Pressure-volume Area Research Articles

A life cycle approach to optimizing carbon footprint and costs of a residential building

Finding life cycle optimized building designs is a challenging task. It requires the inclusion of all phases of the building life cycle in a single optimization problem. The present study demonstrates a life cycle simulation-based optimization approach, by including the operational carbon footprint (OCF) and embodied carbon footprint (ECF) of a building. Particularly, finding and analyzing the difference between life cycle (OCF + ECF) optimized design and operational (only OCF) performance-based optimized design is the primary goal of the current study. The life cycle optimization method is applied to a townhouse in Finland to determine carbon-cost optimal designs. Different options of building envelope insulation thicknesses, window types, heating systems, heat recovery units, and PV area are explored as design variables. It has been found that the heating system is a dominant design variable, which results in clearly separated pareto fronts for each system. Generally, a majority of the design variables' optimal values, obtained from OCF + ECF optimization, suggest thinner insulation for the building envelope and a larger PV area, compared to the optimal solutions from OCF optimization. In a carbon optimal solution, the share of ECF is 39% of the life cycle carbon footprint, whereas in a cost optimal solution, the share of ECF is 28% of the life cycle carbon footprint.

Glucagon-Like Peptide 1 Receptor Activation Augments Cardiac Output and Improves Cardiac Efficiency in Obese Swine After Myocardial Infarction.

This study tested the hypothesis that glucagon-like peptide 1 (GLP-1) therapies improve cardiac contractile function at rest and in response to adrenergic stimulation in obese swine after myocardial infarction. Obese Ossabaw swine were subjected to gradually developing regional coronary occlusion using an ameroid occluder placed around the left anterior descending coronary artery. Animals received subcutaneous injections of saline or liraglutide (0.005–0.015 mg/kg/day) for 30 days after ameroid placement. Cardiac performance was assessed at rest and in response to sympathomimetic challenge (dobutamine 0.3–10 μg/kg/min) using a left ventricular pressure/volume catheter. Liraglutide increased diastolic relaxation (dP/dt; Tau 1/2; Tau 1/e) during dobutamine stimulation (P < 0.01) despite having no influence on the magnitude of myocardial infarction. The slope of the end-systolic pressure volume relationship (i.e., contractility) increased with dobutamine after liraglutide (P < 0.001) but not saline administration (P = 0.63). Liraglutide enhanced the slope of the relationship between cardiac power and pressure volume area (i.e., cardiac efficiency) with dobutamine (P = 0.017). Hearts from animals treated with liraglutide demonstrated decreased β1-adrenoreceptor expression. These data support that GLP-1 agonism augments cardiac efficiency via attenuation of maladaptive sympathetic signaling in the setting of obesity and myocardial infarction.

Harmonic Analysis of PSO Tuned PI Controller Gains for Multilevel Inverter Base P and O MPPT Photovoltaic System

Objectives: The problem of instability in utilization of energy from PV system and harmonics injection due that is concerned here. The Analyzing of PV system and implementing with suitable techniques to attain permissible THD value is main objective of the work. Methods/Statistical Analysis: In this work for tracking maximum power perturb & observer method is employed. This PV system is integrated using Diode Clamped Multilevel Inverter (DCMLI), for this DCMLI APOD modulation technique is developed. PSA and PSO optimization methods are adopted for PI controller tuning which acts as voltage controller for DCMLI. As PSA is basic and local best optimization technique and PSO for its global best characteristics these methods are opted. Findings: The proposed closed loop system gives better control over open loop system. Tuning of the PI controller plays a crucial role in this closed loop system. In the applied heuristics tuning methods Particle Swarm Optimization (PSO) gives best THD control than Pattern Search Algorithm (PSA). The proposed techniques using PSO optimization is well suitable for PV system as the THD obtained by this is within standard acceptable limits. Actual existing systems like PV system with optimizations employed for MPPT’s or PV system with different multilevel topologies involves more complexity and less output quality than the proposed system. An integrated system is developed i.e. PV with suitable MPPT and multilevel inverter with advanced multilevel modulation tuned with heuristic optimization methods are proposed together for a standalone and also for grid application. Here the proposed system in the area of PV using optimization technique employed for multilevel inverter along with the multilevel modulation technique employed for the DCMLI plays an important role. Application/Improvements: The proposed system is developed based on voltage controller of multilevel inverter it can also be developed along with current controller system. The main objective of this work is to harmonic analysis a PV system with a multilevel inverter in standalone and grid connected mode using PSO and PSA optimization techniques. Keywords: Diode Clamped Multilevel Inverter, Harmonic Analysis, MPPT Technique, Optimization Techniques, PV Array, Tuning of PI Controller

