Ventricular End-systolic Elastance Research Articles

444 PULSE WAVE VELOCITY TO GLOBAL WORK EFFICIENCY RATIO IN HYPERTENSION: A NEW WAY TO EXPLORE VENTRICULAR-ARTERIAL COUPLING

Abstract Introduction Ventricular–arterial coupling (VAC) is considered as the cornerstone of the functional interaction between ventricles and the arterial system. VAC is commonly assessed as arterial elastance (Ea) to ventricular end-systolic elastance (Ees) ratio and it has independent prognostic value in hypertension, so it may be used to refine risk stratification and monitor therapeutic interventions in hypertensive patients. Therefore, VAC may be better characterized by the measurement of each component of this ratio through novel and more sensitive markers of myocardial function (e.g. global longitudinal strain and myocardial work parameters) and arterial function (e.g. pulse wave velocity). In this context, we aim to investigate whether new coupling indices may be able to identify left ventricular (LV) performance changes induced by blood pressure (BP) overload earlier than conventional ones. Methods 50 young individuals were prospectively enrolled, distinguishing between newly diagnosed untreated hypertensives (n= 25; 40±8 years) and controls (n=25; 39±9 years), matched for age and gender. All patients underwent at the same time carotid-femoral pulse wave velocity (PWV) measurement through an applanation tonometer (SphygmoCor® XCEL) and a transthoracic echocardiogram to calculate Ea/Ees ratio, assessed as end-systolic volume to stroke volume ratio (ESV/SV), global longitudinal strain (GLS) and myocardial work efficiency (GWE). Two new indices of VAC were derived: PWV/GLS, previously validated and PWV/GWE, still unknown. Results Ea/Ees ratio was lower in hypertensives (0,48±0,17) than in controls (0,57±0,14) but without any significant difference (p=0.18), whereas PWV/GLS was significantly higher in hypertensives than in controls (0,45±0,19 vs 0,35 ± 0,09 m/sec%; p= 0,02). PWV/GLS ratio correlated to Ea/Ees (r= 0,52; p < 0,01), diastolic dysfunction degree (r=-0,59; p<0,001), age (r=-0,64; p<0,001), systolic BP (r=-0,41; p=0,002), diastolic BP (r=-0,39; p=0,005) and mean arterial pressure (MAP) (r=-0,40; p=0,004). PWV/GWE was higher in hypertensives than in controls (0,10± 0,02 vs 0,08±0,01 m/sec%; p=0,001) and it was associated with Ea/Ees (r=- 0,55; p = 0,006), age (r= 0,59; p<0,001), diastolic dysfunction degree (r=0,55;p< 0,001), systolic BP (r=0,8; p< 0,001), diastolic BP (r=0,5;p< 0,001) and MAP (r=0,52; p<0,001). Conclusions Innovative indices of ventricular-arterial coupling could be more sensitive to investigate the impact of hypertension on LV performance.

Ventricular-arterial coupling predicts outcomes in adults with a systemic right ventricle

Abstract Background Patients with a systemic right ventricle (SRV) and biventricular circulation experience high incidence of cardiovascular morbidities and decreased survival [1]. Non-invasive measures of subclinical ventricular dysfunction are needed to appropriately identify patients at increased risk for adverse outcomes. Ventricular-arterial coupling (VAC), the ratio between the effective arterial elastance (Ea) and ventricular end-systolic elastance (Ees), may predict clinical outcomes in patients with SRV [2]. Objectives To assess VAC in adults with SRV and evaluate its correlation with clinical outcomes. Methods Consecutive cardiovascular magnetic resonance (CMR) examinations of adults with D-loop transposition of great arteries (TGA) after atrial switch operation and L-loop TGA performed at Boston Children's Hospital between 2005 and 2019 were analyzed. VAC was calculated as Ea/Ees (Ea = mean arterial blood pressure (MBP)/ventricular stroke volume; Ees = MBP/end-systolic volume). Global myocardial strain was measured by feature tracking analysis on cine steady-state free precession sequences. Cox proportional hazards regression analysis was performed to assess the association of SRV functional parameters with clinical outcomes. The analysis was adjusted for age, sex, and body mass index. The primary outcome was defined as a composite of death, cardiovascular arrest, hospitalizations for heart failure (HF); the secondary outcome as atrial arrhythmias; the tertiary outcome included other causes of cardiovascular hospitalizations (percutaneous or surgical interventions, device implantation, other cardiovascular disease). Cumulative incidence of the study outcomes was estimated using Kaplan-Meier method. Results One hundred sixty-seven adults (mean age 32±10 years, 59% men) with SRV were analyzed. Patients with HF (n=48, 29%) had higher VAC values as compared to those without HF (1.4±0.8 vs. 1.1±0.5, p=0.01). Over a mean follow-up of 6.5±4.2 years, 15 over 139 patients (11%) experienced the primary outcome with an incidence rate of 1.7 per 100 patient-years (95% confidence interval (CI), 1.04–2.85). Higher VAC values were significantly associated with an increased risk of the primary outcome (p for trend = 0.01, Figure 1). VAC was the only functional parameter associated with the primary outcome (hazard ratio (HR) 1.99, 95% CI: 1.06–3.73, p=0.031), secondary outcome (HR 2.33, 95% CI: 1.12–4.82, p=0.023) and tertiary outcome (HR 1.63, 95% CI: 1.09–2.44, p=0.018) in the adjusted analysis (Table 1). Ejection fraction (EF) was not associated with the study outcomes in the adjusted analysis (p>0.05, Table 1) whereas global circumferential and radial strain showed an association limited to the tertiary endpoint (p=0.004, Table 1). Conclusions CMR-derived VAC is associated with adverse outcomes in SRV patients and may improve risk stratification of this unique population. Funding Acknowledgement Type of funding sources: None.

