vascular resistance from pressures exerted on arteries by sustained muscular contraction. Though it is the case that eccentric hypertrophy is largely considered to be a healthy response to increased cardiac demand, it is also associated with risks. For example, in athletes with significantly increased left ventricular weight there is also a corresponding increased risk for conduction abnormalities and sudden cardiac death. Additionally, in pregnant individuals, a subpopulation progress to peripartum cardiomyopathy, characterized by a dilation of the left ventricle and a corresponding deficit in heart function. There are suggestions that this progression is partially determined by underlying metabolic derangement (diabetes) and hypertension which may result in a more maladaptive cardiac response to pregnancy. As such, though it is convenient to consider clear cut distinctions between pathologic and physiologic cardiac hypertrophy, there may be a broader range of phenotypes than may be accounted for by gross cardiac phenotypes alone. The development of pathologic states in LVH is complex. Electrical abnormalities are commonly found in individuals with LVH, both ventricular and super-ventricular tachycardia. Additionally, cytoarchitecture and the extracellular environment of the myocardium are altered, specifically genes typically expressed in the fetal heart are induced, as are collagen and other fibrotic proteins. LVH may interfere with heart functionality in a number of ways. Before progression to a dilated phenotype, mechanical obstruction of the outflow tract can occur, leading to reduced cardiac output. Additionally, increased fibrosis of the ventricle can result in a failure to relax appropriately which impairs cardiac filling and may lead to diastolic dysfunction or heart failure with preserved ejection fraction. Mechanics of cardiac growth As described in the previous section, it is believed that the eccentric hypertrophy is induced by volume-overload and that the concentric hypertrophy is induced by pressure-overload. Biomechanical approaches have been adopted to investigate the progression of cardiac hypertrophy for these two different types. In the framework of continuum mechanics, the volumetric growth is often modeled using a multiplicative decomposition of the deformation gradient into an elastic part and a growth part , where . For the generic orthotropic growth, the growth tensor can be represented as , where and are normally the orthonormal vectors of the microstructure, and is often referred as growth multipliers, which regulates the growth according to certain growth laws. In eccentric growth, cardiomyocyte lengthens in the direction of the cell's long axis, . Therefore, the eccentric growth tensor can be expressed as