The Concept of CMR

Blood pressure regulation and the pathophysiology of hypertension

Cardiac output and systemic vascular resistance modulate arterial BP. Accordingly, factors affecting both cardiac output and systemic vascular resistance influence arterial BP. Among the factors that influence cardiac output are sodium intake, renal function, and mineral corticoids (6). Increased extracellular fluid volume, heart rate, and contractility also determine inotropic action. The sympathetic nervous system—via vasoconstriction and vasodilation—as well as humoral factors (angiotensin, catecholamines, prostaglandins, kinins, etc.) and local autoregulation all act on peripheral vascular resistance (6).

The exact cause of essential hypertension is not yet known. However, a mixture of adrenergic hyperactivity, genetic predisposition, altered calcium homeostasis, excess dietary salt intake, and alteration of the vascular endothelium are some likely contributors (6). Compared to patients with hypertension alone, patients who are both hypertensive and obese have lower peripheral vascular resistance and higher cardiac output associated with an increased preload. Obesity-related hypertension also has a negative effect on renal function and is linked to an increased incidence of renal failure (6).