The athlete's heart: allometric considerations on published papers and relation to cardiovascular variables

To evaluate the morphology of the "athlete's heart", left ventricular (LV) wall thickness (WT) and end-diastolic internal diameter (LVIDd) at rest were addressed in publications on skiers, rowers, swimmers, cyclists, runners, weightlifters (n = 927), and untrained controls (n = 173) and related to the acute and maximal cardiovascular response to their respective disciplines. Dimensions of the heart at rest and functional variables established during the various sport disciplines were scaled to body weight for comparison among athletes independent of body mass. The two measures of LV were related (r = 0.8; P = 0.04) across athletic disciplines. With allometric scaling to body weight, LVIDd was similar between weightlifters and controls but 7%-15% larger in the other athletic groups, while WT was 9%-24% enlarged in all athletes. The LVIDd was related to stroke volume, oxygen pulse, maximal oxygen uptake, cardiac output, and blood volume (r =  ~ 0.9, P < 0.05), while there was no relationship between WT and these variables (P > 0.05). In conclusion, while cardiac enlargement is, in part, essential for the generation of the cardiac output and thus stroke volume needed for competitive endurance exercise, an enlarged WT seems important for the development of the wall tension required for establishing normal arterial pressure in the enlarged LVIDd.

Impact of respiratory cycle during mechanical ventilation on beat-to-beat right ventricle stroke volume estimation by pulmonary artery pulse wave analysis

BACKGROUND

The same principle behind pulse wave analysis can be applied on the pulmonary artery (PA) pressure waveform to estimate right ventricle stroke volume (RVSV). However, the PA pressure waveform might be influenced by the direct transmission of the intrathoracic pressure changes throughout the respiratory cycle caused by mechanical ventilation (MV), potentially impacting the reliability of PA pulse wave analysis (PAPWA). We assessed a new method that minimizes the direct effect of the MV on continuous PA pressure measurements and enhances the reliability of PAPWA in tracking beat-to-beat RVSV.

METHODS

Continuous PA pressure and flow were simultaneously measured for 2-3 min in 5 pigs using a high-fidelity micro-tip catheter and a transonic flow sensor around the PA trunk, both pre and post an experimental ARDS model. RVSV was estimated by PAPWA indexes such as pulse pressure (SVPP), systolic area (SVSystAUC) and standard deviation (SVSD) beat-to-beat from both corrected and non-corrected PA signals. The reference RVSV was derived from the PA flow signal (SVref).

RESULTS

The reliability of PAPWA in tracking RVSV on a beat-to-beat basis was enhanced after accounting for the direct impact of intrathoracic pressure changes induced by MV throughout the respiratory cycle. This was evidenced by an increase in the correlation between SVref and RVSV estimated by PAPWA under healthy conditions: rho between SVref and non-corrected SVSD - 0.111 (0.342), corrected SVSD 0.876 (0.130), non-corrected SVSystAUC 0.543 (0.141) and corrected SVSystAUC 0.923 (0.050). Following ARDS, correlations were SVref and non-corrected SVSD - 0.033 (0.262), corrected SVSD 0.839 (0.077), non-corrected SVSystAUC 0.483 (0.114) and corrected SVSystAUC 0.928 (0.026). Correction also led to reduced limits of agreement between SVref and SVSD and SVSystAUC in the two evaluated conditions.

CONCLUSIONS

In our experimental model, we confirmed that correcting for mechanical ventilation induced changes during the respiratory cycle improves the performance of PAPWA for beat-to-beat estimation of RVSV compared to uncorrected measurements. This was demonstrated by a better correlation and agreement between the actual SV and the obtained from PAPWA.

Dataset on stroke infarct volume in rodents: A comparison of MRI and histological methods

This dataset offers images of mouse brains impacted by photothrombotic stroke in the sensorimotor cortex published by Weber et al. NeuroImage (2024). Data is gathered using two primary techniques: (1) whole-brain ex-vivo magnetic resonance imaging (MRI) and (2) 40 µm thick coronal histological sections that undergo immunofluorescence staining with NeuroTrace. Infarct areas and volumes are assessed through MRI at two distinct time frames-three days (acute) and 28 days (chronic) following photothrombotic stroke induction. Subsequently, the brains are sectioned into 40 µm thick coronal slices, stained with NeuroTrace, and imaged as whole sections. The dataset holds considerable value for reuse, particularly for researchers focused on stroke volume estimation methods as well as those interested in comparing the efficacy of MRI and histological techniques.

Cardiovascular hardware simulator and artificial aorta-generated central blood pressure waveform database according to various vascular ages for cardiovascular health monitoring applications

This study presents a database of central blood pressure waveforms according to cardiovascular health conditions, to supplement the lack of clinical data in cardiovascular health research, constructed by a cardiovascular simulator. Blood pressure (BP) is the most frequently measured biomarker, and in addition to systolic and diastolic pressure, its waveform represents the various conditions of cardiovascular health. A BP waveform is formed by overlapping the forward and reflected waves, which are affected by the pulse wave velocity (PWV). The increase in vascular stiffness with aging increases PWV, and the PWV-age distribution curve is called vascular age. For cardiovascular health research, extensive data of central BP waveform is essential, but the clinical data published so far are insufficient and imbalanced in quantity and quality. This study reproduces the central BP waveform using a cardiovascular hardware simulator and artificial aortas, which mimic the physiological structure and properties of the human. The simulator can adjust cardiovascular health conditions to the same level as humans, such as heart rate of 40-100 BPM, stroke volume of 40-100 mL, and peripheral resistance of 12 steps. Also, 6 artificial aortas with vascular ages in the 20-70 were fabricated to reproduce the increase in vascular stiffness due to aging. Vascular age calculated from measured stiffness of artificial aorta and central BP waveform showed an error of less than 3 years from the clinical value. Through this, a total of 636 waveforms were created to construct a central BP waveform database according to controlled various cardiovascular health conditions.

Risk factors for pregnancy-associated heart failure with preserved ejection fraction and adverse pregnancy outcomes: a cross-sectional study

BACKGROUND

Although pregnancy-associated heart failure with preserved ejection fraction (HFpEF) is increasing and contributing to maternal morbidity, little is known about its impact on pregnancy. We examined the risk factors for and adverse pregnancy outcomes of HFpEF in pregnant women.

METHODS

We conducted a cross-sectional analysis of pregnancy-related hospitalizations from 2009 to 2020 using the perinatal database of seven multicenters. Cases of HFpEF were identified using the International Classification of Diseases and echocardiography findings. The patients were categorized into the HFpEF and control groups. Risk factors were evaluated using multivariate logistic regression analysis to generate odds ratios (OR) and 95% confidence intervals (CI). Furthermore, adjusted associations between HFpEF and adverse pregnancy outcomes were determined. Risk scores for the stratification of women at a high risk of HFpEF were calculated using a statistical scoring model.

RESULTS

Of the 34,392 women identified, 258 (0.76%) were included in the HFpEF group. In multivariate analysis, HFpEF was significantly associated with old maternal age (OR, 1.04; 95% CI 1.02-1.07), multiple pregnancy (OR, 2.22; 95% CI 1.53-3.23), rheumatic disease (OR, 2.56; 95% CI 1.54-4.26), pregnancy induce hypertension (OR 6.02; 95% CI 3.61-10.05), preeclampsia (OR 24.66; 95% CI 18.61-32.66), eclampsia or superimposed preeclampsia (OR 32.74; 95% CI 21.60-49.64) and transfusion in previous pregnancy (OR 3.89; 95% CI 1.89-8.01). A scoring model to predict HFpEF with those factors achieved an area under the curve of 0.78 at cutoff value of 3. Women with HFpEF also had increased odds ratios of intensive care unit admission during the perinatal period (odds ratio, 5.98; 95% confidence interval, 4.36-8.21) and of postpartum hemorrhage (odds ratio, 5.98; 95% confidence interval, 2.02-3.64).

CONCLUSIONS

Pregnancy-associated HFpEF is associated with adverse pregnancy outcomes. A scoring model may contribute to screening HFpEF using echocardiography and preparing adverse pregnancy outcomes.

New perspectives in the echocardiographic hemodynamics multiparametric assessment of patients with heart failure

International Guidelines consider left ventricular ejection fraction (LVEF) as an important parameter to categorize patients with heart failure (HF) and to define recommended treatments in clinical practice. However, LVEF has some technical and clinical limitations, being derived from geometric assumptions and is unable to evaluate intrinsic myocardial function and LV filling pressure (LVFP). Moreover, it has been shown to fail to predict clinical outcome in patients with end-stage HF. The analysis of LV antegrade flow derived from pulsed-wave Doppler (stroke volume index, stroke distance, cardiac output, and cardiac index) and non-invasive evaluation of LVFP have demonstrated some advantages and prognostic implications in HF patients. Speckle tracking echocardiography (STE) is able to unmask intrinsic myocardial systolic dysfunction in HF patients, particularly in those with LV preserved EF, hence allowing analysis of LV, right ventricular and left atrial (LA) intrinsic myocardial function (global peak atrial LS, (PALS)). Global PALS has been proven a reliable index of LVFP which could fill the gaps "gray zone" in the previous Guidelines algorithm for the assessment of LV diastolic dysfunction and LVFP, being added to the latest European Association of Cardiovascular Imaging Consensus document for the use of multimodality imaging in evaluating HFpEF. The aim of this review is to highlight the importance of the hemodynamics multiparametric approach of assessing myocardial function (from LVFP to stroke volume) in patients with HF, thus overcoming the limitations of LVEF.

Leg-focused high-weight resistance training improves ventricular stroke volume, exercise capacity and strength in young patients with a Fontan circulation

AIMS

Effective therapy to improve exercise capacity in Fontan patients is lacking. Leg-focused high-weight resistance training might augment the peripheral muscle pump and thereby improve exercise capacity.

