IntroductionVentriculoarterial coupling (VAC), traditionally assessed using the invasive “gold standard” Ea/Ees ratio (arterial elastance to end-systolic elastance), is clinically important but requires approximations that are impractical at the bedside. Oscillatory power fraction (OPF), defined as the ratio of oscillatory to total hydraulic power and derived from synchronized aortic flow–pressure measurements, has been proposed as a pragmatic VAC surrogate. This study aimed to clarify the possible correlation between VAC and OPF in pharmacologically induced hemodynamic extremes.MethodsIn 14 juvenile pigs challenged with vasoactive (phenylephrine, nitroprusside) and cardioactive drugs (dobutamine, esmolol) titrated toward protocolized targets (± 40% MAP, ± 50% dP/dt), we obtained a comprehensive dataset using intracardiac conductance catheters, intraaortic pressure probes, and ascending aortic flow probes. Linear mixed models with animal as a random effect compared baseline and drug-effect states. The coupling of the two responses was assessed from each animal’s baseline-to-effect change, corrected for measurement error estimated from the replicate recordings.ResultsEa/Ees changed by 10%–36% across the four interventions, whereas OPF changed by 1.5%–12%, and under phenylephrine and dobutamine, the change in OPF was negligible (|d| < 0.2, both p > 0.2) despite measurable changes in Ea/Ees. Esmolol was the only challenge under which both indices changed substantially in the same direction (Ea/Ees: + 35.4%, OPF: + 12.2%). Whether the magnitudes of the two responses were coupled could not be determined. Dobutamine markedly increased Ees, total power, and oscillatory power while preserving OPF despite a reduction in Ea/Ees, indicating improved VAC but stable pulsatile efficiency. Vasoactive drugs (phenylephrine, nitroprusside) substantially altered Ea/Ees without relevant OPF changes.ConclusionEa/Ees and OPF are not interchangeable. OPF responded far less strongly than Ea/Ees to the loading changes imposed here and did not resolve them under two of the four challenges. This is consistent with the two indices reflecting predominantly steady and pulsatile aspects of arterial load, although the present data do not demonstrate that separation directly. While OPF cannot replace Ea/Ees, power-derived indices offer practical adjuncts for characterizing ventriculoarterial interactions and the effects of selected drugs at the intensive care bedside.

Abstract Background Measuring mitral annular plane systolic excursion (MAPSE) serially in a single wall may be an effective method for monitoring global left ventricular (LV) function, especially when automated with a novel deep learning method using transesophageal echocardiography, called autoMAPSE. However, this assumption is untested in postoperative ICU patients, and the impact of regional wall motion abnormalities (RWMA) is unclear. Aim To assess the ability of single-wall autoMAPSE in tracking changes in global LV function (i.e., trending ability) using manual global MAPSE averaged from four walls as reference, and to explore how this ability was affected by RWMA. Methods This study was a secondary analysis of a prospective observational study. The changes in single-wall autoMAPSE and manual global MAPSE were calculated in 49 patients undergoing cardiac surgery. Trending ability evaluates how well a novel method detects changes in a reference method, which we assessed using four-quadrant plots with concordance rates. To explore the effects of RWMA, we classified RWMA by temporal behavior (persistent or dynamic) and by location relative to single-wall autoMAPSE (same or remote wall), yielding four patterns for analysis of trending ability: (i) remote wall, dynamic RWMA, (ii) remote wall, persistent RWMA, (iii) same wall, dynamic RWMA, and (iv) same wall, persistent RWMA. Results Overall, single-wall autoMAPSE had adequate trending ability (concordance rate 91%). All LV walls showed adequate trending ability (concordance rate ≥ 90%), except for the septal wall (concordance rate 88%). The effect of RWMA was negligible, as the concordance rates of the four patterns ranged from 89 to 96%. Conclusions In this secondary analysis, single-wall autoMAPSE tracked changes in global LV function in 9 out of 10 cases, irrespective of RWMA. Graphical Abstract

