Estimation Of Left Ventricular Pressure Research Articles

Diagnostic performance of the non-invasive myocardial work indices in predicting subclinical myocardial work impairment in Fontan patients

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): public hospital sources. Background The Fontan procedure is an operation that has allowed many paediatric patients suffering from severe congenital heart disease to reach adulthood. More and more frequently we come to interface with the consequences of Fontan's circulation, such as cardiac function and exercise capacity deterioration. Recently the new non-invasive method for calculating myocardial work (MW) based on spackle tracking analysis with the estimation of left ventricular pressure and the measurement of non-invasive blood pressure has been introduced. Purpose Aim of this study was to evaluate the diagnostic performance of the non-invasive myocardial work indices in predicting subclinical myocardial work impairment in patients with Fontan circulation. Methods A total of 69 patients were included and compared with healthy age- and sex- matched controls (CTRL). Ventricular systolic function and global longitudinal strain (GLS) were assessed. Cardiopulmonary exercise test was performed. Global myocardial work index (MWI) was calculated as the area of the LV pressure strain loops. From MWI, global Constructive Work (MCW), Wasted Work (MWW) and Work Efficiency (MWE) were estimated. Results The two groups were comparable for blood pressure, weight end height. Mean age of Fontan patients was 21.0±9.2 years. MWI (1162 ± 364 mmHg% vs 1777 ± 240 mmHg%, p < 0.001), MCW (1554 ± 450 mmHg% vs 2102 ± 221 mmHg%, p = 0.001) and MWE (90 ± 6% vs 96 ± 2% p = 0.001) were significantly reduced in Fontan patients compared with healthy CTRL. Moreover, GLS (−13,9± 3,1 % vs −21,2 ± 1.5%, p < 0.001) and the ejection fraction (EF) (58,9 ± 4.5% vs 63.3 ± 3.9%, p < 0.002) were significantly lower in Fontan patients. Fontan patients with normal EF showed, however, significantly reduced values of MWI compared with CTRL (p<0.05). Fontan patients with functional right ventricle showed significantly reduced MWE compared with patients with functional left ventricle (p = 0.030).In univariate analysis, peak VO2 was significantly associated with age, SatO2, MWI. In multivariate regression, lower peak VO2 was associated with older age (p = 0.003) and lower MWI (p = 0.026). Conclusions Fontan's physiology is associated with impaired ventricular work. Estimation of myocardial work indices may be a more sensitive indicator of impaired myocardial work compared with ejection fraction and is able to predict exercise capacity.

A noninvasive method of estimating patient-specific left ventricular pressure waveform

Background and objectiveThe left ventricular pressure waveform is indispensable for the construction of the pressure strain loop when investigating coronary artery disease (CAD) patients. In previous studies by others, exclusion of CAD patients has not allowed a reliable estimation of the left ventricular pressure waveform from the pressure strain loop of these patients. To remedy this, we propose a patient-specific noninvasive method for the estimation of left ventricular pressure. MethodsA simplified systemic circulation model consisting primarily of a single fiber model and a 1D simulation of the arterial tree was used. Sensitivity analysis based on the Morris method was performed to select a subset of the important parameters. Following this, the important parameter subset and the set of all the parameters were identified in the model using the pressure waveform of a peripheral artery as input, in a two-step process. In addition, the left ventricular pressure waveform was estimated using the set of all parameters. ResultsReducing the size of the parameter subset significantly decreases the computational cost of parameter optimization in the first step and greatly simplifies the identification of the full parameter set in the second step. Comparison with the reference left ventricular pressure waveform from CAD patients, showed that the proposed method provides a good estimate of the reference left ventricular pressure waveform. The correlation coefficients between the estimated and reference were r = 0.907, r = 0.904 and r = 0.780 for systolic blood pressure, pulse pressure and mean blood pressure, respectively. ConclusionsThis work may provide a convenient surrogate for the estimation of the left ventricular pressure waveform.

