The aortic valve is a valve in the heart of humans and most other animals, located between the

left ventricle A ventricle is one of two large chambers located toward the bottom of the heart that collect and expel blood towards the peripheral beds within the body and lungs. The blood pumped by a ventricle is supplied by an atrium, an adjacent chamber in t ...

and the

aorta The aorta ( ; : aortas or aortae) is the main and largest artery in the human body, originating from the Ventricle (heart), left ventricle of the heart, branching upwards immediately after, and extending down to the abdomen, where it splits at ...

. It is one of the four valves of the heart and one of the two

semilunar valves A heart valve is a biological Check valve, one-way valve that allows blood flow, blood to flow in one direction through the chambers of the heart. A mammalian heart usually has four valves. Together, the valves determine the direction of blood flow ...

, the other being the

pulmonary valve The pulmonary valve (sometimes referred to as the pulmonic valve) is a valve of the heart that lies between the right ventricle and the pulmonary artery, and has three cusps. It is one of the four valves of the heart and one of the two semiluna ...

. 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 va ...

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 heart defects involving an abnormal spatial arrangement of any of the great vessels: superior and/or inferior venae cavae, pulmonary artery, pulmonary veins, and aorta. Congenit ...

, 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 Systole ( ) is the part of the cardiac cycle during which some chambers of the heart contract after refilling with blood. Its contrasting phase is diastole, the relaxed phase of the cardiac cycle when the chambers of the heart are refilling ...

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and eve ...

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 in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood is com ...

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 steth ...

(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 regurgitation (also known as 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 regurgitation can reduce perfusion of the heart. Consequently, heart failure and pulmonary edema can develop. Slowly worsening aortic insufficiency results in a chronic aortic regurgitation which permits the heart to compensate (unlike acute aortic regurgitataion). This compensation is through dilation of the left ventricle and return to normal filling pressures.

Stenosis

Inadequate opening of the aortic valve, often through

calcific aortic valve disease Aortic stenosis (AS or AoS) is the narrowing of the exit of the left ventricle of the heart (where the aorta begins), such that problems result. It may occur at the aortic valve as well as above and below this level. It typically gets worse o ...

, 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 diagnostic indications of an illness, injury, or condition. Signs are objective and externally observable; symptoms are a person's reported subjective experiences. A sign for example may be a higher or lower temperature ...

such as fatigue, low energy, and shortness of breath with exertion. Common causes of

aortic regurgitation Aortic regurgitation (AR), also known as aortic insufficiency (AI), is the leaking of the aortic valve of the heart that causes blood to flow in the reverse direction during ventricular diastole, from the aorta into the left ventricle. As a conse ...

include

vasodilation Vasodilation, also known as vasorelaxation, is the widening of blood vessels. It results from relaxation of smooth muscle cells within the vessel walls, in particular in the large veins, large arteries, and smaller arterioles. Blood vessel wa ...

of the aorta, previous

rheumatic fever Rheumatic fever (RF) is an inflammation#Disorders, inflammatory disease that can involve the heart, joints, skin, and brain. The disease typically develops two to four weeks after a Streptococcal pharyngitis, streptococcal throat infection. Si ...

, infection such as

infective endocarditis Infective endocarditis is an infection of the inner surface of the heart (endocardium), usually the heart valve, valves. Signs and symptoms may include fever, petechia, small areas of bleeding into the skin, heart murmur, feeling tired, and anem ...

, degeneration of the aortic valve, and

Marfan's syndrome Marfan syndrome (MFS) is a multi-systemic genetic disorder that affects the connective tissue. Those with the condition tend to be tall and thin, with long arms, legs, fingers, and toes. They also typically have exceptionally flexible joints ...

. Aortic stenosis can also be caused by

and degenerative

calcification Calcification is the accumulation of calcium salts in a body tissue. It normally occurs in the formation of bone, but calcium can be deposited abnormally in soft tissue,Miller, J. D. Cardiovascular calcification: Orbicular origins. ''Nature M ...

