The Cardio-Ankle Vascular Index (CAVI) is a new indicator of the stiffness of arteries from the origin of the aorta to the ankle of the lower leg. The theory is based on the stiffness parameter β. CAVI is essentially independent of blood pressure at a measuring time. This is confirmed by the study using adrenergic β1 receptor-blocking agent, metoprolol in human. When metoprolol is administered to men, blood pressure decreased and pulse wave velocity is decreased. But, CAVI remains constant. This result was also confirmed by the study on the rabbits using same apparatus.

CAVI increased with aging and showed higher values in males than in females. CAVI showed high value in patients with cerebral infarction, coronary stenosis, and chronic kidney disease.

As for the risks of coronary artery disease, CAVI showed high value in hypertension, diabetes mellitus, dyslipidemia, smoking, and metabolic syndrome. Furthermore, improvement of those risk factors by drugs or lifestyle changes reduced CAVI in most cases. In other words, CAVI is a useful indicator for the management of coronary risk factors.

CAVI is decreased with alfa1 selective blocker, doxazosin. Therefore, CAVI is supposed to be composed of organic stiffness and also of contracture of smooth muscle cells. Moreover, the relationships between CAVI and cardiac functions were reported.

Thus, CAVI may be not only a surrogate maker of arteriosclerosis and vascular age, but, also an indicator of contracture of smooth muscle cells. CAVI might develop a new field of vascular function.