Abstract In this proof‐of‐concept study, we evaluated the feasibility of non‐invasive estimation of cardiac power metrics—total power, steady power, oscillatory power, and oscillatory power fraction—and compared the prognostic and diagnostic value with established echocardiographic metrics. We prospectively included 29 patients (mean age 76 ± 13 years, 24% women) hospitalized with decompensated heart failure. Left ventricular outflow tract flow waveforms were derived from Doppler echocardiography and synchronized with a continuous arterial pressure waveform from a finger‐volume‐clamp device (INL382, Finapres Medical Systems B.V., Amsterdam, Netherlands). Total power was computed as the integral of the instantaneous pressure‐flow product per second, steady power as mean arterial pressure multiplied by mean flow, and oscillatory power as their difference. All measures were calculated from the same consecutive heartbeats covering three respiratory cycles. The feasibility of obtaining cardiac power metrics was 91%. Total, steady, and oscillatory power predicted short‐term all‐cause mortality (log rank p < 0.015), whereas left ventricular ejection fraction, global longitudinal strain, and myocardial work indices did not. These findings suggest that cardiac power metrics may be useful in risk stratification and warrant validation in larger cohorts.

Continuous physiological time series from wearable devices are widely used in research, aided by the growth of open data sharing. Open datasets rarely pair wearable-derived waveforms with simultaneous ground-truth invasive blood pressure measurements during motion and hemodynamic stress. The ErgoBP dataset comprises recordings from 25 healthy adults who performed moderate- to high-intensity exercise on a cycle ergometer in two body positions. For each participant, approximately one hour of data was collected, spanning rest, graded exercise, and recovery in each posture, encompassing diverse cardiovascular mechanics. Measurements include invasive radial artery blood pressure, photoplethysmography, electrocardiography, wrist accelerometry, and radial tonometry. The dataset includes segmented waveforms, summary measures, quality indices, and auxiliary scripts to aid preprocessing and analysis. The inclusion of invasive blood pressure during exercise in multiple body positions distinguishes ErgoBP from other openly available datasets.

Deterioration of ventriculoarterial coupling is detrimental to cardiovascular and left ventricular function. To enable continuous monitoring of left ventricular function, we have developed autoMAPSE , a new tool that combines transoesophageal echocardiography with deep learning for automatic measurement of mitral annular plane systolic excursion. We hypothesised that autoMAPSE could be used to monitor systemic ventriculoarterial coupling and detect alterations in postoperative cardiac biomarkers. To test this hypothesis, we monitored 50 patients for 120 min immediately after cardiac surgery by measuring autoMAPSE and mean arterial pressure (MAP) every 5 min. Postoperative N-terminal pro B-type natriuretic peptide (ProBNP) and high-sensitivity troponin-T (TnT) were measured twice daily until the evening of postoperative day 1. Ventriculoarterial coupling was assessed non-invasively by calculating arterial elastance and end-systolic elastance (Ea/Ees-ratio). The relationship between autoMAPSE and ventriculoarterial coupling was assessed by 1) correlating Ea/Ees-ratio with one simultaneous autoMAPSE measurement, and 2) relating the measurements of autoMAPSE with corresponding MAP within each patient using a linear mixed model with random slopes. We found that autoMAPSE correlated negatively with Ea/Ees-ratio ( rho = − 0.61, P < 0.05). Furthermore, the individual slopes relating autoMAPSE to MAP were highly significant ( P < 0.001) and markedly heterogeneous (both positive and negative), suggesting that ventriculoarterial coupling differs substantially in different individual patients. Finally, continuous autoMAPSE measurements were negatively correlated with both peak postoperative ProBNP ( rho = − 0.46, P < 0.001) and TnT ( rho = − 0.29, P < 0.05). In conclusion, continuous monitoring using autoMAPSE in the first two postoperative hours reflected ventriculoarterial coupling as well as peak ProBNP and TnT during the subsequent 24 h. Graphical abstract

