Simulation of fibroblast cardiomyocyte interaction: The impact that ventricular fibroblast-rich tissue may have on heart rhythm was studied in a network of over 16,000 ventricular cardiomyocytes. In these simulations a scar model was implemented in the centre of a 128×128 grid of cells by locally connecting myocytes to model fibroblasts. Since cardiac fibroblasts are mechanosensitive, whether they might contribute to stretch-induced depolarizations of adjacent cardiomyocytes was investigated.The size of the fibrotic focus is a critical factor in determining the electrophysiological effect on the surrounding tissue. When the parameters described above are used, fibroblast-rich tissue regions smaller than 27 cells in diameter do not trigger action potentials in neighbouring cardiomyocytes in the model. The only effect of very small scar models is a local, subthreshold depolarization of the tissue, similar to the state illustrated in Figure 2 (top centre). Intermediate sized regions (28 to 31 cells in diameter) are capable of locally triggering action potentials in electrically connected cardiomyocytes. This excitation, however, is confined to the fibroblast-rich tissue region and does not spread throughout the whole ventricular model. Only scars measuring 32 or more cells in diameter induce stretch-evoked ectopics in the entire tissue model.
Another factor that determines the general response of the tissue model is the amplitude of stretch applied. Increasing the stretch-induced conductance by a further 20 nS reduces the minimal size of the damaged region required to trigger generalized excitation by more than 6%, from 32 to 30 cells.Thus, in the model a circular fibroblast-rich focus of 30 to 32 cells in diameter is capable of inducing ectopic excitation of myocardium in a stretch-dependent manner. The underlying mechanism of this response is based purely on interaction of cardiomyocytes with mechanosensitive connective tissue cells. Safe online shopping for drugs: generic cialis mastercard to make your drugs cheaper.