Assessment of Arterial Stiffness in Clinical Trials

In recent years, great emphasis has been placed on the role of arterial stiffness in the development of cardiovascular (CV) diseases. Arterial stiffness is the major cause of heart attacks, heart failure, and stroke and the assessment of arterial stiffness is increasingly used in the clinical assessment of patients.  In contrast to systemic arterial stiffness, which can only be estimated from models of the circulation, regional and local arterial stiffness can be measured directly and noninvasively at various sites along the arterial tree.
 

Clinical Applications

Arterial stiffness and wave reflection are now well accepted as the most important determinants of increasing systolic and pulse pressures, not only for assessing CV risk but also for predicting CV outcomes. To be practical for routine clinical use and for use in clinical trials, central pressure has to be measured simply, accurately, and non‐invasively.
 

Medifacts offers a range of static and ambulatory central recording methodologies which include:

  • Pulse wave velocity
  • Pulse wave analysis
  • Central aortic systolic pressure (CASP)
  • 24-hour central aortic systolic pressure (24-hour CASP)


Pulse Wave Velocity

The measurement of pulse wave velocity (PWV) is generally accepted as the most simple, non-invasive, robust, and reproducible method to determine arterial stiffness. PWV is a well-established technique for obtaining a measure of arterial stiffness between any two locations in the arterial tree. The velocity of the blood pressure pulse along an artery is dependent on the stiffness of the artery. Serial measurement of pulse wave velocity in a section of artery will indicate the magnitude of change in arterial stiffness. Most commonly, pulse wave velocity is measured between the carotid and femoral peripheral artery sites in order to provide a measure of aortic stiffness.
 

Pulse Wave Analysis

The arterial pressure waveform has 2 components – the first is the forward traveling wave when the left ventricle contracts and the second is the reflected wave returning from the periphery. In the case of stiff arteries, PWV rises and the reflected wave arrives back at the central arteries earlier, which leads to augmentation of the central aortic pressure further increasing left ventricular work. This phenomenon can be quantified through the augmentation index (AIx) which is defined as the difference between the second and first systolic peaks. These changes in pulse pressure cannot be appreciated by the measurement of simple brachial BP.