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Cardiac surgery patients are urged to resume light physical activity on the first postoperative day, even if cardiac function may not have recovered fully after the operation. To elucidate the postoperative recovery process, we examined cardiac surgery patients with exercise echocardiography before and on the first day after the operation. Patients undergoing on-pump coronary artery bypass grafting were examined with echocardiography during semirecumbent cycle exercise. Patients exercised for five minutes at 10 W intensity and five minutes at 30 W intensity in bed with the upper body supported to approximately 30°. Fourteen patients were studied. Mitral annulus excursion and pulsed wave Doppler from the left ventricular outflow tract indicated postoperatively reduced cardiac stroke volume. Early diastolic tissue velocities of the mitral annulus were reduced, and early trans-mitral flow velocity was increased. The ratio between early mitral flow velocity and early diastolic mitral tissue velocity was increased postoperatively, indicating impaired left ventricular relaxation and increased left atrial pressure. Postoperative systolic mitral annulus tissue velocities were similar to preoperative velocities, indicating maintained systolic function. Postoperative exercise was associated with improvements in myocardial function indices and cardiac stroke volume similar to preoperative improvements. There were no signs of further deterioration in myocardial function during 30 W exercise. In summary, reduced left ventricular diastolic function after surgery resulted in reduced cardiac stroke volume, increased left atrial pressure and a higher rate of perceived exertion on the first postoperative day. [ABSTRACT FROM AUTHOR]

Background: Changes in cardiac power parameters incorporate changes in both aortic flow and blood pressure. We hypothesized that dynamic and non-dynamic cardiac power parameters would track hypovolemia better than equivalent flow- and pressure parameters, both during spontaneous breathing and non-invasive positive pressure ventilation (NPPV). Methods: Fourteen healthy volunteers underwent lower body negative pressure (LBNP) of 0, -20, -40, -60 and -80 mmHg to simulate hypovolemia, both during spontaneous breathing and during NPPV. We recorded aortic flow using suprasternal ultrasound Doppler and blood pressure using Finometer, and calculated dynamic and non-dynamic parameters of cardiac power, flow and blood pressure. These were assessed on their association with LBNP-levels. Results: Respiratory variation in peak aortic flow was the dynamic parameter most affected during spontaneous breathing increasing 103 % (p <0.001) from baseline to LBNP-80 mmHg. Respiratory variation in pulse pressure was the most affected dynamic parameter during NPPV, increasing 119 % (p <0.001) from baseline to LBNP -80 mmHg. The cardiac power integral was the most affected non-dynamic parameter falling 59 % (p <0.001) from baseline to LBNP -80 mmHg during spontaneous breathing, and 68 % (p <0.001) during NPPV. Conclusions: Dynamic cardiac power parameters were not better than dynamic flow- and pressure parameters at tracking hypovolemia, seemingly due to previously unknown variation in peripheral vascular resistance matching respiratory changes in hemodynamics. Of non-dynamic parameters, the power parameters track hypovolemia slightly better than equivalent flow parameters, and far better than equivalent pressure parameters. [ABSTRACT FROM AUTHOR]

Background: An acute increase in oxygen demand can be compensated for either by increased cardiac index (CI) or increased oxygen extraction, resulting in reduced mixed venous oxygen saturation (SvO2). We tested the hypothesis that post-operative cardiac dysfunction may explain why oxygen extraction alone is increased during early mobilization after cardiac surgery. Methods: Twenty patients with a pre-operative ejection fraction > 50% were included in an open prospective observational study comparing the changes in SvO2 and hemodynamics during mobilizations immediately prior to surgery and on the first post-operative morning. Results: Mobilization induced an absolute reduction in SvO2 of 17.7 ± 7.4% pre- and 19.0 ± 5.5% post-operatively (NS). ANOVA for a series of measurements throughout the mobilization sequence identified no different effect on SvO2 between pre- and post-operative mobilizations ( P = 0.567). The SvO2 level was reduced post-operatively resulting in a SvO2 during standing exercise of 55% before and 49% after the surgery ( P < 0.01). Mobilization increased the heart rate (HR) and decreased the stroke volume index (SVI), leaving CI unchanged. This response was similar pre- and post-operatively (NS). Compared with pre-operative measurements, CI and HR increased post-operatively while SVI remained unchanged despite elevated cardiac filling pressures and reduced systemic vascular resistance. The left ventricular stroke work index was reduced, indicating reduced myocardial performance. Conclusion: Myocardial function was reduced on the first morning after coronary artery bypass grafting (CABG), but during post-operative mobilization this reduction did not significantly influence the changes in CI or SvO2. [ABSTRACT FROM AUTHOR]