. The most common

congenital heart defect A congenital heart defect (CHD), also known as a congenital heart anomaly, congenital cardiovascular malformation, and congenital heart disease, is a defect in the structure of the heart or great vessels that is present at birth. A congenital h ...

is the

bicuspid aortic valve Bicuspid aortic valve (BAV) is a 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 (bicuspid) valve instead of the normal three-leaflet (tricuspid) valve. BAV is ...

(fusion of two cusps together) commonly found in

Turner syndrome Turner syndrome (TS), commonly known as 45,X, or 45,X0,Also written as 45,XO. is a chromosomal disorder in which cells of females have only one X chromosome instead of two, or are partially missing an X chromosome (sex chromosome monosomy) lea ...

. 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 Transcatheter aortic valve replacement (TAVR) is the implantation of the aortic valve of the heart through the blood vessels without actual removal of the native valve (as opposed to the aortic valve replacement by open heart surgery, surgical ...

(TAVR) or TAVI transcatheter aortic valve implantation delivers a prosthetic valve through a

catheter In medicine, a catheter ( ) is a thin tubing (material), tube made from medical grade materials serving a broad range of functions. Catheters are medical devices that can be inserted in the body to treat diseases or perform a surgical procedure. ...

. 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 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 to replace a heart valve that is not functioning properly ( valvular heart disease). Artificial heart valves can be separated into three broad classes: mechanical he ...

: 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 Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemor ...

. 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, commonly from the

pig The pig (''Sus domesticus''), also called swine (: swine) or hog, is an omnivorous, domesticated, even-toed, hoofed mammal. It is named the domestic pig when distinguishing it from other members of the genus '' Sus''. Some authorities cons ...

. 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 Greek) is the transplantation of cells, tissues, or organs to a recipient from a genetically non-identical donor of the same species. The transplant is called an allograft, allogeneic transplant, ...

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 procedure, also known as pulmonary autograft, is a heart valve replacement operation to treat severe aortic valve disease, such as in children and young adults with a bicuspid aortic valve. It involves removing the diseased aortic va ...

(after Donald Ross) or pulmonary

autograft Autotransplantation is the transplantation of organs, tissues, or even particular proteins from one part of the body to another in the same person ('' auto-'' meaning "self" in Greek). The autologous tissue (also called autogenous, autogen ...

. 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

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 an American Nonprofit organization, nonprofit 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 O ...

in 1996. .

Evaluation

Evaluation of the aortic valve can be done with several modalities. Auscultation with a

stethoscope The stethoscope is a medicine, medical device for auscultation, or listening to internal sounds of an animal or human body. It typically has a small disc-shaped resonator that is placed against the skin, with either one or two tubes connected t ...

is quick and easy. It contributes the A₂ component to the

and changes with inspiration ("splitting")

Transthoracic echocardiography Echocardiography, also known as cardiac ultrasound, is the use of ultrasound to examine the heart. It is a type of medical imaging, using standard ultrasound or Doppler ultrasound. The visual image formed using this technique is called an echoc ...

(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 A transesophageal echocardiogram (TEE; also spelled transoesophageal echocardiogram; TOE in British English) is an alternative way to perform an echocardiogram. A specialized probe containing an ultrasound transducer at its tip is passed into th ...

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 into a heart chamber, chamber or Blood vessel, vessel of the heart. This is done both for diagnostic and interventional purposes. A common example of cardiac catheterization is c ...

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 (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main di ...

, showing surface relations of

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...

lungs The lungs are the primary organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the backbone on either side of the heart. Their function in the respiratory syste ...

(purple),

pleura The pleurae (: pleura) are the two flattened closed sacs filled with pleural fluid, each ensheathing each lung and lining their surrounding tissues, locally appearing as two opposing layers of serous membrane separating the lungs from the med ...

(blue), and

heart The heart is a muscular Organ (biology), organ found in humans and other animals. This organ pumps blood through the blood vessels. The heart and blood vessels together make the circulatory system. The pumped blood carries oxygen and nutrie ...

(red outline).

Heart valves A heart valve is a biological one-way valve that allows blood to flow in one direction through the chambers of the heart. A mammalian heart usually has four valves. Together, the valves determine the direction of blood flow through the heart. Hea ...

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

References

External links

* {{DEFAULTSORT:Aortic Valve Cardiac anatomy Heart valves