Abstract

MIGLIORE, Ricardo A. et al. Effect of Effective Arterial Elastance on Left Ventricular Systolic Function in Severe Valvular Aortic Stenosis. Rev. argent. cardiol. [online]. 2008, vol.76, n.4, pp.278-285. ISSN 1850-3748.

Background Left ventricular dysfunction in valvular aortic stenosis (AS) is related to an elevated afterload. This increase may be related to a reduction in aortic valve area (AVA), to changes in ventricular geometry and to the characteristics of the arterial vessels. Effective arterial elastance (E_a) is an index of arterial vascular load which incorporates the characteristic arterial impedance, and arterial resistance and distensibility. Objective To assess the effect of E_a on left ventricular systolic function in severe valvular AS. Material and Methods We prospectively studied 54 patients with severe AS; transvalvular gradient, AVA, valvular resistance and energy loss index were assessed. E_a was estimated as the end-systolic pressure/stroke volume ratio. Carotid blood pressure waveform was calibrated against blood pressure measured by conventional cuff sphygmomanometry to calculate endsystolic pressure. We estimated global afterload by the “valvulo-arterial impedance” (Zva) formulated as follows: (systolic arterial pressure + mean net pressure gradient)/ stroke-volume index. Zva considers the effect of AS and E_a. Patients were divided in three groups: G1, AS with heart failure (NYHA III-IV) (n = 13), G2, symptomatic AS without heart failure (n = 13), and G3, asymptomatic AS (n =28). Results Ejection fraction (EF) (%) was lower in G1 (33±15) compared to G2 (42±16) and to G3 (65±14); p<0.01. E_a (mm Hg/ml) and Zva (mm Hg/ml/m²) were greater in G1 (2.46±0.8 and 6.5±2.2, respectively) than in G2 and G3 (1.83±0.52 and 1.73±0.47; p<0.01, and 4.8±1.0 y 4.7±1.5; p < 0.01, respectively). When univariate analysis was performed, Zva correlated with E_a (r=0.88; p<0.0001) and EF (r=-0.41; p<0.01). In multivariate analysis E_a and Zva were independent predictors for EF. Conclusions In severe AS, the increase of the vascular component of the afterload, assessed by the E_a, contributes to a reduction in systolic function.

Keywords : Aortic Valve Stenosis; Left Ventricular Function; Doppler Echocardiography.

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