Abstract Background Heart failure (HF) is a complex and debilitating condition. The pathophysiology of HF is related to the dynamic interplay governing the energy transfer from the heart to the vascular bed. This energy transfer can be estimated by calculating the heart's external power, measured in watts, which is the product of flow and pressure divided by time. Although power measurements can potentially improve hemodynamic assessment in patients with heart failure, clinical estimation of cardiovascular energy transfer is rarely used due to cumbersome analyses and dependence on invasive measurements. We propose a novel method based on echocardiography and continuous non-invasive blood pressure measurement to estimate cardiovascular energy transfer. Aim To test whether non-invasive estimates of cardiovascular energy transfer can differentiate between HF patients with reduced and preserved left ventricular ejection fraction (LVEF). Methods We included patients hospitalized with decompensated HF not optimally treated in the study. All patients underwent an echocardiographic examination using a GE HealthCare Vivid E95 scanner. We used the biplane Simpson method to calculate LVEF and the pulsed wave Doppler velocity spectrum in the left ventricular outflow tract to estimate flow. Continuous non-invasive blood pressure measurements were obtained using a Finapres finger cuff device calibrated with the brachial blood pressure. We developed an application for tracing the velocity spectrum, synchronizing flow and pressure curves, and calculating the power curves as the product of continuous synchronized flow and pressure curves. The patients were categorized into two groups based on whether LVEF was < 40% or ≥ 40%. Results We observed that cardiovascular energy transfer, estimated as external power, differed between patients with LVEF <40% vs. ≥40%. The study cohort comprised twenty-eight patients (25% women), averaging 76 years (SD 11). Eighteen patients had LVEF <40%, with a mean LVEF of 27% (SD = 9%), mean velocity time index (VTI) 11.7 cm (SD = 2.94), and) and mean systolic blood pressure 116 mmHg (SD = 19). Ten patients had LVEF ≥40%, with a mean LVEF of 47% (SD = 6 %), VTI 16.5 cm (SD = 5.50), and mean systolic blood pressure 143 mmHg (SD = 20). External power was significantly different between patients with LVEF <40% vs. ≥40%, 0.81 W (SD = 0.21 W) vs. 1.43 W (SD = 0.41 W), respectively, p<0.0001 (Fig. 1). We observed a modest but significant correlation between LVEF and power (R = 0.28, P-value < 0.005). Conclusion Cardiovascular energy transfer, estimated non-invasively as external power, was significantly lower in acutely decompensated heart failure patients with LVEF <40% compared to those with LVEF ≥ 40%. More extensive studies should explore the possible value of estimating cardiovascular energy transfer in stratification and therapeutic decisions in patients with HF.

AIMS:Ventricular relaxation creates an intraventricular pressure difference (IVPD) and resultant diastolic suction. Non-invasive estimation by echocardiographic techniques would allow to clinically evaluate IVPD as an important component of diastolic functional assessment. The aims of the current study were to evaluate the accuracy of IVPD estimation based on Blood Speckle Tracking (BST) echocardiography compared with invasive pressure measurements and to clinically apply the method in children with univentricular hearts (UVH) and controls. METHODS AND RESULTS:The accuracy of BST-based IVPD-estimates was assessed in an open-chest porcine model, comparing BST-based IVPD with simultaneous repeated invasive pressure measurements in six pigs using micromanometer catheters. BST-based IVPD assessment during early diastolic filling was performed in 83 healthy controls and 44 patients with UVH and compared between the groups. The validation in pigs included 103 measurements, demonstrating a mean difference of -0.01 mmHg (P = 0.33) and high correlation (r = 0.95, P value < 0.001) between IVPD from BST (-1.31 ± 0.28 mmHg) and invasive measurements (-1.30 ± 0.31 mmHg). In the paediatric patients, age range 6 months-17.76 years, feasibility was 93.9% in controls and 88.6% in UVH patients. Median IVPD was significantly higher in controls compared with UVH (-1.82 vs. -0.88 mmHg, P < 0.001). Intraclass correlation coefficients for variability of clinical BST-data were 0.99 (interobserver) and 0.98 (intraobserver) respectively. CONCLUSION:BST echocardiography provides accurate estimation of IVPD in early diastole. IVPD was significantly lower in children with UVH compared with controls suggesting lower diastolic suction, which can impact overall filling dynamics.

