Left ventricular (LV) function is determined by the complex interactions between tissue anatomy, myocardial contractility, and prevailing hemodynamics. Among the four cardiac chambers the LV is unique in having a double-helical myocardial fiber arrangement. Sub-endocardially, the spiral holds a left-handed helix while a right-handed helix exists in the epicardium. Simultaneous contraction of both helices causes opposite rotation of the LV base and apex, resulting in a twisting motion around the long-axis of the LV. When viewed from the LV apex, the apex rotates in an overall counterclockwise direction and the base rotates clockwise. Functionally, LV twist has been suggested to equalize transmural mechanical stress, and contribute to a relatively high ejection fraction despite limited myofiber shortening. The increasing availability of data due to advances in imaging platforms and analysis software has fueled growing interest in the assessment of LV twist mechanics in normal physiology and cardiovascular disease. However, image acquisition, measurement, and presentation of LV twist mechanics data require careful attention to methodology to ensure accuracy and reproducibility. This article provides a contemporary review of LV twist mechanics with specific emphasis on; its assessment and role in the normal CV response to changes in cardiac load, exercise, aging and disease.
- cardiovascular disease
- Copyright © 2016, American Journal of Physiology - Heart and Circulatory Physiology