Aortic valve
Encyclopedia
The aortic valve is one of the valves
of the heart
. It is normally tricuspid (with three leaflets), although in 1% of the population it is found to be congenitally bicuspid (two leaflets). It lies between the left ventricle
and the aorta
.
, 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
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 A2 component of the second heart sound (S2). fdfd
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 insufficiency
, 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.
. 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.
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 become either leaky (regurgitant
or insufficient) or stuck partially shut (stenotic
). Aortic valve replacement currently requires open heart surgery. Research is being done now to develop valves that can be implanted using a catheter
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 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
(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 valve
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
in 1996.
Heart valve
A heart valve normally allows blood flow in only one direction through the heart. The four valves commonly represented in a mammalian heart determine the pathway of blood flow through the heart...
of the heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
. It is normally tricuspid (with three leaflets), although in 1% of the population it is found to be congenitally bicuspid (two leaflets). It lies between the left ventricle
Left ventricle
The 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 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...
.
Function and physiology
During ventricular systoleSystole (medicine)
Systole is the contraction of the heart. Used alone, it usually means the contraction of the left ventricle.In all mammals, the heart has 4 chambers. The left and right ventricles pump together. The atria and ventricles pump in sequence...
, pressure
Pressure
Pressure 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 blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic 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 A2 component of the second heart sound (S2). fdfd
Disease of the aortic valve
Aortic insufficiency
Aortic 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 feverRheumatic feverRheumatic fever is an inflammatory disease that occurs following a Streptococcus pyogenes infection, such as strep throat or scarlet fever. Believed to be caused by antibody cross-reactivity that can involve the heart, joints, skin, and brain, the illness typically develops two to three weeks after...
, degenerative calcification, and congenital diseases such as bicuspid aortic valveBicuspid aortic valveA bicuspid aortic valve is most commonly a congenital condition of the aortic valve where two of the aortic valvular leaflets fuse during development resulting in a valve that is bicuspid instead of the normal tricuspid configuration. Normally the only cardiac valve that is bicuspid is the mitral...
. - Common causes of aortic regurgitation include dilation of the aorta, previous rheumatic feverRheumatic feverRheumatic fever is an inflammatory disease that occurs following a Streptococcus pyogenes infection, such as strep throat or scarlet fever. Believed to be caused by antibody cross-reactivity that can involve the heart, joints, skin, and brain, the illness typically develops two to three weeks after...
, infection, i.e. infective endocarditisInfective endocarditisInfective endocarditis is a form of endocarditis, or inflammation, of the inner tissue of the heart, such as its valves, 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 valveBicuspid aortic valve
A bicuspid aortic valve is most commonly a congenital condition of the aortic valve where two of the aortic valvular leaflets fuse during development resulting in a valve that is bicuspid instead of the normal tricuspid configuration. Normally the only cardiac valve that is bicuspid is the mitral...
. 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
Aortic valve replacement is a cardiac surgery procedure in which a patient's failing aortic valve is replaced with an alternate healthy 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 become either leaky (regurgitant
Mitral regurgitation
Mitral regurgitation , mitral insufficiency or mitral incompetence is a disorder of the heart in which the mitral valve does not close properly when the heart pumps out blood. It is the abnormal leaking of blood from the left ventricle, through the mitral valve, and into the left atrium, when...
or insufficient) or stuck partially shut (stenotic
Stenosis
A 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 catheter
Catheter
In medicine, a catheter is a tube that can be inserted into a body cavity, duct, or vessel. Catheters thereby allow drainage, administration of fluids or gases, or access by surgical instruments. The process of inserting a catheter is catheterization...
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 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
Ross procedure
The Ross procedure is a cardiac surgery operation where a diseased aortic valve is replaced with the person's own pulmonary valve. A pulmonary allograft 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 valve
Pulmonary valve
The 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 Clinic
Cleveland Clinic
The Cleveland Clinic is a multispecialty academic medical center located in Cleveland, Ohio, United States. The Cleveland Clinic is currently regarded as one of the top 4 hospitals in the United States as rated by U.S. News & World Report...
in 1996.