Cognitive functions and patterns of brain activity in patients after simultaneous coronary and carotid artery revascularization

BackgroundOn-pump coronary artery bypass grafting (CABG) is associated with a high risk of neurological complications in patients with severe carotid stenosis. Moreover, early postoperative cognitive dysfunction (POCD) incidence remains high in patients undergoing simultaneous coronary and carotid surgery. Recent studies have shown that even moderate carotid stenosis (≥50%) is associated with postoperative cognitive decline after CABG. Data on brain health in the postoperative period of simultaneous coronary and carotid surgery are limited.ObjectivesThis study aimed to analyze early postoperative changes in the cognitive function and patterns of brain electrical activity in patients after simultaneous coronary and carotid artery revascularization.Materials and methodsBetween January 2017 and December 2020, consecutive patients were assigned to on-pump CABG with or without carotid endarterectomy (CEA) according to clinical indications. An extended neuropsychological and electroencephalographic (EEG) assessment was performed before surgery and at 7–10 days after CABG or CABG + CEA.ResultsA total of 100 patients were included [median age 59 (55; 65), 95% men, MMSE 27 (26; 28)], and among these, 46 underwent CEA. POCD was diagnosed in 29 (63.0%) patients with CABG + CEA and in 32 (59.0%) patients with isolated CABG. All patients presented with a postoperative theta power increase. However, patients with CABG + right-sided CEA demonstrated the most pronounced theta power increase compared to patients with isolated CABG.ConclusionThe findings of our study show that patients with CABG + CEA and isolated CABG have comparable POCD incidence; however, patients with CABG + right-sided CEA presented with lower brain activity

Влияние предоперационного когнитивного расстройства на изменения электрической активности головного мозга у пациентов, перенесших одномоментное вмешательство на каротидных и коронарных артериях

HighlightsThe presence of preoperative mild cognitive impairment (MCI) in patients undergoing combined carotid endarterectomy and coronary artery bypass grafting is associated with an increased theta activity at the frontal and parieto-occipital regions of both hemispheres after surgery. AbstractAim. To study the impact of preoperative cognitive impairment on changes in electrical activity of the brain in patients undergoing combined carotid endarterectomy and coronary artery bypass grafting.Methods. Sixty-three patients undergoing combined carotid endarterectomy (CAE) and coronary artery bypass grafting (CABG) were included in the study. The patients were divided into three groups, depending on the preoperative cognitive functions: without cognitive impairment (n = 17), with MCI (n = 29), and with severe cognitive impairment (n = 17). High-resolution electroencephalography (EEG) (62 channels, bandpass filtered between 0.1–50.0 Hz, sampling rate of 1000 Hz) was performed 3–5 days before and 7–10 days after surgery.Results. Patients with severe cognitive impairment at baseline presented with higher theta activity at the frontal region of the left hemisphere compared to patients without cognitive impairment and patients with MCI (p = 0.048). At the same time, patients with MCI showed the most pronounced theta activity increase after surgery compared to preoperative levels at the frontal and parieto-occipital cortical regions of both the left and right hemispheres (p≤0.05). Postoperative changes of theta activity in patients with severe cognitive impairment were minimal and statistically insignificant.Conclusion. Patients without severe preoperative cognitive impairment presented with higher grade brain dysfunction in the form of increased theta activity at the frontal and parieto-occipital regions after combined CAE and CABG. A smaller decrease in theta power after surgery in patients with severe preoperative cognitive impairment, on the one hand, can indicate compensation after cerebral ischemia and resistance to hypoperfusion during on-pump cardiac surgery, and on the other, can be a manifestation of the ceiling effect and insufficiency of brain functional reserves.Основные положенияНаличие предоперационного умеренного когнитивного расстройства у пациентов, перенесших одномоментное вмешательство на каротидных и коронарных артериях, ассоциировано с выраженным послеоперационным увеличением тета-активности во фронтальных и парието-окципитальных отделах обоих полушарий. РезюмеЦель. Изучено влияние предоперационного когнитивного расстройства на изменения электрической активности головного мозга у больных, перенесших одномоментное вмешательство на каротидных и коронарных артериях.Материалы и методы. В исследовании участвовали 63 пациента, перенесших одномоментно каротидную эндартерэктомию и коронарное шунтирование с применением искусственного кровообращения. В зависимости от предоперационного состояния когнитивных функций участники разделены на три группы: без когнитивного расстройства (n = 17), с умеренным (n = 29) и тяжелым (n = 17) когнитивным расстройством. Электроэнцефалография высокого разрешения (62 канала, полоса пропускания 0,1–50,0 Гц, частота дискретизации 1 000 Гц) проведена за 3–5 дней и на 7–10-е сутки после вмешательства.Результаты. Установлено, что до операции у пациентов с тяжелым когнитивным расстройством показатели тета-активности во фронтальных отделах левого полушария были выше, чем у лиц без когнитивного расстройства и с умеренным когнитивным нарушением (p = 0,048). При этом после вмешательства у пациентов с умеренным когнитивным расстройством наблюдалось максимально выраженное увеличение тета-активности по сравнению с предоперационным уровнем во фронтальных и парието-окципитальных отделах коры левого и правого полушарий (p≤0,05). Тогда как у лиц с тяжелым когнитивным расстройством послеоперационные изменения тета-ритма были минимальны и не достигали статистической значимости.Заключение. Пациенты без тяжелых форм предоперационного когнитивного дефицита после одномоментного вмешательства на каротидных и коронарных артериях демонстрируют большую выраженность мозговой дисфункции по показателям тета-активности фронтальных и парието-окципитальных областей коры мозга. При этом меньшая выраженность изменений тета-ритма после операции у больных с тяжелым предоперационным когнитивным расстройством, с одной стороны, может быть индикатором компенсации хронической ишемии головного мозга и устойчивости к гипоперфузии при искусственном кровообращении, с другой – проявлением потолочного эффекта и недостаточности функциональных резервов

