Structural changes of small resistance vessels in essential hypertension

The main hemodynamic characteristic of established essential hypertension is a raised peripheral resistance, while cardiac output is usually within normal limits [1]. Precapillary resistance vessels give the major contribution to the total peripheral resistance in the systemic circulation. Although the high peripheral resistance in essential hypertension can be related to an elevated vasoconstrictor tone, it has been demonstrated that an increased wall thickness in relation to the lumen in the precapillary vessels is of great importance for the maintenance and probably also for the progressive worsening of the hypertensive disease [2, 3]. In fact, many years ago Folkow and coworkers showed that as a consequence of the increased wall-to-lumen ratio, there must always be a greater change in resistance for any given degree of smooth muscle shortening in blood vessels [4].