Aims:Continuous monitoring of left ventricular (LV) function may improve cardiopulmonary management. Therefore, we have developed 3D autoMAPSE, a novel method that combines 3D transesophageal echocardiography and deep learning to automatically measure mitral annular plane systolic excursion (MAPSE). We hypothesized that 3D autoMAPSE could provide continuous monitoring of LV function in perioperative patients. Methods and results:This prospective observational study included 50 adult intensive care patients after cardiac surgery. Single-beat full-volume 3D recordings were obtained every 5 min over a 120-min period using a hands-free method that simulated continuous monitoring with transesophageal echocardiography. Precision and agreement with manual MAPSE were determined by a test-retest study design during hemodynamic stability. Our results show that continuous monitoring by 3D autoMAPSE had excellent feasibility (99%). It analysed 10 cycles instantaneously (55 ± 15 s) with high precision (least significant change 1.6 mm). 3D autoMAPSE had adequate agreement with manual MAPSE (bias -1.4 mm, limits of agreement -4.0 to 1.2 mm). Continuous 3D autoMAPSE was associated with both N-terminal pro B-type natriuretic peptide (rho = -0.37, P = 0.008) and high-sensitivity troponin-T (rho = -0.28, P = 0.047). This association was slightly stronger than for LV ejection fraction or any other single echocardiographic measurement. Conclusion:3D autoMAPSE provided continuous monitoring of LV function in perioperative patients by obtaining highly feasible and precise measurements that agree with manual echocardiography and postoperative biomarkers. Thus, continuous 3D autoMAPSE may be an attractive complement to hemodynamic monitoring that can aid cardiopulmonary management.

Background:Reference ranges for myocardial work indices are limited by the scarcity of data from the clinically relevant group of elderly individuals. Myocardial work indices constitute load-adjusted left ventricular function, and main components include global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE). Aims:To establish reference values for myocardial work indices and pressure-strain loop shape from guideline-directed recordings in a healthy population spanning a broad age range. Methods and results:We assessed myocardial work in healthy participants from the HUNT4Echo study. Global longitudinal strain was obtained by two expert cardiologists using two-dimensional speckle tracking, and systolic blood pressure from brachial measurements. Timing of valve events was performed by a single observer supervised by the expert cardiologists. Among 1239 participants (mean age 57, 55% female), reference ranges for myocardial work indices were as follows: GWI 1367-2583 mmHg%, GCW 1664-2972 mmHg%, GWW 38-328 mmHg%, and GWE 88-98%. Age was associated with lower GWI and GWE, and higher GCW and GWW (all P < 0.05). Sex influenced myocardial work indices, with somewhat higher GWI and GCW in females (P ≤ 0.001). The shape of the pressure-strain loops was narrower in older groups, while GWI (the area encompassed by the loop) remained constant across age groups. Conclusion:Myocardial work indices were influenced by age and sex, but effects were minor and have limited clinical relevance. Despite preserved GWI by higher age, the pressure-strain loop shape changes significantly - underscoring the importance of integrating strain and afterload when assessing left ventricular function. Trial registration number:Not applicable.

Abstract Background Continuous monitoring of mitral annular plane systolic excursion (MAPSE) using transesophageal echocardiography (TEE) may improve the evaluation of left ventricular (LV) function in postoperative intensive care patients. We aimed to assess the utility of continuous monitoring of LV function using TEE and artificial intelligence (autoMAPSE) in postoperative intensive care patients. Methods In this prospective observational study, we monitored 50 postoperative intensive care patients for 120 min immediately after cardiac surgery. We recorded a set of two-chamber and four-chamber TEE images every five minutes. We defined monitoring feasibility as how often the same wall from the same patient could be reassessed, and categorized monitoring feasibility as excellent if the same LV wall could be reassessed in ≥ 90% of the total recordings. To compare autoMAPSE with manual measurements, we rapidly recorded three sets of repeated images to assess precision (least significant change), bias, and limits of agreement (LOA). To assess the ability to identify changes (trending ability), we compared changes in autoMAPSE with the changes in manual measurements in images obtained during the initiation of cardiopulmonary bypass as well as before and after surgery. Results Monitoring feasibility was excellent in most patients (88%). Compared with manual measurements, autoMAPSE was more precise (least significant change 2.2 vs 3.1 mm, P < 0.001), had low bias (0.4 mm), and acceptable agreement (LOA − 2.7 to 3.5 mm). AutoMAPSE had excellent trending ability, as its measurements changed in the same direction as manual measurements (concordance rate 96%). Conclusion Continuous monitoring of LV function was feasible using autoMAPSE. Compared with manual measurements, autoMAPSE had excellent trending ability, low bias, acceptable agreement, and was more precise. Graphical Abstract

