modal transfer of directional information to high-level visual cortex in healthy humans.

The effect of different pulse durations in the treatment of nail psoriasis with 595-nm pulsed dye laser: a randomized, double-blind, intrapatient left-to-right study

Several studies have proven the efficacy of pulsed dye laser (PDL) in the treatment of plaque type psoriasis. However, only two published studies indicate the effectiveness of PDL on nail psoriasis.