METHODS AND RESULTS

This randomized semi-cross-over controlled trial investigated the effects of a 12-week leg-focused high-weight resistance training plus high-protein diet, on (sub)maximal exercise capacity, cardiac function (assessed with cardiovascular magnetic resonance), muscle strength, and quality of life in paediatric Fontan patients. Twenty-eight paediatric Fontan patients were included, 27 patients, (median age 12.9 [10.5-15.7]), and successfully completed the programme. Peak oxygen uptake (PeakVO2) at baseline was reduced [33.3 mL/kg/min (27.1-37.4), 73% (62-79) of predicted]. After training PeakVO2/kg and Peak workload improved significantly with +6.2 mL/kg/min (95%CI: 3.4-9.0) (+18%) P < 0.001 and +22 Watts (95%CI: 12-32) (+18%) P < 0.001, respectively, compared to the control period. Indexed single ventricle stroke volume increased significantly [43 mL/beat/m2 (40-49) vs. 46 (41-53), P = 0.014], as did inferior vena cava flow [21 mL/beat/m2 (18-24) vs. 23 (20-28), P = 0.015], while superior vena cava flow remained unchanged. The strength of all measured leg-muscles increased significantly compared to the control period. Self-reported quality of life improved on the physical functioning and change in health domains of the child health questionnaire, parent-reported quality of life improved the bodily pain, general health perception, and change in health domains compared to the control period.

CONCLUSION

In a relatively large group of 27 older Fontan children, 12-weeks of leg-focused high-weight resistance training improved exercise capacity, stroke volume, (sub)maximal exercise capacity, muscle strength, and domains of quality of life.

REGISTRATION

International Clinical Trials: Trial NL8181.

Prediction of preload dependency using phenylephrine-induced peripheral perfusion index during general anaesthesia: a prospective observational study

BACKGROUND

Tracking preload dependency non-invasively to maintain adequate tissue perfusion in the perioperative period can be challenging.The effect of phenylephrine on stroke volume is dependent upon preload. Changes in stroke volume induced by phenylephrine administration can be used to predict preload dependency. The change in the peripheral perfusion index derived from photoplethysmography signals reportedly corresponds with changes in stroke volume in situations such as body position changes in the operating room. Thus, the peripheral perfusion index can be used as a non-invasive potential alternative to stroke volume to predict preload dependency. Herein, we aimed to determine whether changes in perfusion index induced by the administration of phenylephrine could be used to predict preload dependency.

METHODS

We conducted a prospective single-centre observational study. The haemodynamic parameters and perfusion index were recorded before and 1 and 2 min after administering 0.1 mg of phenylephrine during post-induction hypotension in patients scheduled to undergo surgery. Preload dependency was defined as a stroke volume variation of ≥ 12% before phenylephrine administration at a mean arterial pressure of < 65 mmHg. Patients were divided into four groups according to total peripheral resistance and preload dependency.

RESULTS

Forty-two patients were included in this study. The stroke volume in patients with preload dependency (n = 23) increased after phenylephrine administration. However, phenylephrine administration did not impact the stroke volume in patients without preload dependency (n = 19). The perfusion index decreased regardless of preload dependency. The changes in the perfusion index after phenylephrine administration exhibited low accuracy for predicting preload dependency. Based on subgroup analysis, patients with high total peripheral resistance tended to exhibit increased stroke volume following phenylephrine administration, which was particularly prominent in patients with high total peripheral resistance and preload dependency.

CONCLUSION

The findings of the current study revealed that changes in the perfusion index induced by administering 0.1 mg of phenylephrine could not predict preload dependency. This may be attributed to the different phenylephrine-induced stroke volume patterns observed in patients according to the degree of total peripheral resistance and preload dependency.

TRIAL REGISTRATION

University Hospital Medical Information Network (UMIN000049994 on 9/01/2023).

Intraoperative haemodynamic monitoring and management of adults having non-cardiac surgery: Guidelines of the German Society of Anaesthesiology and Intensive Care Medicine in collaboration with the German Association of the Scientific Medical Societies

Haemodynamic monitoring and management are cornerstones of perioperative care. The goal of haemodynamic management is to maintain organ function by ensuring adequate perfusion pressure, blood flow, and oxygen delivery. We here present guidelines on "Intraoperative haemodynamic monitoring and management of adults having non-cardiac surgery" that were prepared by 18 experts on behalf of the German Society of Anaesthesiology and Intensive Care Medicine (Deutsche Gesellschaft für Anästhesiologie und lntensivmedizin; DGAI).

A toolkit for stroke infarct volume estimation in rodents

Stroke volume is a key determinant of infarct severity and an important metric for evaluating treatments. However, accurate estimation of stroke volume can be challenging, due to the often confined 2-dimensional nature of available data. Here, we introduce a comprehensive semi-automated toolkit to reliably estimate stroke volumes based on (1) whole brains ex-vivo magnetic resonance imaging (MRI) and (2) brain sections that underwent immunofluorescence staining. We located and quantified infarct areas from MRI three days (acute) and 28 days (chronic) after photothrombotic stroke induction in whole mouse brains. MRI results were compared with measures obtained from immunofluorescent histologic sections of the same brains. We found that infarct volume determined by post-mortem MRI was highly correlated with a deviation of only 6.6 % (acute) and 4.9 % (chronic) to the measurements as determined in the histological brain sections indicating that both methods are capable of accurately assessing brain tissue damage (Pearson r > 0.9, p < 0.001). The Dice similarity coefficient (DC) showed a high degree of coherence (DC > 0.8) between MRI-delineated regions of interest (ROIs) and ROIs obtained from histologic sections at four to six pre-defined landmarks, with histology-based delineation demonstrating higher inter-operator similarity compared to MR images. We further investigated stroke-related scarring and post-ischemic angiogenesis in cortical peri‑infarct regions and described a negative correlation between GFAP+fluorescence intensity and MRI-obtained lesion size.

Inferior vena cava collapsibility index and stroke volume as predictors of blood transfusion in upper gastrointestinal bleeding in the emergency department

BACKGROUND AND AIM

This study investigates the effectiveness of bedside ultrasonography in predicting blood transfusion requirements in patients with upper gastrointestinal bleeding (UGIB). It focuses on evaluating the inferior vena cava (IVC) diameter, IVC collapsibility index (CI), and stroke volume (SV) as ultrasonographic measures.

METHODS

A hundred adult patients enrolled in this prospective clinical study. The patients were divided into two groups (group 1: only saline administered group, group 2: saline and blood administered group). IVC diameter, IVC CI, and SV were measured at the time of admission and after treatment.

RESULTS

At the initial admission, group 1 exhibited an IVC CI of 20.4% and an SV of 65.0 mL, whereas group 2 displayed an IVC CI of 26.6% and an SV of 58.0 mL. Upon analyzing the relationship between the Glasgow-Blatchford score (GBS) and SV, we identified a significant negative correlation (r = -0.7350; P < 0.001). Similarly, a weak negative correlation was observed between the Rockall score (RS) and SV (r = -0.4718; P < 0.001). It is worth noting that patients with UGIB require blood transfusion if their SV falls below 62.5 mL, with an area under the curve (AUC) of 89.1% and a 95% confidence interval (CI) ranging from 82.8% to 95.4%.

CONCLUSION

IVC CI and SV can be used as parameters to predict the need for blood transfusion in the ED in patients with UGIB.

Cerebral hypometabolism mediates the effect of stroke volume on cognitive impairment in heart failure patients

AIMS

The present study aimed to phenotype the cerebral structural and glucose metabolic alterations in patients with heart failure (HF) using simultaneous positron emission tomography (PET)/magnetic resonance (MR) and to investigate their relationship to cardiac biomarkers and cognitive performance.

METHODS AND RESULTS

Forty-two HF patients caused by ischaemic heart disease (mean age 67.2 ± 10.4, 32 males) and 32 age- and sex-matched healthy volunteers (mean age 61.3 ± 4.8, 18 males) were included in this study. Participants underwent simultaneous cerebral fluorine-18 (18 F) fluorodeoxyglucose PET/MR followed by cardiac MR scan, and neuropsychological scores were obtained to assess cognitive performance. The grey matter volume (GMV) and standardized uptake value ratio (SUVR) were calculated to examine cerebral structural and metabolic alterations. Cardiac biomarkers included cardiac MR parameters and cardiac serum laboratory tests. Mediation analysis was performed to explore the associations among cerebral alterations, cardiac biomarkers, and cognitive performance. HF patients demonstrated notable cognitive impairment compared with normal controls (P < 0.001). Furthermore, HF patients exhibited regional brain hypometabolism in the bilateral calcarine cortex, caudate nucleus, thalamus, hippocampus, precuneus, posterior cingulate cortex, lingual and olfactory cortex, and GMV reduction in bilateral thalamus and hippocampus (cluster level at P < 0.05, Gaussian random field correction). The SUVR of the hypometabolic brain regions was correlated with the Montreal Cognitive Assessment (MoCA) scores (r = 0.55, P = 0.038) and cardiac stroke volume (r = 0.49, P = 0.002). Cerebral hypometabolism played a key role in the relationship between the decreased stroke volume and MoCA scores, with a mediation effect of 33.2%.

CONCLUSIONS

HF patients suffered cerebral metabolic and structural alterations in regions associated with cognition. The observed correlation between cardiac stroke volume and cognitive impairment underscored the potential influence of cerebral hypometabolism, suggesting that cerebral hypometabolism due to chronic systemic hypoperfusion may significantly contribute to cognitive impairment in HF patients.