Sunlight availability and potential food and energy self-sufficiency in tropical generic residential districts

A transition to a solar-based carbon neutral economy is crucial to reduce the overall ecological footprint and greenhouse gas (GHG) emissions while providing new housing for the growing urban population worldwide. One of the key measures to achieve such reductions as a way to mitigate and adapt to climate change is to increase food and energy self-sufficiency in residential areas. The objective of this study is to explore the potential self-sufficiency in terms of food and energy in generic residential districts in Singapore and Southeast Asia. Computational tools are employed to obtain quantifiable indicators based on sunlight availability. A series of building typologies and urban forms was created as abstractions from actual residential developments in Singapore (1.3°N). In total, 57 cases were assessed in terms of sunlight availability and the impact of three density and geometry parameters: plot ratio, site coverage and building height were considered. Results from selected cases were compared to Hanoi’s conditions (21°N).The results show that the indicators having the higher impact on the food and energy self-sufficiency are plot ratio and building height. The cases with the lowest plot ratio (PR<1.9) achieved food self-sufficiency when a hybrid higher-yield farming method was applied. Regarding energy harvesting, the cases with the lowest building height (<42m) achieve energy self-sufficiency due to the maximum exposed area with PV per number of residents. In low-latitude regions, solar access is more evenly distributed among all facade orientations than in higher latitudes, therefore providing all facade orientations with food and energy harvesting potential. Food and energy self-sufficiency in equatorial regions is more heavily influenced by the available farming and PV area in relation to the total population than by the reduction of sunlight availability due to building typology and morphology.

Systolic and diastolic unloading by mechanical support of the acute vs the chronic pressure overloaded right ventricle

Right ventricular (RV) mechanical support is well described in cases of sudden increase in RV afterload. In cases of chronic RV pressure overload (e.g., pulmonary arterial hypertension), it has rarely been described. The pulmonary artery was banded in 18 sheep. In the acute group (n = 9), we immediately implanted a Synergy Pocket Micro-Pump. Blood was withdrawn from the right atrium to the pulmonary artery. In the chronic group (n = 9), this pump was implanted 8 weeks after banding. Hemodynamics and pressure-volume loops were recorded before and 15 minutes after pump activation. Low-flow RV mechanical support significantly improved arterial blood pressure in both groups, but cardiac output only in the acute group. Intrinsic RV contractility was not affected. The RV contribution to the total right-sided cardiac output was 54% ± 8 in the acute group vs 10% ± 13 in the chronic group (p < 1.10-5), indicating a more profound unloading in the latter. Diastolic unloading (reflected by decreases in central venous pressure, end-diastolic pressure and volume, and ventricular capacitance) was successful in both groups. Decreases in pressure-volume area and RV peak pressure reflected successful systolic unloading only in the chronic group. Low-flow RV mechanical support improved arterial blood pressure in both conditions but caused a more profound unloading in the chronic group. Diastolic unloading was successful in both groups, but systolic unloading was successful only in the chronic group. The potential use of low-flow mechanical support for a chronic pressure overloaded right ventricle warrants further research to assess its long-term effects.

Left ventricular function: time-varying elastance and left ventricular aortic coupling.

Many aspects of left ventricular function are explained by considering ventricular pressure–volume characteristics. Contractility is best measured by the slope, Emax, of the end-systolic pressure–volume relationship. Ventricular systole is usefully characterized by a time-varying elastance (ΔP/ΔV). An extended area, the pressure–volume area, subtended by the ventricular pressure–volume loop (useful mechanical work) and the ESPVR (energy expended without mechanical work), is linearly related to myocardial oxygen consumption per beat. For energetically efficient systolic ejection ventricular elastance should be, and is, matched to aortic elastance. Without matching, the fraction of energy expended without mechanical work increases and energy is lost during ejection across the aortic valve. Ventricular function curves, derived from ventricular pressure–volume characteristics, interact with venous return curves to regulate cardiac output. Thus, consideration of ventricular pressure–volume relationships highlight features that allow the heart to efficiently respond to any demand for cardiac output and oxygen delivery.