A new way to explore ventricular-arterial coupling in young patients with untreated hypertension

Abstract Introduction Commonly assessed as arterial elastance (Ea) to ventricular end-systolic elastance (Ees) ratio, ventricular-arterial coupling (VAC) has independent prognostic value in hypertension. Aim To investigate whether new coupling indices may be able to identify left ventricular (LV) performance changes induced by blood pressure (BP) overload earlier than conventional ones. Materials and methods 50 young individuals were prospectively enrolled: 25 (40±8 years) newly diagnosed untreated hypertensives and 25 controls (38±9 yrs). All underwent at the same time carotid-femoral pulse wave velocity (PWV) measurement through a tonometer and an echocardiogram to calculate global longitudinal strain (GLS) and myocardial work efficiency (GWE). Two new indices of VAC were derived: PWV/GLS, previously validated and PWV/GWE, still unknown. Results ESV/SV ratio was lower in hypertensive (0.48±0.17) than in controls (0.57±0.14) but without any significant difference (p=0.18), whereas PWV/GLS was significantly lower in hypertensives than in controls (−0.45±0.19 vs −0.35±0.09 m/sec%; p=0.02). PWV/GLS ratio correlated with Ea/Ees (r=0.52; p<0.01), diastolic dysfunction degree (r=−0.59; p<0.001), age (r=−0.64; p<0.001), systolic BP (r=−0.41; p=0.002), diastolic BP (r=−0.39; p=0.005) and mean arterial pressure (MAP) (r=−0.40; p=0.004). PWV/GWE was higher in hypertensives than in controls (0.10±0.02 vs 0.08±0.01 m/sec%; p=0.001) and it was associated with Ea/Ees (r=−0.55; p=0.006), age (r=0.59; p<0.001), diastolic dysfunction degree (r=0.55; p<0.001), systolic BP (r=0.8; p<0.001), diastolic BP (r=0.5; p<0.001) and MAP (r=0.52; p<0.001). Conclusions Innovative indices of ventricular-arterial coupling could be more sensitive for investigating the impact of hypertension on LV performance. Funding Acknowledgement Type of funding sources: Public hospital(s). Main funding source(s): G. Martino University Hospital, Department of Clinical and Experimental Medicine - Cardiology Unit, University of Messina, Messina, Italy

The choice of echocardiographic parameters for determining the hemodynamics phenotype in children after Fontan procedure

Aim. Evaluation of echocardiographic parameters to characterize the hemodynamics phenotype in children after Fontan procedure.Methods. 30 children aged 8.06 ± 4.3 years, body surface area 0.95 ± 0.33 m2, 12 boys (40%) with a functionally single ventricle after total cavopulmonary connection with extracardiac conduit fenestration. In addition to traditional echocardiographic parameters we assessed: systemic ventricular preload (stroke volume index, SVI), ventricular afterload (arterial elastance), arterial compliance, end–systolic ventricular elastance (VE), ventricular–arterial coupling (VAC), transpulmonary gradient (TPG).Results. In 33.3% (n = 10) children, the parameters of the single ventricle function were comparable to the normative values in biventricular hemodynamics. In 3 (10%) patients decreased values of the single ventricle systolic function were found (ejection fraction 40.0 ± 3.5%, fraction area changes 44.6 ± 3.5%, longitudinal strain −4.03 ± 0.87%), preload (SVI 13.30 ± 0.64 ml/m2), arterial compliance, (0.47 ± 0.17 ml/mm Hg), increased VAC (1.81 ± 0.10). In 36.6% of children (n = 11), a decrease in preload was found (SVI 27.4 ± 1.2 ml/m2), an increase in ventricular-arterial coupling (2.17 ± 0.16), and a decrease VE (1.98 ± 0.45 mm Hg/ml), an increase E/e´ (13.2 ± 1.7). In 20% of cases (n = 6) an increase in TPG was determined (11.6 ± 0.9 mm Hg).Conclusion. In children after Fontan procedure, 4 hemodynamic phenotypes were revealed in accordance with echocardiographic parameters: compensated, hypocontractile, with impaired diastolic properties of the systemic ventricle and with increased pulmonary vascular resistance. With a hypocontractile phenotype of hemodynamics, a significantly increased concentration of the pro-brain natriuretic peptide is determined. The phenotype of hemodynamics with increased pulmonary vascular resistance is more often associated with a higher functional class of heart failure. Received 10 September 2021. Revised 4 October 2022. Accepted 14 December 2022. Funding: The study did not have sponsorship. Conflict of interest: Authors declare no conflict of interest. Contribution of the authors: The authors contributed equally to this article.

