Model of a normal<unk>  (left); and a weakened<unk> , with over-stretched muscle and dilation of left ventricle (right); both during diastole<unk>  is caused by any condition that reduces the efficiency of the<unk>  muscle, through damage or overloading. Over time, these increases in workload, which are mediated by long-term activation of neurohormonal systems such as the renin–angiotensin system, lead to fibrosis, dilation, and structural changes in the shape of the left ventricle from elliptical to spherical. The<unk>  of a person with<unk>  may have a reduced force of contraction due to overloading of the ventricle. In a normal<unk> , increased filling of the ventricle results in increased contraction force by the Frank–Starling law of the<unk> , and thus a rise in cardiac output. In<unk> , this mechanism fails, as the ventricle is loaded with blood to the point where<unk>  muscle contraction becomes less efficient. This is due to reduced ability to cross-link actin and myosin filaments in over-stretched<unk>  muscle.
Heart failure
Anemia
Kidney failure
Obesity
Liver failure
Lung cancer
Thyroid disease
Cirrhosis