3D Real-Time Echocardiography Combined with Mini Pressure Wire Generate Reliable Pressure-Volume Loops in Small Hearts

BACKGROUND: Pressure-volume loops (PVL) provide vital information regarding ventricular performance and pathophysiology in cardiac disease. Unfortunately, acquisition of PVL by conductance technology is not feasible in neonates and small children due to the available human catheter size and resulting invasiveness. The aim of the study was to validate the accuracy of PVL in small hearts using volume data obtained by real-time three-dimensional echocardiography (3DE) and simultaneously acquired pressure data. METHODS: In 17 piglets (weight range: 3.6–8.0 kg) left ventricular PVL were generated by 3DE and simultaneous recordings of ventricular pressure using a mini pressure wire (PVL3D). PVL3D were compared to conductance catheter measurements (PVLCond) under various hemodynamic conditions (baseline, alpha-adrenergic stimulation with phenylephrine, beta-adrenoreceptor-blockage using esmolol). In order to validate the accuracy of 3D volumetric data, cardiac magnetic resonance imaging (CMR) was performed in another 8 piglets. RESULTS: Correlation between CMR- and 3DE-derived volumes was good (enddiastolic volume: mean bias -0.03ml ±1.34ml). Computation of PVL3D in small hearts was feasible and comparable to results obtained by conductance technology. Bland-Altman analysis showed a low bias between PVL3D and PVLCond. Systolic and diastolic parameters were closely associated (Intraclass-Correlation Coefficient for: systolic myocardial elastance 0.95, arterial elastance 0.93, diastolic relaxation constant tau 0.90, indexed end-diastolic volume 0.98). Hemodynamic changes under different conditions were well detected by both methods (ICC 0.82 to 0.98). Inter- and intra-observer coefficients of variation were below 5% for all parameters. CONCLUSIONS: PVL3D generated from 3DE combined with mini pressure wire represent a novel, feasible and reliable method to assess different hemodynamic conditions of cardiac function in hearts comparable to neonate and infant size. This methodology may be integrated into clinical practice and cardiac catheterization programs and has the capability to contribute to clinical decision making even in small hearts

Einheit von Park und Architektur : der Park am IG Hochhaus

Cerebellar granule cells, which constitute half the brain's neurons, supply Purkinje cells with contextual information necessary for motor learning, but how they encode this information is unknown. Here we show, using two-photon microscopy to track neural activity over multiple days of cerebellum-dependent eyeblink conditioning in mice, that granule cell populations acquire a dense representation of the anticipatory eyelid movement. Initially, granule cells responded to neutral visual and somatosensory stimuli as well as periorbital airpuffs used for training. As learning progressed, two-thirds of monitored granule cells acquired a conditional response whose timing matched or preceded the learned eyelid movements. Granule cell activity covaried trial by trial to form a redundant code. Many granule cells were also active during movements of nearby body structures. Thus, a predictive signal about the upcoming movement is widely available at the input stage of the cerebellar cortex, a

Cognitive Reserve and the Prevention of Dementia: the Role of Physical and Cognitive Activities

Purpose of Review: The article discusses the two most significant modifiable risk factors for dementia, namely, physical inactivity and lack of stimulating cognitive activity, and their effects on developing cognitive reserve. Recent Findings: Both of these leisure-time activities were associated with significant reductions in the risk of dementia in longitudinal studies. In addition, physical activity, particularly aerobic exercise, is associated with less age-related gray and white matter loss and with less neurotoxic factors. On the other hand, cognitive training studies suggest that training for executive functions (e.g., working memory) improves prefrontal network efficiency, which provides support to brain functioning in the face of cognitive decline. Summary: While physical activity preserves neuronal structural integrity and brain volume (hardware), cognitive activity strengthens the functioning and plasticity of neural circuits (software), thus supporting cognitive reserve in different ways. Future research should examine whether lifestyle interventions incorporating these two domains can reduce incident dementia

Closing the Loop: Modelling of Heart Failure Progression from Health to End-Stage Using a Meta-Analysis of Left Ventricular Pressure-Volume Loops

