415 Comparison between two methods for assessing ventricular-arterial coupling: the Chen single-beat method and carotid artery wave intensity

Abstract

Abstract Background Ventricular arterial coupling (VAC) can be defined as the ratio of the arterial elastance (Ea) to the ventricular elastance (Ees). . The Ea/Ees ratio has been consistently demonstrated to be a reliable and effective measure of cardiovascular performance. The Chen single-beat method is the most used non-invasive method for this measurement. Carotid artery wave intensity (WI) is also considered a index of VAC, as the first peak (W1) represents the forward compression wave, reflecting left ventricle (LV) contractile function. However, data about the relationship between the two methods are nowadays scarce. Purpose Aim of the study was to compare carotid WI and Ventricular-Arterial Coupling (VAC) in a population of patient with heart failure. Methods We examined 50 consecutive patients with heart failure (9 females, 41 males, mean age 67 + 12 years, range 29-97 years, 34 ischemic, 16 not ischemic). Carotid artery wave intensity was achieved merging the echo-tracking of the vessel with its doppler signal. Simultaneous not-invasive oscillometric blood pressure was obtained. The VAC was assessed by the ratio between the arterial elastance (Ea) and the end-systolic ventricular elastance (Ees). Ea was calculated from stroke volume (SV) and end-systolic pressure (Ea=(Systolic BP x 0.9)/SV) and Ees was calculated by the modified single-beat Chen method, using an estimated normalized ventricular elastance at arterial end-diastole (ENd) Ees = [Diastolic BP-(ENd(est) x Systolic BP x 0.9)]/(ENd(est) x SV). Three subgroups were created according to the left ventricle ejection fraction values (LVEF ≤ 35%, LVEF >35% <50%, LVEF ≥ 50%, with 26, 14, 10 patients respectively). Results The correlation between Ea/Ees and W1 was significant (Pearson’s correlation r= -0.35, p 0.01). The W1 and VAC values of the three LVEF-sorted subgroups were processed with ANOVA test (p 0.054 and p 0.0002 respectively). W1 values resulted to be, as expected, reduced especially in the group of severe ventricular dysfunction (mean 4,97+- 3,29), as well as the ventricular-arterial coupling was increased (mean 2.04 +- 1.04). Interestingly W1 shows to be correlated with the Left atrial volume index (Pearson’s correlation r= -0,30 p = 0,037). Conclusions Carotid WI technique seems to be a reliable method to estimate the ventricular-arterial interplay. Larger studies are needed to evaluate the respective role of W1 and Ea/Ees in the prognostic evaluation. Results EF ≤ 35 (n = 10) 35 < EF < 50 (n = 14) EF≥ 50 (n = 26) p value W1 4.97 ± 3.29 8.05 ± 3.79 7.85 ± 3.12 0.054 Ea/Ees 2.04 ± 1.04 1.39 ± 0.31 1.16 ± 0.3 0.0002 Abstract 415 Figure.