Elastance
Encyclopedia
Compliance is a measure
of the tendency of a hollow organ
to resist recoil
toward its original dimensions
upon removal of a distending or compressing force. It is the reciprocal
of "elastance".
and respiratory physiology
. An increase in blood volume occurs in a vessel when the pressure in that vessel is increased. The tendency of the arteries and veins to stretch in response to pressure has a large effect on perfusion and blood pressure.
Venous compliance is 20-24 times larger than arterial compliance.
Compliance is calculated using the following equation, where ΔV is the change in volume, and ΔP is the change in pressure:
Physiologic compliance is generally in agreement with the above and adds dP/dt as a common academic physiologic measurement of both pulmonary and cardiac tissues. Mathematical adaptation of utility formulas once best applied to rubber
and latex
now allow measurement of complex and dynamic physiologic states, specifically addressed here in pulmonary and cardiac tissue compliance.
Vulcanization
of natural rubber occurs when elements such as sulfur are introduced to the media. In industry, sulfur or similar additions are titrated to the desired compliance performance definition of the media. The Myocardium is decidedly not made of rubber but certainly shares many characteristics regarding infiltration by other agents. Introduction of Calcium
within myocardial mass is a similar process that detracts from compliance and heralds Diastolic Dysfunction
.
Current proponents of restoration of Ventricular Dyssynchrony purport that cardiac dP/dt curves can be reversed, thus demonstrating clinical improvement. One could then assume that inexpensive echocardiographically defined reversal of derived E:A time intervals of flow across the mitral valve would follow these curves in support of the theory espoused.
Veins have a much higher compliance than arteries (largely due to their thinner walls.) Veins which are abnormally compliant can be associated with edema
. Pressure stockings
are sometimes used to externally reduce compliance, and thus keep blood from pooling in the legs.
Arterial compliance, an index of the elasticity
of large arteries such as the thoracic aorta
. Arterial compliance is an important cardiovascular risk factor. Compliance diminishes with age and menopause. Arterial compliance is measured by ultrasound
as a pressure (carotid artery
) and volume (outflow into aorta
) relationship.
Arterial compliance in simple words is the action in which artery
yields to pressure or force without disruption. It is used as an indication of arterial stiffening. An increase in the age and also in the systolic blood pressure
(SBP) is accompanied with decrease on arterial compliance.
Endothelial dysfunction results in reduced compliance (increased arterial stiffness), especially in the smaller arteries. This is characteristic of patients with hypertension
. However, it may seen in normotensive patients (with normal blood pressure) before the appearance of clinical hypertension. Reduced arterial compliance is also seen in patients with diabetes and also in smokers. It is actually a part of a vicious cycle that further elevates blood pressure, aggravates atherosclerosis
(hardening of the arteries), and leads to increased cardiovascular risk. Arterial compliance can be measured by several techniques. Most of them are invasive and are not clinically appropriate. Pulse contour analysis is a non -invasive method that allows easy measurement of arterial elasticity to identify patients at risk for cardiovascular events.
A study concluded that arterial compliance, which diminishes with menopause
, was significantly improved with red clover
isoflavones.
Measurement
Measurement is the process or the result of determining the ratio of a physical quantity, such as a length, time, temperature etc., to a unit of measurement, such as the metre, second or degree Celsius...
of the tendency of a hollow organ
Organ (anatomy)
In biology, an organ is a collection of tissues joined in structural unit to serve a common function. Usually there is a main tissue and sporadic tissues . The main tissue is the one that is unique for the specific organ. For example, main tissue in the heart is the myocardium, while sporadic are...
to resist recoil
Recoil
Recoil is the backward momentum of a gun when it is discharged. In technical terms, the recoil caused by the gun exactly balances the forward momentum of the projectile and exhaust gasses, according to Newton's third law...
toward its original dimensions
Dimensions
Dimensions is a French project that makes educational movies about mathematics, focusing on spatial geometry. It uses POV-Ray to render some of the animations, and the films are release under a Creative Commons licence....
upon removal of a distending or compressing force. It is the reciprocal
Multiplicative inverse
In mathematics, a multiplicative inverse or reciprocal for a number x, denoted by 1/x or x−1, is a number which when multiplied by x yields the multiplicative identity, 1. The multiplicative inverse of a fraction a/b is b/a. For the multiplicative inverse of a real number, divide 1 by the...
of "elastance".
Blood vessels
The terms elastance and compliance are of particular significance in cardiovascular physiologyCardiovascular physiology
Cardiovascular physiology is the study of the circulatory system. More specifically, it addresses the physiology of the heart and blood vessels ....
and respiratory physiology
Respiratory physiology
Respiratory physiology is the branch of human physiology focusing upon respiration.Topics include:-Volumes:* lung volumes* vital capacity* functional residual capacity* dead space* spirometry* body plethysmography* peak flow meter-Mechanics:...
. An increase in blood volume occurs in a vessel when the pressure in that vessel is increased. The tendency of the arteries and veins to stretch in response to pressure has a large effect on perfusion and blood pressure.
Venous compliance is 20-24 times larger than arterial compliance.
