Background and History
Heart valve surgery is a procedure developed over the years with the aim to treat heart valve deficiencies. This surgery has changed the natural history of valvular heart problems. The invention of the heart-lung machine in 1953 allowed the development of open-heart surgery techniques such as heart valve surgery.
Open-heart surgery made it possible to perform surgery on important valves such as the mitral and pulmonary ones and also made it possible to work on the aortic valve for the first time. The first mechanical replacement valve was designed and implanted by Albert Star and Lowell Edwards in 1960. The first valve replacement from a human patient was done in 1962.
Since then the development of mechanical valves has been huge, together with the use of homograft (valves taken from humans) and xenografts (valves from different species such as pigs). In recent years new, minimally invasive and endovascular approaches for valve delivery are being performed and studied as replacement for open-heart surgery, although the conventional and traditional surgery is still performed.
The heart consists of four chambers: two upper chambers (atria), and two lower chambers (ventricles). The valves are located between the atria and ventricle and between the ventricles and the great vessels: pulmonary artery and aorta. The main function of the valves is to prevent the backward flow of the blood. There are four heart valves including the tricuspid valve (connecting right atrium with the right ventricle), pulmonary valve (connecting right ventricle with the pulmonary artery), mitral valve (connecting left atrium with the left ventricle) and aortic valve (connecting left ventricle with the aorta)
The valves open and close, allowing the flow of the blood into the ventricles and great vessels during the diastole and systole of the heart.
The heart valves can have abnormal functions related to the anatomy and function such as regurgitation or insufficiency and stenosis. In the case of the regurgitation, the valve does not close completely, producing a backflow. Stenotic valves are those suffering from a narrowing. The valve does not open properly reducing the blood flow. The main consequence of this process is the increase in intracavitary pressure modifying the ejection fraction of the heart.
The indications of Heart Valve replacement are defined by the American Heart Association of Cardiology and the European Society of Cardiology. The decision of surgical intervention is determined by the severity of the stenosis or regurgitation as well as the combination of other factors such as left ventricular function and heart contractility. The most common valves replaced are aortic and mitral valves. Pulmonary and tricuspid valve replacements are somewhat uncommon in adults.
The most frequent surgical procedure is aortic valve replacement due to aortic stenosis.
Details on the procedure and different techniques
There are three common types of heart valve procedures.
- Open heart surgery to repair or replace a valve.
- Transcatheter aortic valve implantation.
Heart valve repair
The valves can be repaired using different techniques:
- Commissurotomy. This procedure is used for stenotic valves, with thickened leaflets due to fibrosis secondary to a systemic inflammatory disease that affects collagen tissue. The valve is opened by cutting the junction points of the leaflets
- Valvuloplasty. This procedure helps by increasing strength to the leaflets allowing better function. This is achieved by implanting a device around the valve opening.
- Reshaping is a surgical procedure performed by reshaping the valve leaflets allowing the valve to open and close more completely
- Decalcification helps to remove calcium deposit from the leaflets.
- Repair of structural support (chordae tendineae and the papillary muscles)
- Patching covers with a tissue patch.
Transcatheter Aortic Valve Implantation (TAVI)
Transcatheter aortic valve implantation is considered a minimally invasive procedure to repair a damaged or diseased aortic valve. It is performed while the heart is beating. For the TAVI procedure, a catheter is placed in the femoral artery or radial artery. The catheter is guided into the heart. A compressed tissue heart valve is placed on the balloon catheter and positioned directly inside the diseased aortic valve. Once the new valve is in position, the balloon is inflated to secure the valve in place. The balloon is then deflated and the catheter is withdrawn. The tissue valve is made of bovine (cow) pericardium supported by a metal stent.
The procedure is performed with general anaesthesia by a team of interventional cardiologists and imaging specialists, using fluoroscopy and echocardiography guiding the valve to the site of implantation/replacement.
It is only appropriate for patients with severe symptomatic aortic stenosis who are not candidates for traditional open-heart surgery or who are considered high-risk candidates.
Heart valve replacement
If the heart valve can’t be repaired a heart valve replacement will be necessary. To replace a heart valve, the surgeon removes the heart valve and replaces it with a mechanical valve or a valve made from biological tissue.
There are two kinds of valves typically used for heart valve replacement: mechanical valves and biological valves.
- Mechanical valves are manufactured from different materials such as carbon, or metal. They are very strong, and they have a long lifetime. The main inconvenience is the increased risk of thrombosis. As a result, the patient needs to use anticoagulant medications for the rest of their life.
- Biological valves are constituted of natural tissues or taken from a donated human heart. Patients with this type of valves don’t need anticoagulation therapy. These valves need to be replaced every 10 years.
Minimally Invasive Valve Surgery
Minimally invasive heart valve surgery is a technique that uses smaller incisions to repair or replace heart valves. It also reduces the pain, the length of the hospital stay and the recovery time.
This type of surgery cannot be done in patients with severe valve damage, patients with more than one valve to be repaired or replaced, or patients with associated risk factors such as atherosclerosis or obesity
In some cases, it can be done using robotic surgery.
Heart valve surgery
Heart valve surgery can be performed during an open-heart surgery, which involves a large incision in the chest. The patient receives general anaesthesia and will be unconscious during the procedure. The patient will be connected to a heart-lung bypass machine which keeps blood moving through the body even when the heart will stop beating to allow the surgeons to perform surgery on it.
Possible complications / Risks
- Heart attack
- Valve dysfunction affecting the replaced valve
- Irregular heart rhythm (arrhythmia)
Post-Op details and follow ups
After the heart valve surgery, the patient will spend one day or more in the intensive care unit. After the ICU, the patient will be transferred to a regular room for five to seven days. The Cardiac rehabilitation program is very important during this period. The patient will start to walk regularly and will do breathing exercises. Minimally invasive procedures like TAVI or valvuloplasty don’t require long hospital stays or recovery periods.
After the first week, the patient can go home. It takes between six to twelve weeks for the sternum to heal completely. During this time, the patient will need to avoid lifting heavy objects and doing movements that put stress on the chest and needs to continue the cardiac rehabilitation.
The patient can usually go back to work after 4 to 6 weeks but patients with physically active jobs may need to wait longer.
Most valve repair and replacement operations are successful. In some rare cases, a valve repair may fail and another operation may be needed. Patients with a biological valve may need to have the valve replaced in 10 to 15 years. Mechanical valves may also fail, so patients should alert their doctor if they are having any symptoms of valve failure.
The endocarditis as a fatal complication needs to be prevented. The patient needs to advise the dentist or doctor in case of a surgical or dental procedure. The use of antibiotics is extremely important as part of the plan of prevention of bacterial endocarditis.