Evaluation of the image quality and validity of handheld echocardiography for stroke volume and left ventricular ejection fraction quantification: a method comparison study

Bedside quantification of stroke volume (SV) and left ventricular ejection fraction (LVEF) is valuable in hemodynamically compromised patients. Miniaturized handheld ultrasound (HAND) devices are now available for clinical use. However, the performance level of HAND devices for quantified cardiac assessment is yet unknown. The aim of this study was to compare the validity of HAND measurements with standard echocardiography (SE) and three-dimensional echocardiography (3DE). Thirty-six patients were scanned with HAND, SE and 3DE. LVEF and SV quantification was done with automated software for the HAND, SE and 3DE dataset. The image quality of HAND and SE was evaluated by scoring segmental endocardial border delineation (2 = good, 1 = poor, 0 = invisible). LVEF and SV of HAND was evaluated against SE and 3DE using correlation and Bland-Altman analysis. The correlation, bias, and limits of agreement (LOA) between HAND and SE were 0.68 [0.46:0.83], 1.60% [- 2.18:5.38], and 8.84% [- 9.79:12.99] for LVEF, and 0.91 [0.84:0.96], 1.32 ml [- 0.36:4.01], 15.54 ml [- 18.70:21.35] for SV, respectively. Correlation, bias, and LOA between HAND and 3DE were 0.55 [0.6:0.74], - 0.56% [- 2.27:1.1], and 9.88% [- 13.29:12.17] for LVEF, and 0.79 [0.62:0.89], 6.78 ml [2.34:11.21], 12.14 ml [- 26.32:39.87] for SV, respectively. The image quality scores were 9.42 ± 2.0 for the apical four chamber views of the HAND dataset and 10.49 ± 1.7 for the SE dataset and (P < 0.001). Clinically acceptable accuracy, precision, and image quality was demonstrated for HAND measurements compared to SE. In comparison to 3DE, HAND showed a clinically acceptable accuracy and precision for LVEF quantification.

Left ventricular outflow tract velocity-time integral improves outcome prediction in patients with secondary mitral regurgitation

AIMS

Left ventricular outflow velocity-time integral (LVOT-VTI) has been shown to improve outcome prediction in different patients' subsets, with or without heart failure (HF). Nevertheless, the prognostic value of LVOT-VTI in patients with HF and secondary mitral regurgitation (MR) has never been investigated so far. Therefore, in the present study, we aimed to assess the prognostic value different metrics of LV forward output, including LVOT-VTI, in HF patients with secondary MR.

METHODS AND RESULTS

Consecutive patients with HF and moderate-to-severe/severe secondary MR and systolic dysfunction (i.e., left ventricular ejection fraction [LVEF] <50%) were retrospectively selected and followed-up for the primary endpoint of cardiac death. Out of the 287 patients analyzed (aged 74 ± 11 years, 70% men, 46% ischemic etiology, mean LVEF 30 ± 9%, mean LVOT-VTI 20 ± 5 cm), 71 met the primary endpoint over a 33-month median follow-up (16-47 months). Patients with an LVOT-VTI ≤17 cm (n = 96, 32%) showed the greatest risk of cardiac death (Log Rank 44.3, p < 0.001) and all-cause mortality (Log rank 8.6, p = 0.003). At multivariable regression analysis, all the measures of LV forward volume (namely LVOT-VTI, stroke volume index, cardiac output, and cardiac index) were predictors of poor outcomes. Among these, LVOT-VTI was the most accurate in risk prediction (univariable C-statistics 0.70 [95%CI 0.64-0.77]).

CONCLUSION

Left ventricular forward output, noninvasively estimated through LVOT-VTI, improves outcome prediction in HF patients with low LVEF and secondary MR.

Effect of assessing velocity time integral at different locations across ventricular outflow tracts when calculating cardiac output in neonates

This study aims to evaluate the effect of assessing velocity time integral at different locations across ventricular outflow tracts for calculating cardiac output (CO) in neonates. Velocity time integral (VTI) and CO were measured at 3 different locations across right and left ventricular outflow tracts using transthoracic echocardiography in healthy term neonates without any major congenital heart disease. ANOVA with Bonferroni correction was used to determine the differences between the VTI and CO sampled at these three locations. Forty-one neonates met inclusion criteria with mean gestational age of 38.6 ± 1 weeks and mean birth weight of 3155 ± 463 g. The median hours after birth when echocardiography was obtained was 23 h (range 11-68 h after birth). Left CO were 121 ± 30 mL/kg/min, 155 ± 38 mL/kg/min, and 176 ± 36 mL/kg/min measured below the valve, hinges of the valve, and tip of the valve, respectively. Right CO were 197 ± 73 mL/kg/min, 270 ± 83 mL/kg/min, and 329 ± 104 mL/kg/min measured below the valve, hinges of the valve, and tip of the valve, respectively. A statistically significant difference (P < 0.001) was found in the VTI and CO measured at the 3 different locations across both left and right ventricular outflow tracts.     Conclusions: There is a significant difference in measurements of VTI and CO depending on the location of Doppler gate sampling across the ventricular outflow tracts. Consistency and precision in Doppler gate location are essential for measuring VTI and calculating CO while assessing changes in hemodynamic status in critically ill infants. What is Known: • Targeted Neonatal Echocardiography is increasingly applied to measure cardiac output in critically ill neonates and serial assessments are performed to assess the trend in changes in cardiac output. • Noninvasive measurement using velocity time integral to calculate cardiac output is commonly performed. However, location of Doppler sample gate to measure ventricular outflow tract velocity time integral is not consistent. What is New: • Statistically significant changes in measured velocity time integral and cardiac output are noted based on the location of Doppler gate sampling. • To monitor the cardiac output for trending, it is important to be consistent with regards to the location of the Doppler sample gate to assess changes in cardiac output in critically ill newborns.

Effect of once versus twice intracoronary injection of allogeneic-derived mesenchymal stromal cells after acute myocardial infarction: BOOSTER-TAHA7 randomized clinical trial

BACKGROUND

Mesenchymal stromal cell (MSC) transplantation can improve the left ventricular ejection fraction (LVEF) after an acute myocardial infarction (AMI). Transplanted MSCs exert a paracrine effect, which might be augmented if repeated doses are administered. This study aimed to compare the effects of single versus double transplantation of Wharton's jelly MSCs (WJ-MSCs) on LVEF post-AMI.

METHODS

We conducted a single-blind, randomized, multicenter trial. After 3-7 days of an AMI treated successfully by primary PCI, 70 patients younger than 65 with LVEF < 40% on baseline echocardiography were randomized to receive conventional care, a single intracoronary infusion of WJ-MSCs, or a repeated infusion 10 days later. The primary endpoint was the 6-month LVEF improvement as per cardiac magnetic resonance (CMR) imaging.

RESULTS

The mean baseline EF measured by CMR was similar (~ 40%) in all three groups. By the end of the trial, while all patients experienced a rise in EF, the most significant change was seen in the repeated intervention group. Compared to the control group (n = 25), single MSC transplantation (n = 20) improved the EF by 4.54 ± 2%, and repeated intervention (n = 20) did so by 7.45 ± 2% when measured by CMR imaging (P < 0.001); when evaluated by echocardiography, these values were 6.71 ± 2.4 and 10.71 ± 2.5%, respectively (P < 0.001).

CONCLUSIONS

Intracoronary transplantation of WJ-MSCs 3-7 days after AMI in selected patients significantly improves LVEF, with the infusion of a booster dose 10 days later augmenting this effect.

TRIAL REGISTRATION

Trial registration: Iranian Registry of Clinical Trials, IRCT20201116049408N1. Retrospectively Registered 20 Nov. 2020, https://en.irct.ir/trial/52357.

Pressure- vs. volume-controlled ventilation and their respective impact on dynamic parameters of fluid responsiveness: a cross-over animal study

BACKGROUND AND GOAL OF STUDY

Pulse pressure variation (PPV) and stroke volume variation (SVV), which are based on the forces caused by controlled mechanical ventilation, are commonly used to predict fluid responsiveness. When PPV and SVV were introduced into clinical practice, volume-controlled ventilation (VCV) with tidal volumes (VT) ≥ 10 ml kg- 1 was most commonly used. Nowadays, lower VT and the use of pressure-controlled ventilation (PCV) has widely become the preferred type of ventilation. Due to their specific flow characteristics, VCV and PCV result in different airway pressures at comparable tidal volumes. We hypothesised that higher inspiratory pressures would result in higher PPVs and aimed to determine the impact of VCV and PCV on PPV and SVV.

METHODS

In this self-controlled animal study, sixteen anaesthetised, paralysed, and mechanically ventilated (goal: VT 8 ml kg- 1) pigs were instrumented with catheters for continuous arterial blood pressure measurement and transpulmonary thermodilution. At four different intravascular fluid states (IVFS; baseline, hypovolaemia, resuscitation I and II), ventilatory and hemodynamic data including PPV and SVV were assessed during VCV and PCV. Statistical analysis was performed using U-test and RM ANOVA on ranks as well as descriptive LDA and GEE analysis.

RESULTS

Complete data sets were available of eight pigs. VT and respiratory rates were similar in both forms. Heart rate, central venous, systolic, diastolic, and mean arterial pressures were not different between VCV and PCV at any IVFS. Peak inspiratory pressure was significantly higher in VCV, while plateau, airway and transpulmonary driving pressures were significantly higher in PCV. However, these higher pressures did not result in different PPVs nor SVVs at any IVFS.

CONCLUSION

VCV and PCV at similar tidal volumes and respiratory rates produced PPVs and SVVs without clinically meaningful differences in this experimental setting. Further research is needed to transfer these results to humans.

Rightward imbalanced pulmonary perfusion predicts better exercise stroke volume in children after Fallot repair

BACKGROUND

Residual lesions following Fallot repair are primarily pulmonary regurgitation and right ventricular outflow tract obstruction. These lesions may impact exercise tolerance, particularly because of a poor increase in left ventricular stroke volume. Pulmonary perfusion imbalance is also common, but its effect on cardiac adaptation to exercise is not known.

AIM

To assess the association between pulmonary perfusion asymmetry and peak indexed exercise stroke volume (pSVi) in young patients.