Cardiac and Vascular Remodeling After 6 Months of Therapy With Sacubitril/Valsartan: Mechanistic Insights From Advanced Echocardiographic Analysis.

BackgroundEffects of Sacubitril/Valsartan (S/V) on left ventricular (LV) mechanics and ventricular-arterial coupling in patients with heart failure with reduced ejection fraction (HFrEF) are not completely understood. The aim of this study was to evaluate both cardiac and vascular remodeling in a group of HFrEF patients undergoing S/V therapy.MethodsFifty HFrEF patients eligible to start a therapy with S/V were enrolled. Echocardiographic evaluation was performed at baseline and after 6 months of follow-up (FU). Beside standard evaluation, including global longitudinal strain (GLS), estimated hemodynamic forces (HDFs) and non-invasive pressure-volume curves (PV loop) were assessed using dedicated softwares. HDFs were evaluated over the entire cardiac cycle, in systole and diastole, both in apex to base (A-B) and latero-septal (L-S) directions. The distribution of LV HDFs was evaluated by L-S over A-B HDFs ratio (L-S/A-B HDFs ratio). Parameters derived from estimated PV loop curves were left ventricular end-systolic elastance (Ees), arterial elastance (Ea), and ventricular-arterial coupling (VAC).ResultsAt 6 months of FU indexed left ventricular end-diastolic and end-systolic volumes decreased (EDVi: 101 ± 28 mL vs. 86 ± 30 mL, p < 0.001; ESVi: 72 ± 23 mL vs. 55 ± 24 mL, p < 0.001), ejection fraction and GLS significantly improved (EF: 29 ± 6% vs. 37 ± 7%, p < 0.001; GLS: −9 ± 3% vs. −13 ± 4%, p < 0.001). A reduction of Ea (2.11 ± 0.91 mmHg/mL vs. 1.72 ± 0.44 mmHg/mL, p = 0.008) and an improvement of Ees (1.01 ± 0.37 mmHg/mL vs. 1.35 ± 0.6 mmHg/mL, p < 0.001) and VAC (2.3 ± 1.1 vs. 1.5 ± 0.7, p < 0.001) were observed. Re-alignment of HDFs occurred, with a reduction of diastolic L-S/A-B HDFs ratio [23 (20–35)% vs. 20 (11–28) %, p < 0.001].ConclusionS/V therapy leads to a complex phenomenon of reverse remodeling involving increased myocardial contractility, HDFs distribution improvement, and afterload reduction.

Prediction of Adverse Post-Infarction Left Ventricular Remodeling Using a Multivariate Regression Model.

Background. In order to provide personalized medicine and improve cardiovascular outcomes, a method for predicting adverse left ventricular remodeling (ALVR) after ST-segment elevation myocardial infarction (STEMI) is needed. Methods. A total of 125 STEMI patients, mean age 51.2 (95% CI 49.6; 52.7) years were prospectively enrolled. The clinical, laboratory, and instrumental examinations were performed between the 7th and 9th day, and after 24 and 48 weeks, including plasma analysis of brain natriuretic peptide (BNP), transthoracic echocardiography, analysis of left ventricular-arterial coupling, applanation tonometry, ultrasound examination of the common carotid arteries with RF signal amplification. Results. Patients were divided into 2 groups according to echocardiography: “ALVR” (n = 63)—end-diastolic volume index (EDVI) >20% and/or end-systolic volume index (ESVI) >15% after 24 weeks compared with initial values; “non-ALVR” (n = 62)—EDVI <20% and ESVI <15%. In the ALVR group, hard endpoints (recurrent myocardial infarction, unstable angina, hospitalization for decompensated heart failure, ventricular arrhythmias, cardiac surgery, cardiovascular death) were detected in 19 people (30%). In the non-ALVR group, hard endpoints were noted in 3 patients (5%). The odds ratio of developing an adverse outcome in ALVR vs. non-ALVR group was 8.5 (95% CI 2.4–30.5) (p = 0.0004). According to the multivariate analysis, the contribution of each of the indicators to the relative risk (RR) of adverse cardiac remodeling: waist circumference, RR = 1.02 (95% CI 1.001–1.05) (p = 0.042), plasma BNP—RR = 1.81 (95% CI 1.05–3.13) (p = 0.033), arterial elastance to left ventricular end-systolic elastance (Ea/Ees)—RR = 1.96 (95% CI 1.11–3.46) (p = 0.020). Conclusion. Determining ALVR status in early stages of the disease can accurately predict and stratify the risk of adverse outcomes in STEMI patients.

