Aortic valve replacement
Encyclopedia
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 (aortic insufficiency
/ regurgitation) or partially blocked (aortic stenosis). Aortic valve replacement is open heart surgery
.
A catheter
-based approach (percutaneous aortic valve replacement
or PAVR), approved in Europe and in clinical trials in the United States, eliminates the need for open heart surgery, but is associated with a higher risk of stroke.
There are alternatives to animal tissue valves. In some cases a homograft - a human aortic valve—can be implanted. Homograft valves are donated by patients and harvested after the patient dies. The durability of homograft valves is comparable to porcine and bovine tissue valves. Another procedure for aortic valve replacement is the Ross procedure
(or pulmonary autograft). In a Ross procedure, the aortic valve is removed and replaced with the patient's own pulmonary valve
. A pulmonary homograft (pulmonary valve taken from a cadaver) is then used to replace the patient's own pulmonary valve. This procedure was first used in 1967 and is used primarily in children, as the procedure allows the patient's own pulmonary valve (now in the aortic position) to grow with the child.
for the rest of their lives, making the patient more prone to bleeding.
Warfarin is the traditional drug used as an anticoagulant. There is a study underway into the use of Plavix instead of Warfarin, which could significantly simplify blood clotting control. Estimated Study Completion Date: March 2015.
There is a promising new valve replacement procedure called a Trans-catheter Aortic Valve (TCAV). It is currently only available for high risk patients and still in the research stage. In the future it may be possible for the recipient of a prosthetic tissue valve to have a much less invasive surgery performed to insert a new valve once the replacement valve wears out. A new valve is compressed and positioned orthoscopically and then it is expanded within the first replacement valve forcing it open and allowing the TCAV to operate. The current expected life span of the TCAV is approximately 10–15 years. It is also expected that yet another TCAV can be implanted within the first TCAV. As technology advances the lifespan of the TCAV may be extended.
, meaning the incision is made by cutting through the sternum. Once the pericardium
has been opened, the patient is put on a cardiopulmonary bypass machine, also known as the heart-lung machine. This machine takes over the task of breathing for the patient and pumping their blood around while the surgeon replaces the heart valve.
Once the patient is on bypass, a cut is made in the aorta and a crossclamp applied. The surgeon then removes the patient's diseased aortic valve and a mechanical or tissue valve is put in its place. Once the valve is in place and the aorta has been closed, the patient is taken off the heart-lung machine. Transesophageal echocardiogram
(TEE, an ultra-sound of the heart done through the esophagus) can be used to verify that the new valve is functioning properly. Pacing wires are usually put in place, so that the heart can be manually paced should any complications arise after surgery. Drainage tubes are also inserted to drain fluids from the chest and pericardium following surgery. These are usually removed within 36 hours while the pacing wires are generally left in place until right before the patient is discharged from the hospital.
Recovery from aortic valve replacement will take about three months, if the patient is in good health. Patients are advised not to do any heavy lifting for 4–6 months after surgery, to avoid damage to the sternum (the breast bone).
implants the valves using a catheter, without open heart surgery. It is used in Europe in patients who are at high risk to undergo open heart surgery, but is in clinical trial
s in North America, at Cedars-Sinai Medical Center
and elsewhere. The SAPIEN valve is made by Edwards Lifesciences. The Medtronic Corevalve device is another device used for this procedure
In high-risk patients with severe aortic stenosis, transcatheter and surgical procedures for aortic-valve replacement had similar rates of survival at 1 year, although there were important differences in risks associated with the procedure. The transcatheter procedure was associated with a higher risk of stroke than the surgical replacement (5.5% vs. 2.4% after 30 days; 8.3% vs. 4.3% after 1 year).
http://en.wikipedia.org/wiki/Pericardial_heart_valves
Cardiac surgery
Cardiovascular surgery is surgery on the heart or great vessels performed by cardiac surgeons. Frequently, it is done to treat complications of ischemic heart disease , correct congenital heart disease, or treat valvular heart disease from various causes including endocarditis, rheumatic heart...
procedure in which a patient's failing aortic valve
Aortic valve
The aortic valve is one of the valves of the heart. It is normally tricuspid , although in 1% of the population it is found to be congenitally bicuspid . It lies between the left ventricle and the aorta....
is replaced with an alternate healthy valve. The aortic valve can be affected by a range of diseases; the valve can either become leaky (aortic insufficiency
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....
