Longitudinally and circumferentially directed movements of the left ventricle studied by cardiovascular magnetic resonan
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RESEARCH
Open Access
Longitudinally and circumferentially directed movements of the left ventricle studied by cardiovascular magnetic resonance phase contrast velocity mapping Ion Codreanu1,2, Matthew D Robson2, Stephen J Golding3, Bernd A Jung4, Kieran Clarke1, Cameron J Holloway1,2*
Abstract Objective: Using high resolution cardiovascular magnetic resonance (CMR), we aimed to detect new details of left ventricular (LV) systolic and diastolic function, to explain the twisting and longitudinal movements of the left ventricle. Methods: Using CMR phase contrast velocity mapping (also called Tissue Phase Mapping) regional wall motion patterns and longitudinally and circumferentially directed movements of the left ventricle were studied using a high temporal resolution technique in healthy male subjects (n = 14, age 23 ± 3 years). Results: Previously undescribed systolic and diastolic motion patterns were obtained for left ventricular segments (based on the AHA segmental) and for basal, mid and apical segments. The summation of segmental motion results in a complex pattern of ventricular twisting and longitudinal motion in the normal human heart which underlies systolic and diastolic function. As viewed from the apex, the entire LV initially rotates in a counterclockwise direction at the beginning of ventricular systole, followed by opposing clockwise rotation of the base and counter-clockwise rotation at the apex, resulting in ventricular torsion. Simultaneously, as the entire LV moves in an apical direction during systole, the base and apex move towards each other, with little net apical displacement. The reverse of these motion patterns occur in diastole. Conclusion: Left ventricular function may be a consequence of the relative orientations and moments of torque of the sub-epicardial relative to the sub-endocardial myocyte layers, with influence from tethering of the heart to adjacent structures and the directional forces associated with blood flow. Understanding the complex mechanics of the left ventricle is vital to enable these techniques to be used for the evaluation of cardiac pathology.
Background Left ventricular (LV) function is geometrically and mechanically complex. Advances in cardiac imaging techniques have accompanied ongoing efforts to define the mechanisms of three dimensional ventricular motion [1-7]. Current theories explaining LV motion are controversial. The “myocardial band model” divides the myocardium into two distinct helicoids [6,7], but fails to explain the mechanisms of myocardial contraction after * Correspondence: [email protected] 1 Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK Full list of author information is available at the end of the article
repolarization and ventricular motion in diastole. Additionally, the embryological development of the heart, and the failure of anatomists to separate “bands” on anatomical dissection, have further challenged this theory [8-12]. Cardiovascular magnetic resonance (CMR) has allowed detailed ev
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