AbstractBackgroundEarly diastolic relaxation creates an intraventricular pressure difference (IVPD) and resulting diastolic suction. Non-invasive estimation by echocardiographic techniques would allow to clinically evaluate this IVPD as an important component of ventricular filling. Recently, Blood Speckle Tracking (BST) echocardiography was introduced, allowing two-dimensional assessment of ventricular flow dynamics. Mitral inflow BST data can be used to estimate IVPD. The aims of the current study were to evaluate the accuracy of BST-based IVPD estimation compared to invasive pressure measurements in an in vivo animal model, and to clinically apply the method by comparing IVPD in children with univentricular hearts (UVH) and healthy controls.MethodsThe accuracy of BST-based IVPD-estimates was assessed in an open-chest porcine model, comparing BST-based IVPD with simultaneous repeated invasive pressure measurements in six pigs using micromanometer catheters. BST-based IVPD assessment was performed in 120 healthy controls and 44 patients with UVH < 18 years of age. Total IVPD (from base to apex) and apical IVPD (from the apical 2/3 of the ventricle) during early diastolic filling of the systemic ventricle was compared between patients with UVH and healthy controls.ResultsThe validation in pigs included 103 measurements, demonstrating a mean difference of - 0.01mmHg (p=0.33) and high correlation (r = 0.95, p-value < 0.001) between IVPD from BST (-1.31 ± 0.28 mmHg) and invasive measurements (-1.30 ± 0.31 mmHg). In the pediatric patients, age range 2 days-17.76 years, feasibility was 96% in controls and 88.6% in UVH patients. Total and apical IVPD were significantly higher in controls compared to UVH (-1.82 vs -0.88 mmHg and -0.63 vs -0.33 mmHg, p < 0.001).Variability was low with intraclass correlation coefficients of 0.99/0.96 (interobserver) and 0.98/0.99 (intraobserver) for total and apical IVPD respectively.ConclusionsBST echocardiography provides accurate estimation of early diastolic IVPD. When clinically applied in children, we found high feasibility and reproducibility. IVPD was significantly lower in children with UVH compared to controls suggesting lower diastolic suction which can impact overall filling dynamics.Clinical perspectiveWhat is newBlood speckle tracking echocardiography provides non-invasive estimation of intraventricular pressure difference in early diastole using two-dimensional blood flow velocitiesIntraventricular pressure difference based on blood speckle tracking is highly feasible, accurate and reproducibleBlood speckle tracking demonstrates significantly reduced intraventricular pressure difference in early diastole in children with univentricular hearts indicating impaired relaxation and suction in these patientsWhat are the clinical implicationsIntraventricular pressure difference based on blood speckle tracking is a novel and potential sensitive echocardiographic parameter to describe early diastolic ventricular relaxation and diastolic function in children with univentricular heartsBlood speckle tracking could improve assessment of diastolic function in children with congenital heart diseaseNon-invasive estimation of intraventricular pressure difference based on blood speckle tracking could improve assessment of diastolic function both in children and adults with heart disease

We have developed a method to automatically assess LV function by measuring mitral annular plane systolic excursion (MAPSE) using artificial intelligence and transesophageal echocardiography (autoMAPSE). Our aim was to evaluate autoMAPSE as an automatic tool for rapid and quantitative assessment of LV function in critical care patients. In this retrospective study, we studied 40 critical care patients immediately after cardiac surgery. First, we recorded a set of echocardiographic data, consisting of three consecutive beats of midesophageal two- and four-chamber views. We then altered the patient’s hemodynamics by positioning them in anti-Trendelenburg and repeated the recordings. We measured MAPSE manually and used autoMAPSE in all available heartbeats and in four LV walls. To assess the agreement with manual measurements, we used a modified Bland–Altman analysis. To assess the precision of each method, we calculated the least significant change (LSC). Finally, to assess trending ability, we calculated the concordance rates using a four-quadrant plot. We found that autoMAPSE measured MAPSE in almost every set of two- and four-chamber views (feasibility 95

