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Figure 1 | Stem Cell Research & Therapy

Figure 1

From: Biomechanical regulation of in vitro cardiogenesis for tissue-engineered heart repair

Figure 1

Heart and cardiomyocyte biomechanics. The smallest functional unit of the heart at the micrometer scale is the sarcomere (typically spans 1.5 to 2 μm). Sarcomeres are aligned anisotropically in the cardiomyocytes (typical dimensions: length 110 μm, width 25 μm [18]), which are assembled as continuous muscle sheets. Coordinated contractions of these muscle sheets enable the typical wringing motion or twist of the heart. Each contraction cycle can be displayed as a pressure–volume loop (typically measured by conductance catheterization), comprising phases of iso(volu)metric and isotonic sarcomere contraction (systole) followed by iso(volu)metric and isotonic relaxation (diastole). These phases are shortened or prolonged in case of pathologically increased preload (for example, in case of mitral valve insufficiency) or increased afterload (for example, in case of aortic stenosis); note that in most clinical cases mixed phenotypes are observed. Pressure–volume loops adapted from [29].

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