MPS 09-01 PARAMETERS OF VENTRICULAR-ARTERIAL COUPLING AND THEIR PROGNOSTIC VALUE IN STABLE PATIENTS WITH ARTERIAL HYPERTENSION AND HEART FAILURE WITH REDUCED EJECTION FRACTION

Objective: The purpose of the study was to determine the prognostic value of ventricular-arterial coupling (VAC) in patients with arterial hypertension (AH) and stable heart failure with reduced ejection fraction (HFrEF). Design and Method: In prospective study (follow-up 12–24 months, median 18 months) prognosis of 93 stable patients with controlled hypertension and HFrEF was evaluated. Adverse outcomes included all cause death or first HF hospitalization. 2-dimentional echocardiography was used to assess arterial elastance (Ea) and end-systolic LV elastance (Ees). VAC was assessed as the ratio Ea/Ees. Arterial stiffness was assessed using applanation tonometry. Clinical and demographic parameters, parameters of LV function, VAC and arterial stiffness were included in multivariate analysis. P < 0.05 was considered significant. Results: Adverse outcomes were revealed in 39% of patients (15% deaths, 24% HF hospitalizations). The following factors increased the risk of adverse outcomes: LVEF <25%, index of VAC 33.3, stroke work (SW)/pressure volume area (PVA) (LV work efficiency) <38%, augmentation index (AI) ≥25%, time to reflected wave (Tr) <135. Pulse wave velocity ≥15 m/s, office systolic BP <120 mmHg were associated with increased risk of HF hospitalizations. AI >35%, office systolic BP <120 and diastolic BP <70, Tr <116, SW/PVA <48% were associated with increased risk of all-cause death. Conclusions: Parameters of VAC and arterial stiffness have independent prognostic value as well as LVEF and BP in patients with AH and HFrEF. Assessment of VAC via Ea/Ees, an additional noninvasively derived metric, can be used for risk stratification of patients with HFrEF.

PP.18.01] VENTRICULAR-ARTERIAL COUPLING MAY BE AN EARLY MARKER OF CARDIAC REMODELING AFTER MYOCARDIAL INFARCTION TREATED WITH PERCUTANEOUS CORONARY INTERVENTION

Objective: Ventricular remodeling may occur following myocardial infarction (MI) of the left ventricle (LV) and such remodeling has been shown to be correlated with increased patient morbidity and mortality. It is important to estimate the likelihood of remodeling from the state of the infarcted LV. The aim of the study was to assess the ventricular-arterial coupling (VAC) in patients with ST segment elevation (STEMI) and non ST segment elevation MI (NSTEMI) treated with percutaneous coronary intervention (PCI). Design and method: In 93 patients with acute coronary syndrome and PCI (70% male, age 61,5 ± 10,1 years (M ± SD), 57 (61,3%) with STEMI, smokers 25%, arterial hypertension 20.4%, blood pressure (BP) 129 ± 6/82 ± 7 mmHg, LVEF 47,4 ± 4,3%) 2-dimentional echocardiography was performed to assess arterial elastance (Ea) and end-systolic LV elastance (Ees) on admission and in 4 weeks. VAC was assessed as the ratio Ea/Ees. Results: Baseline LF EF was 47.4 ± 4.3, E/A 0.95 ± 0,18, Ea 1.9 ± 0.3 mmHg/ml/m2, Ees 2.1 ± 0.4 mmHg/ml/m2, VAC 0.89 ± 0.1. At baseline all patients had LVEF >40% and VAC in optimal range. In 4 weeks after PCI VAC >1.2 (upper optimal level) was revealed in 19% of patients with STEMI and 44% with NSTEMI. In patients with achieved VAC >1.2 Ees (2.1 ± 0.4 vs 1.6 ± 0.2 mmHg/ml/m2, p < 0.001), stroke work (SW) (6254 ± 1516 vs 6112 ± 1059 mmHg*ml/m2, p>0.05), potential energy (PE) (62.8 ± 4.3 vs 56.3 ± 5.4 mmHg*ml/m2, p < 0.001), pressure-volume area (PVA) (6317 ± 2136 vs 6179 ± 1060 mmHg*ml/m2, p < 0.001), LV work efficiency (SW/PVA) significantly decreased (p < 0.001) while Ea (1.9 ± 0.3 to 2.1 ± 0.4 mmHg/ml/m2, p > 0.05) did not change. In patients with VAC in optimal range in 4 weeks Ees decreased from 2.3 ± 0.3 to 2.1 ± 0.4 mmHg/ml/m2 (p < 0.001), Ea (p < 0.001) and VAC (p < 0.001) did not change. Conclusions: Impairment of functioning of cardio-vascular system assessed by increased value of VAC > 1.2 was revealed in 27% of patients with acute coronary syndrome. Increase of VAC is associated predominantly with decrease of Ees and LV work efficiency (SW/PVA). Increased in the VAC index > 1.2 indicating LV-arterial uncoupling may be an early marker of cardiovascular remodeling in MI or systolic dysfunction.