METHODS

We retrospectively studied 82 consecutive patients with Fallot repair (mean age 15.2±3.8 years) who underwent echocardiography, four-dimensional flow magnetic resonance imaging and cardiopulmonary testing with pSVi measurement by thoracic bioimpedance. Normal pulmonary flow distribution was defined as right pulmonary artery perfusion between 43 and 61%.

RESULTS

Normal, rightward and leftward flow distributions were found in 52 (63%), 26 (32%) and four (5%) patients, respectively. Independent predictors of pSVi were right pulmonary artery perfusion (β=0.368, 95% confidence interval [CI] 0.188 to 0.548; P=0.0003), right ventricular ejection fraction (β=0.205, 95% CI 0.026 to 0.383; P=0.049), pulmonary regurgitation fraction (β=-0.283, 95% CI -0.495 to -0.072; P=0.006) and Fallot variant with pulmonary atresia (β=-0.213, 95% CI -0.416 to -0.009; P=0.041). The pSVi prediction was similar when the categorical variable right pulmonary artery perfusion>61% was used (β=0.210, 95% CI 0.006 to 0.415; P=0.044).

CONCLUSION

In addition to right ventricular ejection fraction, pulmonary regurgitation fraction and Fallot variant with pulmonary atresia, right pulmonary artery perfusion is a predictor of pSVi, in that rightward imbalanced pulmonary perfusion favours greater pSVi.

Predictors of fluid responsiveness in the operating room: a narrative review

Prediction of fluid responsiveness has been considered an essential tool for modern fluid management. However, most studies in this field have focused on patients in intensive care unit despite numerous research throughout several decades. Therefore, the present narrative review aims to show the representative method's feasibility, advantages, and limitations in predicting fluid responsiveness, focusing on the operating room environments. Firstly, we described the predictors of fluid responsiveness based on heart-lung interaction, including pulse pressure and stroke volume variations, the measurement of respiratory variations of inferior vena cava diameter, and the end-expiratory occlusion test and addressed their limitations. Subsequently, the passive leg raising test and mini-fluid challenge tests were also mentioned, which assess fluid responsiveness by mimicking a classic fluid challenge. In the last part of this review, we pointed out the pitfalls of fluid management based on fluid responsiveness prediction, which emphasized the importance of individualized decision-making. Understanding the available representative methods to predict fluid responsiveness and their associated benefits and drawbacks through this review will aid anesthesiologists in choosing the most reliable methods for optimal fluid administration in each patient during anesthesia in the operating room.

Heated environment offsets the cardiovascular responses to prolonged rowing exercise in competitive athletes

Prolonged rowing exercise sessions are often prescribed considering competitive training schedules, and under hostile environments (e.g., heated ambient). The study aimed to investigate the effect of heat stress (HS) on physical performance, Lactate concentration ([Lac]), and cardiorespiratory responses during prolonged exercise sessions in competitive rowers. Twelve rowers performed preliminary exercise tests (2-km test and five-step incremental lactate test) to assess the target workload intensity corresponding to a 2.5 mmol^.L^-1 of [Lac]. On two separate days, participants were enrolled in two exercise sessions of 12 km in a rowing machine under HS (∼30 °C) and thermal comfort (TC 22 °C) conditions. Heart rate (HR), stroke volume (SV), cardiac output (CO), oxygen uptake (VO₂), [Lac], and the rating of perceptual exertion (RPE) were obtained. From baseline, HS increased the maximum temperature of the face compared to TC. Workload and VO₂ reduced while RPE increased at 9- and 12-km of rowing exercise under HS compared to TC. From baseline to the last stage of exercise, HS shifted SV downwards and HR upwards compared to TC. Consequently, CO did not change between thermal conditions (TC vs. HS). Therefore, HS provokes a cardiovascular drift during prolonged rowing in comparison to TC. The last stages of prolonged rowing sessions under HS seem to be critical to physical performance and relative perceptual of effort in rowers.

A method for calculating left ventricular end-diastolic volume as an index of left ventricular preload from the pre-ejection period, ejection time, blood pressure, and stroke volume: a prospective, observational study

BACKGROUND

Left ventricular end-diastolic volume (EDV) is a major determinant of cardiac preload. However, its use in fluid management is limited by the lack of a simple means to measure it noninvasively. This study presents a new noninvasive method that was validated against simultaneously measured EDV by transthoracic echocardiography (TTE). The goal of this study was to develop and validate a method to estimate EDV in humans non-invasively from left ventricular arterial coupling (Ees/Ea) and stroke volume (SV).

METHODS

Ees/Ea can be calculated non-invasively from the four parameters of end-systolic arterial pressure (Pes), diastolic arterial pressure (DBP), pre-ejection period (PEP), and ejection time (ET), using the approximation formula. In addition, if SV can be assessed, EDV can be calculated. Therefore, using a vascular screening system (VaSera 1000/1500, Fukuda Denshi Co., Ltd., Tokyo, Japan), blood pressure, PEP, and ET were measured noninvasively, the SV value was obtained using an ultrasound diagnostic device, EDV was calculated (EDV calc), and it was compared with EDV obtained using the ultrasound diagnostic device (EDV echo). The results are shown as mean ± standard deviation values.

RESULTS

There were 48 healthy subjects (40 men, 8 women), with a mean age of 24 ± 4 years, mean height of 169 ± 7 cm, and mean weight of 65 ± 12 kg. EDV echo was 91 ± 16 ml, and EDV calc was 102 ± 21 ml. There was a significant correlation between EDV echo and EDV calc (R² = 0.81, p < 0.01). A Bland-Altman plot between EDV echo and EDV calc showed that the bias and limits of agreement were -11.2 ml (-36.6, + 14.2 ml).

CONCLUSIONS

The results suggest that EDV can be measured non-invasively from Ees/Ea and SV. This suggests that continuous measurements may potentially work, using equipment available in the intraoperative setting.

Right ventricular echocardiographic parameters and prediction of stroke volume in ischemic cardiogenic shock: A retrospective study

PURPOSE

This study investigated which commonly used right ventricular (RV) echocardiographic parameter correlates best with stroke volume (SV) estimated by Doppler echocardiography in ischemic cardiogenic shock (CS).

MATERIALS AND METHODS

We retrospectively reviewed the records of 100 patients admitted to the ICU over 34 months with CS. Tricuspid annular plane systolic excursion (TAPSE), Tricuspid annulus systolic velocity (RV S'), Tricuspid regurgitation maximum velocity (TR Vmax), and RV outflow tract velocity time integral (RVOT VTI) were correlated to SV.

RESULTS

Mean age was 62.6 ± 12.7 years and 78% were male. The mean SV, TAPSE, RV S', TR Vmax, and RVOT VTI were 47 ± 16 ml, 16 ± 5 mm, 11 ± 4 mm/s, 1.97 ± 0.73 m/s, and 12.7 ± 5 cm, respectively. RVOT VTI correlated best to SV (r = 0.39 p = 0.01) compared to TAPSE, RV S', and TR Vmax (r = 0.26 p = 0.01, r = 0.15 p = 0.21, r = 0.03 p = 0.78). RVOT VTI independently predicted SV. Univariate analysis demonstrated that only RVOT VTI predicted SV (OD = 1.18 p = 0.04) and had the best area under the curve (0.70, p = 0.03).

CONCLUSION

RVOT VTI correlated better (albeit weakly) to and best predicted SV compared to TAPSE, RV S', and TR Vmax in patients admitted to intensive care with CS. This study suggests that RVOT VTI has the potential as a therapeutic target to optimize SV in CS.

Carotid flow as a surrogate of the left ventricular stroke volume

Transthoracic echocardiography (TTE) is a fundamental tool for hemodynamic monitoring in critical patients. It allows evaluating the left ventricle's stroke volume based on the measurement of the velocity-time integral (VTI) of the left ventricle outflow tract (LVOT). However, in the intensive care unit obtaining adequate echocardiographic views may present a challenge. We propose to measure, as a surrogate of the stroke volume, the carotid flow with a novel technique. This is an observational, prospective, and simple blind study, conducted in the intensive care unit of Sanatorio de los Arcos and Hospital Aleman, in Buenos Aires, Argentina. We measured the carotid systodiastolic flow (CSD) VTI and the carotid systolic flow (CS) VTI at the level of the left supraclavicular fossa and we compared it with the LVOT VTI obtained by TTE. We evaluated 43 subjects. Spearman's correlation coefficient between LVOT VTI and CS VTI was 0.81 (95% CI 0.67-0.89) and between LVOT VTI and CSD VTI was 0.89 (95% CI 0.81-0.94). The Bland-Altman method analysis of the 5-chamber apical window LVOT VTI compared to the CSD VTI showed a bias of - 0.2 (95% CI - 0.82 to 0.43), with a concordance interval between - 4.2 (95% CI - 5.2 to - 3.1) and 3.8 cm (95% CI 2.7 to 4.9). The percentage error was 37.9%. Almost 100% of the values fell within the concordance limits, and no trend was observed in bias across the spectrum of mean variables. Although the CSD VTI could not be interchangeable with the LVOT VTI, it could be considered as its surrogate.

Acyl ghrelin improves cardiac function in heart failure and increases fractional shortening in cardiomyocytes without calcium mobilization

BACKGROUND AND AIMS

Ghrelin is an endogenous appetite-stimulating peptide hormone with potential cardiovascular benefits. Effects of acylated (activated) ghrelin were assessed in patients with heart failure and reduced ejection fraction (HFrEF) and in ex vivo mouse cardiomyocytes.

