Regional differences in myocardial work of the left ventricle in patients with idiopathic dilated cardiomyopathy: Implications for the surgical technique used for left ventriculoplasty

Abstract

Objectives: In this study we measured regional myocardial work of the left ventricle in patients with dilated cardiomyopathy and examined the existence of regional differences in myocardial work. Background: Left ventriculoplasty aims to improve the ejection fraction by excluding a region with decreased wall motion and decreasing wall tension. If regional differences in myocardial work are present, left ventriculoplasty will be more effective when a region with decreased myocardial work is excluded. Methods: The study group consisted of 10 patients with idiopathic dilated cardiomyopathy. Regional work of the ventricle normalized to a unit volume of myocardium (RWM) is given as follows: RWM = -∫ σd[1n(1/H)], where σ is mean wall stress, and H is wall thickness of the region. After right-sided catheterization, left ventricular pressure was measured with a 3F micromanometer catheter. Echocardiography was performed simultaneously, and a short-axis view of the left ventricle at the level of the papillary muscles was obtained. The derived M-mode image was recorded with left ventricular pressure, σ - 1n(1/H) relations for the ventricle were delineated, and regional work of the interventricular septum and posteroinferior wall were determined. Relationships between regional work of the myocardium and wall thickness, interventricular septal regional work of the myocardium and right ventricular systolic pressure, and right ventricular ejection fraction were also studied. Results: Interventricular septal regional work ranged from -0.84 to 3.34 mJ/cm3 (0.74 ± 1.51 mJ/cm3). Posteroinferior wall regional work ranged from 1.59 to 4.29 mJ/cm3 (2.77 ± 0.86 mJ/cm3). In the study group, interventricular septal regional work was lower than posteroinferior wall regional work (P < .05). In 8 of these 10 patients, interventricular septal regional work was lower than posteroinferior wall regional work. In the other 2 patients, conversely, interventricular septal regional work was higher than posteroinferior wall regional work. Conclusions: The existence of differences in regional work between the interventricular septum and the posteroinferior wall suggests the importance of the evaluation of regional work in the selection of an effective treatment for dilated cardiomyopathy.