ABSTRACT
Since the publication of William Harvey’s treatise in 1628, it has been recognized that the heart and blood vessels play a critical role in maintaining bodily functions through the provision of circulation to vital organs. The cardiovascular system sustains the metabolic demands of all organs, with the pumping action of the heart being responsible for generating and maintaining an adequate blood supply to all the tissues. This pumping activity of the heart determines cardiac output (CO) which, coupled with systemic vascular resistance (SVR), determines the blood pressure (BP) and blood flow. CO or SVR, or both, can be affected by a number of factors, resulting in an alteration in the normal regulation of BP. Hypertension refers to an increase in intra-arterial pressure. Currently, most guidelines around the world define hypertension as systolic BP levels in excess of 140 mmHg or diastolic BP levels greater than 90 mmHg; normal BP is 120/80 mmHg or lower. Any BP level between those two ranges is now called either prehypertension or borderline hypertension. Large numbers of people both in developed and developing societies throughout the world will eventually develop hypertension at some point in their lifetime (Figure 1.1).
