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The aortic valve is a
valve A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries A slurry composed of glass beads in silicone oil flowing down an inclined plane A slurry is a mix ...
in the
human heart The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste ...

human heart
between the
left ventricle A ventricle is one of two large chambers toward the bottom of the heart The heart is a muscle, muscular Organ (anatomy), organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped blood carries ...
and the
aorta The aorta ( ) is the main and largest artery An artery (plural arteries) () is a blood vessel The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vas ...

aorta
. It is one of the two semilunar valves of the heart, the other being the
pulmonary valve The pulmonary valve (sometimes referred to as the pulmonic valve) is a valve of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood vessels of the circulatory system ...
. The heart has four valves; the other two are the
mitral The mitral valve (), also known as the bicuspid valve or left atrioventricular valve, is one of the four heart valve A heart valve is a that allows in one direction through the chambers of the . Four valves are usually present in a mammalian h ...
and the
tricuspid The tricuspid valve, or right atrioventricular valve, is on the right dorsal side of the mammalian heart, at the superior portion of the right ventricle A ventricle is one of two large chambers toward the bottom of the heart The heart is ...
valves. The aortic valve normally has three cusps or leaflets, although in 1–2% of the population it is found to congenitally have two leaflets. The aortic valve is the last structure in the heart the blood travels through before stopping the flow through the systemic circulation.


Structure

The aortic valve normally has three cusps however there is some discrepancy in their naming. They may be called the left coronary, right coronary and non-coronary cusp. Some sources also advocate they be named as a left, right and posterior cusp. Anatomists have traditionally named them the left posterior (origin of left coronary), anterior (origin of the right coronary) and right posterior. The three cusps, when the valve is closed, contain a sinus called an
aortic sinus An aortic sinus, also known as a sinus of Valsalva, is one of the anatomic dilations of the ascending aorta, which occurs just above the aortic valve. These widenings are between the wall of the aorta and each of the three cusps of the aortic valve ...
or sinus of Valsalva. In two of these cusps, the origin of the coronary arteries are found. The width of the sinuses in cross-section is wider than the left ventricular outflow tract as well as wider than the ascending aorta. The junction of the sinuses with the aorta is called the sinotubular junction. The aortic valve is located posterior to the pulmonary valve and the commissure where the anterior two cusps join together points toward the pulmonary valve. It is these two sinuses that contain the origin of the coronary arteries. In the congenital disease known as
transposition of the great arteries Transposition of the great vessels (TGV) is a group of congenital congenital heart defect, heart defects involving an abnormal spatial arrangement of any of the great vessels: superior vena cava, superior and/or inferior vena cava, inferior venae ...
, these two valves are reversed (the anterior valve is the aortic valve) and the origin of the coronaries still follows this "rule" that the origins are in the sinuses facing the pulmonary valve. The term 'Semilunar" refers to an approximate half-moon shape of the valve leaflets.


Function

When the left ventricle contracts (
systole The systole ( ) is the part of the cardiac cycle The cardiac cycle is the performance of the human heart The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood vessels of ...
),
pressure Pressure (symbol: ''p'' or ''P'') is the force In physics, a force is an influence that can change the motion (physics), motion of an Physical object, object. A force can cause an object with mass to change its velocity (e.g. moving fr ...

pressure
rises in the left ventricle. When the pressure in the left ventricle rises above the pressure in the aorta, the aortic valve opens, allowing
blood Blood is a body fluid Body fluids, bodily fluids, or biofluids are liquid A liquid is a nearly incompressible In fluid mechanics or more generally continuum mechanics, incompressible flow (isochoric process, isochoric flow) refers t ...

blood
to exit the left ventricle into the aorta. When ventricular systole ends, pressure in the left ventricle rapidly drops. When the pressure in the left ventricle decreases, the momentum of the vortex at the outlet of the valve forces the aortic valve to close. The closure of the aortic valve contributes the A2 component of the second
heart sound Heart sounds are the noises generated by the beating heart and the resultant flow of blood through it. Specifically, the sounds reflect the turbulence created when the heart valves snap shut. In cardiac auscultation, an examiner may use a ste ...
(S2).


Insufficiency

Closure of the aortic valve permits maintaining high pressures in the systemic circulation while reducing pressure in the left ventricle to permit blood flow from the lungs to fill the left ventricle. Abrupt loss of function of the aortic valve results in acute aortic insufficiency and loss in the normal diastolic blood pressure resulting in a wide pulse pressure and bounding pulses. The endocardium perfuses during diastole and so acute aortic insufficiency can reduce perfusion of the heart. Consequently, heart failure and pulmonary edema can develop. Slowly worsening aortic insufficiency results in a chronic insufficiency which permits the heart to compensate (unlike acute insufficiency). This compensation is through hypertrophy of the left ventricle and return to normal filling pressures.


Stenosis

Inadequate opening of the aortic valve, often through calcification, results in higher flow velocities through the valve and larger pressure gradients. Diagnosis of aortic stenosis is contingent upon quantification of this gradient. This condition also results in hypertrophy of the left ventricle.