/ regurgitation) or partially blocked (aortic stenosis). Aortic valve replacement is open heart surgery
Open Heart Surgery
Open Heart Surgery was released on August 8, 2000 by rock band Virginwool. The band signed to Breaking/Atlantic Records after initially beginning signed to Universal Records. The album was produced and mixed by Brad Wood....
.
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...
-based approach (percutaneous aortic valve replacement
Percutaneous aortic valve replacement
In Percutaneous aortic valve replacement or Transcatheter Aortic Valve Implantation , a replacement valve is passed through a hole in the groin by a puncture of the femoral artery and advanced up to the ascending aorta of the patient. It substitutes for a more invasive procedure in which the chest...
or PAVR), approved in Europe and in clinical trials in the United States, eliminates the need for open heart surgery, but is associated with a higher risk of stroke.
Types of heart valves
There are two basic types of artificial heart valve: mechanical valves and tissue valves.Tissue valves
Tissue heart valves are usually made from animal tissue, either animal heart valve tissue or animal pericardial tissue. The tissue is treated to prevent rejection and calcification.There are alternatives to animal tissue valves. In some cases a homograft - a human aortic valve—can be implanted. Homograft valves are donated by patients and harvested after the patient dies. The durability of homograft valves is comparable to porcine and bovine 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...
(or pulmonary autograft). In a Ross procedure, the aortic valve is removed and replaced with the patient's own 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...
. A pulmonary homograft (pulmonary valve taken from a cadaver) is then used to replace the patient's own pulmonary valve. This procedure was first used in 1967 and is used primarily in children, as the procedure allows the patient's own pulmonary valve (now in the aortic position) to grow with the child.
Mechanical valves
Mechanical valves are designed to outlast the patient, and have typically been stress-tested to last several hundred years. Although mechanical valves are long-lasting and generally present a one-surgery solution, there is an increased risk of blood clots forming with mechanical valves. As a result, mechanical valve recipients must take anticoagulant (blood thinning) drugs such as warfarinWarfarin
Warfarin is an anticoagulant. It is most likely to be the drug popularly referred to as a "blood thinner," yet this is a misnomer, since it does not affect the thickness or viscosity of blood...
for the rest of their lives, making the patient more prone to bleeding.
Warfarin is the traditional drug used as an anticoagulant. There is a study underway into the use of Plavix instead of Warfarin, which could significantly simplify blood clotting control. Estimated Study Completion Date: March 2015.
Valve selection
Tissue valves tend to wear out faster with increased flow demands - such as with a more active (typically younger) person. Tissue valves typically last 10–15 years in less active (typically elderly) patients, but wear out faster in younger patients. When a tissue valve wears out and needs replacement, the person must undergo another valve replacement surgery. For this reason, younger patients are often recommended mechanical valves to prevent the increased risk (and inconvenience) of another valve replacement.There is a promising new valve replacement procedure called a Trans-catheter Aortic Valve (TCAV). It is currently only available for high risk patients and still in the research stage. In the future it may be possible for the recipient of a prosthetic tissue valve to have a much less invasive surgery performed to insert a new valve once the replacement valve wears out. A new valve is compressed and positioned orthoscopically and then it is expanded within the first replacement valve forcing it open and allowing the TCAV to operate. The current expected life span of the TCAV is approximately 10–15 years. It is also expected that yet another TCAV can be implanted within the first TCAV. As technology advances the lifespan of the TCAV may be extended.
Surgical Procedure
Aortic valve replacement is most frequently done through a median sternotomyMedian sternotomy
Median sternotomy is a type of surgical procedure in which a vertical inline incision is made along the sternum, after which the sternum itself is divided, or "cracked"...
