Within the chambers of our heart, there are four valves. One of these, the mitral valve, is located on the left side of the heart between the left atrium and the left ventricle. Under normal conditions, it is a one-way valve that opens and closes, allowing blood to flow only from the atrium into the ventricle. The mitral valve ensures that all the oxygen-rich blood coming from the lungs into the left atrium passes completely into the left ventricle. From there, with each contraction of the heart, this clean blood is pumped into the aorta, the body’s main artery. In other words, the mitral valve functions much like a door that opens in one direction and closes securely at the point it should. To perform its role properly, it must open during the relaxation phase of the heart muscle and close completely when the heart contracts.
Structurally, the mitral valve consists of two leaflets that meet tightly with no gaps. These leaflets are firmly anchored to a region called the annulus, positioned between the atrium and ventricle, and they open and close in one direction. Their movement is supported by thin, string-like structures called chordae, which are attached to the tips and body of the leaflets and move in coordination with the heart’s contraction. When the mitral valve is open, all the blood entering the left atrium should pass into the left ventricle. During systole, the phase when the heart contracts, the mitral valve must close completely so that all the blood collected in the left ventricle is pumped through the aortic valve into the body. If the valve cannot open or close properly, part of the blood that should be delivered to the body flows back into the left atrium. This leads to increased pressure in the vessels leading to the lungs (pulmonary arteries), a condition known as pulmonary hypertension.
In conditions such as rheumatic heart disease or congenital structural abnormalities of the mitral valve, the valve gradually loses its normal elasticity. Over time, the valve tissue thickens and becomes calcified. As the valve loses its flexibility, it can no longer open fully. In this situation, not all of the oxygen-rich blood coming from the lungs can pass into the left ventricle during diastole, and part of it remains in the left atrium. The accumulation of blood in the atrium eventually causes thickening of the atrial wall and an increase in atrial pressure. This rise in pressure is transmitted backward into the pulmonary artery, leading to elevated pulmonary pressure. Patients begin to experience shortness of breath during exertion and palpitations.
Initially, the palpitations occur with a regular rhythm, but later they may become irregular due to the development of atrial fibrillation (AF). Blood clots (thrombi) may form within the left atrium, and if a clot travels to the brain, it can cause a stroke in patients with mitral valve disease. When symptoms such as shortness of breath and palpitations appear in patients with mitral valve stenosis, it generally indicates that surgical intervention is needed. In some cases, non-calcified stenotic valves can be opened with a balloon procedure, but most often surgery is required. If the valve can be repaired, repair is the preferred option; if not, it is replaced. Additionally, if the patient has AF, this rhythm disorder can also be treated during surgery.
Today, mitral regurgitation is seen more frequently than mitral stenosis. The most common cause is degenerative mitral valve disease. In this condition, the chordae tendineae – the thread-like structures that attach the mitral valve leaflets to the heart muscle – become weakened, and prolonged exposure to pressure may eventually cause them to rupture. When the chordae loosen or rupture, the connection between the valve leaflets and the heart weakens. As a result, when the heart contracts, blood flows backward into the left atrium instead of moving forward into the aorta.
Another important cause of mitral regurgitation is the enlargement of the heart due to weakening of the heart muscle. As the heart enlarges, the annulus – the ring-like structure to which the valve leaflets attach – becomes dilated. When the annulus enlarges, the leaflets can no longer meet properly, leaving a gap between them. During systole, blood from the left ventricle leaks through this gap into the left atrium, raising atrial pressure. Over time, this causes the atrium to enlarge, creating a predisposition for atrial fibrillation (AF). The development of AF further worsens symptoms.
Ischemic heart disease and previous heart attacks are also significant causes of mitral regurgitation. When part of the heart muscle loses its contractile function due to a heart attack, the synchronization of the valve leaflets is disrupted. As the heart enlarges over time, the mitral valve fails to close completely during systole, leading to regurgitation. In patients who have undergone bypass surgery, mild regurgitation present before surgery may progress due to gradual heart enlargement. This worsening regurgitation is often the main reason for shortness of breath after bypass surgery.
Another severe cause of mitral regurgitation is infective endocarditis. In this condition, an infection in the body settles on the mitral valve, damaging its structure and causing regurgitation. This is a life-threatening condition and requires urgent treatment.