METHODS AND RESULTS

In a randomized placebo-controlled double-blind trial, 31 patients with chronic HFrEF were randomized to synthetic human acyl ghrelin (0.1 µg/kg/min) or placebo intravenously over 120 min. The primary outcome was change in cardiac output (CO). Isolated mouse cardiomyocytes were treated with acyl ghrelin and fractional shortening and calcium transients were assessed. Acyl ghrelin but not placebo increased cardiac output (acyl ghrelin: 4.08 ± 1.15 to 5.23 ± 1.98 L/min; placebo: 4.26 ± 1.23 to 4.11 ± 1.99 L/min, P < 0.001). Acyl ghrelin caused a significant increase in stroke volume and nominal increases in left ventricular ejection fraction and segmental longitudinal strain and tricuspid annular plane systolic excursion. There were no effects on blood pressure, arrhythmias, or ischaemia. Heart rate decreased nominally (acyl ghrelin: 71 ± 11 to 67 ± 11  b.p.m.; placebo 69 ± 8 to 68 ± 10  b.p.m.). In cardiomyocytes, acyl ghrelin increased fractional shortening, did not affect cellular Ca2+ transients, and reduced troponin I phosphorylation. The increase in fractional shortening and reduction in troponin I phosphorylation was blocked by the acyl ghrelin antagonist D-Lys 3.

CONCLUSION

In patients with HFrEF, acyl ghrelin increased cardiac output without causing hypotension, tachycardia, arrhythmia, or ischaemia. In isolated cardiomyocytes, acyl ghrelin increased contractility independently of preload and afterload and without Ca2+ mobilization, which may explain the lack of clinical side effects. Ghrelin treatment should be explored in additional randomized trials.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05277415.

Evaluating corrected carotid flow time as a non-invasive parameter for trending cardiac output and stroke volume in cardiac surgery patients

PURPOSE

The corrected carotid flow time (ccFT) is derived from a pulsed-wave Doppler signal at the common carotid artery. Several equations are currently used to calculate ccFT. Its ability to assess the intravascular volume status non-invasively has recently been investigated. The purpose of this study was to evaluate the correlation and trending ability of ccFT with invasive cardiac output (CO) and stroke volume (SV) measurements.

METHODS

Eighteen cardiac surgery patients were included in this prospective observational study. ccFT measurements were obtained at three time points: after induction of anesthesia (T1), after a passive leg raise (T2), and post-bypass (T3). Simultaneously, CO and SV were measured by calibrated pulse contour analysis. Three different equations (Bazett, Chambers, and Wodey) were used to calculate ccFT. The correlation and percentage change in time (concordance) between ccFT and CO and between ccFT and SV were evaluated.

RESULTS

Mean ccFT values differed significantly for the three equations (p < 0.001). The correlation between ccFT and CO and between ccFT and SV was highest for Bazett's (ρ = 0.43, p < 0.0001) and Wodey's (ρ = 0.33, p < 0.0001) equations, respectively. Concordance between ΔccFT and ΔCO and between ΔccFT and ΔSV was highest for Bazett's (100%) and Wodey's (82%) equations, respectively. Subgroup analysis demonstrated that correlation and concordance between SV and ccFT improved when assessed within limited heart rate (HR) ranges.

CONCLUSION

The use of different ccFT equations leads to variable correlation and concordance rates between ccFT and CO/SV measurements. Bazett's equation acceptably tracked CO changes in time, while the trending capability of SV was poor.

Real-Time Measurements of Relative Tidal Volume and Stroke Volume Using Electrical Impedance Tomography with Spatial Filters: A Feasibility Study in a Swine Model Under Normal and Reduced Ventilation

Continuous monitoring of both hemodynamic and respiratory parameters would be beneficial to patients, e.g., those in intensive care unit. The objective of this exploratory animal study was to test the feasibility of simultaneous measurements of relative tidal volume (rTV) and relative stroke volume (rSV) using an electrical impedance tomography (EIT) device equipped with a new real-time source separation algorithm implemented as two spatial filters. Five pigs were anesthetized and mechanically ventilated. The supplied tidal volume from a mechanical ventilator was reduced to 70, 50 and 30% from the 100% normal volume to simulate hypoventilation. The respiratory volume signal and cardiac volume signal were generated by applying the spatial filters to the acquired EIT data, from which values of rTV and rSV were extracted. The measured rTV values were compared with the TV values from the mechanical ventilator using the four-quadrant concordance analysis method. For changes in TV, the concordance rate in each animal ranged from 81.8% to 100%, while it was 92.5% when the data from all five animals were pooled together. When the measured rTV values for each animal were scaled to the absolute TV_EIT values in mL using the TV_Vent data from the mechanical ventilator, the smallest 95% limits of agreement (LoA) were - 6.04 and 7.44 mL for the 70% ventilation level, and the largest 95% LoA were - 18.1 and 19.4 mL for the 50% ventilation level. The percentage error between TV_EIT and TV_Vent was 10.3%. Although similar statistical analyses on rSV data could not be performed due to limited intra-animal variability, changes in rSV values measured by the EIT device were comparable to those measured by an invasive hemodynamic monitor. In this animal study, we were able to demonstrate the feasibility of an EIT device for noninvasive and simultaneous measurements of rTV and rSV in real time. However, the performance of the real-time source separation method needs to be further validated on animals and human subjects, particularly over a wide range of SV values. Future clinical studies are needed to assess the potential usefulness of the new method in dynamic cardiopulmonary monitoring and explore other clinical applications.

The clinical impact of the systolic volume variation guided intraoperative fluid administration regimen on surgical outcomes after pancreaticoduodenectomy: a retrospective cohort study

BACKGROUND

Pancreaticoduodenectomy is associated with high morbidity. Many preoperative variables are risk factors for postoperative complications, but they are primarily non-modifiable. It is not clear whether an intraoperative goal-directed fluid regimen might be associated with fewer postoperative surgical complications compared to current conservative, non-goal-directed fluid practices. We hypothesize that the use of Systolic Volume Variation (SVV)-guided intraoperative fluid administration might be beneficial.

METHODS

Data from 223 patients who underwent pancreaticoduodenectomy in our institution between 2015 and 2019 were reviewed. Patients were classified into two groups based on the use of intraoperative use of SVV to guide the administration of fluids. The decision to use SVV or not was made by the attending anesthesiologist. Subjects were classified into SVV-guided intraoperative fluid therapy (SVV group) and non-SVV-guided intraoperative fluid therapy (non-SVV group). Uni and multivariate regression analyses were conducted to determine if SVV-guided fluid therapy was significantly associated with a lower incidence of postoperative surgical complications, such as Postoperative Pancreatic Fistula (POPF), Delayed Gastric Emptying (DGE), among others, after adjusting for confounders.

RESULTS

Baseline, demographic, and intraoperative characteristics were similar between SVV and non-SVV groups. In the multivariate analysis, the use of SVV guidance was significantly associated with fewer postoperative surgical complications (OR = 0.48; 95% CI 0.25-0.91; p = 0.025), even after adjusting for significant covariates, such as perioperative use of epidural, pancreatic gland parenchyma texture, and diameter of the pancreatic duct.

CONCLUSIONS

VV-guided intraoperative fluid administration might be associated with fewer postoperative surgical complications after pancreaticoduodenectomy.

Optimising fluid requirements after initial resuscitation: A pilot study evaluating mini-fluid challenge and passive leg raising test in patients with predicted severe acute pancreatitis

BACKGROUND

The goals and approaches to fluid therapy vary through different stages of resuscitation. This pilot study was designed to test the safety and feasibility of a fluid therapy protocol for the second or optimisation stage of resuscitation in patients with predicted severe acute pancreatitis (SAP).

METHODS

Spontaneously breathing patients with predicted SAP were admitted after initial resuscitation and studied over a 24-h period in a tertiary hospital ward. Objective clinical assessment (OCA; heart rate, mean arterial pressure, urine output, and haematocrit) was done at 0, 4, 8, 12, 18-20, and 24 h. All patients had mini-fluid challenge (MFC; 250 ml intravenous normal saline within 10 min) at 0 h and repeated at 4 and 8 h if OCA score ≥2. Patients who were fluid responsive (>10% change in stroke volume after MFC) received 5-10 ml/kg/h, otherwise 1-3 ml/kg/h until the next time point. Passive leg raising test (PLRT) was done at each time point and compared with OCA for assessing volume status and predicting fluid responsiveness.

RESULTS

This fluid therapy protocol based on OCA, MFC, and PLRT and designed for the second stage of resuscitation was safe and feasible in spontaneously breathing predicted SAP patients. The PLRT was superior to OCA (at 0 and 8 h) for predicting fluid responsiveness and guiding fluid therapy.

CONCLUSIONS

This pilot study found that a protocol for intravenous fluid therapy specifically for the second stage of resuscitation in patients with predicted SAP was safe, feasible, and warrants further investigation.

A 72-channel receive array coil allows whole-heart cine MRI in two breath holds

BACKGROUND

A new 72-channel receive array coil and sensitivity encoding, compressed (C-SENSE) and noncompressed (SENSE), were investigated to decrease the number of breath-holds (BHs) for cardiac magnetic resonance (CMR).

METHODS

Three-T CMRs were performed using the 72-channel coil with SENSE-2/4/6 and C-SENSE-2/4/6 accelerated short-axis cine two-dimensional balanced steady-state free precession sequences. A 16-channel coil with SENSE-2 served as reference. Ten healthy subjects were included. BH-time was kept under 15 s. Data were compared in terms of image quality, biventricular function, number of BHs, and scan times.

