Pathophysiology of blood pressure-related dysfunctions

Blood pressure is affected by two major influences: cardiac output and total peripheral vascular resistance, thus pathogenic mechanisms that affect the levels of these two parameters may affect susceptibility to hypertension. Cardiac output for most individuals may become elevated at the outset of some illnesses; however this is often not reflected by elevation of total peripheral resistance. Nevertheless autoregulatory feedback mechanisms may return cardiac output to normal levels with increased total peripheral resistance increase. Disorders such as thyrotoxicosis, aortic regurgitation that increase cardiac output, especially when stroke volume is increased, result in isolated systolic hypertension. Some patients develop isolated systolic hypertension with normal or low cardiac output, due to inelasticity of the aorta and its major branches.