Clinical significance

A normally functioning valve permits normal physiology and dysfunction of the valve results in left ventricular hypertrophy and heart failure. Dysfunctional aortic valves often present as heart failure by
non-specific symptoms Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showi ...
such as fatigue, low energy, and shortness of breath with exertion. Common causes of
aortic regurgitation Aortic insufficiency (AI), also known as aortic regurgitation (AR), is the leaking of the aortic valve The aortic valve is a in the between the and the . It is one of the two of the heart, the other being the . The heart has four valves; the ...

aortic regurgitation
include
vasodilation Vasodilation is the widening of blood vessel The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. ...

vasodilation
of the aorta, previous
rheumatic fever Rheumatic fever (RF) is an inflammatory disease that can involve the heart The heart is a muscle, muscular Organ (anatomy), organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped blood ca ...
, infection such as
infective endocarditis Infective endocarditis is an infection An infection is the invasion of an organism's body Tissue (biology), tissues by Pathogen, disease-causing agents, their multiplication, and the reaction of host (biology), host tissues to the infectious ag ...
, degeneration of the aortic valve, and
Marfan's syndrome Marfan syndrome (MFS) is a genetic disorder A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene In biology, a gene (from ''genos'' "...Wilhelm Joha ...
. Aortic stenosis can also be caused by
rheumatic fever Rheumatic fever (RF) is an inflammatory disease that can involve the heart The heart is a muscle, muscular Organ (anatomy), organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped blood ca ...
and degenerative
calcification Calcification is the accumulation of calcium Calcium is a chemical element with the Symbol (chemistry), symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when expose ...
. The most common
congenital A birth defect, also known as a congenital disorder, is a condition present at birth Birth is the act or process of bearing or bringing forth offspring, also referred to in technical contexts as parturition. In mammals, the process is initiate ...
abnormality of the heart is the
bicuspid aortic valve Bicuspid aortic valve (BAV) is an inherited form of heart disease in which two of the leaflets of the aortic valve fuse during development in the womb resulting in a two-leaflet valve (bicuspid valve) instead of the normal three-leaflet valve (tric ...
(fusion of two cusps together).
Turner syndrome Turner syndrome (TS), also known 45,X, or 45,X0, is a genetic condition in which a female is partly or completely missing an X chromosome. Signs and symptoms vary among those affected. Often, a short and webbed neck, low-set ears, low hairline at ...
, a congenital condition that affects females, can often have a bicuspid aortic valve as one of its symptoms. Once diagnosed, the two options are to repair or replace the valve.


Aortic valve repair

Aortic valve repair or aortic valve reconstruction describes the reconstruction of both form and function of the native and dysfunctioning aortic valve. Most frequently it is applied for the treatment of aortic regurgitation. It can also become necessary for the treatment of aortic aneurysm, or less frequently for congenital aortic stenosis.


Aortic valve replacement

Replacement of the aortic valve is done by replacing the native valve with a prosthetic valve. Traditionally, this has been a surgical procedure (surgical AVR or SAVR) but a non-surgical option called
transcatheter aortic valve replacement Percutaneous aortic valve replacement (PAVR), also known as percutaneous aortic valve implantation (PAVI), transcatheter aortic valve implantation (TAVI) or transcatheter aortic valve replacement (TAVR), is the replacement of the aortic valve of ...
(TAVR) or
TAVI Percutaneous aortic valve replacement (PAVR), also known as percutaneous aortic valve implantation (PAVI), transcatheter aortic valve implantation (TAVI) or transcatheter aortic valve replacement (TAVR), is the replacement of the aortic valve o ...

TAVI
transcatheter aortic valve implantation delivers a prosthetic valve through a
catheter In medicine Medicine is the science Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity, awareness, or understanding of someone or something, such as facts ( descriptive knowledge) ...

catheter
. The choice between SAVR and TAVR often relies on the open-heart surgical risk and indications for other open heart surgeries (etc., coronary bypass, other valve dysfunction). The
Bentall procedure The Bentall procedure is a type of cardiac surgery involving composite graft replacement of the aortic valve The aortic valve is a valve in the human heart between the left ventricle and the aorta. It is one of the two semilunar valves of the ...
is a type of surgical procedure when the aortic valve, aortic root, and ascending aorta are replaced in a single operation. There are two basic types of
artificial heart valve An artificial heart valve is a one-way valve implanted into a person's heart The heart is a muscle, muscular Organ (anatomy), organ in most animals, which pumps blood through the blood vessels of the circulatory system. The pumped bloo ...
: mechanical and tissue. * Mechanical valves are made of metal and have evolved over time ("ball and cage", "bileaflet"). Mechanical valves require lifelong anticoagulation to avoid forming blood clots on the valves that can lead to embolism often resulting in
stroke A stroke is a medical condition A disease is a particular abnormal condition that negatively affects the structure or function (biology), function of all or part of an organism, and that is not due to any immediate external injury. Di ...

stroke
. These tend to be favored in younger individuals as they typically last longer than tissue valves. The shape of these valves do not mimic normal heart valves. * Tissue heart valves are usually made from animal tissues, either animal heart valve tissue or animal pericardial tissue, and commonly
porcine A pig is any of the animals in the genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term ...

