Aortic valve replacement is a procedure in which a failed patient aortic valve is replaced by an artificial heart valve. Aortic valves can be affected by various diseases; the valve may become leaky (aortic insufficiency) or partially obstructed (aortic stenosis). Current aortic valve replacement approaches include open heart surgery through sternotomy, minimally invasive cardiac surgery (MICS) and transcacheter aortic valve replacement (TAVR).
Video Aortic valve replacement
Medical use
Because the risk of aortic valve surgery has decreased and long-term data on survival and quality of life of people after valve replacement is available, evidence-based guidelines for aortic valve replacement have been developed. The American Heart Association and the American College of Cardiology Guidelines for Management of Patients with Valvular Heart Disease are widely accepted sources of information for cardiologists and surgeons.
Aortic stenosis
Patients with severe aortic stenosis, where the aortic valve narrows and the blood flow from the hampered heart are candidates for surgery when they develop symptoms or when heart function is affected. Patients with no specific symptoms may also be candidates for surgery, especially if the stress test exercises are positive. Aortic_insufficiency Aortic insufficiency
Patients with a leaky aortic valve (aortic insufficiency) often tolerate even the degree of weight of insufficiency for a relatively long time before symptoms develop. Surgery is indicated for symptoms such as shortness of breath, and in cases where the heart has begun to swell (enlarge) from pumping up the volume of blood that leaks back through the valve.
Maps Aortic valve replacement
Valve type
There are two basic types of artificial heart valves: mechanical valves and tissue valves.
Network valve
The heart valve tissue is usually made of animal tissue, either the animal heart valve tissue or the animal's pericardial tissue. Networks are treated to prevent rejection and liming.
There is an alternative to animal tissue valves. In some cases, homograft - the human aortic valve - can be implanted. Homograft valves are donated by the patient and restored after the patient dies. The durability of the homograft valve is proportional to the valve of pig and bovine tissue. Another procedure for aortic valve replacement is Ross procedure (or autograft pulmonary). In the Ross procedure, the aortic valve is removed and replaced by the patient's own pulmonary valve. The lung homograft (pulmonary valve taken from the corpse) is then used to replace the patient's own pulmonary valve. This procedure was first used in 1967 and is used primarily in children, since this 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 patients, and usually have been stress tested for the last few hundred years. Although mechanical valves are durable and generally present a one-operation solution, there is an increased risk of blood clot formation with mechanical valves. As a result, mechanical valve recipients should take anticoagulant drugs (blood thinners) such as warfarin for the rest of their lives, making patients more susceptible to bleeding. The sound of mechanical valves can be heard and degrade the quality of life.
Valve options
Tissue valves tend to run out faster with increasing flow requirements - as with more active (usually younger) people. The tissue valves increase for longer - now usually around 20 years, but they may wear out more quickly in younger people. When the network valve runs out and needs to be replaced, the person has to undergo valve replacement surgery. For this reason, younger patients often receive mechanical valves to prevent increased risk (and discomfort) of valve replacement.
Surgical procedure
Aortic valve replacement is most often performed through the median sternotomy, which means the incision is made by cutting the sternum. After the pericardium is opened, the patient is inserted into a cardiopulmonary shortcut, also known as a heart-lung machine. This machine takes over the task of breathing for the patient and pumps blood around them while the surgeon replaces the heart valve.
After the patient performs a bypass, the cutting is done in the aorta and the crossclamp is applied. The surgeon then lifts the aortic valve of the sick patient and the mechanical valve or tissue is placed in place. Once the valve is in place and the aorta has been closed, the patient is taken from the heart-lung machine. A transesophageal echocardiogram (TEE, an ultra-heart sound done through the esophagus) can be used to verify that the new valve is functioning properly. The pacing wires are usually installed in place, so the heart can be manually moved if there are complications arising after surgery. Drainage of the tube is also included to drain fluid from the chest and pericardium after surgery. These are usually removed within 36 hours while the pacing wires are generally left in place until just before the patient is discharged from the hospital.
Hospital stay and recovery time
After aortic valve replacement, patients will often stay in the intensive care unit for 12-36 hours. Patients can often go home after this, about four days, unless complications arise. Common complications include heart block, which usually requires permanent insertion of pacemaker.
Recovery from aortic valve replacement will take about three months, if the patient is in good health. Patients are advised not to do heavy lifting for 4-6 months after surgery, to avoid damage to the sternum (breast bone).
Results
The risk of death or serious complications from aortic valve replacement is usually quoted between 1-3%, depending on the health and age of the patient. Older patients, as well as those who are weak and/or have some comorbidities (ie other health problems), may face significantly higher surgical risk.
Minimally invasive surgery
Recently, some cardiac surgeons have performed aortic valve replacement procedure using an approach called minimally invasive heart surgery (MICS), where surgeons replace the valve through a small incision between two and four inches long using a special surgical instrument rather than by cutting a six to ten inch incision in the middle of the sternum. MICs typically involve shorter recovery times and more attractive cosmetic results.
Another promising alternative for many high-risk and older patients is the transcatheter aortic valve replacement (TAVR), which provides a new valve to where the diseased valve passes through the catheter. Replacement valves collapsed and packed in a manner similar to a stent. Once the place is expanded, push the old valve leaflet out of the way, and work in place of the old valve. The catheter can be inserted through the femoral artery or through a small incision in the chest and then through the large artery or left ventricular end.
Guidelines recommend TAVR for the majority of patients over 75 and surgical replacement for most patients is less than 75. Ultimately, the best treatment option is a decision based on many individual factors.
History
The initial surgical approach to aortic valve disease is limited by the need for surgery by heart beating. In the 1950s the Hufnagel valve was implanted in the descending thoracic aorta in patients with aortic insufficiency. The substitute of the first aortic valve was successfully reported in 1960 by Harken, and the early adoption of this technique went slowly based on the limitations of available replacement valves and a relatively primitive technique for protecting the heart during the operations available at the time. With the evolution of mechanical heart valves and gradual development in cardiopulmonary bypass and cardioplegia that allow the heart to stop safely during surgery, aortic valve replacement becomes the accepted therapy for patients with severe aortic insufficiency or regurgitation.
See also
- Aortic valve repair
- Artificial heart valves
- Valvular heart disease
- Minimally invasive heart surgery
- Pericardial heart valve
- Open aortic surgery
References
External links
- Aortic Valve Replacement Information for Patients
- Information on Aortic Valve Replacement
- Aorta Valve Replacement Animation
Source of the article : Wikipedia
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