Early Hemodynamic Improvement after Percutaneous Mitral Valve Repair Evaluated by Noninvasive Pressure-Volume Analysis

Mitral regurgitation represents a volume load on the left ventricle leading to congestion and symptoms of heart failure. The aim of this study was to characterize early hemodynamic adaptions after percutaneous mitral valve (MV) repair. Forty-six consecutive patients with symptomatic high-grade MV insufficiency (mean age, 72years; 54% men) were prospectively included in the study and examined before and after successful catheter-based clip implantation. Seventy percent of patients had secondary mitral regurgitation. Noninvasive pressure-volume loops were reconstructed from echocardiography with simultaneous blood pressure measurements. MV repair reduced left ventricular end-diastolic volume index from 87±41 to 80±40mL/m(2) (P<.0001). End-systolic volume index was 55±37mL/m(2) before versus 54±37mL/m(2) after repair (P=.52). Hence, total stroke volume decreased from 60±23 to 49±16mL (P<.0001), as did total ejection fraction (from 41±14% to 37±13%, P=.002) and global longitudinal strain (from -11±4.9% to -9.1±4.4%, P=.0001). Forward stroke volume, forward ejection fraction, and forward cardiac output remained constant (43±12mL vs 42±11mL, 33±17% vs 35±18%, and 3.2±0.9L/min vs 3.4±0.8L/min, respectively). Parameters of left ventricular contractility (end-systolic elastance and peak power index) and measurements of afterload (arterial elastance, end-systolic wall stress, and total peripheral resistance) were similar before and after MV repair. Forward ejectionfraction correlated more strongly with end-systolic elastance (r=0.61, P<.0001) than did total ejection fraction (r=0.35, P=.0007) or global longitudinal strain (r=-0.38, P=.0002). Total mechanical energy (pressure-volume area) decreased from10,903±4,410 to 9,124±2,968mmHg×mL (P=.0007) because of reduced stroke work (5,546±2,241mmHg×mL vs 4,414±1,412mmHg×mL, P<.0001). At 3months, symptom statushad improved (76% of patients in New York Heart Association classes I and II), and 97% of patients had mitral regurgitation grade ≤2+. Left ventricular contractility and forward cardiac output remained unchanged after percutaneous MV repair despite decreases in total ejection fraction and global longitudinal strain. The left ventricle was unloaded through reduced end-diastolic volume. Thus, MV repair is associated with an improved hemodynamic state in noninvasive pressure-volume analysis.

Spatial Optimization of Residential Urban District - Energy and Water Perspectives

Many cities around the world have reached a critical situation when it comes to energy and water supply, threatening the urban sustainable development. The aim of this paper is to develop a spatial optimization model for the planning of residential urban districts with special consideration of renewables and water harvesting integration. In particular, the paper analyses the optimal configuration of built environment area, PV area, wind turbines number and relative occupation area, battery and water harvester storage capacities, as a function of electricity and water prices. The optimization model is multi-objective which uses a genetic algorithm to minimize the system life cycle costs, and maximize renewables and water harvesting reliability.The developed model can be used for spatial optimization design of new urban districts. It can also be employed for analyzing the performances of existing urban districts under an energy-water-economic viewpoint.Assuming a built environment area equal to 75% of the total available area, the results show that the reliability of the renewables and water harvesting system cannot exceed the 6475 and 2500 hours/year, respectively. The life cycle costs of integrating renewables and water harvesting into residential districts are mainly sensitive to the battery system specific costs since most of the highest renewables reliabilities are guaranteed through the energy storage system.