RESULTS

BHs decreased from 7 with C-SENSE-2 (scan time 70 s, 2 slices/BH) to 3 with C-SENSE-4 (scan time 42 s, 4-5 slices/BH) and 2 with C-SENSE-6 (scan time 28 s, 7 slices/BH). Compared to reference, image sharpness was similar for SENSE-2/4/6, slightly inferior for C-SENSE-2/4/6. Blood-to-myocardium contrast was unaffected. C-SENSE-4/6 was given lower qualitative median scores, but images were considered diagnostically adequate to excellent, with C-SENSE-6 suboptimal. Biventricular end-diastolic (EDV), end-systolic (ESV) and stroke volumes, ejection fractions (EF), cardiac outputs, and left ventricle (LV)-mass were similar for SENSE-2/4/6 with no systematic bias and clinically appropriate limits of agreements. C-SENSE slightly underestimated LV-EDV (-6.38 ± 6.0 mL, p < 0.047), LV-ESV (-7.94 ± 6.0 mL, p < 0.030) and overestimated LV-EF (3.16 ± 3.10%; p < 0.047) with C-SENSE-4. Bland-Altman analyses revealed minor systematic biases in these variables with C-SENSE-2/4/6 and for LV-mass with C-SENSE-6.

CONCLUSIONS

Using the 72-channel coil, short-axis CMR for quantifying biventricular function was feasible in two BHs where SENSE slightly outperformed C-SENSE.

The Impact of Goal-Directed Fluid Therapy on Postoperative Nausea and Vomiting in High-Risk Patients Undergoing Laparoscopic Sleeve Gastrectomy

PURPOSE

Patients with laparoscopic sleeve gastrectomy (LSG) are at high risk of postoperative nausea and vomiting (PONV). Goal-directed fluid therapy (GDFT) has been proven effective in improving postoperative gastrointestinal function in patients with obesity, but its effect on prevention of PONV remains controversial. This study aimed to investigate the impact of GDFT on PONV in high-risk patients with LSG.

METHODS

In a randomized, single-blinded, two-arm trial, patients with an Apfel score ≥ 3 and scheduled for LSG were included. Patients in the GDFT group received stroke volume-guided fluid therapy. Patients in the control group received conventional fluid therapy. The primary outcome was the incidence of PONV within 48 h after LSG. The second outcome included intensity of PONV, use of rescue therapy, recovery of gastrointestinal function, and postoperative length of stay (LOS).

RESULTS

A total of 137 patients were analyzed. The incidence of PONV in the GDFT group was lower than that in the control group (47.1% vs. 71.6%; odds ratio [95%CI], 0.35 [0.17-0.72]; P = 0.004). Fewer patients in the GDFT group received rescue therapy (30% vs. 58.2%; P = 0.001). Patients following GDFT protocol had a faster return of flatus (27.5 (19, 31) vs. 31 (20, 48) hours, P = 0.037) and shorter postoperative LOS (6.1 ± 1.0 vs. 6.6 ± 1.1 days; P = 0.007).

CONCLUSION

GDFT is conducive to deceasing PONV occurrence, restoring intestinal function, and shortening postoperative LOS in high-risk patients undergoing LSG.

Development potentials of commonly used high-intensity training strategies on central and peripheral components of maximal oxygen consumption

The aim of this study was to reveal the development potentials of five high-intensity training models on central and peripheral components of maximal oxygen consumption (VO_2max). Following VO_2max determination, maximal cardiac output (Q_max), maximal stroke volume (SV_max), and maximal arteriovenous O₂ difference (a-vO_{2diff_max}) were analysed. Short-interval- (short-HIIT), long-interval (long-HIIT), alternating work-rate continuous (alter-HIT), constant work-rate continuous (const-HIT), and sprint interval (SIT) sessions were performed on separate days with iso-effort and iso-time methods. Time spent (t_spent) at > 95% of VO_2max was the highest in long-HIIT (p < 0.05). The t_spent at > 90% of Q_max was higher in alter-HIT than long-HIIT and SIT (p < 0.05), while there was no significant difference for t_spent at > 90% of SV_max amongst high-intensity trainings. The t_spent at > 90% of a-vO_2diff__max was higher in short-HIIT and long-HIIT than other modalities (p < 0.05). It can be said that continuous modalities seem to have a higher potential to improve central part of VO_2max, while interval modalities may be better to develop peripheral component.

Management strategies in heart failure with preserved ejection fraction

The diagnosis and therapy of heart failure with preserved ejection fraction (HFpEF) remain challenging. Currently, there are ongoing discussions on whether the diagnosis of HFpEF should be based solely on left ventricular ejection fraction, which may not account for the heterogeneity of HFpEF syndrome. This aspect has been addressed by the recently proposed HFA-PEFF and the H2FPEF algorithms, which take numerous diagnostic modalities into account to establish the diagnosis of HFpEF. Moreover, this review focuses on the adequate treatment of comorbidities and risk factors in HFpEF that should be an essential part of any HFpEF therapy. Furthermore, the management of fluid level in HFpEF patients is pointed out, as it plays an important role in symptom control. In addition, the value of LCZ696 therapy in HFpEF is discussed. Although LCZ696 had neutral effects in the large PARAGON-HF trial, it had previously been granted an extended indication by the Food and Drug Administration. Since the publication of the EMPEROR-Preserved trial, empagliflozin now represents the first drug to significantly improve the prognosis of HFpEF patients. Therefore, the role of SGLT2 inhibitors in HFpEF management is highlighted. Overall, this review aims to enhance the knowledge on the diagnostic processes and best treatments available for HFpEF patients.

Can temperature-dependent changes in myocardial contractility explain why fish only increase heart rate when exposed to acute warming?

Fish increase heart rate (f_H), not stroke volume (V_S), when acutely warmed as a way to increase cardiac output (Q). To assess whether aspects of myocardial function may have some basis in determining temperature-dependent cardiac performance, we measured work and power (shortening, lengthening and net) in isolated segments of steelhead trout (Oncorhynchus mykiss) ventricular muscle at the fish's acclimation temperature (14°C), and at 22°C, when subjected to increased rates of contraction (30–105 min⁻¹, emulating increased f_H) and strain amplitude (8–14%, mimicking increased V_S). At 22°C, shortening power (indicative of Q) increased in proportion to f_H, and the work required to re-lengthen (stretch) the myocardium (fill the heart) was largely independent of f_H. In contrast, the increase in shortening power was less than proportional when strain was augmented, and lengthening work approximately doubled when strain was increased. Thus, the derived relationships between f_H, strain and myocardial shortening power and lengthening work, suggest that increasing f_H would be preferable as a mechanism to increase Q at high temperatures, or in fact may be an unavoidable response given constraints on muscle mechanics as temperatures rise. Interestingly, at 14°C, lengthening work increased substantially at higher f_H, and the duration of lengthening (i.e. diastole) became severely constrained when f_H was increased. These data suggest that myocardial contraction/twitch kinetics greatly constrain maximal f_H at cool temperatures, and may underlie observations that fish elevate V_S to an equal or greater extent than f_H to meet demands for increased Q at lower temperatures.

Summary: Myocardial contraction and twitch kinetics provide mechanistic explanations as to why heart rate, but not stroke volume, increases in fish with temperature, and why maximal heart rate is constrained at cool/cold temperatures.

Handling of derived imbalanced dataset using XGBoost for identification of pulmonary embolism-a non-cardiac cause of cardiac arrest

Relationship between pulmonary embolism and heart failure is presented in this paper. The proposed research is divided into two phases. The first phase includes the establishment of a novel database with the help of a Cleveland's database for cardiology in order to establish a link between pulmonary embolism and heart failure. The connectivity is based on the relationship between the stroke volume and the pulse pressure (Pp < 25% (ap_hi)). The second phase includes the applicability of machine learning on the novel database. Novel database formed in this work is imbalanced, resulting in the overfitting problem. XGBoost has been used to get rid of overfitting problem. Efficiency has been increased by formulating an ensemble technique by combining extreme learning machines, IB3 tree, logistic regression, and averaged neural network (avNNet) models.

Carotid artery velocity time integral and corrected flow time measured by a wearable Doppler ultrasound detect stroke volume rise from simulated hemorrhage to transfusion

Objective

Doppler ultrasonography of the common carotid artery is used to infer stroke volume change and a wearable Doppler ultrasound has been designed to improve this workflow. Previously, in a human model of hemorrhage and resuscitation comprising approximately 50,000 cardiac cycles, we found a strong, linear correlation between changing stroke volume, and measures from the carotid Doppler signal, however, optimal Doppler thresholds for detecting a 10% stroke volume change were not reported. In this Research Note, we present these thresholds, their sensitivities, specificities and areas under their receiver operator curves (AUROC).

Results

Augmentation of carotid artery maximum velocity time integral and corrected flowtime by 18% and 4%, respectively, accurately captured 10% stroke volume rise. The sensitivity and specificity for these thresholds were identical at 89% and 100%. These data are similar to previous investigations in healthy volunteers monitored by the wearable ultrasound.

Changes in stroke volume induced by lung recruitment maneuver can predict fluid responsiveness during intraoperative lung-protective ventilation in prone position

Background

The present study aimed to evaluate the reliability of hemodynamic changes induced by lung recruitment maneuver (LRM) in predicting stroke volume (SV) increase after fluid loading (FL) in prone position.

Methods

Thirty patients undergoing spine surgery in prone position were enrolled. Lung-protective ventilation (tidal volume, 6–7 mL/kg; positive end-expiratory pressure, 5 cmH₂O) was provided to all patients. LRM (30 cmH₂O for 30 s) was performed. Hemodynamic variables including mean arterial pressure (MAP), heart rate, SV, SV variation (SVV), and pulse pressure variation (PPV) were simultaneously recorded before, during, and at 5 min after LRM and after FL (250 mL in 10 min). Receiver operating characteristic curves were generated to evaluate the predictability of SVV, PPV, and SV decrease by LRM (ΔSV_LRM) for SV responders (SV increase after FL > 10%). The gray zone approach was applied for ΔSV_LRM.

Results

Areas under the curve (AUCs) for ΔSV_LRM, SVV, and PPV to predict SV responders were 0.778 (95% confidence interval: 0.590–0.909), 0.563 (0.371–0.743), and 0.502 (0.315–0.689), respectively. The optimal threshold for ΔSV_LRM was 30% (sensitivity, 92.3%; specificity, 70.6%). With the gray zone approach, the inconclusive values ranged 25 to 75% for ΔSV_LRM (including 50% of enrolled patients).

