Ventricular-arterial coupling (VAC) in a population-based cohort of middle-aged individuals: The STANISLAS cohort

Hemodynamics of ventricular-arterial coupling under enhanced external counterpulsation: An optimized dual-source lumped parameter model

BACKGROUND AND OBJECTIVE

Enhanced external counterpulsation (EECP) is a mechanically assisted circulation technique widely used in the rehabilitation and management of ischemic cardiovascular diseases. It contributes to cardiovascular functions by regulating the afterload of ventricle to improve hemodynamic effects, including increased diastolic blood pressure at aortic root, increased cardiac output and enhanced blood perfusion to multiple organs including coronary circulation. However, the effects of EECP on the coupling of the ventricle and the arterial system, termed ventricular-arterial coupling (VAC), remain elusive. We aimed to investigate the acute effect of EECP on the dynamic interaction between the left ventricle and its afterload of the arterial system from the perspective of ventricular output work.

METHODS

A neural network assisted optimization algorithm was proposed to identify the ordinary differential equation (ODE) relation between aortic root blood pressure and flow rate. Based on the optimized order of ODE, a lumped parameter model (LPM) under EECP was developed taking into consideration of the simultaneous action of cardiac and EECP pressure sources. The ventricular output work, in terms of aortic pressure and flow rate cooperated with the LPM, was used to characterize the VAC of ventricle and its afterload. The VAC subjected to the principle of minimal ventricular output work was validated by solving the Euler-Poisson equation of cost function, ultimately determining the waveforms of aortic pressure and flow rate.

RESULTS

A third-order ODE can precisely describe the hemodynamic relationship between aortic pressure and flow rate. An optimized dual-source LPM with three energy-storage elements has been constructed, showing the potential in probing VAC under EECP. The LPM simulation results demonstrated that the VAC in terms of aortic pressure and flow rate yielded to the minimal ventricular output work under different EECP pressures.

CONCLUSIONS

The ventricular-arterial coupling under EECP is subjected to the minimal ventricular output work, which can serve as a criterion for determining aortic pressure and flow rate. This study provides insight for the understanding of VAC and has the potential in characterizing the performance of the ventricular and arterial system under EECP.

Feasibility and prognostic significance of ventricular-arterial coupling after myocardial infarction: the RIGID-MI cohort

AIMS

The clinical significance and feasibility of the recently described non-invasive parameters exploring ventricular-arterial coupling (VAC) remain uncertain. This study aimed to assess VAC parameters for prognostic stratification in stable patients with left ventricular ejection fraction (LVEF) ≥40% following myocardial infarction (MI).

METHODS AND RESULTS

Between 2018 and 2021, patients with LVEF ≥40% were evaluated 1 month following MI using transthoracic echocardiography (TTE) and arterial tonometry at rest and after a handgrip test. VAC was studied via the ratio between arterial elastance (Ea) and end-systolic LV elastance (Ees) and between pulse wave velocity (PWV) and global longitudinal strain (GLS). Patients were followed for major adverse cardiovascular events (MACE): all-cause death, acute heart failure, stroke, AMI, and urgent cardiovascular hospitalization. Among the 374 patients included, Ea/Ees and PWV/GLS were obtained at rest for 354 (95%) and 253 patients (68%), respectively. Isometric exercise was workable in 335 patients (85%). During a median follow-up of 32 months (interquartile range: 16-42), 41 (11%) MACE occurred. Patients presenting MACE were significantly older and had a higher prevalence of peripheral arterial disease, lower GLS, higher Ea, PWV, and PWV/GLS ratio. The Ea/Ees ratio and standard TTE parameters during isometric exercise were not associated with MACE. After adjustment, the PWV/GLS ratio was the only VAC parameter independently associated with outcome. Receiver operating characteristic curve analysis identified a PWV/GLS ratio >0.70 (Youden's index = 0.37) as the best threshold to identify patients developing MACE: hazard ratio (95% confidence interval) = 2.2 (1.14-4.27), P = 0.02.

CONCLUSION

The PWV/GLS ratio, assessed 1 month after MI, identifies a group of patients at higher risk of MACE providing additional value on top of conventional non-invasive parameters.

Association of aortic stiffness early post myocardial infarction with left ventricular remodelling

BACKGROUND

Adverse left ventricular (LV) remodelling after myocardial infarction is associated with heart failure. We investigated whether aortic stiffness during acute ST-segment elevation myocardial infarction is associated with LV remodelling at long-term follow-up.

METHODS

In 109 patients within 48 h of myocardial infarction post-primary percutaneous coronary intervention and after 2 years, we measured: (a) carotid to femoral pulse wave velocity (PWV), (b) LV global longitudinal strain (GLS) and left atrial strain using speckle-tracking echocardiography, (c) PWV/GLS ratio as a surrogate marker of ventricular-arterial interaction, and (d) LV end-diastolic and end-systolic volumes. A > 15% decrease from the baseline in LV end-systolic volume at 2-year follow-up was considered as a criterion of reverse LV remodelling.

RESULTS

Compared with baseline, all patients had reduced PWV, LV end-diastolic and end-systolic volumes while PWV/GLS, GLS and reservoir left atrial strain were improved (p < .05) after 2 years. Baseline values of PWV, GLS, PWV/GLS ratio and reservoir left atrial strain were associated with percentage change of LV end-systolic volume at 2 years (p < .05). Multivariable analysis revealed that lower baseline values of PWV and a less impaired GLS and PWV/GLS were independently associated with reverse LV remodelling at 2 years with a C-statistic of .748, .711 and .787, respectively.

CONCLUSION

Aortic stiffness early post-infarction determines LV remodelling after 2 years of the ischemic event despite post successful revascularization.

CLINICAL TRIAL REGISTRATION-URL

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CLINICALTRIALS

gov. Unique identifier: NCT03984123, 30/04/2020.