Reassessing Diagrams of Cardiac Mechanics: From Otto Frank and Ernest Starling to Hiroyuki Suga.

This article explores the importance of diagrams in the history of the understanding of cardiac function, by comparing Ernest Starling's famous "Law of the Heart" (1918) with the mathematically based view of cardiac mechanics put forward by Otto Frank (1897). Whereas Frank's diagrams gained influence in German cardio-physiological publications, they were widely unknown abroad until 1969, when Hiroyuki Suga began to present similar approaches for warm-blooded animals as Frank had done for the frog. Suga succeeded in correlating the pressure volume area (PVA)-a composite of Frank's work loop plus the area of remaining potential energy-with the oxygen consumption of the beating heart. With the concept of time-varying elastance as an index of cardiac contractility, Suga's approach became attractive for clinical applications, and Daniel Burkhoff and colleagues were able to use these insights for real-time, interactive simulations of the cardiovascular system. Such tools can be used for exploring basic hemodynamic principles and, thanks to technical developments of miniature pumps within the same time frame (Καιρός, the "right moment," or "the opportune"), to test the effects of device-based treatment for heart failure. These outcomes confirm that old analyses of the heart's activity may still be useful today.

Cardiac Energetics in Presence of Lung Assist Devices: &amp;lt;i&amp;gt;In Silico&amp;lt;/i&amp;gt; Study

The treatment with a mechanical ventilator is required whenever a patient’s respiratory system becomes unable to keep the concentrations of O2 and CO2 in blood at tolerable levels. However, in particular cases, the thoracic artificial lung (TAL) can be regarded as a viable alternative to mechanical ventilation (MV). We aim at studying the effects of mechanical ventilators and thoracic artificial lungs devices will have on the cardiovascular system. We will give careful consideration to cardiovascular energetic parameters, such as left and right ventricular external work, pressure-volume area, and cardiac mechanical efficiency. We simulated both, mechanically ventilated patients who are not subject to the application of an artificial lung and patients who are provided with a thoracic artificial lung (TAL). In the case of a thoracic artificial lung, we involved in our simulation studies all the usual operating modes of a TAL, viz. series mode, parallel mode, and hybrid mode of the TAL with regard to the native lung. In particular, the presented simulation results will contribute to elucidate the specific characteristics of each of the aforementioned operating modes. Generally, the energetic variables are influenced by different values of input TAL resistance in both modes: parallel and in series. In this paper, we concentrated on simulation studies of the effects evoked by TAL assistance on cardiac energetic and some other important circulatory parameters. The simulation results presented show that at all modes of TAL assistance exists a strong dependency on the TAL input variables and on the value of the mean intrathoracic pressure which has been assumed for a given situation.

Celsior preserves cardiac mechano-energetics better than University of Wisconsin solution by preventing oxidative stress.

Identity of the optimal heart preservation solution remains unknown. Because oxidative stress contributes to contractile failure in the ischaemic/reperfused myocardium and the main characteristic of Celsior is its antioxidant effect, it is important to elucidate the relationship between the inhibitory effect on oxidative stress and cardiac mechano-energetics. We therefore evaluated the efficacy of Celsior from both aspects by comparison with the University of Wisconsin solution (UWS). We used 18 excised cross-circulated canine hearts. Excised hearts were preserved with UWS (n = 6) or Celsior (n = 6) for 3 h at 4 °C; the remaining six served as controls. Hearts were then cross-circulated and rewarmed. The end-systolic pressure-volume ratio (LV Emax) and the ventricular pressure-volume area, which is a measure of total mechanical energy, were assessed after reperfusion. Biopsies were taken from the endocardium after excising the heart, before reperfusion, after reperfusion and 4 h after reperfusion to assess the inhibitory effect of each agent on oxidative stress. Endo-myocardial biopsy samples were studied immunohistochemically for expression of 4-hydroxy-2-nonenal (HNE)-modified protein, which is a major lipid peroxidation product. Emax in the UWS group was significantly smaller than in the control group, whereas the Emax in the Celsior group was preserved. Oxygen cost of Emax in the UWS group was significantly higher than in the Celsior group. Myocardial HNE-modified protein levels increased gradually, both under preservation and after reperfusion in the UWS group. Myocardial HNE-modified protein levels in the Celsior group were lower, mainly before and 4 h after reperfusion compared with the UWS group. Celsior may maintain cardiac contractility and conserve oxygen cost by inhibiting oxidative stress.

