Impact of hypertension on ventricular-arterial coupling and regional myocardial work at rest and during isometric exercise

Abstract

Background: To understand better the mechanism of left ventricular (LV) remodeling related to hypertension, it is important to evaluate LV function in relation to the changes in loading conditions. The aim of this study was to investigate changes in conventional ventricular-arterial coupling indexes, LV strain, and a new index reflecting regional myocardial work assessed noninvasively at rest and during isometric exercise in a random sample including participants with normal blood pressure and those with hypertension.

Methods: A total of 148 participants (53.4% women; mean age, 52.0 years; 39.2% with hypertension) underwent simultaneous echocardiographic and arterial data acquisition at rest and during increased afterload (handgrip exercise). End-systolic pressure was determined from the carotid pulse wave. Arterial elastance (Ea) and LV elastance (Ees) were calculated as end-systolic pressure/stroke volume and end-systolic pressure/end-systolic volume. Doppler tissue imaging and two-dimensional speckle tracking were used to derive LV longitudinal strain. Regional myocardial work (ejection work density [EWD]) was the area of the pressure-strain loop during ejection.

Results: At rest, with adjustments applied, Ees (3.06 vs 3.71 mm Hg/mL, P = .0003), Ea/Ees (0.54 vs 0.47, P = .002) and EWD (670 vs 802 Pa/m(2), P = .0001) differed significantly between participants with normal blood pressure and those with hypertension. During handgrip exercise, Ea and Ea/Ees significantly increased (P < .0001) in both groups. Doppler tissue imaging and two-dimensional LV strain decreased in participants with hypertension (P ≤ .008). Only in subjects with normal blood pressure EWD significantly increased (+14.7%, P = .0009).

Conclusions: Although patients with hypertension compared with those with normal blood pressure have increased LV systolic stiffness and regional myocardial work to match arterial load at rest, they might have diminished cardiac reserve to increase myocardial performance, as estimated by EWD during isometric exercise.

Copyright © 2012 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.

Figures

Figure 1

From color Doppler myocardial imaging of the LV wall and simultaneously recorded carotid pressure waveforms (A), we derived carotid artery pressure (B) and DTI strain (C) curves to construct the pressure-strain loop (D). Regional myocardial work density during LV ejection phase was calculated (D) (dashed area).

Figure 2

Scatterplots of the changes in LV ESV, SV, and Ea/Ees ratio versus changes in ESP during handgrip exercise in multivariate-adjusted analyses of 148 participants, including 90 subjects with normal BP (squares) and 58 patients with hypertension (circles). The solid and dotted lines represent the regression line and the 95% CI, respectively. The regression slopes were standardized to the means of the distributions of sex, values at rest, and age.

Figure 3

Scatterplots of the changes in DTI and 2D strain versus changes in ESP during handgrip exercise in multivariate-adjusted analyses of 148 participants, including 90 subjects with normal BP (squares) and 58 patients with hypertension (circles). The solid and dotted lines represent the regression line and the 95% CI, respectively. The regression slopes were standardized to the means of the distributions of sex, values at rest, and age.