, meaning the incision is made by cutting through the sternum. Once the pericardium
Pericardium
The pericardium is a double-walled sac that contains the heart and the roots of the great vessels.-Layers:...
has been opened, the patient is put on a cardiopulmonary bypass machine, also known as the heart-lung machine. This machine takes over the task of breathing for the patient and pumping their blood around while the surgeon replaces the heart valve.
Once the patient is on bypass, a cut is made in the aorta and a crossclamp applied. The surgeon then removes the patient's diseased aortic valve and a mechanical or tissue valve is put in its place. Once the valve is in place and the aorta has been closed, the patient is taken off the heart-lung machine. Transesophageal echocardiogram
Transesophageal echocardiogram
A transesophageal echocardiogram, or TEE , is an alternative way to perform an echocardiogram. A specialized probe containing an ultrasound transducer at its tip is passed into the patient's esophagus...
(TEE, an ultra-sound of the heart done through the esophagus) can be used to verify that the new valve is functioning properly. Pacing wires are usually put in place, so that the heart can be manually paced should any complications arise after surgery. Drainage tubes are also inserted to drain fluids from the chest and pericardium following surgery. These are usually removed within 36 hours while the pacing wires are generally left in place until right before the patient is discharged from the hospital.
Hospital stay and recovery time
After aortic valve replacement, the patient will frequently stay in an intensive care unit for 12–36 hours. The patient is often able to go home after this, in about four days, unless complications arise. Common complications include heart block, which typically requires the permanent insertion of a cardiac pacemaker.Recovery from aortic valve replacement will take about three months, if the patient is in good health. Patients are advised not to do any heavy lifting for 4–6 months after surgery, to avoid damage to the sternum (the breast bone).
Surgical outcome and risk of procedure
The risk of death or serious complications from aortic valve replacement is typically quoted as being between 1-3%, depending on the health and age of the patient, as well as the skill of the surgeon. Older patients, as well as more fragile ones, are sometimes ineligible for surgery because of elevated risks.Percutaneous aortic valve replacement
Percutaneous aortic valve replacementPercutaneous aortic valve replacement
In Percutaneous aortic valve replacement or Transcatheter Aortic Valve Implantation , a replacement valve is passed through a hole in the groin by a puncture of the femoral artery and advanced up to the ascending aorta of the patient. It substitutes for a more invasive procedure in which the chest...
implants the valves using a catheter, without open heart surgery. It is used in Europe in patients who are at high risk to undergo open heart surgery, but is in clinical trial
Clinical trial
Clinical trials are a set of procedures in medical research and drug development that are conducted to allow safety and efficacy data to be collected for health interventions...
s in North America, at Cedars-Sinai Medical Center
Cedars-Sinai Medical Center
Originally established as Kaspare Cohn Hospital in 1902, Cedars-Sinai Medical Center is a non-profit, tertiary 958-bed hospital and multi-specialty academic health science centre located in Los Angeles, California, US. Part of the Cedars-Sinai Health System, the hospital employs a staff of over...
and elsewhere. The SAPIEN valve is made by Edwards Lifesciences. The Medtronic Corevalve device is another device used for this procedure
In high-risk patients with severe aortic stenosis, transcatheter and surgical procedures for aortic-valve replacement had similar rates of survival at 1 year, although there were important differences in risks associated with the procedure. The transcatheter procedure was associated with a higher risk of stroke than the surgical replacement (5.5% vs. 2.4% after 30 days; 8.3% vs. 4.3% after 1 year).
See also
- Aortic valve repair
- Artificial heart valveArtificial heart valveAn artificial heart valve is a device implanted in the heart of a patient with heart valvular disease. When one of the four heart valves malfunctions, the medical choice may be to replace the natural valve with an artificial valve. This requires open-heart surgery.Valves are integral to the normal...
- Valvular heart diseaseValvular heart diseaseValvular heart disease is any disease process involving one or more of the valves of the heart . Valve problems may be congenital or acquired...
- Minimally Invasive Heart Surgery
http://en.wikipedia.org/wiki/Pericardial_heart_valves