Myocardial hypertrophy contribute to ventricular diastolic dysfunction and can lead to heart failure, arrhythmia and evensudden death. It have been shown that during development of hypertrophy the concentration of the glycosaminoglycanhyaluronan increases. The increased concentration correlates to the increased gene expression of fetal and extracellularmatrix genes that is associated with cardiac remodeling.Moreover it has been shown that high molecular weight hyaluronan depolarize the membrane potential of cells.The increase of hyaluronan in cardiac hypertrophy could hypothetically affect the resting membrane potential incardiomyocytes and thus affect the conduction through the heart.Hypothesis. The role of hyaluronan as a molecule adapting the extracellular matrix when the heart is growing could potentiallydevelop to be harmful to cardiomyocyte resting membrane potential and hence contribute to the risk of arrhythmia.