ABSTRACT
INTRODUCTION Hemodynamics describes the circulation of blood in the vasculature, particularly the arterial system. The main elements are the intravascular hydrostatic pressure-the blood pressure (BP)—and the amount and speed of blood being pumped out from the heart into the aorta and the arterial tree-the cardiac output (CO). A third component is the resistance against the blood flow through the vascular system-the total peripheral resistance (TPR). The above components have been referred to as central or systemic hemodynamics. Collectively, the variables reflect the sum of circulation in the multiple vascular beds throughout the body. There is a large array of studies on regional circulation, for example, in the kidneys, brain, heart, lungs, forearm, and skin (1-9). These are not discussed in this chapter. Another important aspect of hemodynamics is stiffness of the vascular walls, which may be both the consequence and cause of hemodynamic abnormalities (10). Arterial stiffness also relates directly to cardiovascular morbidity and mortality (11,12). Mainly based on pulse wave analysis, a number of indices of arterial stiffness have been introduced, for example, arterial distensibility, pulse wave velocity, central BP, augmentation index, and forearm blood flow velocity (11-15). Indices of arterial stiffness are dealt with in Chapters 19 and 26, while measurement and characteristics of central hemodynamics in hypertension are discussed in this chapter.
