The
aortic valve is one of the
valvesIn anatomy, the heart valves maintain the unidirectional flow of blood in the heart by opening and closing depending on the difference in pressure on each side...
of the
heartThe heart is a muscular organ found in all vertebrates that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
. It lies between the
left ventricleThe left ventricle is one of four chambers in the human heart. It receives oxygenated blood from the left atrium via the mitral valve, and pumps it into the aorta via the aortic valve.-Shape:...
and the
aortaThe aorta is the largest artery in the body, originating from the left ventricle of the heart and bringing oxygenated blood to all parts of the body in the systemic circulation....
.
During ventricular
systoleSystole , is a phase of the cardiac cycle where the myocardium is contracting in a coordinated manner in response to an endogenous electrical stimulus, and pressure is being generated within the chambers of the heart driving blood flow....
,
pressurePressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
rises in the left ventricle. When the pressure in the left ventricle rises above the pressure in the aorta, the aortic valve opens, allowing
bloodBlood is a specialized bodily fluid that delivers necessary substances to the body's cells — such as nutrients and oxygen — and transports waste products away from those same cells....
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 aortic pressure forces the aortic valve to close.
The
aortic valve is one of the
valvesIn anatomy, the heart valves maintain the unidirectional flow of blood in the heart by opening and closing depending on the difference in pressure on each side...
of the
heartThe heart is a muscular organ found in all vertebrates that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
. It lies between the
left ventricleThe left ventricle is one of four chambers in the human heart. It receives oxygenated blood from the left atrium via the mitral valve, and pumps it into the aorta via the aortic valve.-Shape:...
and the
aortaThe aorta is the largest artery in the body, originating from the left ventricle of the heart and bringing oxygenated blood to all parts of the body in the systemic circulation....
.
Function and physiology
During ventricular
systoleSystole , is a phase of the cardiac cycle where the myocardium is contracting in a coordinated manner in response to an endogenous electrical stimulus, and pressure is being generated within the chambers of the heart driving blood flow....
,
pressurePressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
rises in the left ventricle. When the pressure in the left ventricle rises above the pressure in the aorta, the aortic valve opens, allowing
bloodBlood is a specialized bodily fluid that delivers necessary substances to the body's cells — such as nutrients and oxygen — and transports waste products away from those same cells....
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 aortic pressure forces the aortic valve to close. The closure of the aortic valve contributes the A
2 component of the second heart sound (S
2).
Disease of the aortic valve
There are two protypical processes that can affect the aortic valve - aortic stenosis in which the valve fails to open fully, thereby obstructing blood flow out from the heart, and
aortic insufficiencyAortic insufficiency , also known as aortic regurgitation , 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....
, also called aortic regurgitation, in which the aortic valve is incompetent and blood flows passively back to the heart in the wrong direction. These two conditions frequently co-exist.
- Common causes of aortic stenosis include rheumatic fever
Rheumatic fever is an inflammatory disease that may develop two to three weeks after a Group A streptococcal infection . It is believed to be caused by antibody cross-reactivity and can involve the heart, joints, skin, and brain...
, degenerative calcification, and congenital diseases such as bicuspid aortic valveA bicuspid aortic valve is a defect of the aortic valve that results in the formation of two leaflets or cusps instead of the normal three. Normally only the mitral valve has two cusps ; situated between the left atrium and left ventricle...
.
- Common causes of aortic regurgitation include dilation of the aorta, previous rheumatic fever
Rheumatic fever is an inflammatory disease that may develop two to three weeks after a Group A streptococcal infection . It is believed to be caused by antibody cross-reactivity and can involve the heart, joints, skin, and brain...
, infection, i.e. infective endocarditisInfective endocarditis is a form of endocarditis caused by infectious agents. The agents are usually bacterial, but other organisms can also be responsible....
, myxomatous degeneration of the aortic valve, and Marfan's syndrome.
Bicuspid aortic valve
The most common congenital abnormality of the heart is the
bicuspid aortic valveA bicuspid aortic valve is a defect of the aortic valve that results in the formation of two leaflets or cusps instead of the normal three. Normally only the mitral valve has two cusps ; situated between the left atrium and left ventricle...
. In this condition, instead of three cusps, the aortic valve has two cusps. This condition is often undiagnosed until later in life when the person develops symptomatic aortic stenosis. Aortic stenosis occurs in this condition usually in patients in their 40s or 50s, an average of 10 years earlier than can occur in people with congenitally normal aortic valves.
Patients with Turner's Syndrome usually have associated bicuspid aortic valves.
Aortic Valve Replacement
Aortic valve replacementAortic valve replacement is a cardiac surgery procedure in which a patient's aortic valve is replaced by a different valve. The aortic valve can be affected by a range of diseases; the valve can either become leaky or partially blocked...
means that a patient's aortic valve is replaced by a different valve. The aortic valve can be affected by a range of diseases and require aortic valve replacement. The valve can either become leaky (
regurgitantMitral regurgitation , a valvular heart disease also known as mitral insufficiency or mitral incompetence, is the abnormal leaking of blood through the mitral valve, from the left ventricle into the left atrium of the heart.-Etiology:...
or insufficient) or stuck partially shut (
stenoticA stenosis is an abnormal narrowing in a blood vessel or other tubular organ or structure.It is also sometimes called a "stricture" ....
). Aortic valve replacement currently requires open heart surgery. Research is being done now to develop valves that can be implanted using a
catheterIn medicine a catheter is a tube that can be inserted into a body cavity, duct or vessel. Catheters thereby allow drainage, injection of fluids or access by surgical instruments. The process of inserting a catheter is catheterization. In most uses a catheter is a thin, flexible tube , although...
without open heart surgery. There are two basic types of artificial heart valve, mechanical valves and tissue valves. Tissue heart valves are usually made from animal tissues, either animal heart valve tissue or animal pericardial tissue. The tissue is treated to prevent rejection and to prevent calcification.
There are alternatives to animal tissue valves. In some cases a human aortic valve can be implanted. These are called homografts. Homograft valves are donated by patients and harvested after the patient expires. The durability of homograft valves is probably the same for porcine tissue valves. Another procedure for aortic valve replacement is the
Ross procedureThe Ross procedure is a cardiac surgery operation where a diseased aortic valve is replaced with the person's own pulmonary valve. A pulmonary homograft is then used to replace the patient's own pulmonary valve...
(after Donald Ross) or pulmonary autograft. 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 valveThe pulmonary valve is the semilunar valve of the heart that lies between the right ventricle and the pulmonary artery and has three cusps. Similar to the aortic valve, the pulmonary valve opens in ventricular systole, when the pressure in the right ventricle rises above the pressure in the...
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 ClinicThe Cleveland Clinic is a multispecialty academic medical center located in Cleveland, Ohio, United States...
in 1996.