Arterial stiffness occurs as a consequence of

biological aging Senescence () or biological aging is the gradual deterioration of functional characteristics in living organisms. The word ''senescence'' can refer to either cellular senescence or to senescence of the whole organism. Organismal senescence inv ...

and

arteriosclerosis Arteriosclerosis is the thickening, hardening, and loss of elasticity of the walls of Artery, arteries. This process gradually restricts the blood flow to one's organs and tissues and can lead to severe health risks brought on by atherosclerosis ...

. Inflammation plays a major role in arteriosclerosis development, and consequently it is a major contributor in large arteries stiffening. Increased arterial stiffness is associated with an increased risk of cardiovascular events such as

myocardial infarction A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which may ...

, hypertension, heart failure and

stroke A stroke is a medical condition in which poor blood flow to the brain causes cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop functionin ...

, the two leading causes of death in the developed world. The

World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of h ...

predicts that in 2010,

cardiovascular disease Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, h ...

will also be the leading killer in the developing world and represents a major global health problem. Several degenerative changes that occur with age in the walls of large elastic

arteries An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pu ...

are thought to contribute to increased stiffening over time, including the mechanical fraying of lamellar

elastin Elastin is a protein that in humans is encoded by the ''ELN'' gene. Elastin is a key component of the extracellular matrix in gnathostomes (jawed vertebrates). It is highly elastic and present in connective tissue allowing many tissues in the bod ...

structures within the wall due to repeated cycles of mechanical stress; changes in the kind and increases in content of arterial

collagen Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whole ...

proteins, partially as a compensatory mechanism against the loss of arterial elastin and partially due to

fibrosis Fibrosis, also known as fibrotic scarring, is a pathological wound healing in which connective tissue replaces normal parenchymal tissue to the extent that it goes unchecked, leading to considerable tissue remodelling and the formation of perma ...

; and crosslinking of adjacent collagen fibers by

advanced glycation endproducts Advanced glycation end products (AGEs) are proteins or lipids that become glycated as a result of exposure to sugars. They are a bio-marker implicated in aging and the development, or worsening, of many degenerative diseases, such as diabetes, at ...

(AGEs).

Background

When the

heart The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide t ...

contracts it generates a pulse or energy wave that travels through the circulatory system. The speed of travel of this pulse wave (

pulse wave velocity Pulse wave velocity (PWV) is the velocity at which the blood pressure pulse propagates through the circulatory system, usually an artery or a combined length of arteries. PWV is used clinically as a measure of arterial stiffness and can be readil ...

(PWV)) is related to the stiffness of the arteries. Other terms that are used to describe the mechanical properties of arteries include elastance, or the reciprocal (inverse) of elastance, compliance. The relationship between arterial stiffness and pulse wave velocity was first predicted by Thomas Young in his Croonian Lecture of 1808 but is generally described by the

Moens–Korteweg equation In biomechanics, the Moens–Korteweg equation models the relationship between wave speed or pulse wave velocity (PWV) and the incremental elastic modulus of the arterial wall or its distensibility. The equation was derived independently by Adriaa ...

or the Bramwell–Hill equation. Typical values of PWV in the

aorta The aorta ( ) is the main and largest artery in the human body, originating from the left ventricle of the heart and extending down to the abdomen, where it splits into two smaller arteries (the common iliac arteries). The aorta distributes ...

range from approximately 5 m/s to >15 m/s. Measurement of aortic PWV provides some of the strongest evidence concerning the prognostic significance of large artery stiffening. Increased aortic PWV has been shown to predict cardiovascular, and in some cases all cause, mortality in individuals with

end stage kidney disease Chronic kidney disease (CKD) is a type of kidney disease in which a gradual loss of kidney function occurs over a period of months to years. Initially generally no symptoms are seen, but later symptoms may include leg swelling, feeling tired, vo ...

, hypertension,

diabetes mellitus Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...

and in the general population. However, at present, the role of measurement of PWV as a general clinical tool remains to be established. Devices are on the market that measure arterial stiffness parameters (augmentation index, pulse wave velocity). These include Complior, CVProfilor, PeriScope, Hanbyul Meditech, Mobil-O-Graph NG, BP Plus (Pulsecor), PulsePen, BPLab Vasotens, Arteriograph, Vascular Explorer, and SphygmoCor. Also noted are newer pulse wave velocity measurement tools like the iHeart Internal Age device, a fingertip device that measures aortic pulse wave velocity and arterial stiffness through the pulse in the finger.

Pathophysiological consequences of increased arterial stiffness

The primary sites of end-target organ damage following an increase in arterial stiffness are the heart, the brain (stroke, white matter hyperintensities (WMHs)), and the kidneys (age-related loss of kidney function). The mechanisms linking arterial stiffness to end-organ damage are several-fold. Firstly, stiffened arteries compromise the

Windkessel effect Windkessel effect is a term used in medicine to account for the shape of the arterial blood pressure waveform in terms of the interaction between the stroke volume and the compliance of the aorta and large elastic arteries (Windkessel vessels) an ...

of the arteries. The Windkessel effect buffers the pulsatile ejection of blood from the heart converting it into a more steady, even outflow. This function depends on the elasticity of the arteries and stiffened arteries require a greater amount of force to permit them to accommodate the volume of blood ejected from the heart (stroke volume). This increased force requirement equates to an increase in pulse pressure. The increase in pulse pressure may result in increased damage to blood vessels in target organs such as the brain or kidneys. This effect may be exaggerated if the increase in arterial stiffness results in reduced wave reflection and more propagation of the pulsatile pressure into the microcirculation. An increase in arterial stiffness also increases the load on the heart, since it has to perform more work to maintain the

stroke volume In cardiovascular physiology, stroke volume (SV) is the volume of blood pumped from the left ventricle per beat. Stroke volume is calculated using measurements of ventricle volumes from an echocardiogram and subtracting the volume of the blood i ...

. Over time, this increased workload causes

left ventricular hypertrophy Left ventricular hypertrophy (LVH) is thickening of the heart muscle of the left ventricle of the heart, that is, left-sided ventricular hypertrophy and resulting increased left ventricular mass. Causes While ventricular hypertrophy occurs na ...

and left

ventricular remodelling In cardiology, ventricular remodeling (or cardiac remodeling) refers to changes in the size, shape, structure, and function of the heart. This can happen as a result of exercise (physiological remodeling) or after injury to the heart muscle (pathol ...

, which can lead to

heart failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, a ...

. The increased workload may also be associated with a higher heart rate, a proportionately longer duration of systole and a comparative reduction of duration of diastole. This decreases the amount of time available for perfusion of cardiac tissue, which largely occurs in diastole. Thus the hypertrophic heart, which has a greater oxygen demand, may have a compromised supply of oxygen and nutrients. Arterial stiffness may also affect the time at which pulse wave reflections return to the heart. As the pulse wave travels through the circulation it undergoes reflection at sites where the transmission properties of the arterial tree change (i.e. sites of impedance mismatch). These reflected waves propagate backwards towards the heart. The speed of propagation (i.e. PWV) is increased in stiffer arteries and consequently reflected waves will arrive at the heart earlier in systole. This increases the load on the heart in systole. Elevated PWV could represent an important parameter for identifying children with CKD and high cardiovascular risk.

Notes

*https://www.mdpi.com/2075-4418/12/1/71 {{DEFAULTSORT:Arterial Stiffness Hypertension Vascular diseases

Background

Pathophysiological consequences of increased arterial stiffness

See also

Notes