Lung assist devices influence cardio-energetic parameters: Numerical simulation study.

We aim at an analysis of the effects mechanical ventilators (MVs) and thoracic artificial lungs (TALs) will have on the cardiovascular system, especially on important quantities, such as left and right ventricular external work (EW), pressure-volume area (PVA) and cardiac mechanical efficiency (CME). Our analyses are based on simulation studies which were carried out by using our CARDIOSIM(©) software simulator. At first, we carried out simulation studies of patients undergoing mechanical ventilation (MV) without a thoracic artificial lung (TAL). Subsequently, we conducted simulation studies of patients who had been provided with a TAL, but did not undergo MV. We aimed at describing the patient's physiological characteristics and their variations with time, such as EW, PVA, CME, cardiac output (CO) and mean pulmonary arterial/venous pressure (PAP/PVP). We were starting with a simulation run under well-defined initial conditions which was followed by simulation runs for a wide range of mean intrathoracic pressure settings. Our simulations of MV without TAL showed that for mean intrathoracic pressure settings from negative (-4 mmHg) to positive (+5 mmHg) values, the left and right ventricular EW and PVA, right ventricular CME and CO decreased, whereas left ventricular CME and the PAP increased. The simulation studies of patients with a TAL, comprised all the usual TAL arrangements, viz. configurations "in series" and in parallel with the natural lung and, moreover, hybrid configurations. The main objective of the simulation studies was, as before, the assessment of the hemodynamic response to the application of a TAL. We could for instance show that, in case of an "in series" configuration, a reduction (an increase) in left (right) ventricular EW and PVA values occurred, whereas the best performance in terms of CO can be achieved in the case of an in parallel configuration.

Network Modeling for Functional Magnetic Resonance Imaging (fMRI) Signals during Ultra-Fast Speech Comprehension in Late-Blind Listeners.

In many functional magnetic resonance imaging (fMRI) studies blind humans were found to show cross-modal reorganization engaging the visual system in non-visual tasks. For example, blind people can manage to understand (synthetic) spoken language at very high speaking rates up to ca. 20 syllables/s (syl/s). FMRI data showed that hemodynamic activation within right-hemispheric primary visual cortex (V1), bilateral pulvinar (Pv), and left-hemispheric supplementary motor area (pre-SMA) covaried with their capability of ultra-fast speech (16 syllables/s) comprehension. It has been suggested that right V1 plays an important role with respect to the perception of ultra-fast speech features, particularly the detection of syllable onsets. Furthermore, left pre-SMA seems to be an interface between these syllabic representations and the frontal speech processing and working memory network. So far, little is known about the networks linking V1 to Pv, auditory cortex (A1), and (mesio-) frontal areas. Dynamic causal modeling (DCM) was applied to investigate (i) the input structure from A1 and Pv toward right V1 and (ii) output from right V1 and A1 to left pre-SMA. As concerns the input Pv was significantly connected to V1, in addition to A1, in blind participants, but not in sighted controls. Regarding the output V1 was significantly connected to pre-SMA in blind individuals, and the strength of V1-SMA connectivity correlated with the performance of ultra-fast speech comprehension. By contrast, in sighted controls, not understanding ultra-fast speech, pre-SMA did neither receive input from A1 nor V1. Taken together, right V1 might facilitate the “parsing” of the ultra-fast speech stream in blind subjects by receiving subcortical auditory input via the Pv (= secondary visual pathway) and transmitting this information toward contralateral pre-SMA.

Left ventricular performance early after repair for posterior mitral leaflet prolapse: Chordal replacement versus leaflet resection