Conclusion

In prone position, LRM-induced SV decrease predicted SV increase after FL with higher reliability than traditional dynamic indices. On the other hand, considering the relatively large gray zone in this study, future research is needed to further improve the clinical significance.

Trial registration

UMIN Clinical Trial Registry UMIN000027966. Registered 28th June 2017.

Effects of blood withdrawal on cardiac, hemodynamic, and pulmonary responses to a moderate acute workload in healthy middle-aged and older females

OBJECTIVES

To investigate the effects of blood withdrawal on cardiac, hemodynamic, and pulmonary responses to submaximal exercise in females.

DESIGN AND METHODS

30 healthy females (63.8 ± 8.3 years) were recruited for this experimental study. Transthoracic echocardiography, non-invasive blood pressure monitoring, and oxygen uptake were assessed during a fixed submaximal workload (100 W) prior to (day 1) and immediately after (day 2) a 10% reduction of blood volume. Main measurements included left ventricular end-diastolic volume, stroke volume, cardiac output, mean arterial pressure, systolic blood pressure, diastolic blood pressure, and oxygen uptake. Blood volume was determined via carbon monoxide rebreathing.

RESULTS

Participant's blood volume ranged from 3.8 to 6.6 L. Following 10% reduction in blood volume (0.5 ± 0.1 L), left ventricular end-diastolic volume (p ≤ 0.030) and stroke volume (p < 0.019) were reduced during submaximal exercise while cardiac output was unchanged (p = 0.139) due to increased heart rate (p < 0.026). Hemodynamic variables including mean arterial pressure (p < 0.015), systolic blood pressure (p < 0.005), and diastolic blood pressure (p < 0.038) were reduced while oxygen uptake was unaltered (p = 0.250).

CONCLUSIONS

Blood withdrawal results in marked reductions in cardiac filling with compensatory chronotropic responses that preserve cardiac output at a moderate submaximal workload in healthy females. Thus, blood volume determines the relative exercise intensity, as typically determined by heart rate, of submaximal efforts in this population.

Agreement analysis of stroke volume and cardiac output measurement between a oscillometric device and transthoracic echocardiogram in normotensive individuals: a preliminary report

INTRODUCTION

The evaluation of stroke volume (SV) is useful in research and patient care. To accomplish this, an ideal device should be noninvasive, continuous, reliable, and reproducible. The Mobil-O-Graph (MOG) is a noninvasive oscillometric matrix validated for measuring aortic and peripheral blood pressure, which through conversion algorithms can estimate hemodynamic parameters.

OBJECTIVES

To compare the MOG measurement of stroke volume, cardiac output, and cardiac index with the transthoracic echocardiogram (TTE).

METHODS

Healthy volunteers aged 18 years or older were included. Two-dimensional TTEs were performed by a single operator. Subsequently, the measurement of noninvasive hemodynamics with MOG was performed with the operator blind to the results of the echocardiogram. Correlation analyses between stroke volume, cardiac output, and cardiac index parameters were performed. The degree of agreement between the methods was verified using the Bland-Altman method.

RESULTS

A total of 38 volunteers were enrolled with a mean age of 27.6 ± 3.8 years; 21 (55%) were male The SV by TTE was 76.8 ± 19.5 mL and 75.7 ± 19.3 mL by MOG, Rho = 0.726, p < 0.0001. The CO by TTE was 5.04 ± 0.8 mL.min^-1 and 5.1 ± 0.8 mL.min^-1 by MOG Rho = 0.510, p = 0.001. Bland-Altman plots showed a good concordance between the two techniques.

CONCLUSIONS

Our study shows that the measurement of SV and CO by noninvasive hemodynamics with the MOG device offers a good concordance with the TTE with very few values beyond the confidence limits.

Changes in left ventricular size, geometry, pump function and left heart pressures during healthy aging

There are cross-sectional and longitudinal imaging studies using echocardiography and cardiac magnetic resonance in healthy adult subjects which have demonstrated associations of left ventricular (LV) structure and pump function with age. There are also cross-sectional data regarding the relationships of age with invasively measured left heart chamber pressures. Increasing age is associated with decreases in LV end-diastolic volume (LVEDV), end-systolic volume (LVESV), end-diastolic length (LVEDL), stroke volume (SV) and cardiac output (CO), and increases in relative wall thickness (RWT), LV mass/LVEDV ratio (LVMVR) and ejection fraction (LVEF). Older age is not accompanied by a change in mean left atrial (LA) pressure, but there is both direct and indirect evidence which suggests that LV end-diastolic pressure (LVEDP) increases with age. LVEDV remains lower in older than younger subjects during fluid infusion and the resulting increases in LA pressure. The combination of an increase in LVEF with reductions of both SV and CO demonstrates an age-related increase in divergence between LVEF and LV pump function. A lower LVEDV in older compared to younger subjects can be characterized as an aging-related decrease in LV capacity, with the higher LVEDP in older subjects also indicating a reduction of preload reserve.

Ability of short-time low peep challenge to predict fluid responsiveness in mechanically ventilated patients in the intensive care

Short-time low PEEP challenge (SLPC, application of additional 5 cmH₂O PEEP to patients for 30 s) is a novel functional hemodynamic test presented in the literature. We hypothesized that SLPC could predict fluid responsiveness better than stroke volume variation (SVV) in mechanically ventilated intensive care patients. Heart rate, mean arterial pressure, stroke volume index (SVI) and SVV were recorded before SLPC, during SLPC and before and after 500 mL fluid loading. Patients whose SVI increased more than 15% after the fluid loading were defined as fluid responders. Reciever operating characteristics (ROC) curves were generated to evaluate the abilities of the methods to predict fluid responsiveness. Fifty-five patients completed the study. Twenty-five (46%) of them were responders. Decrease percentage in SVI during SLPC (SVIΔ%–SLPC) was 11.6 ± 5.2% and 4.3 ± 2.2% in responders and non-responders, respectively (p < 0.001). A good correlation was found between SVIΔ%–SLPC and percentage change in SVI after fluid loading (r = 0.728, P < 0.001). Areas under the ROC curves (ROC–AUC) of SVIΔ%–SLPC and SVV were 0.951 (95% CI 0.857–0.991) and 0.747 (95% CI 0.611–0.854), respectively. The ROC–AUC of SVIΔ%–SLPC was significantly higher than that of SVV (p = 0.0045). The best cut-off value of SVIΔ%–SLPC was 7.5% with 90% sensitivity and 96% specificity. The percentage change in SVI during SLPC predicts fluid responsiveness in intensive care patients who are ventilated with low tidal volumes; the sensitivity and specificity values are higher than those of SVV.

Principles of Resuscitation

Shock from all causes carries a high mortality. Rapid and intentional intervention to resuscitate can reduce mortality and organ injury. Approaches to fluid resuscitation, vasopressor use as well as commonly assessed laboratory values are reviewed in this paper.

Does stroke volume influence heartbeat evoked responses?

We know surprisingly little on how heartbeat-evoked responses (HERs) vary with cardiac parameters. Here, we measured both stroke volume, or volume of blood ejected at each heartbeat, with impedance cardiography, and HER amplitude with magneto-encephalography, in 21 male and female participants at rest with eyes open. We observed that HER co-fluctuates with stroke volume on a beat-to-beat basis, but only when no correction for cardiac artifact was performed. This highlights the importance of an ICA correction tailored to the cardiac artifact. We also observed that easy-to-measure cardiac parameters (interbeat intervals, ECG amplitude) are sensitive to stroke volume fluctuations and can be used as proxies when stroke volume measurements are not available. Finally, interindividual differences in stroke volume were reflected in MEG data, but whether this effect is locked to heartbeats is unclear. Altogether, our results question assumptions on the link between stroke volume and HERs.

Vagal blockade suppresses the phase I heart rate response but not the phase I cardiac output response at exercise onset in humans

Purpose

We tested the vagal withdrawal concept for heart rate (HR) and cardiac output (CO) kinetics upon moderate exercise onset, by analysing the effects of vagal blockade on cardiovascular kinetics in humans. We hypothesized that, under atropine, the φ₁ amplitude (A₁) for HR would reduce to nil, whereas the A₁ for CO would still be positive, due to the sudden increase in stroke volume (SV) at exercise onset.

Methods

On nine young non-smoking men, during 0–80 W exercise transients of 5-min duration on the cycle ergometer, preceded by 5-min rest, we continuously recorded HR, CO, SV and oxygen uptake (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{V} $$\end{document}V˙O₂) upright and supine, in control condition and after full vagal blockade with atropine. Kinetics were analysed with the double exponential model, wherein we computed the amplitudes (A) and time constants (τ) of phase 1 (φ₁) and phase 2 (φ₂).

Results

In atropine versus control, A₁ for HR was strongly reduced and fell to 0 bpm in seven out of nine subjects for HR was practically suppressed by atropine in them. The A₁ for CO was lower in atropine, but not reduced to nil. Thus, SV only determined A₁ for CO in atropine. A₂ did not differ between control and atropine. No effect on τ₁ and τ₂ was found. These patterns were independent of posture.

Conclusion

The results are fully compatible with the tested hypothesis. They provide the first direct demonstration that vagal blockade, while suppressing HR φ₁, did not affect φ₁ of CO.

Effect of trabeculated myocardial mass on left ventricle global and regional functions in noncompaction cardiomyopathy

BACKGROUND

Left ventricular (LV) noncompaction cardiomyopathy is a rare cardiomyopathic subtype that has been recognized in recent years and is being diagnosed at an increased rate. There is no consensus regarding the diagnosis of the disease, and increased trabeculation rates that meet the existing diagnostic criteria may even be present in healthy asymptomatic people. This indicates that differentiating criteria for diagnosis are needed.

