The vascular system strongly influences the condition of the heart. It is also vital in the rest of the body as the blood vessels are in charge of carrying nutrients and the discard of metabolic wastes. Therefore, blood vessel disorder can cause serious complications in the whole body. Coronary arteries are the blood vessels that supply to the heart for its normal function. Blood vessel disorders occur in coronary arteries would affect cardiac activity. For instance, due to atherosclerosis, the plaque would obstruct and causes ischaemia - the reduction of blood flow through the arteries. Ischaemia would then result in the decrease in oxygen supply to the heart, hence weaken the heart. It causes a vicious cycle as a weakened heart contraction would decrease blood supply to the body, including cardiac muscle (muscle of heart). Moreover, if the plaque suddenly ruptures in the heart, it will cause a heart attack. Various factors may affect one's susceptibility to blood vessel disorders, including behavioural (e.g. smoking), demographic (e.g. age) and genetic (family history) factors. Most of these risk factors first promote the increase in blood pressure, followed by other symptoms and signs. The rise of blood pressure is correlated to ageing. The arterial compliance - the amount of tension produced per stretch of arteries, decreases with age, and the stiffness of arteries increases with age. The structural change in blood vessels causes the elderly to be more susceptible to hypertension, which leads to complications in arteries, the heart and even the brain. Having obesity would increase the risk of atherosclerosis. A high-fat and high-cholesterol diet would result in an elevation of lipoprotein level, which is one of the constituents of plaque. Lipoprotein level above > 25–30 mg/dl is considered more susceptible by blood vessel disorders. Some of the blood vessel disorders are inherited. For instance, erythromelalgia is caused by the mutation of the SCN9A gene, which alters the neural pathway to blood vessels. Genetic disorders that affect the circulatory, immune or neural system may contribute to hereditary blood vessel disorder. If one’s family history shows records of vascular disorders, it is more likely to inherit the same disease. Both active or passive smoking may bring harm to the vascular system. For instance, cigarette smoking, cannabinoids and smokeless tobacco use were all found to raise blood pressure and increase the risk of stroke. Moreover, cigar and cigarette smoking may also cause arterial stiffness. Some medications may have the side effect of increasing blood pressure and may even suppress the effect of anti-inflammatory drugs.