Corrigendum to 'The role of ventricular-arterial coupling in cardiac disease and heart failure: assessment, clinical implications and therapeutic interventions. A consensus document of the European Society of Cardiology Working Group on Aorta & Peripheral Vascular Diseases, European Association of Cardiovascular Imaging, and Heart Failure Association' [Eur J Heart Fail 2019;21:402-424

Under the section ‘Methods to assess ventricular–arterial coupling’ on page 405 of the original version of this manuscript, there is a missing parenthesis in the mathematic formula for non-invasive single-beat determination of left ventricular end-systolic elastance, as proposed by Chen. Thus, ‘End (est) = 0.0275 − 0.165 × EF + 0.3656 × (DBP/SBP × 0.9) + 0.515 × End (avg)’ has been corrected to ‘End (est) = 0.0275 − 0.165 × EF + 0.3656 × [DBP/(SBP × 0.9)] + 0.515 × End (avg)’. Furthermore, on page 406 under the same section, there is a typographic error in the formula ‘Ea/Ees = ESV/SV = 1/ (EF − 1)’. Therefore, ‘Ea/Ees = ESV/SV, which equals to 1/ (EF − 1)’ has been corrected to ‘Ea/Ees = ESV/SV, which equals to (1/EF) − 1’.

Optimizing left ventricular-arterial coupling during the initial resuscitation in septic shock \u2013 a pilot prospective randomized study

BackgroundLeft ventricular-arterial coupling (VAC), defined as the ratio of effective arterial elastance (Ea) to left ventricular end-systolic elastance (Ees), has been extensively described as a key determinant of cardiovascular work efficacy. Previous studies indicated that left ventricular-arterial uncoupling was associated with worse tissue perfusion and increased mortality in shock patients. Therefore, this study aims to investigate whether a resuscitation algorithm based on optimizing left VAC during the initial resuscitation can improve prognosis in patients with septic shock.MethodsThis pilot study was conducted in an intensive care unit (ICU) of a tertiary teaching hospital in China. A total of 83 septic shock patients with left ventricular-arterial uncoupling (i.e., the Ea/Ees ratio ≥ 1.36) were randomly assigned to receive usual care (usual care group, n = 42) or an algorithm-based resuscitation that attempt to reduce the Ea/Ees ratio to 1 within the first 6 h after randomization (VAC-optimized group, n = 41). The left VAC was evaluated by transthoracic echocardiography every 2 h during the study period. The primary endpoint was 28-days mortality. The secondary endpoints included lactate clearance rate, length of ICU stay, and duration of invasive mechanical ventilation (IMV).ResultsEighty-two patients (98.8%) completed the study and were included in the final analysis. The Ea/Ees ratio was reduced in both groups, and the decrease in Ea/Ees ratio in the VAC-optimized group was significantly greater than that in the usual care group [median (interquartile range), 0.39 (0.26, 0.45) vs. 0.1 (0.06, 0.22); P < 0.001]. Compared with the usual care group, the VAC-optimized group likely exhibited the potential to reduce the 28-days mortality (33% vs. 50%; log-rank hazard ratio = 0.526, 95% confidence interval: 0.268 to 1.033). Moreover, the VAC-optimized group had a higher lactate clearance rate than the usual care group [27.7 (11.9, 45.7) % vs. 18.3 (− 5.7, 32.1) %; P = 0.038]. No significant difference was observed in terms of the length of ICU stay or duration of IMV.ConclusionsDuring the initial resuscitation of septic shock, optimizing left ventricular-arterial coupling was associated with improved lactate clearance, while likely having a beneficial effect on prognosis.Trial registrationChinese Clinical Trial Registry, ChiCTR1900024031. Registered 23 June 2019 - Retrospectively registered.

Ventriculo-arterial coupling in the intensive cardiac care unit: A non-invasive prognostic parameter

AimsThe aim of this study was to investigate the relationship between ventriculo-arterial coupling (VAC) and in-hospital outcomes and to assess the prognostic value of VAC in critically ill patients. Methods and resultsA total of 329 consecutive patients (mean age 66,7 ± 15.5 years, 66.9% male) admitted to the intensive cardiac care unit of the Sandro Pertini Hospital, Rome (Italy) between January 2019 and December 2019, were included in the study. All patients underwent blood pressure measurement and non-invasive, echocardiography-derived estimates of left ventricular end-systolic elastance (Ees), arterial elastance (Ea) and VAC in a single-beat determination using the iElastance© application. In-hospital events related to acute heart failure and hypoperfusion were recorded and need for invasive ventilation, intra-aortic balloon pump, renal replacement therapy and death were considered as composite. Overall, 39 patients (11,8%) experienced in-hospital complications (group C), and 290 (88,2%) did not (group NoC). Ea and VAC were found to be significantly higher in group C than in group NoC, and a trend toward decreased Ees was observed in group C. VAC was a strong and independent predictor of in-hospital clinical outcome both at univariable and multivariable analysis adjusted for comorbidities [OR (95% CI): 1.868 (1.141–3.059); P = 0.013] and hemodynamic parameters [OR (95% CI): 1674 (1018–2755); P = 0.042]. ConclusionVAC might be an additional non-invasive prognosticator of outcome in critically ill patients.