Aims:To improve monitoring of cardiac function during major surgery and intensive care, we have developed a method for fully automatic estimation of mitral annular plane systolic excursion (auto-MAPSE) using deep learning in transoesophageal echocardiography (TOE). The aim of this study was a clinical validation of auto-MAPSE in patients with heart disease. Methods and results:TOE recordings were collected from 185 consecutive patients without selection on image quality. Deep-learning-based auto-MAPSE was trained and optimized from 105 patient recordings. We assessed auto-MAPSE feasibility, and agreement and inter-rater reliability with manual reference in 80 patients with and without electrocardiogram (ECG) tracings. Mean processing time for auto-MAPSE was 0.3 s per cardiac cycle/view. Overall feasibility was >90% for manual MAPSE and ECG-enabled auto-MAPSE and 82% for ECG-disabled auto-MAPSE. Feasibility in at least two walls was ≥95% for all methods. Compared with manual reference, bias [95% limits of agreement (LoA)] was -0.5 [-4.0, 3.1] mm for ECG-enabled auto-MAPSE and -0.2 [-4.2, 3.6] mm for ECG-disabled auto-MAPSE. Intra-class correlation coefficient (ICC) for consistency was 0.90 and 0.88, respectively. Manual inter-observer bias [95% LoA] was -0.9 [-4.7, 3.0] mm, and ICC was 0.86. Conclusion:Auto-MAPSE was fast and highly feasible. Inter-rater reliability between auto-MAPSE and manual reference was good. Agreement between auto-MAPSE and manual reference did not differ from manual inter-observer agreement. As the principal advantages of deep-learning-based assessment are speed and reproducibility, auto-MAPSE has the potential to improve real-time monitoring of left ventricular function. This should be investigated in relevant clinical settings.

Objective: Ballistocardiogram (BCG) features are of interest in wearable cardiovascular monitoring of cardiac performance. We assess feasibility of wrist acceleration BCG during exercise for estimating pulse transit time (PTT), enabling broader cardiovascular response studies during acute exercise and improved monitoring in individuals at risk for cardiovascular disease (CVD). We also examine the relationship between PTT, blood pressure (BP), and stroke volume (SV) during exercise and posture interventions.Methods: 25 participants underwent a bike exercise protocol with four incremental workloads (0 W, 50 W, 100 W, and 150 W) in supine and semirecumbent postures. BCG, invasive radial artery BP, tonometry, photoplethysmography (PPG) and echocardiography were recorded. Ensemble averages of BCG signals determined aortic valve opening (AVO) timings, combined with peripheral pulse wave arrival times to calculate PTT. We tested for significance using Wilcoxon signed-rank test.Results: BCG was successfully recorded at the wrist during exercise. PTT exhibited a moderate negative correlation with systolic BP (ρSup = −0.65, ρSR = −0.57, ρAll = −0.54). PTT differences between supine and semirecumbent conditions were significant at 0 W and 50 W (p < 0.001), less at 100 W (p = 0.0135) and 150 W (p = 0.031). SBP and DBP were lower in semirecumbent posture (p < 0.01), while HR was slightly higher. Echocardiography confirmed association of BCG features with AVO and indicated a positive relationship between BCG amplitude and SV (ρ = 0.74).Significance: Wrist BCG may allow convenient PTT and possibly SV tracking during exercise, enabling studies of cardiovascular response to acute exercise and convenient monitoring of cardiovascular performance.