ObjectiveTo review hemodynamic performance early after valve repair with chordal replacement versus leaflet resection for posterior mitral leaflet prolapse. MethodsBetween April 2006 and September 2014, 72 consecutive patients underwent valve repair with chordal replacement (30 patients) or leaflet resection (42 patients) for isolated posterior mitral leaflet prolapse. Left ventricular ejection fraction, end-systolic elastance, effective arterial elastance, and ventricular efficiency were noninvasively measured by echocardiography and analyzed preoperatively and ∼ 1 month postoperatively. Mitral valve repair was accomplished in all patients, and no regurgitation (including trivial) was observed postoperatively. ResultsChordal replacement resulted in significantly less reduction in left ventricular ejection fraction, and significantly greater increase in end-systolic elastance than leaflet resection (left ventricular ejection fraction, 4.8% vs 16.7% relative decrease [P = .005] and end-systolic elastance, 19.0% vs −1.3% relative increase [P = .012]). Despite comparable preoperative ventricular efficiency between the groups, the postoperative ventricular efficiency in the chordal replacement group was superior to that in the leaflet resection group (ventriculoarterial coupling, 32.0% vs 89.3% relative increase [P = .007] and ratio of stroke work to pressure-volume area, 4.3% vs 13.4% relative decrease [P = .008]). In multivariate analysis, operative technique was a significant determinant of left ventricular ejection fraction and ratio of stroke work to pressure-volume area (P = .030 and P = .030, respectively). ConclusionsChordal replacement might provide patients undergoing valve repair for posterior mitral leaflet prolapse with better postoperative ventricular performance than leaflet resection. Longer follow-up is required to compare long-term outcomes.

5-Day Bed Rest: Portal and Lower Limb Veins With and Without Artificial Gravity Countermeasures

The objective of the study was to evaluate the effect of short-term, head-down bed rest (HDBR), with and without artificial gravity countermeasures, on splanchnic and lower limb vein properties. Data were collected from 12 men before and after 5 d of continuous -6° HDBR without countermeasures (CON) and with two artificial gravity countermeasure protocols: 30-min continuous centrifugation (AG1), and 30-min intermittent centrifugation (AG2). Portal (PV), tibial (TibV), and gastrocnemius (GastV) veins were investigated by echography supine and after 30 min of head-up tilt. After HDBR, there was no change in PV, TibV, or GastV cross-sectional area at rest in any of the three conditions. In response to tilt, GastV and TibV area increased (168±141% and 192±124%, respectively) with no change in this response post-HDBR in any of the experimental conditions (P>0.05). PV area decreased with tilt (-33±13%) and was not different pre- to post-HDBR in the CON or AG1 conditions. However, there was a greater reduction in PV area in the AG2 group post-HDBR (-32±10% pre, -49±9% post-HDBR, P=0.003). Calf veins were not significantly affected by 5 d of HDBR and did not appear to be negatively impacted by the artificial gravity countermeasures over this time period. In addition, the intermittent protocol resulted in better splanchnic vasoconstriction in response to head-up tilt, which may have contributed to a better maintenance of orthostatic tolerance post-HDBR.

Comparison of circumferential pulmonary vein anatomy mapping guided by 3D mapping versus a mesh mapping catheter

ObjectiveCatheter-based pulmonary vein isolation (PVI) is an established therapy for paroxysmal atrial fibrillation. The high-density mesh mapper (HDMM) guides circumferential PV-atrium isolation without the 3D electroanatomic mapping. This study aims to compare circumferential pulmonary vein (CPV) anatomy mapping between guiding by a 3D mapping system and the HDMM. MethodsForty-four consecutive patients with paroxysmal atrial fibrillation were scheduled for a first procedure for PVI. A CPV ostial anatomy map guided by HDMM was set up in the CARTO system while the operator was blinded to the CARTO screen. Then CARTO-guided ipsilateral PV maps were obtained and PVI was performed. This established another set of CPV ostial anatomy maps. The differences between the two mapping images were compared and analyzed. ResultsAll 176 PVs in 44 patients could be mapped by both HDMM and CARTO. About 44.9% of the PV ostial anatomies were generally similar between the two different map images. The average point-to-point straight distance between the HDMM-guided map and the CARTO-guided map was 6.2 ± 1.4 mm. The area of the circumferential right PV (CRPV) in the HDMM map was larger than that in the CARTO map (P = 0.013). After a mean follow-up of 18.3 ± 4.3 months (6–24 months), 72.7% of patients (32/44) were free of atrial arrhythmia without anti-arrhythmic drugs (AADs). ConclusionCompared to the CARTO-guided CPV anatomy image, a highly similar figure could be achieved by mapping guided by the HDMM. (Clinical trial.gov number, ChiCTR-TNRC-11001390.)

Myosin Activator Omecamtiv Mecarbil Increases Myocardial Oxygen Consumption and Impairs Cardiac Efficiency Mediated by Resting Myosin ATPase Activity.