OBJECTIVES Levosimendan is a novel inotropic agent claimed to improve myocardial contractility by a calcium-sensitizing effect. Our aim was to evaluate dose-dependent effects of levosimendan on left ventricular (LV) contractility and energetic properties in an acute, ischaemic heart failure porcine model. METHODS Six pigs were used in an anaesthetized in vivo open-chest model. The time points of measurements were: baseline, after heart failure induction and after dose 1–4 (D1–D4). Heart failure was induced by microembolization of the left coronary artery before infusion of four different doses (D1: 2.5 µg/kg, D2: 10 µg/kg, D3: 40 µg/kg, D4: 80 µg/kg) of levosimendan. Haemodynamics were assessed by the pressure-conductance catheter technique. LV oxygen consumption was calculated from coronary flow measurements and coronary sinus blood gases. Mitochondrial respiration was studied in biopsies of the LV. RESULTS Levosimendan had no significant, load-independent effect on contractile force (slope of preload recruitable stroke work was 34 mmHg immediately following failure and 39 (P = 0.406), 42 (P = 0.219), 46 (P = 0.067) and 41 (P = 0.267) at D1–D4), although the more load-dependent contractility indicator of dP/dtmax was slightly increased at dose 4 (P < 0.05). LV energy conversion efficiency (PVA–MVO2 relationship) remained unaltered at all doses. Maximal mitochondrial respiration decreased after induction of failure and remained at an unaltered low level during levosimendan infusion. CONCLUSIONS Surprisingly, levosimendan had no significant effect on contractility, energy efficiency and mitochondrial respiration of the LV, in a porcine model of acute heart failure. At high doses, levosimendan induced vasodilatation and increased heart rate and cardiac output. [ABSTRACT FROM AUTHOR]

Objectives: The use of cardiopulmonary bypass in coronary artery bypass grafting (CABG) may contribute to the postoperative inflammatory response. The molecular chaperone heat-shock protein (HSP) 70 may be induced by ischemia, and has been detected both in the myocardium and in the circulation after CABG. In vitro, extracellular HSP70 may activate both innate and adaptive immunity. Hypothesizing that use of cardiopulmonary bypass (CPB) leads to more circulating HSP70, we explored the release of it in 10 patients undergoing CABG with the use of CPB, and in 10 patients undergoing off-pump surgery CABG (OPCAB). Methods: Blood samples were taken preoperatively, twice peroperatively, 2 and 6 h postoperatively and the next day. Serum analyses were performed by means of immunoassays. Results: We detected a significant difference in postoperative circulating HSP70 between on-pump and off-pump patients (median peaks of 2849 and 756 pg/ml, respectively, P<0.01, 2 h postoperatively). Interleukin-6 and -8 increased in all patients, without significant differences between the groups. Serum interleukin-10 increased at the end of the operation in 7 of 10 patients operated with cardiopulmonary bypass (median 51.7 pg/ml), but in none of the off-pump patients. Furthermore, in the first group, interleukin-10 correlated with the HSP70 concentration at the end of the operation, r=0.75, P<0.05. Serum markers of myocardial damage were higher in conventional than off-pump patients on day 1 postoperatively: median cardiac Troponin T was 0.358 and 0.126 μg/l, respectively, P<0.01. Correspondingly, median creatine kinase-MB was 23.6 and 7.8 μg/l in on-pump and off-pump patients, respectively, P<0.01. Peak HSP70 correlated with both Troponin T and creatine kinase-MB measured on day 1. Conclusions: Significantly more HSP70 was released into the circulation following conventional than following off-pump CABG. Circulating HSP70 may indicate cellular stress or damage. Furthermore, HSPs are suggested as immunoregulatory agents, and may be important in the host defence postoperatively. [Copyright &y& Elsevier]

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., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology.)

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 Ca 2+ 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 Ca 2+ handling with more spontaneous Ca 2+ release events, increased diastolic Ca 2+ , lower Ca 2+ amplitude, and prolonged time to diastolic Ca 2+ removal in MI (P < 0.01). Significantly reduced transverse-tubule density (-35%, P < 0.01) and sarcoplasmic reticulum Ca 2+ 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 Ca 2+ 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 Ca 2+ 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., (© 2018 The Authors. ESC Heart Failure published by John Wiley & Sons Ltd on behalf of the European Society of Cardiology.)

In recent years, the focus in peri-operative care of cardiac patients has shifted from trying to create a stress-free environment to hasten the recovery of patients by providing early extubation, early mobilization, and enteral nutrition. Fast-track cardiac surgery has therefore made a paradigm shift in postoperative care. However, evidence on the safety of early postoperative mobilization in high-risk groups like aortic valve replacement surgery is lacking. Physiological evidence from controlled studies in patients undergoing aortic valve replacement (AVR) showed that heart rate increases and stroke volume falls with maintenance of cardiac output. However, the increase of 50% to 60% of oxygen consumption during mobilization is covered by increased oxygen extraction, resulting in marked mixed venous oxygen desaturation. These physiological changes during postoperative mobilization were also seen in CABG patients. The mobilization pattern was also maintained on the second day after surgery. No serious side effects were observed in the controlled trials of mobilization of AVR patients after cardiac surgery. Over a 13-year period, we have mobilized more than 1200 AVR patients. No serious situations have occurred during or in direct connection to mobilization.