ObjectivePostoperative pulmonary complications (PPC) remain a main issue after cardiac surgery. The objective was to report the incidence and identify risk factors of PPC after cardiac surgery.DesignAn international multicenter prospective study (42 international centers in 9 countries).ParticipantsA total of 707 adult patients who underwent cardiac surgery under cardiopulmonary bypass.InterventionsNoneMeasurements and Main ResultsDuring a study period of 2 weeks, the investigators included all patients in their respective centers and screened for PPCs. PPC was defined as the occurrence of at least 1 pulmonary complication among the following: atelectasis, pleural effusion, respiratory failure, respiratory infection, pneumothorax, bronchospasm, or aspiration pneumonitis. Among 676 analyzed patients, 373 patients presented with a PPC (55%). The presence of PPC was significantly associated with a longer intensive care length of stay and hospital length of stay. One hundred ninety (64%) patients were not intraoperatively ventilated during cardiopulmonary bypass. Ventilation settings were similar regarding tidal volume, respiratory rate, inspired oxygen. In the regression model, age, the Euroscore II, chronic obstructive pulmonary disease, preoxygenation modality, intraoperative positive end-expiratory pressure, the absence of pre- cardiopulmonary bypass ventilation, the absence of lung recruitment, and the neuromuscular blockade were associated with PPC occurrence.ConclusionBoth individual risk factors and ventilatory settings were shown to explain the high level of PPCs. These findings require further investigations to assess a bundle strategy for optimal ventilation strategy to decrease PPC incidence.

BACKGROUND:There is significant uncertainty regarding the timing of onset of cardiovascular stunning after cardiac surgery. Cardiovascular stunning is affecting both contractility (Ees) and arterial load. Arterial load may be represented by arterial elastance (Ea) and participates in ventriculo-arterial coupling through the Ea/Ees ratio, giving information on efficiency and performance. An alternative approach to ventriculo-arterial interaction is oscillatory power fraction (OPF). The aim of this study was to investigate the immediate beat-to-beat effects of on-pump coronary artery bypass graft (CABG) surgery on contractility, cardiac power parameters, arterial load and ventriculo-arterial coupling as well as classical haemodynamic parameters.METHODS:We included 41 patients scheduled for fast-track CABG surgery. Measurements were taken before and after cardiopulmonary bypass. A flow and pressure curve were recorded from transoesophageal pulsed wave Doppler and a radial artery catheter, respectively. This enabled the calculation of stroke work, total cardiac energy delivery, OPF and Ea/Ees ratio. Routine haemodynamic monitoring provided the classical haemodynamic parameters.RESULTS:Immediately after cardiopulmonary bypass there was no firm evidence for alterations in contractility, stroke work, stroke volume or arterial elastance. Ea/Ees ratio and OPF remained unchanged.CONCLUSIONS:There was no evidence for clinically relevant cardiac stunning or altered arterial load immediately after cardiopulmonary bypass for CABG surgery. The unchanged Ea/Ees ratio and OPF are indicating unchanged cardiac efficiency before and after cardiopulmonary bypass. This indicates that in elective CABG patients cardiovascular stunning is perhaps a phenomenon of inflammation and not immediate ischaemia-reperfusion injury or mechanical handling.

The rate of energy transfer from the left ventricle to the aorta is viewed in terms of mean power (MP) and total power (TP). The difference between MP and TP is due to the pulsatility of the circulation and is known as oscillatory power (OP). OP is considered the energy spent to accelerate the blood flow. The aim of this study was to investigate the baseline left ventricular oscillatory power fraction (OP/TP) and how this was affected by acute cardiovascular dysfunction and altered preload. Twenty-eight patients undergoing elective coronary artery bypass graft surgery were included. Before administration of anaesthesia, we simultaneously recorded an arterial pressure curve and instantaneous cardiac outflow with pulsed wave Doppler. Postoperatively, prior to extubation, these measurements were repeated in neutral, Trendelenburg and reverse-Trendelenburg position. The final measurements were taken on the awake patient the day after the operation. TP is the mean of the instantaneous product of the flow and pressure curves. MP was calculated by multiplying mean arterial pressure with mean cardiac output. The oscillatory power fraction is therefore calculated as (TP-MP)/TP. The oscillatory power fraction in neutral position decreased from 23% preoperatively to 16% immediately postoperatively (P<0·001) and increased again to 19% the first postoperative day (P = 0·001). The oscillatory power fraction also increased from 16% in neutral to 19% in Trendelenburg (P = 0·001) and decreased comparing to neutral, to 14% in reverse-Trendelenburg (P = 0·04). The oscillatory power fraction is situation-dependent and is influenced by both the operation and the altered preload.