Data-driven clustering supports adaptive remodeling of athlete's hearts: An echocardiographic study from the Taipei Summer Universiade

Sport-specific adaptations of athlete's hearts are still under investigation. This study sought to 1) identify athlete groups with similar characteristics by clustering echocardiographic data; 2) externally validate the data-driven clusters with sport classifications of various dynamic or static loads to support the conventional hypothesis-driven approach in delineating the athlete's heart. Anthropometric, echocardiographic and electrocardiographic assessments were collected during the 2017 Summer Universiade in Taiwan. Besides standard echocardiography and strain measurements, ventricular-arterial coupling (VAC) was assessed by the ratio of effective arterial elastance (Ea) to left ventricular end-systolic elastance (Ees) as calculated by a modified single-beat algorithm. We grouped 598 elite athletes (348 male, age 23±2.5 years, across 24 disciplines) using Mitchell's classification. The hypothesis-driven analysis showed dynamic training-related adaptations in heart rate and morphology, including ventricular size, mass, and stroke volume. In comparison, the unsupervised approach found two clusters for each sex. Male athletes participating in high dynamic-load exercises had larger chambers, supranormal diastolic functions, depressed Ees, lower Ea and preserved optimal VAC implicating the resting status of a reservoir-rich pump, which affirmed sport-specific adaptation. The female athletes could be clustered with more noticeable functional alterations, such as depressed biventricular strain. However, the imbalanced number between clusters impeded the validation of load-related remodeling. Hierarchical clustering could analyze complicated multiparametric interactions among numerous echocardiography-derived phenotypes to discern the adaptive propensity of the athlete's heart. The endorsement or generation of hypotheses by a data-driven approach can be applied to various domains.

Estimation of Left Ventricular End-Systolic Elastance From Brachial Pressure Waveform via Deep Learning.

Determination of left ventricular (LV) end-systolic elastance (E es ) is of utmost importance for assessing the cardiac systolic function and hemodynamical state in humans. Yet, the clinical use of E es is not established due to the invasive nature and high costs of the existing measuring techniques. The objective of this study is to introduce a method to assess cardiac contractility, using as a sole measurement an arterial blood pressure (BP) waveform. Particularly, we aim to provide evidence on the potential in using the morphology of the brachial BP waveform and its time derivative for predicting LV E es via convolution neural networks (CNNs). The requirement of a broad training dataset is addressed by the use of an in silico dataset (n = 3,748) which is generated by a validated one-dimensional mathematical model of the cardiovasculature. We evaluated two CNN configurations: 1) a one-channel CNN (CNN1) with only the raw brachial BP signal as an input, and 2) a two-channel CNN (CNN2) using as inputs both the brachial BP wave and its time derivative. Accurate predictions were yielded using both CNN configurations. For CNN1, Pearson’s correlation coefficient (r) and RMSE were equal to 0.86 and 0.27 mmHg/ml, respectively. The performance was found to be greatly improved for CNN2 (r = 0.97 and RMSE = 0.13 mmHg/ml). Moreover, all absolute errors from CNN2 were found to be less than 0.5 mmHg/ml. Importantly, the brachial BP wave appeared to be a promising source of information for estimating E es . Predictions were found to be in good agreement with the reference E es values over an extensive range of LV contractility values and loading conditions. Therefore, the proposed methodology could be easily transferred to the bedside and potentially facilitate the clinical use of E es for monitoring the contractile state of the heart in the real-life setting.

Physiologic cardiovascular studies in resuscitated normotensive septic shock with persistent hyperlactatemia.

Background: To study effects of increasing vasopressor dosage and fluid resuscitation on ventriculoarterial (VA) coupling and venous return (VR)-related parameters in resuscitated normotensive septic shock patients with persistent hyperlactatemia. Methods: We performed a prospective experimental study in patients with septic shock who was admitted to medical intensive care unit and still had hyperlactatemia even received initial resuscitation to maintain mean arterial pressure (MAP) &gt;65 mmHg. All patients received incremental dose of norepinephrine (NE) to increased MAP, then NE was titrated to baseline dosage and waited for 15 mins, then fluid bolus was given. VA coupling-related parameters [arterial elastance (Ea), left ventricular end-systolic elastance (Ees), left ventricular stroke work (SW), potential energy (PE), stroke volume (SV), and Ea/Ees], and VR-related parameters [central venous pressure (CVP), mean systemic pressure analogue (Pmsa), venous return pressure (Pvr)] were measured at 4 time points including pre-increased NE phase, post-increased NE phase, pre-fluid bolus phase, and post-fluid bolus phase. Primary outcome was average of Ea/Ees. Secondary outcomes were differences in VA coupling-related parameters and VR-related parameters between pre- vs. post- interventions. Results: All 20 patients were normotensive [MAP 74 (66-80) mmHg] with elevated blood lactate [2.7 (2.4-3.6) mmol/L] at enrollment. Average Ea/Ees was 0.89 (0.61-1.16). Compared to pre-increased NE phase, post-increased NE phase had significantly higher MAP, CVP, SV, SW, PE, Pmsa, and Pvr. Likewise, compared to pre-fluid bolus phase, post-fluid bolus raised MAP, CVP, SV, Ees, SW, Pmsa, and Pvr significantly. No difference in Ea/Ees compared between before- vs. after- received both interventions. Conclusions: In resuscitated normotensive septic shock patients with persistent hyperlactatemia, we found an average Ea/Ees of 0.89. Increasing NE dosage or fluid bolus increased most of VA coupling-related parameters and VR-related parameters, but not Ea/Ees. Further large study is warranted to validate these findings.

Sensitivity Analysis of Single Beat Left Ventricular Elastance Estimation by Chen Method.