Compliance is calculated using the following equation, where ΔV is the change in volume, and ΔP is the change in pressure:
Physiologic compliance is generally in agreement with the above and adds dP/dt as a common academic physiologic measurement of both pulmonary and cardiac tissues. Mathematical adaptation of utility formulas once best applied to rubber
Rubber
Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...
and latex
Latex
Latex is the stable dispersion of polymer microparticles in an aqueous medium. Latexes may be natural or synthetic.Latex as found in nature is a milky fluid found in 10% of all flowering plants . It is a complex emulsion consisting of proteins, alkaloids, starches, sugars, oils, tannins, resins,...
now allow measurement of complex and dynamic physiologic states, specifically addressed here in pulmonary and cardiac tissue compliance.
Vulcanization
Vulcanization
Vulcanization or vulcanisation is a chemical process for converting rubber or related polymers into more durable materials via the addition of sulfur or other equivalent "curatives." These additives modify the polymer by forming crosslinks between individual polymer chains. Vulcanized material is...
of natural rubber occurs when elements such as sulfur are introduced to the media. In industry, sulfur or similar additions are titrated to the desired compliance performance definition of the media. The Myocardium is decidedly not made of rubber but certainly shares many characteristics regarding infiltration by other agents. Introduction of Calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
within myocardial mass is a similar process that detracts from compliance and heralds Diastolic Dysfunction
Diastolic dysfunction
Diastolic heart failure or diastolic dysfunction refers to decline in performance of one or both ventricles of the heart during the time phase of diastole...
.
Current proponents of restoration of Ventricular Dyssynchrony purport that cardiac dP/dt curves can be reversed, thus demonstrating clinical improvement. One could then assume that inexpensive echocardiographically defined reversal of derived E:A time intervals of flow across the mitral valve would follow these curves in support of the theory espoused.
Veins have a much higher compliance than arteries (largely due to their thinner walls.) Veins which are abnormally compliant can be associated with edema
Edema
Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...
. Pressure stockings
Compression stockings
Compression stockings and socks are specialised hosiery items designed to increase blood circulation. Their main theraputic purpose is to provide graduated pressure on the lower leg and foot and, in some cases, the thigh, to alleviate circulatory problems such as edema, phlebitis and...
are sometimes used to externally reduce compliance, and thus keep blood from pooling in the legs.
Arterial compliance
The classic definition by Spencer and Denison of compliance (C) is the change in arterial blood volume (ΔV) due to a given change in arterial blood pressure (ΔP). So, C = ΔV/ΔP.Arterial compliance, an index of the elasticity
Elasticity
Elasticity may refer to:*Elasticity , continuum mechanics of bodies that deform reversibly under stressNumerous uses are derived from this physical sense of the term, which is inherently mathematical, such as used in Engineering, Chemistry, Construction and variously in Economics:*Elasticity , the...
of large arteries such as the thoracic aorta
Thoracic aorta
The thoracic aorta is contained in the posterior mediastinal cavity.It begins at the lower border of the fourth thoracic vertebra where it is continuous with the aortic arch, and ends in front of the lower border of the twelfth thoracic vertebra, at the aortic hiatus in the diaphragm where it...
. Arterial compliance is an important cardiovascular risk factor. Compliance diminishes with age and menopause. Arterial compliance is measured by ultrasound
Ultrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
as a pressure (carotid artery
Carotid artery
Carotid artery can refer to:* Common carotid artery* External carotid artery* Internal carotid artery...
) and volume (outflow into aorta
Aorta
The aorta is the largest artery in the body, originating from the left ventricle of the heart and extending down to the abdomen, where it branches off into two smaller arteries...
) relationship.
Arterial compliance in simple words is the action in which artery
Artery
Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries....
yields to pressure or force without disruption. It is used as an indication of arterial stiffening. An increase in the age and also in the systolic blood pressure
Blood pressure
Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...
(SBP) is accompanied with decrease on arterial compliance.
Endothelial dysfunction results in reduced compliance (increased arterial stiffness), especially in the smaller arteries. This is characteristic of patients with hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
. However, it may seen in normotensive patients (with normal blood pressure) before the appearance of clinical hypertension. Reduced arterial compliance is also seen in patients with diabetes and also in smokers. It is actually a part of a vicious cycle that further elevates blood pressure, aggravates atherosclerosis
Atherosclerosis
Atherosclerosis is a condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol...
(hardening of the arteries), and leads to increased cardiovascular risk. Arterial compliance can be measured by several techniques. Most of them are invasive and are not clinically appropriate. Pulse contour analysis is a non -invasive method that allows easy measurement of arterial elasticity to identify patients at risk for cardiovascular events.
A study concluded that arterial compliance, which diminishes with menopause
Menopause
Menopause is a term used to describe the permanent cessation of the primary functions of the human ovaries: the ripening and release of ova and the release of hormones that cause both the creation of the uterine lining and the subsequent shedding of the uterine lining...
, was significantly improved with red clover
Red clover
Trifolium pratense is a species of clover, native to Europe, Western Asia and northwest Africa, but planted and naturalised in many other regions....
isoflavones.