Alterations in Left Ventricular Torsion and Diastolic Recoil After Myocardial Infarction With and Without Chronic Ischemic Mitral Regurgitation

Abstract

Background-Chronic ischemic mitral regurgitation (CIMR) is associated with heart failure that continues unabated whether the valve is repaired, replaced, or ignored. Altered left ventricular (LV) torsion dynamics, with deleterious effects on transmural gradients of oxygen consumption and diastolic filling, may play a role in the cycle of the failing myocardium. We hypothesized that LV dilatation and perturbations in torsion would be greater in animals in which CIMR developed after inferior myocardial infarction (MI) than in those that it did not. Methods-8Ϯ2 days after marker placement in sheep, 3-dimensional fluoroscopic marker data (baseline) were obtained before creating inferior MI by snare occlusion. After 7Ϯ1 weeks, the animals were restudied (chronic). Inferior MI resulted in CIMR in 11 animals but not in 9 (non-CIMR). End-diastolic septal-lateral and anterior-posterior LV diameters, maximal torsional deformation ( max , rotation of the LV apex with respect to the base), and torsional recoil in early diastole ( 5% , first 5% of filling) for each LV free wall region (anterior, lateral, posterior) were measured.

New Noninvasive Method for Assessment of Left Ventricular Rotation

“…The magnitudes of LV apical and basal rotation and torsion, as reported in previous experimental and clinical studies, differ substantially, [2][3][4][5][6]8,9,[12][13][14][15][16][17][18]20,[22][23][24][25]29,[32][33][34][35][36][37][38][39] and a number of factors may explain this variance. As demonstrated by Henson et al, 22 apparent differences in torsion between mice and humans are due to the different sizes of their ventricles.…”

“…The magnitude and characteristics of this torsional deformation have been described in different clinical and experimental studies, and it is well established that LV rotation is sensitive to changes in both regional and global LV function. [5][6][7][8][9][10][11][12][13][14][15][16][17] Therefore, assessment of LV rotation represents an interesting approach for quantifying LV function. However, so far, magnetic resonance imaging (MRI) tagging has been the only clinically available method, 7,13-16,18 -21 and implementation has therefore been limited by complexity and cost.…”

Reduced Left Ventricular Torsion Early After Myocardial Infarction Is Related to Left Ventricular Remodeling

“…This low-efficiency state would further impair myocardial contractility, possibly representing the initial step of a vicious circle of progressive LV dilatation and decline in LV systolic function. 18,24 …”

Torsion Mechanics as an Indicator of More Advanced Left Ventricular Systolic Dysfunction in Secondary Mitral Regurgitation in Patients with Dilated Cardiomyopathy: A 2D Speckle-Tracking Analysis

“…In the dilated left ventricle, the fiber muscles in both layers are stretched and oriented more circumferentially, which leads to additional reduction in chamber contractility and torsion [2, 3]. In addition to LV dilation, chronic MR would reduce LV twist even more, because of the decrease in lever arm force of the epicardial fibers [4]. Thus, twist and torsion may be a sensitive marker of remodeling of LV wall architecture, useful in the monitoring of disease progression and response to therapy.…”