AIM

To examine the increase in myocardial trabeculation and the change in left ventricular global and regional functions.

METHODS

This retrospective study included 65 patients (28 females, 37 males) diagnosed with LV noncompaction cardiomyopathy who underwent cardiac magnetic resonance imaging between January 2011 and August 2016 and had a noncompacted/compacted myocardial thickness ratio of over 2.3 in more than one segment in the left ventricle. The distribution and ratios of trabeculations in apical, midventricular, and basal regions were examined in short-axis images obtained from cardiac magnetic resonance. In addition, by using short-axis cine images, regional ejection fraction (EF) and global EF were calculated using the Simpson method in the left ventricle at apical, basal, and midventricular levels.

RESULTS

While the number of trabeculated segments were similar at the apical (3.2 ± 1.0) and midventricular levels, a statistically significant level of involvement was not observed at the basal level (0.4 ± 0.9) (P > 0.05). The highest noncompacted/compacted (trabeculation) ratio was observed at the apical level (3.9 ± 1.4), while this ratio was higher at the anterior (59%-89.4%) and lateral (62%-84.8%) segments (P > 0.05). Global EF was positively correlated with apical, midventricular, and basal regional EF (P < 0.05). However, there was no significant correlation between regional EF and the number of trabeculated segments or trabeculation ratio in all three regions; nor was there a significant correlation between regional EF and the number of trabeculated segments or trabeculation ratio in the entire LV (P > 0.05).

CONCLUSION

No global or regional relationship was observed between LV dysfunction and trabeculation rate or the number of trabeculated segments. This limits the usefulness of change in LV functions in the differentiation between normal and pathological trabeculation.

Peak oxygen pulse and mortality risk in healthy women and men: The Ball State Adult Fitness Longitudinal Lifestyle Study (BALL ST)

Peak oxygen pulse (O₂ pulse_peak) may have predictive utility for health outcomes yet, presently, has only been examined in men and only using a single baseline measure.

PURPOSE

The primary aim of this investigation was to evaluate the relationship between O₂ pulse_peak and all-cause mortality in apparently healthy women and men. A secondary aim was to explore the relationship between longitudinal changes to O₂ pulse_peak and mortality.

METHODS

The sample included 3877 participants (43% women) for the primary aim and 759 participants (32% women) who performed two cardiopulmonary exercise tests ≥1 year apart for the secondary aim. Cox proportional hazard models were performed to determine the relationship between O₂ pulse_peak and mortality. Prognostic peak oxygen consumption (VO_2peak) and O₂ pulse_peak models were compared using the concordance index and Akaike information criterion (AIC).

RESULTS

In the assessment from baseline, there were 730 deaths over a 24.7 ± 11.8 year follow-up period. For men, a single measure of O₂ pulse_peak was inversely associated with risk for mortality (P < 0.05). However, the concordance index and AIC indicated lower discrimination compared to VO_2peak models and O₂ pulse_peak did not provide complementary benefit to VO_2peak models. For women, O₂ pulse_peak was not associated with mortality risk. In the longitudinal analysis, there were 168 deaths over a follow-up of 20.1 ± 11.4 years. Changes to O₂ pulse_peak were not significantly related to mortality in either sex.

CONCLUSIONS

Within an apparently healthy cohort, a single assessment of O₂ pulse_peak is related to all-cause mortality in men but not women. Further, longitudinal changes to O₂ pulse_peak are not predictive of mortality in either sex. These findings suggest O₂ pulse_peak may have limited prognostic utility in healthy individuals, particularly within healthy women.

Decreased exercise capacity in young athletes using self-adapted mouthguards

PURPOSE

There is evidence of both the preventive effects and poor acceptance of mouthguards. There are various effects on performance depending on the type of mouthguard model. Hemodynamic responses to wearing a mouthguard have not been described. The aim of this study was to investigate the effects of self-adapted mouthguards with breathing channels (SAMGvent).

METHODS

In this randomized crossover study, 17 healthy, active subjects (age 25.12 ± 2.19 years) underwent body plethysmography and performed two incremental exertion tests wearing a (SAMGvent) and not wearing (CON) a mouthguard. Blood lactate, spirometrics, and thoracic impedance were measured during these maximum exercise tests.

RESULTS

The mean values using a SAMGvent revealed significantly greater airway resistance compared to CON (0.53 ± 0.16 kPa·L-1 vs. 0.35 ± 0.10 kPa·L-1, respectively; p = < 0.01). At maximum load, ventilation with SAMGvent was less than CON (118.4 ± 28.17 L min-1 vs. 128.2 ± 32.16 L min-1, respectively; p = < 0.01). At submaximal loads, blood lactate responses with SAMGvent were higher than CON (8.68 ± 2.20 mmol·L-1 vs. 7.89 ± 1.65 mmol·L-1, respectively; p < 0.01). Maximum performance with a SAMGvent was 265.9 ± 59.9 W, and without a mouthguard was 272.9 ± 60.8 W (p < 0.01). Maximum stroke volume was higher using a SAMGvent than without using a mouthguard (138.4 ± 29.9 mL vs. 130.2 ± 21.2 mL, respectively; p < 0.01).

CONCLUSION

Use of a self-adapted mouthguard led to increased metabolic effort and a significant reduction in ventilation parameters. Unchanged oxygen uptake may be the result of cardiopulmonary compensation and increased breathing efforts, which slightly affects performance. These results and the obvious preventive effects of mouthguards support their use in sports.

Changes in corrected carotid flow time induced by recruitment maneuver predict fluid responsiveness in patients undergoing general anesthesia

Non-invasive methods to assess patients' fluid responsiveness during lung-protective ventilation are needed. We hypothesized changes in the corrected carotid flow time induced by the recruitment maneuver predict fluid responsiveness under general anesthesia. Thirty patients undergoing general anesthesia in the supine position were prospectively enrolled. The study protocol was conducted when the patient was hemodynamically stable during surgery. Flow time was measured on Doppler images of the common carotid artery. Carotid flow time, heart rate, stroke volume, stroke volume variation, and pulse pressure variation were recorded before and after a recruitment maneuver at a continuous airway pressure of 30 cmH₂O for 30 s, and before and after volume expansion with 250 mL for 10 min. Patients were defined as fluid responders if the increase in stroke volume was > 10% after volume expansion. Twenty patients (67%) were fluid responders. All Doppler images for carotid flow time were obtained within 30 s. Changes in the corrected flow time accurately predicted fluid responsiveness (area under the curve: 0.82, 95% confidence interval [CI] 0.64-0.94, p = 0.002). The optimal threshold for changes in the corrected flow time was - 11.7% with a sensitivity of 95.0% (95% CI 75.1-99.9%) and a specificity of 80.0% (95% CI 44.4-97.5%). The gray-zone of changes in the corrected flow time was from - 25.1 to - 12.2% and included 12 patients (40%). Changes in the corrected carotid flow time were a useful, technically easy-to-perform, and non-invasive method to predict fluid responsiveness without a need for hemodynamic monitoring or arterial cannulation.

Tube-load model: A clinically applicable pulse contour analysis method for estimation of cardiac stroke volume

BACKGROUND AND OBJECTIVES

Accurate, reproducible, and reliable real-time clinical measurement of stroke volume (SV) is challenging. To accurately estimate arterial mechanics and SV by pulse contour analysis, accounting for wave reflection, such as by a tube-load model, is potentially important. This study tests for the first time whether a dynamically identified tube-load model, given a single peripheral arterial input signal and pulse transit time (PTT), provides accurate SV estimates during hemodynamic instability.

METHODS

The model is tested for 5 pigs during hemodynamic interventions, using either an aortic flow probe or admittance catheter for a validation SV measure. Performance is assessed using Bland-Altman and polar plot analysis for a series of long-term state-change and short-term dynamic events.

RESULTS

The overall median bias and limits of agreement (2.5th, 97.5th percentile) from Bland-Altman analysis were -10% [-49, 36], and -1% [-28,20] for state-change and dynamic events, respectively. The angular limit of agreement (maximum of 2.5th, 97.5th percentile) from polar-plot analysis for state-change and dynamic interventions was 35.6^∘, and 35.2^∘, respectively.

CONCLUSION

SV estimation agreement and trending performance was reasonable given the severity of the interventions. This simple yet robust method has potential to track SV within acceptable limits during hemodynamic instability in critically ill patients, provided a sufficiently accurate PTT measure.

Effect of vitamin D supplements on left ventricular ejection fraction in patients with heart failure: A systematic review and meta-analysis of randomized controlled trials

Cardiovascular diseases (CVD) are the most common cause of death worldwide. Among CVDs, heart failure (HF) is known to be the most common cause of hospitalization in patients over 65. Despite all proposed treatments for CVDs, mortality and morbidity still remain high. There are controversial reports available on vitamin D efficacy in patients with HF. In this systematic review and meta-analysis, we aimed to investigate whether vitamin D is effective at enhancing ejection fraction (EF) in patients with HF. We performed a systematic search across different databases (PubMed, SCOPUS, Web of Science, EMBASE, SciELO and Google Scholar) up to 1 Jan 2020 without any language or location limitations. Our suggested Population/Intervention/Comparison/Outcome/Type of study (PICOT) was P: patients with HF, I: vitamin D, C: placebo or no treatment, O: EF and T: clinical trials. To achieve the highest sensitivity, only keywords associate with P and I were selected for the search query. A total number of 5397 primary studies were found, of which 13 were elected for data synthesis. Clinical trials were published and available since 2005 up to 2019 and a total number of 1215 patients were included. Our results showed that vitamin D can significantly enhance left ventricular EF in HF patients by 3.304% (95% confidence interval [CI] 0.954, 5.654, p=0.006). Based on our observations, we conclude that before conducting a large number of high quality clinical trials and further meta-analysis, vitamin D should be prescribed to all patients with HF.