Phenological shifts of abiotic events, producers and consumers across a continent

Ongoing climate change can shift organism phenology in ways that vary depending on species, habitats and climate factors studied. To probe for large-scale patterns in associated phenological change, we use 70,709 observations from six decades of systematic monitoring across the former Union of Soviet Socialist Republics. Among 110 phenological events related to plants, birds, insects, amphibians and fungi, we find a mosaic of change, defying simple predictions of earlier springs, later autumns and stronger changes at higher latitudes and elevations. Site mean temperature emerged as a strong predictor of local phenology, but the magnitude and direction of change varied with trophic level and the relative timing of an event. Beyond temperature-associated variation, we uncover high variation among both sites and years, with some sites being characterized by disproportionately long seasons and others by short ones. Our findings emphasize concerns regarding ecosystem integrity and highlight the difficulty of predicting climate change outcomes. The authors use systematic monitoring across the former USSR to investigate phenological changes across taxa. The long-term mean temperature of a site emerged as a strong predictor of phenological change, with further imprints of trophic level, event timing, site, year and biotic interactions.Peer reviewe

Changes in event-related synchronization/desynchronization of brain electric activity in cardiosurgical patients with postoperative cognitive dysfunction

Aim of the study was to analyze the event-related synchronization/desynchronization of brain electrical activity during visual selection task in patients underwent on-pump coronary artery bypass grafting (CABG) with and without postoperative cognitive dysfunction (POCD). Material and methods. The study included 32 men who underwent on-pump CABG, mean age 57,2 ± 6,08 years. All patients carried out extended neuropsychological testing, a multi-channel computer electroencephalography (EEG) 3-5 days before CABG and on the 7-10th day after the surgery. The POCD was determined according to the criterion: 20 % decrease in the cognitive indicator compared to that at baseline on 20 % of the tests included in the neuropsychological battery. Monopolar EEGs were recorded in 62 sites of 10-20 system with NEUVO encephalograph (Compumedics, USA) during cognitive task performing in patients with and without POCD. Statistical processing was performed using the STATISTICA 10.0. Results. It was found that the POCD patients had less pronounced theta desynchronization in the left frontal-central regions during the stage of 200-400 ms at the 7-10 days after CABG in comparison to patients without cognitive decline. Moreover, in the left parietal leads POCD patients had decreased theta desynchronization during the stage of 200-400 ms even before the surgery. At the 7-10 days after CABG, only the patients without POCD had a decrease of event-related theta activity in the left parietal leads compared with baseline. During the stage of 600-800 ms, the POCD patients had a lower degree of theta-desynchronization of both frontal-central and parietal regions of right hemisphere compared to patients without cognitive decline. Conclusion. The cognitive decline in patients after CABG determined according to neuropsychological testing is accompanied by pathological changes in the event-related theta activity. An analysis of event-related synchronization/desynchronization can be used both as predictor of postoperative cognitive impairment and as objective marker of POCD

Differences in spatial versus temporal reaction norms for spring and autumn phenological events

For species to stay temporally tuned to their environment, they use cues such as the accumulation of degree-days. The relationships between the timing of a phenological event in a population and its environmental cue can be described by a population-level reaction norm. Variation in reaction norms along environmental gradients may either intensify the environmental effects on timing (cogradient variation) or attenuate the effects (countergradient variation). To resolve spatial and seasonal variation in species' response, we use a unique dataset of 91 taxa and 178 phenological events observed across a network of 472 monitoring sites, spread across the nations of the former Soviet Union. We show that compared to local rates of advancement of phenological events with the advancement of temperature-related cues (i.e., variation within site over years), spatial variation in reaction norms tend to accentuate responses in spring (cogradient variation) and attenuate them in autumn (countergradient variation). As a result, among-population variation in the timing of events is greater in spring and less in autumn than if all populations followed the same reaction norm regardless of location. Despite such signs of local adaptation, overall phenotypic plasticity was not sufficient for phenological events to keep exact pace with their cues-the earlier the year, the more did the timing of the phenological event lag behind the timing of the cue. Overall, these patterns suggest that differences in the spatial versus temporal reaction norms will affect species' response to climate change in opposite ways in spring and autumn