Left ventricular (LV) end-systolic elastance (Ees) can be estimated using single-beat (Ees(sb)) Chen method, employing systolic and diastolic arm-cuff pressures, stroke volume (SV), ejection fraction and estimated normalized ventricular elastance at arterial end-diastole. This work aims to conduct a sensitivity analysis of Chen formula to verify its reliability and applicability in clinical scenario. Starting from a baseline condition, we evaluated the sensitivity of Ees(sb) to the parameters contained in the formula. Moreover, a mathematical model of the cardiovascular system was used to evaluate the sensitivity of Ees(sb) to end-diastolic LV elastance (Eed), Ees, arterial systemic resistance (Ras) and heart rate (HR). In accordance with Ees definition, Ees(sb) increases by increasing aortic pressure and pre-ejection time, reaching the highest value for a pre-ejection time = 40 ms, and then decreases. In contrast with Ees definition, Ees(sb) increases (from 3.21 mmHg/mL to 12.15 mmHg/mL) by increasing the LV end-systolic volume and decreases by increasing the SV. In the majority of the analysis with the mathematical model, Ees was underestimated using the Chen method: by increasing Ees (from 0.5 to 2.5 mmHg/mL), Ees(sb) passes only from 0.56 to 1.54 mmHg/mL. Ees(sb) increases for higher Eed (from 1.03 to 2.33 mmHg/mL). Finally, Ees(sb) decreases (increases) for HR < 50 bpm (< 50 bpm), and for Ras < 1100 mmHg/gcm4 (> 1100 mmHg/gcm4). Unexpectedly Ees(sb) increases for higher LV end-systolic volume and decreases for higher SV. These results contrast with Ees definition, which is the ratio between the LV end-systolic pressure and the LV end-systolic volume. Moreover, Ees(sb) is influenced by cardiocirculatory parameters such as LV Eed, HR, Ras, ejection time, and pre-ejection time. Finally, Ees(sb) computed with the model output often underestimates model Ees.

AI-Based Estimation of End-Systolic Elastance From Arm-Pressure and Systolic Time Intervals.

Left ventricular end-systolic elastance (Ees) is a major determinant of cardiac systolic function and ventricular-arterial interaction. Previous methods for the Ees estimation require the use of the echocardiographic ejection fraction (EF). However, given that EF expresses the stroke volume as a fraction of end-diastolic volume (EDV), accurate interpretation of EF is attainable only with the additional measurement of EDV. Hence, there is still need for a simple, reliable, noninvasive method to estimate Ees. This study proposes a novel artificial intelligence—based approach to estimate Ees using the information embedded in clinically relevant systolic time intervals, namely the pre-ejection period (PEP) and ejection time (ET). We developed a training/testing scheme using virtual subjects (n = 4,645) from a previously validated in-silico model. Extreme Gradient Boosting regressor was employed to model Ees using as inputs arm cuff pressure, PEP, and ET. Results showed that Ees can be predicted with high accuracy achieving a normalized RMSE equal to 9.15% (r = 0.92) for a wide range of Ees values from 1.2 to 4.5 mmHg/ml. The proposed model was found to be less sensitive to measurement errors (±10–30% of the actual value) in blood pressure, presenting low test errors for the different levels of noise (RMSE did not exceed 0.32 mmHg/ml). In contrast, a high sensitivity was reported for measurements errors in the systolic timing features. It was demonstrated that Ees can be reliably estimated from the traditional arm-pressure and echocardiographic PEP and ET. This approach constitutes a step towards the development of an easy and clinically applicable method for assessing left ventricular systolic function.

Pralidoxime improves the hemodynamics and survival of rats with peritonitis-induced sepsis

Several studies have suggested that sympathetic overstimulation causes deleterious effects in septic shock. A previous study suggested that pralidoxime exerted a pressor effect through a mechanism unrelated to the sympathetic nervous system; this effect was buffered by the vasodepressor action of pralidoxime mediated through sympathoinhibition. In this study, we explored the effects of pralidoxime on hemodynamics and survival in rats with peritonitis-induced sepsis. This study consisted of two sub-studies: survival and hemodynamic studies. In the survival study, 66 rats, which survived for 10 hours after cecal ligation and puncture (CLP), randomly received saline placebo, pralidoxime, or norepinephrine treatment and were monitored for up to 24 hours. In the hemodynamic study, 44 rats were randomly assigned to sham, CLP-saline placebo, CLP-pralidoxime, or CLP-norepinephrine groups, and hemodynamic measurements were performed using a conductance catheter placed in the left ventricle. In the survival study, 6 (27.2%), 15 (68.1%), and 5 (22.7%) animals survived the entire 24-hour monitoring period in the saline, pralidoxime, and norepinephrine groups, respectively (log-rank test P = 0.006). In the hemodynamic study, pralidoxime but not norepinephrine increased end-diastolic volume (P <0.001), stroke volume (P = 0.002), cardiac output (P = 0.003), mean arterial pressure (P = 0.041), and stroke work (P <0.001). The pressor effect of norepinephrine was short-lived, such that by 60 minutes after the initiation of norepinephrine infusion, it no longer had any significant effect on mean arterial pressure. In addition, norepinephrine significantly increased heart rate (P <0.001) and the ratio of arterial elastance to ventricular end-systolic elastance (P = 0.010), but pralidoxime did not. In conclusion, pralidoxime improved the hemodynamics and 24-hour survival rate in rats with peritonitis-induced sepsis, but norepinephrine did not.