Prospective validation of a non-invasive method to estimate myocardial work in aortic stenosis

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): ANR - Maestro project Background Stratification of aortic stenosis patients remains challenging and robust indices are required. Myocardial work assessment is a new afterload independent alternative to evaluate left ventricular function. Although, this method was developed in patients with normal aortic valve. We previously developed an integrated cardiovascular system simulated by a computational model to estimate non-invasively myocardial work in aortic stenosis patients* (figure 1A). In the present study, we tested our model in a prospective population of AS patients. Method and results 9 patients with severe AS (aortic valve area < 1cm2) were included. A complete trans-thoracic echocardiography with a non-invasive blood pressure by brachial artery cuff were realized immediately before a left heart catheterization to have an invasive left ventricular pressure. Myocardial work is then calculated with non-invasive and invasive LV pressure combined to LV strain curves. For constructive and wasted work, root mean squared between invasive and estimated measures were respectively r2 = 0.92 and r2 = 0.94 (figure 1B) Conclusion The proposed model is efficient to estimate non-invasively myocardial work indices in AS-patients. These afterload independent indices could permit in future to better stratify this population. *Owashi KP, Hubert A and al. Model-based estimation of left ventricular pressure and myocardial work in aortic stenosis. PlosOne 2020. Mar 3;15(3):e0229609 Abstract Figure 1

Model-based estimation of left ventricular pressure and myocardial work in aortic stenosis.

This paper proposes a model-based estimation of left ventricular (LV) pressure for the evaluation of constructive and wasted myocardial work of patients with aortic stenosis (AS). A model of the cardiovascular system is proposed, including descriptions of i) cardiac electrical activity, ii) elastance-based cardiac cavities, iii) systemic and pulmonary circulations and iv) heart valves. After a sensitivity analysis of model parameters, an identification strategy was implemented using a Monte-Carlo cross-validation approach. Parameter identification procedure consists in two steps for the estimation of LV pressures: step 1) from invasive, intraventricular measurements and step 2) from non-invasive data. The proposed approach was validated on data obtained from 12 patients with AS. The total relative errors between estimated and measured pressures were on average 11.9% and 12.27% and mean R2 were equal to 0.96 and 0.91, respectively for steps 1 and 2 of parameter identification strategy. Using LV pressures obtained from non-invasive measurements (step 2) and patient-specific simulations, Global Constructive (GCW), Wasted (GWW) myocardial Work and Global Work Efficiency (GWE) parameters were calculated. Correlations between measures and model-based estimations were 0.88, 0.80, 0.91 respectively for GCW, GWW and GWE. The main contributions concern the proposal of the parameter identification procedure, applied on an integrated cardiovascular model, able to reproduce LV pressure specifically to each AS patient, by non-invasive procedures, as well as a new method for the non-invasive estimation of constructive, wasted myocardial work and work efficiency in AS.

Regional myocardial work by cardiac magnetic resonance and non-invasive left ventricular pressure: a feasibility study in left bundle branch block.

Regional myocardial work may be assessed by pressure-strain analysis using a non-invasive estimate of left ventricular pressure (LVP). Strain by speckle tracking echocardiography (STE) is not always accessible due to poor image quality. This study investigated the estimation of regional myocardial work from strain by feature tracking (FT) cardiac magnetic resonance (CMR) and non-invasive LVP. Thirty-seven heart failure patients with reduced ejection fraction, left bundle branch block (LBBB), and no myocardial scar were compared to nine controls without LBBB. Circumferential strain was measured by FT-CMR in a mid-ventricular short-axis cine view, and longitudinal strain by STE. Segmental work was calculated by pressure-strain analysis. Twenty-five patients underwent 18F-fluorodeoxyglucose (FDG) positron emission tomography. Segmental values were reported as percentages of the segment with maximum myocardial FDG uptake. In LBBB patients, net CMR-derived work was 51 ± 537 (mean ± standard deviation) in septum vs. 1978 ± 1084 mmHg·% in the left ventricular (LV) lateral wall (P < 0.001). In controls, however, there was homogeneous work distribution with similar values in septum and the LV lateral wall (non-significant). Reproducibility was good. Segmental CMR-derived work correlated with segmental STE-derived work and with segmental FDG uptake (average r = 0.71 and 0.80, respectively). FT-CMR in combination with non-invasive LVP demonstrated markedly reduced work in septum compared to the LV lateral wall in patients with LBBB. Work distribution correlated with STE-derived work and energy demand as reflected in FDG uptake. These results suggest that FT-CMR in combination with non-invasive LVP is a relevant clinical tool to measure regional myocardial work.

Estimation of left ventricular pressure with the pump as "sensor" in patients with a continuous flow LVAD.