porcine
. The tissue is pretreated by removing antigens to prevent rejection and to prevent calcification. These valves tend to model after normal valves by having leaflets that form cusps and sinuses. There are alternatives to animal tissue valves. In some cases, a human aortic valve can be implanted. These are called
homograft Allotransplant (''allo-'' meaning "other" in Ancient Greek, Greek) is the Organ transplant, transplantation of cell (biology), cells, Biological tissue, tissues, or Organ (anatomy), organs to a recipient from a genetically non-identical donor of th ...
s. Homograft valves are donated by patients and recovered after the patient expires. The durability of homograft valves is probably the same as for porcine tissue valves. Another procedure for aortic valve replacement is the
Ross procedure The Ross-Yacoub procedure (or pulmonary autograft) is a cardiac surgery Cardiac surgery, or cardiovascular surgery, is surgery on the heart or great vessels performed by cardiac surgeons. It is often used to treat complications of ischemic hear ...

Ross procedure
(after Donald Ross) or pulmonary
autograft Autotransplantation is the organ transplantation, transplantation of Organ (anatomy), organs, Biological tissue, tissues, or even particular proteins from one part of the body to another in the same person (''wikt:auto-, auto-'' meaning "self" in ...
. The Ross procedure involves going to surgery to have the aortic valve removed and replacing it with the patient's own pulmonary valve. A pulmonary homograft (a
pulmonary valve The pulmonary valve (sometimes referred to as the pulmonic valve) is a valve of the heart The heart is a cardiac muscle, muscular Organ (biology), organ in most animals, which pumps blood through the blood vessels of the circulatory system ...
taken from a cadaver) or a valvular prothesis is then used to replace the patient's own pulmonary valve. The first minimally invasive aortic valve surgery took place at the
Cleveland Clinic Cleveland Clinic is a Nonprofit organization, nonprofit American Academic health science center, academic Medical centers in the United States, medical center based in Cleveland, Ohio. Owned and operated by the Cleveland Clinic Foundation, an Ohi ...

Cleveland Clinic
in 1996.


Endocarditis

Endocarditis Endocarditis is an inflammation Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a p ...

Endocarditis
is infection of the heart and this often results in vegetations growing on valves. While it is possible for it to affect the aortic valve, it is not the most likely spot.


Evaluation

Evaluation of the aortic valve can be done with several modalities. Auscultation with a
stethoscope The stethoscope is an acoustic medical Medicine is the science and Praxis (process) , practice of caring for a patient, managing the diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment, Palliative care , palliation o ...

stethoscope
is quick and easy. It contributes the A2 component to the second heart sound and changes with inspiration ("splitting") Transthoracic echocardiography (TTE) is used as the first test because it is non-invasive. Using TTE, the degree of stenosis and insufficiency can be quantified to grade the valve dysfunction.
Transesophageal echocardiography Transesophageal echocardiography diagram A transesophageal echocardiogram, or TEE (TOE in the United Kingdom and other countries such as Australia, reflecting the spelling ''transoesophageal''), is an alternative way to perform an echocardiogram ...
is less often used for aortic stenosis & insufficiency because the angle between the probe and the aortic valve is not optimal (the best window is a transgastric view). MRI and CT can be used to evaluate the valve, but much less commonly than TTE. Quantification of the maximum velocity through the valve, the area of the opening of the valve, calcification, morphology (tricuspid, bicuspid, unicuspid), and size of the valve (annulus, sinuses, sinotubular junction) are common parameters when evaluating the aortic valve. Invasive measurement of the aortic valve can be done during a
cardiac catheterization Cardiac catheterization (heart cath) is the insertion of a catheter In medicine Medicine is the science Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity, awareness, or understan ...
in which the pressure in the left ventricle and aorta can be measured simultaneously.


Additional images

File:BiologicalValves.JPG, A replaceable model of Cardiac Biological Valve Prosthesis. File:Gray1216.svg, Front of
thorax The thorax or chest is a part of the anatomy Anatomy (Greek ''anatomē'', 'dissection') is the branch of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Bioc ...

thorax
, showing surface relations of
bone A bone is a rigid tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth found in North America * ''Triphosa dubit ...

bone
s,
lungs The lungs are the primary organs of the respiratory system The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animal ...

lungs
(purple),
pleura The pulmonary pleurae (''sing.'' pleura) are the two opposing layers of serous membrane In anatomy Anatomy (Greek ''anatomē'', 'dissection') is the branch of biology concerned with the study of the structure of organism In biology ...

pleura
(blue), and
heart The heart is a muscular MUSCULAR (DS-200B), located in the United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain,Usage is mixed. The Guardian' and Telegraph' use ...

heart
(red outline).
Heart valves A heart valve is a one-way valve check valve Image:Check Valve.svg, 140px, Check valve symbol on piping and instrumentation diagrams. The arrow shows the flow direction. A check valve, non-return valve, reflux valve, retention valve, foot valve ...

Heart valves
are labeled with " B", " T", "A", and " P". File:Slide7xxxx.JPG, Aortic valve


References


External links

* {{DEFAULTSORT:Aortic Valve Cardiac anatomy Heart valves