Omecamtiv mecarbil (OM) is a novel inotropic agent that prolongs systolic ejection time and increases ejection fraction through myosin ATPase activation. We hypothesized that a potentially favorable energetic effect of unloading the left ventricle, and thus reduction of wall stress, could be counteracted by the prolonged contraction time and ATP-consumption. Postischemic left ventricular dysfunction was created by repetitive left coronary occlusions in 7 pigs (7 healthy pigs also included). In both groups, systolic ejection time and ejection fraction increased after OM (0.75 mg/kg loading for 10 minutes, followed by 0.5 mg/kg/min continuous infusion). Cardiac efficiency was assessed by relating myocardial oxygen consumption to the cardiac work indices, stroke work, and pressure-volume area. To circumvent potential neurohumoral reflexes, cardiac efficiency was additionally assessed in ex vivo mouse hearts and isolated myocardial mitochondria. OM impaired cardiac efficiency; there was a 31% and 23% increase in unloaded myocardial oxygen consumption in healthy and postischemic pigs, respectively. Also, the oxygen cost of the contractile function was increased by 63% and 46% in healthy and postischemic pigs, respectively. The increased unloaded myocardial oxygen consumption was confirmed in OM-treated mouse hearts and explained by an increased basal metabolic rate. Adding the myosin ATPase inhibitor, 2,3-butanedione monoxide abolished all surplus myocardial oxygen consumption in the OM-treated hearts. Omecamtiv mecarbil, in a clinically relevant model, led to a significant myocardial oxygen wastage related to both the contractile and noncontractile function. This was mediated by that OM induces a continuous activation in resting myosin ATPase.

Left ventricular mass is related to post-saline load plasma aldosterone levels in primary hypertension

The purpose of the study was to determine the prognostic value of ventricular-arterial coupling (VAC) in patients with arterial hypertension and stable heart failure with reduced ejection fraction (HFrEF). Methods: In prospective study (follow-up 12-24 months, median 18 months) prognosis of 93 stable patients (75% male, age 64 9 years (M SD), history of myocardial infarction 67%, diabetes mellitus 32%, heart rate 75 13/min) with controlled hypertension (blood pressure (BP) <160/100 mmHg, 131 14/80 10 mmHg), symptoms and signs of HF, left ventricular (LV) EF 100 pg/ml (650 679 pg/ml), II/III NYHA class 25/75% was evaluated. Adverse outcomes included all cause death or first HF hospitalization. 2-dimentional echocardiography was used to assess arterial elastance (Ea) and end-systolic LV elastance (Ees). VAC was assessed as the ratio Ea/Ees. Arterial stiffness was assessed using applanation tonometry. Clinical and demographic parameters, parameters of LV function, VAC and arterial stiffness were included in multivariate analysis. P<0.05 was considered significant. Results: Adverse outcomes were revealed in 39% of patients (15% deaths, 24% HF hospitalizations). The following factors increased the risk of adverse outcomes: LVEF <25% (odds ratio (OR) 26.1, 95% confidential interval (CI) 24.9-27.3), index of VAC 3.3 (OR 23.3, 95% CI 22.124.5), stroke work (SW)/pressure volume area (PVA) (LV work efficiency) <38% (OR 8.2, 95% CI 7.0-9.4), augmentation index (AI) 25% (OR 2.3, 95% CI 1.3-3.2), time to reflected wave (Tr) <135 ms (OR 2.1, 95% CI 1.2-3.0). Pulse wave velocity 15 m/s (OR 5.4, 95% CI 3.7-7.1), office systolic BP <120 mmHg (OR 5.1, 95% CI 4.2-6.0) were associated with increased risk of HF hospitalizations. AI 35% (OR 7.3, 95% CI 5.9-8.6), office systolic BP <120 mmHg (OR 3.4, 95% CI 1.3-5.5) and diastolic BP <70 mmHg (OR 3.4, 95% CI 1.3-5.5), Tr <116 ms (OR 2.3, 95% CI 1.1-3.5), SW/PVA <48% (OR 2.3, 95% CI 1.1-3.5) were associated with increased risk of all-cause death. Conclusions: Parameters of VAC, LV work efficiency and arterial stiffness have independent prognostic value as well as LVEF and BP in patients with arterial hypertension and HFrEF. Assessment of VAC via Ea/Ees, an additional noninvasively derived metric, can be used for risk stratification of patients with HFrEF.