Left ventricular-arterial coupling as a predictor of stroke volume response to norepinephrine in septic shock \u2013 a prospective cohort study

BackgroundLeft ventricular-arterial coupling (VAC), defined as the ratio of arterial elastance (Ea) to left ventricular end-systolic elastance (Ees), is a key determinant of cardiovascular performance. This study aims to evaluate whether left VAC can predict stroke volume (SV) response to norepinephrine (NE) in septic shock patients.MethodsThis was a prospective cohort study conducted in an intensive care unit of a tertiary teaching hospital in China. We recruited septic shock patients who had persistent hypotension despite fluid resuscitation and required NE to maintain mean arterial pressure (MAP) > 65 mmHg. Those patients in whom the target MAP was not reached after NE infusion were ineligible. Echocardiographic variables were measured before (baseline) and after NE infusion. SV responder was defined by a ≥ 15% increase in SV after NE infusion.ResultsOf 34 septic shock patients included, 19 (56%) were SV responders. Before NE infusion, SV responders had a lower Ees (1.13 ± 0.24 mmHg/mL versus 1.50 ± 0.46 mmHg/mL, P = 0.005) and a higher Ea/Ees ratio (1.47 ± 0.40 versus 1.02 ± 0.30, P = 0.001) than non-responders, and Ea in SV responders was comparable to that in non-responders (1.62 ± 0.36 mmHg/mL versus 1.43 ± 0.28 mmHg/mL, P = 0.092). NE significantly increased Ea and Ees in both groups. The Ea/Ees ratio was normalized by NE administration in SV responders but unchanged in non-responders. The baseline Ea/Ees ratio was positively correlated with NE-induced SV increases (r = 0.688, P < 0.001). Logistic regression analysis indicated that the baseline Ea/Ees ratio was a predictor of SV increases induced by NE (odd ratio 0.008, 95% confidence interval (CI): 0.000 to 0.293), with an area under the receiver operating characteristic curve of 0.816 (95% CI: 0.646 to 0.927).ConclusionsThe left VAC has the ability to predict SV response to NE infusion in septic shock patients.Trial registrationChinese Clinical Trial Registry, ChiCTR1900024031, Registered 23 June 2019 - Retrospectively registered, http://www.chictr.org.cn/edit.aspx?pid=40359&htm=4.

Echocardiographic estimation of left ventricular-arterial coupling in dogs with myxomatous mitral valve disease.

BackgroundThe effective arterial elastance (Ea) to left ventricular (LV) end‐systolic elastance (Ees) ratio (Ea/Ees) is an index of the interaction between LV and systemic arterial systems, left ventricular‐arterial coupling (VAC). The Ea is an index of total arterial load of the LV, whereas Ees is an index of LV systolic function. In humans, inappropriate VAC based on increased Ea/Ees estimated using echocardiography is associated with more advanced heart disease severity.HypothesisLeft ventricular‐arterial coupling assessed by echocardiographic estimation of Ea/Ees is associated with disease severity in dogs with myxomatous mitral valve disease (MMVD).AnimalsNinety MMVD dogs and 61 healthy dogs.MethodsProspective cross‐sectional study. The MMVD dogs were classified into stages B1, B2, or C according to American College of Veterinary Internal Medicine guidelines. Effective arterial elastance was echocardiographically estimated using the formula: mean blood pressure/(forward stroke volume/body weight). End‐systolic elastance was echocardiographically estimated using the formula: mean blood pressure/(LV end‐systolic volume/body weight). The ratio Ea/Ees was calculated.ResultsThe ratio Ea/Ees was higher in stage B2 dogs than in healthy dogs and dogs stage B1 (both P < .0001), and higher in stage C dogs than in healthy dogs and dogs in the other 2 stages (healthy vs C and B1 vs C, P < .0001; B2 vs C, P = .0005). Multivariable logistic regression analysis showed that Ea/Ees and the peak velocity of early diastolic transmitral flow to isovolumic relaxation time ratio were independent predictors of stage C among echocardiographic indices in MMVD dogs.Conclusions and Clinical ImportanceInappropriate VAC assessed by echocardiographically estimated Ea/Ees is associated with advanced disease severity in dogs with MMVD.

