Aortopathies: From Etiology to the Role of Arterial Stiffness

Abstract

The aorta and aortic wall have a complex biological system of structural, biochemical, biomolecular, and hemodynamic elements. Arterial stiffness could be considered a manifestation of wall structural and functional variations, and it has been revealed to have a strong connection with aortopathies and be a predictor of cardiovascular risk, especially in patients affected by hypertension, diabetes mellitus, and nephropathy. Stiffness affects the function of different organs, especially the brain, kidneys, and heart, promoting remodeling of small arteries and endothelial dysfunction. This parameter could be easily evaluated using different methods, but pulse-wave velocity (PWV), the speed of transmission of arterial pressure waves, is considered the gold standard for a good and precise assessment. An increased PWV value indicates an elevated level of aortic stiffness because of the decline in elastin synthesis and activation of proteolysis and the increase in fibrosis that contributes to parietal rigidity. Higher values of PWV could also be found in some genetic diseases, such as Marfan syndrome (MFS) or Loeys-Dietz syndrome (LDS). Aortic stiffness has emerged as a major new cardiovascular disease (CVD) risk factor, and its evaluation using PWV could be very useful to identify patients with a high cardiovascular risk, giving some important prognostic information but also being used to value the benefits of therapeutic strategies.

Keywords: aorta; aortopathies; arterial stiffness; genetics; heritable connective tissue disorders; pulse wave velocity.

Figure 1

Non-invasive determination of pulse wave velocity (PWV) between the carotid artery and the terminal aorta. PWV is determined by the ratio between the distance from the carotid to the terminal aorta (L) and the differential time between the arrival of the pulse wave in the two districts (ΔT).

Figure 2

Insults leading to structural changes in the aorta and its functioning. Legend: AS, arterial stiffness; BP, blood pressure; ECM, extracellular matrix; LV, left ventricular; PWV, pulse wave velocity.

Figure 3

Graphical representation of the augmentation index. The augmentation index is expressed as a percentage and represents the ratio between pulse pressure (the difference between systolic and diastolic pressure) and the augmented pressure (the difference between central systolic pressure and the pressure of the reflected wave). The increase in arterial stiffness is directly proportional to the pressure of the reflected wave, and as a consequence, to the augmentation index.