In long-term ventricular support of patients with LVADs, left ventricular pressure (p(lv)) is relevant for indicating the unloading level of the heart. Monitoring of p(lv) over time might give more insight into the increase or decrease in native ventricular function. In this study, we aim to assess dynamic p(lv) noninvasively, using the LVAD as a pressure sensor. Pressure head (dp(lvad)) was estimated from pump flow with a dynamic pump model (1). Estimated dp(lvad) and measured aortic pressure were used to calculate left ventricular pressure. Moreover, parameters dp/dtmax and mean, minimum, and maximum p(lv) were derived.The method was validated with a porcine ex vivo beating heart model by measurements conducted in 4 hearts supported with a Micromed DeBakey VAD and 3 hearts with a Heartmate II VAD. During each measurement, aortic and left ventricular pressure, pump flow, and pressure head were recorded for 30 s with a sampling frequency of 1 kHz. The estimation of left ventricular pressure appeared to be accurate for both pumps. The parameters mean and minimum pressure were estimated with high accuracy. The degree of accuracy of the estimated p(lv) was proportional to the degree of accuracy of the dynamic pump model. We proved that the LVAD model described in this paper can be used as a pressure indicator to determine LV pressure at any time based on noninvasive measurements of pump flow, aortic pressure, and the properties of the outlet graft.

The Effect of Type 2 Diabetes And Low Aerobic Fitness On Diastolic Function

Individuals with type 2 diabetes are at greater risk of developing heart failure as a consequence of diabetic cardiomyopathy. Diabetic cardiomyopathy is characterized by diastolic dysfunction. Despite the prevalence of impaired diastolic filling in type 2 diabetic subjects, evidence implicating hyperglycemia as a specific cause is equivocal. A reduced aerobic capacity could also contribute to the diastolic dysfunction in individuals with type 2 diabetes. PURPOSE To determine whether low aerobic fitness or glycemic control was associated with diastolic dysfunction in a group of type 2 diabetic subjects. METHODS Subjects aged from 40 to 60 years old were divided into three groups: 13 sedentary type 2 diabetic subjects, 15 sedentary nondiabetic subjects and 10 trained nondiabetic athletes. Mitral valve pulsed Doppler and tissue Doppler imaging (TDI), which is relatively preload independent, were used to assess left ventricular diastolic function. RESULTS Peak early mitral inflow velocity (E), peak late mitral inflow velocity (A) and E/A were not different between type 2 diabetic and sedentary control groups, however A was lower in the trained athletes compared to type 2 diabetic and sedentary control groups (p<0.01). As a result, the E/A ratio was higher in athletes (p<0.05). TDI showed that peak early mitral annular velocity (E') and the ratio of E' and peak late mitral annular velocity (E'/A') were lower and E/E', an estimate of left ventricular pressure, was higher in type 2 diabetic compared to the trained athletes and sedentary control subjects. TDI variables were similar among the sedentary controls and athletes. Multiple regression of the type 2 diabetic and sedentary control groups showed that HbA1c, but not VO2max was inversely correlated with E'/A' and positively correlated with E/E'. Moreover, 69% of the type 2 diabetic subjects had impaired diastolic filling patterns vs. 40% of sedentary control subjects. None of the trained athletes had an impaired diastolic filling pattern. CONCLUSIONS This study demonstrates that diastolic filling is impaired in individuals with type 2 diabetes, even when compared with similarly sedentary non-diabetic subjects. The results suggest that the abnormalities of diastolic filling may be associated with the diabetes per se rather than impaired exercise capacity although this requires confirmation in other studies.

Accurate Noninvasive Estimation of Left Ventricular End-Diastolic Pressure: Comparison with Catheterization

We evaluated the accuracy of a new Doppler-based method using the mitral regurgitant velocity at the time of aortic valve opening for the noninvasive estimation of left ventricular end-diastolic pressure. Sixty unselected patients were studied immediately before routine catheterization. Invasive left ventricular end-diastolic pressure was obtained using a fluid-filled pig-tail catheter. Noninvasive estimation of left ventricular pressure at aortic valve opening was taken as systemic diastolic pressure using an automated cuff. Noninvasive left ventricular end-diastolic pressure was calculated as diastolic blood pressure - 4 × (mitral regurgitant velocity at aortic opening) 2 . Those making noninvasive determinations were blinded to catheterization results. An adequate mitral regurgitant Doppler recording was obtained in 24 patients (40%). In patients with a left ventricular end-diastolic pressure greater than 15 mm Hg the yield was 65%. Left ventricular end-diastolic pressures ranged from 4 mm Hg to 30 mm Hg. Bland and Altman analysis revealed no systematic bias and close agreement was found, with individual discrepancies not exceeding 5 mm Hg. (J Am Soc Echocardiogr 1998;11:126–31.)