In this work we study the function and development of the myocardium by creating models that have been stripped down to essentials. The model for the adult myocardium is based on the double helical band formation of the heart muscle fibers, observed in both histological studies and advanced DTMRI images. The muscle fibers in the embryonic myocardium are modeled as a helical band wound around a tubular chamber. We model the myocardium as an elastic body, utilizing the finite element method for the computations. We show that when the spiral band architecture is combined with spatial wave excitations the structure is twisted, thus driving the development of the embryonic heart into an adult heart. The double helical band model of the adult heart allows us to gain insight into the long standing paradox between the modest, by only 15 %, ability of muscle fibers to contract, and the large left ventricular volume ejection fraction of 60 %. We show that the double helical band structure is the essential factor behind such efficiency. Additionally, when the double helical band model is excited following the path of the Purkinje nerve network, physiological twist behavior is reproduced. As an additional validation, we show that when the stripped down double helical band is placed inside a sack of soft collagen-like tissue it is capable of producing physiologically high pressures.
We further develop the model to understand the different factors behind the loss of efficiency in heart with a common pathology such as dilated cardiomyopathy. Using the stripped down model we are able to show that the change to fiber angle is the much more important factor to heart function than the change in gross geometry. This finding has the potential to greatly impact the strategy used in certain surgical procedures.</p