Maternal hemodynamics, arterial stiffness and elastic aortic properties in twin pregnancy

Objective: There is scant information about maternal cardiovascular hemodynamic change during twin pregnancies. Aim of the study is to investigate longitudinal changes in maternal arterial stiffness, elastic aortic properties and ventricular-arterial coupling (VAC) in uncomplicated twin pregnancies compared to singleton ones. Approach: In this prospective longitudinal study, we performed applanation tonometry and transthoracic echocardiography in the first (T1; 10–15 weeks’ gestation (w)), second (T2; 19–26 w) and third trimesters (T3; 30–38 w) in women with uncomplicated twin pregnancies, both monochorionic and dichorionic. Heart-rate-corrected augmentation index (AIx@75) was studied as indicator of arterial stiffness. Aortic diameters and elastic properties were calculated. VAC was defined as the ratio between aortic elastance (Ea) and left ventricular end-systolic elastance (Ees). Finally, stroke volume (SV), cardiac output (CO) and total vascular resistance (TVR) were evaluated. The findings were compared to those of women with uncomplicated singleton pregnancies. Main results: Thirty women with twin gestations (11 monochorionic) and 30 singleton controls were obtained for analysis. Blood pressure and TVR significantly decreased from T1 to T2 and then rose in T3, with higher values in twins than in singletons. AIx@75 showed the same trend in both groups with lower values at T2 in twins. SV and CO linearly increased throughout gestation with no significant intergroup difference. Aortic diameters and elastic properties remained stable throughout gestation, with no significant intergroup differences. Both Ea and Ees were greater (i.e. worse) in twins than in singletons at T1 and T3, showing a significant linear trend towards reduction in the two groups, meaning lower vascular and ventricular loads. Using longitudinal analysis blood pressure, TVR, Ea and Ees depended from both multiple gestation and gestational age. Significance: In twins, maternal hemodynamics does not seem to undergo more significant changes than in singletons being characterized by higher blood pressures and TVR with no differences in CO, SV, aortic dimensions and elastic properties. Despite VAC is maintained within its normal range, total vascular load (i.e., Ea) resulted higher in twin than singleton pregnancies throughout gestation. It is conceivable that these findings may represent one of the underlying cause for the increased risk of adverse obstetric outcomes described in multiple gestations.

Single-Beat Measurement of Left Ventricular Contractility in Normothermic Ex Situ Perfused Porcine Hearts.

For heart transplantation, donor heart status needs to be evaluated during normothermic ex situ perfusion (ESHP). Left ventricular end-systolic elastance (E es) measures the left ventricular contractile function, but its estimation requires the occlusion of the left atrium line in the ESHP, which may cause unnecessary damage to the donor heart. We present a novel method to quantify E es based on hemodynamic parameters obtained from only one steady-state PV loop in ESHP. E es was obtained by the end-systolic point (P es, V es) and the volume axis intercept point of E es (V 0). V 0 was estimated through the support vector machine regression (SVR) method using parameters derived from the measured steady-state PV loop. To achieve high V 0 estimation accuracy, a filter-based support vector machine recursive feature elimination method (SVM-RFE) algorithm selected the parameters for V 0 estimation. Hemodynamic parameter samples (n = 101) obtained from ESHP experiments with pig's hearts were used to train the E es calculation model. Early post-transplantation outcomes in six heart transplantation experiments were then estimated from the trained E es calculation model. E es calculated by the proposed method agreed well with conventional multi-beat estimates obtained by the occlusion process (r = 0.88, p <0.001, n = 101) and was capable of predicting the early post-transplant cardiac index (r = 0.84, p <0.05, n = 6). This method effectively assesses left ventricular contractility during ESHP and predicts early post-transplant outcomes in the porcine model. Our approach is the first to quantify E es by estimating V 0 from steady-state beats in ESHP for accurately predicting early post-transplantation outcomes.

Abstract 16138: Validation of a Non-invasive Approach for the Assessment of Left Ventricular-arterial Coupling Following Transcatheter Aortic Valve Replacement

Introduction: Transcatheter aortic valve replacement (TAVR) is an established treatment for patients with severe, symptomatic aortic stenosis (AS). Ventriculoarterial (LV-arterial) coupling defined as the ratio of total arterial elastance (Ea) to left ventricular end-systolic elastance (Ees) reflects effective cardiac energetics and is a well-accepted index for quantification of LV-arterial coupling. Despite its usefulness, estimating Ees/Ea has technical difficulties. Intrinsic Frequency (IF) method is a noninvasive and single waveform system-based approach for quantification of LV-arterial coupling. The objective of this study was to compare IF variables with Ea/Ees in predicting optimum LV-arterial energetics following TAVR. Method: Twenty-eight patients with severe AS, undergoing TAVR were included. Mean age was 85±4, 53% male with mean ejection fraction 59±6.4. IFs during systole (ω1), diastole (ω2), and total IF variation (Δω=ω1-ω2) were computed from the ascending aortic pressure waveforms at baseline and following TAVR. Ea/Ees was computed using single-beat technique proposed by Takeuchi et al. ( Circulation . 1991;83(1):202-212). Results: There was a significant decrease in Ea/Ees (p&lt;0.001) toward optimum coupling immediately after TAVR (Figure 1a). There was a statistically significant correlation between Ea/Ees and Δω (r= 0.68, p&lt;0.01) (Figure 1b). Conclusion: IF appears to be an accurate and reliable index for quantification of LV-arterial coupling given significant concordance with Ea/Ees. The management of patients with acutely altered hemodynamic states post TAVR can benefit from the assessment of LV-arterial coupling. Since IFs can be measured noninvasively using hand-held devices (e.g. an iPhone), this approach should broaden the clinical applicability of this useful parameter for assessing systolic function, therapeutic response and ventricular-arterial interaction post TAVR.