The energy delivery per second from the left ventricle is viewed in terms of mean power (MP) and total power (TP). The difference between MP and TP is due to the pulsatile nature of the circulation, and is known as oscillatory power (OP) 1. OP is considered the energy spent to accelerate the blood flow. The microcirculation is improved when the flow is pulsatile 2. The aim of this study was to assess the effect of acute cardiovascular dysfunction and altered preload on OP.

This study assesses positional changes in cardiac power output and stroke work compared with classic hemodynamic variables, measured before and after elective coronary artery bypass graft surgery. The hypothesis was that cardiac power output was altered in relation to cardiac stunning. The study is a retrospective analysis of data from two previous studies performed in a tertiary care university hospital. Thirty-six patients scheduled for elective coronary artery bypass graft surgery, with relatively preserved left ventricular function, were included. A pulmonary artery catheter and a radial artery catheter were placed preoperatively. Cardiac power output and stroke work were calculated through thermodilution both supine and standing prior to induction of anesthesia and again day one postoperatively. Virtually all systemic hemodynamic parameters changed significantly from pre- to postoperatively, and from supine to standing. Cardiac power output was maintained at 0.9-1.0 (+/- 0.3) W both pre- and postoperatively and from supine to standing on both days. Stroke work fell from pre- to postoperatively from 1.1 to 0.8 J (P<0.001), there was a significant fall in stroke work with positional change preoperatively from 1.1 to 0.9 J (P<0.001). Postoperatively the stroke work remained at 0.8 J despite positional change. Cardiac power output was the only systemic hemodynamic variable which remained unaltered during all changes. Stroke work appears to be a more sensitive marker for temporary cardiovascular dysfunction than cardiac power output. Further studies should explore the relationship between stroke work and cardiac performance and whether cardiac power output is an autoregulated intrinsic physiological parameter.

AIMS:Cellular processes in the heart rely mainly on studies from experimental animal models or explanted hearts from patients with terminal end-stage heart failure (HF). To address this limitation, we provide data on excitation contraction coupling, cardiomyocyte contraction and relaxation, and Ca2+ handling in post-myocardial-infarction (MI) patients at mid-stage of HF. METHODS AND RESULTS:Nine MI patients and eight control patients without MI (non-MI) were included. Biopsies were taken from the left ventricular myocardium and processed for further measurements with epifluorescence and confocal microscopy. Cardiomyocyte function was progressively impaired in MI cardiomyocytes compared with non-MI cardiomyocytes when increasing electrical stimulation towards frequencies that simulate heart rates during physical activity (2 Hz); at 3 Hz, we observed almost total breakdown of function in MI. Concurrently, we observed impaired Ca2+ handling with more spontaneous Ca2+ release events, increased diastolic Ca2+ , lower Ca2+ amplitude, and prolonged time to diastolic Ca2+ removal in MI (P < 0.01). Significantly reduced transverse-tubule density (-35%, P < 0.01) and sarcoplasmic reticulum Ca2+ adenosine triphosphatase 2a (SERCA2a) function (-26%, P < 0.01) in MI cardiomyocytes may explain the findings. Reduced protein phosphorylation of phospholamban (PLB) serine-16 and threonine-17 in MI provides further mechanisms to the reduced function. CONCLUSIONS:Depressed cardiomyocyte contraction and relaxation were associated with impaired intracellular Ca2+ handling due to impaired SERCA2a activity caused by a combination of alteration in the PLB/SERCA2a ratio and chronic dephosphorylation of PLB as well as loss of transverse tubules, which disrupts normal intracellular Ca2+ homeostasis and handling. This is the first study that presents these mechanisms from viable and intact cardiomyocytes isolated from the left ventricle of human hearts at mid-stage of post-MI HF.