In a new review article published in Physiology, researchers speculate that arterial stiffness in middle-aged adults may actually be the body’s way of trying to compensate for widening of the blood vessel walls as we age. But that benefit turns into a risk with aging as it increases the flow of blood into organs like the brain, kidney, and heart and damages the small blood vessels in those organs. Interestingly, smoking, blood sugar, cholesterol, as well as body fat do not appear to play a major role on the normal age-related increases in aortic stiffness. According to the authors, blood pressure and age itself appear to play the largest role in older adults.
Arteries typically become increasingly stiff as we age. In other words, they become less stretchy. The problem with stiff arteries is that they can lead to cardiovascular diseases. The aorta is the large artery that transports blood from the heart to the body. Normally, the aorta widens to accept blood from the heart with each beat because the elastic fibers are stretchy. After the blood enters the aorta, those elastic fibers essentially recoil and help send blood to other parts of the body. The body compensates for stiffness by widening the aorta, which reduces the thickness of the elastic layer. The problem with aortic stiffness is that it increases the speed and pressure of the blood because it is no longer able to stretch and absorb the high pressure exerted by the heart when it pumps out blood.
Aortic stiffness can be measured clinically by determining the pulse wave velocity from the carotid artery to the femoral artery. In other words, this test measures the time it takes for a pulse in the aorta to move from the carotid artery in the neck to the femoral artery in the thigh. Because aortic stiffness increases the pressure and speed of the blood exiting the heart, it increases the speed at which the pulse travels from the carotid artery to the femoral artery. Given the association between these measurements and cardiovascular diseases and strokes, especially in younger adults, they are an important indicator of vascular health in aging. As we age, however, high blood pressure may appear together with aortic stiffness and further increase the risk of cardiovascular diseases. Therefore, it is important to measure blood pressure, aortic stiffness, as well as screen for atherosclerosis in patients.
Interestingly, an article published in the European Heart Journal described how some avian species like turkeys have high blood pressure and are known to be at risk of early death caused by ruptured aortas resulting from atherosclerosis and aneurysms – similar to humans. For this reason, farmers began treating turkeys with medication to lower blood pressure and hence reduce the risk of untimely death. Similar to the above data suggesting that lifestyle factors like smoking, diet, blood sugar, and lipids only modestly contribute to the risk of degenerating arteries, studies in turkeys found a genetic link that predisposes some birds to early death as a result of aortic rupture.
GL Pierce, TA Coutinho, LE BuBose, AJ Donato. Is It Good to Have a Stiff Aorta with Aging? Causes and Consequences. Physiology. 37(3): 154-173, 2022. https://doi.org/10.1152/physiol.00035.2021
CS Hayward, A Adji, MF O’Rourke. Arterial stiffening and arterial dilation as heritable traits caused by defective vital rubber? European Heart Journal. 39(24): 2289-2290, 2018. https://doi.org/10.1093/eurheartj/ehy231
JJ Collins Jr. Dissecting aneurysms in turkeys and man. The Archives of Surgery. 102(2): 159-160, 1971. https://doi:10.1001/archsurg.1971.01350020069019