When mitral regurgitation develops, blood leaking back into the left atrium raises atrial pressure and causes blood to pool in the lungs. Pulmonary congestion makes it difficult for oxygen to pass into the blood, resulting in shortness of breath. The severity of breathlessness is directly related to the degree of regurgitation. Over time, the development of atrial fibrillation further aggravates symptoms.
The most effective treatment for mitral regurgitation is surgical repair of the underlying cause whenever possible. Proper and skillful surgery can eliminate regurgitation and restore normal heart function.
In cardiac surgery, the most frequently used method is sternotomy, which involves cutting through the breastbone (sternum). This approach is highly effective for accessing the heart and provides a wide surgical view, allowing almost any type of cardiac procedure to be performed with ease. For this reason, it has long been the preferred technique among cardiac surgeons. However, the relatively long recovery period, the increasing popularity of minimally invasive or scarless surgeries across all surgical fields, and the rising cosmetic expectations of patients have motivated cardiac surgeons to seek alternative approaches that are as safe and effective as traditional methods but achieved through smaller or alternative incisions. Minimally invasive mitral valve surgery was born out of this pursuit.
In this modern technique, the breastbone is left intact. Instead, a small incision (about 3–4 cm) is made on the right side of the chest—at nipple level or around the breast tissue in men, and just beneath the breast in women—to access the heart between the ribs. An additional small incision (2–3 cm) is made in the groin to reach the femoral artery and vein. Cannulas are placed into these vessels to connect the patient to the heart-lung machine. Using specially designed surgical instruments for this method, the heart is stopped, the left atrium is opened, and the mitral valve is either repaired or replaced. All of these steps are performed with the aid of a high-definition camera, projected onto a large monitor for the surgical team.
What makes this camera technology particularly valuable is its ability to transmit images in extremely high resolution and in three dimensions when viewed with special glasses, similar to robotic surgery. This provides not only magnification that allows surgeons to see the finest details invisible to the naked eye, but also depth perception, enabling highly precise and safe procedures by looking directly at the monitor.
In this approach, the incision is not made to directly visualize the heart but rather to serve as an entry point for prosthetic valves, annuloplasty rings, or other surgical materials. As a result, the incisions are significantly smaller compared to traditional minimally invasive procedures performed under direct vision. This offers excellent cosmetic results, while the absence of rib spreading means postoperative pain is greatly reduced.
With smaller incisions, less manipulation of the heart is required, resulting in reduced surgical trauma. In women, the incision is hidden beneath the breast, leaving no visible external scar. Since the sternum is not cut, patients are not restricted to lying on their back after surgery. Blood transfusion requirements are also reduced. Patients can return to work in as little as two weeks, resume driving shortly after surgery, and completely avoid the risk of the dreaded sternal infection, as there is no bone incision involved. In short, the recovery period is reduced from 2–3 months, as in traditional surgery, to just 2–3 weeks.
This method not only allows mitral valve surgery but also enables tricuspid valve procedures and surgical interventions for atrial fibrillation (AF) to be performed simultaneously, offering patients a comprehensive and advanced treatment option with faster recovery and superior comfort.
Mitral regurgitation occurs when the mitral valve leaflets lose proper contact with each other. In advanced cases, medical treatment alone becomes insufficient, and patients may begin to experience shortness of breath even at rest. Normally, such patients should undergo surgical treatment. However, if surgery is not an option due to advanced age or the presence of multiple additional health conditions, the MitraClip procedure can help control mitral regurgitation. The procedure is usually performed in the cath lab, and recovery is generally quite fast in the beginning. However, if the underlying cause of mitral regurgitation is annular dilation, shortness of breath may return over time since this area is not directly addressed. The main treatment for mitral regurgitation remains surgical mitral valve repair. The MitraClip method is typically offered to patients who are not suitable candidates for surgery, with the aim of reducing symptoms such as shortness of breath.
Together with my cardiac surgery team, which provides 24/7 service to our patients, we have been performing such procedures with very high success for a long time.
If you have a heart valve problem that requires surgery, you can consult us to learn more about minimally invasive endoscopic mitral valve surgery.
''The mitral valve ensures that all the oxygenated blood coming from the lungs into the left atrium of the heart passes completely and efficiently into the left ventricle.''
The mitral valve is structurally composed of two leaflets that are positioned opposite each other, making full contact without leaving any gaps in between.