Introduction The American Heart Association (AHA)/American College of Cardiology (ACC) guidelines for the classification of heart failure (HF) are descriptive but lack precise and objective measures which would assist in categorising such patients. Our aim was two fold, firstly to demonstrate quantitatively the progression of HF through each stage using a meta-analysis of existing left ventricular (LV) pressure-volume (PV) loop data and secondly use the LV PV loop data to create stage specific HF models. Methods and Results A literature search yielded 31 papers with PV data, representing over 200 patients in different stages of HF. The raw pressure and volume data were extracted from the papers using a digitising software package and the means were calculated. The data demonstrated that, as HF progressed, stroke volume (SV), ejection fraction (EF%) decreased while LV volumes increased. A 2-element lumped parameter model was employed to model the mean loops and the error was calculated between the loops, demonstrating close fit between the loops. The only parameter that was consistently and statistically different across all the stages was the elastance (Emax). Conclusions For the first time, the authors have created a visual and quantitative representation of the AHA/ACC stages of LVSD-HF, from normal to end-stage. The study demonstrates that robust, load-independent and reproducible parameters, such as elastance, can be used to categorise and model HF, complementing the existing classification. The modelled PV loops establish previously unknown physiological parameters for each AHA/ACC stage of LVSD-HF, such as LV elastance and highlight that it this parameter alone, in lumped parameter models, that determines the severity of HF. Such information will enable cardiovascular modellers with an interest in HF, to create more accurate models of the heart as it fails

TGF alpha and AVP in the mouse suprachiasmatic nucleus:Anatomical relationship and daily profiles

Daily rhythms in behavior and physiology are under control of the suprachiasmatic nucleus (SCN), the main mammalian circadian pacemaker located in the hypothalamus. The SCN communicates with the rest of the brain via various output systems. The aim of the present study was to determine the neuroanatomical and temporal relationship between two output systems, arginine-vasopressin (AVP) and transforming growth factor a (TGF alpha), in the mouse SCN. TGF alpha-positive cells were found throughout the SCN, but more abundantly in the core than the shell area, while AVP was predominantly found in the shell. Fluorescent double labeling revealed a total lack of co-expression for the two proteins in SCN cells. The circadian profile, studied by way of optical density in immunostaining at 3 h intervals, showed peak values for AVP shortly after the LD transitions. Immunoreactivity for TGF alpha was highly variable, especially at time points before the LD transitions. In addition, strong lateralization in TGF alpha immunostaining in the SCN was found in some individuals. Daily fluctuations in the paraventricular nucleus were absent for TGF alpha, and only weakly present for AVP. The main conclusion derived from this study is that these two output systems of the biological clock are anatomically separated with different daily profiles in expression. (c) 2005 Elsevier B.V. All rights reserved

Preexisting heart failure is an underestimated risk factor in cardiac surgery

BACKGROUND: Heart failure is characterised as a strong risk factor for systemic failure after cardiac surgery. However, the impact has never been substantiated. METHODS: Patients with heart failure (n = 48) - scheduled for elective ventricular reconstruction or external constraint device-were compared with a one-to-one matched control group of patients without heart failure undergoing cardiac surgery between 2006 and 2009. RESULTS: As expected, patients with heart failure more frequently experienced complications definitely related to pump failure (p = 0.01). However, complications not related to their pump failure were also more often observed, such as prolonged mechanical ventilation, sepsis and vasoplegia (p = 0.01). Overall, organ dysfunction-circulatory, renal, and pulmonary failure-was often observed in heart failure patients, contributing to a prolonged stay in the intensive care unit (p < 0.001) as well as in hospital (p = 0.01). CONCLUSION: The adverse postoperative course in patients with heart failure is not only directly related to circulatory failure, but merely reflects a systemic dysregulation. Our findings suggest that heart failure impacts outcome and should therefore be included in prevailing risk classification systems. Offensive perioperative treatment strategies, focused on the main complications in patients with heart failure, will lead to improved results after cardiac surgery.Cardiolog