Index
It’s basically a leaky mitral valve.
It is also known as mitral valve regurgitation . The mitral valve usually keeps blood from backing up and keeps blood going to the body where it is needed.
In mitral regurgitation, blood is allowed to leak backward into the upper chamber of the heart.
How common is mitral regurgitation?
Mitral regurgitation becomes more common with age. This is due to age-related valve wear. In the population as a whole, about 2% of people have at least moderate mitral regurgitation.
In those under 40 years of age, it is likely only about 0.5% and in those over 75 years it is close to 10%.
Different types of mitral regurgitation
Mitral regurgitation can be classified as primary or secondary. In primary mitral regurgitation, there is a problem with the valve itself.
In secondary mitral regurgitation, there is a problem with the structures surrounding the valve (such as the gate frame being too large for the gates not to meet in the center leaving a gap).
In secondary mitral regurgitation, an enlarged heart often makes the valve unable to meet in the middle.
Classification: trivial, mild, moderate, severe and torrential mitral regurgitation.
Based on information obtained from ultrasound of the heart (echocardiogram), mitral regurgitation can be classified according to its severity.
Trivial mitral regurgitation is an essentially normal and non-worrisome finding.
For moderate and major mitral regurgitation, there are several features of the heart scan that are taken together to determine severity.
In moderate mitral regurgitation, about 30% of the blood in the heart is leaking backward.
In severe mitral regurgitation, about 50% of the blood in the heart is leaking backward.
In torrential mitral regurgitation, most of the blood is receding, this happens in conditions such as a leaflet.
Causes of mitral regurgitation
As explained above, there is primary mitral regurgitation in which the valve leaflets are affected and there is secondary mitral regurgitation in which the structures that hold the valve in place are affected.
Mitral valve prolapse
In mitral valve prolapse, the leaflets become thick and spongy and, if severe, can lead to valve leakage. Click here for a detailed article on mitral valve prolapse and regurgitation.
Chord break
Sometimes chords, which are the strings that hold the valve in place, can render that part of the valve ineffective. The rupture of a large chord can lead to a condition known as flail leaflet, leading to torrential mitral regurgitation, which is described in detail here.
Mitral valve endocarditis
Endocarditis is an infection within the valve that directly destroys the valve tissue. This basically leads to a hole eating out of the valve and the leakage occurring through the hole.
Rheumatic fever
This starts with a strep throat infection and years later can damage the valve due to a reaction in the body that causes it to attack its own valve.
This used to be a common cause although it has now decreased significantly due to early treatment of strep infections.
Rheumatic heart disease remains one of the most common causes of mitral valve disease in developing countries.
Valve calcification
As we age, there may be degeneration of the heart valves, similar to the way joints degenerate. In some cases, this degeneration can deform the valve leaflets and interfere with valve function leading to regurgitation.
The drugs
Although much less common now, medications have been used in the past, such as weight loss or migraine medications that caused damage to the valve leaflets.
These medications are:
- Ergot alkaloids (methysergide and ergotamine).
- Ergot-derived dopamine agonists (such as pergolide and cabergoline).
- Medicines metabolized in norfenfluramine (such as fenfluramine, dexfenfluramine and benfluorex).
Secondary mitral regurgitation, also known as functional mitral regurgitation, where the structures that hold the valve in place are affected.
Heart failure / cardiomyopathy
In some conditions that lead to heart failure, the heart enlarges and heart function decreases. The heart can sometimes become so large that the mitral valve leaflets cannot meet in the middle and allow blood to leak backward.
Coronary artery disease
The coronary arteries supply blood to the heart muscle, including the muscles that control mitral valve function. If the blockages are severe, then the heart muscle can fail and lead to a process called remodeling.
This remodeling of the heart can distort the mitral valve and lead to malfunction and regurgitation.
Heart attack complication: There are two large muscles in the heart known as papillary muscles that are associated with one of the leaflets of the mitral valve.
In a heart attack, the blood supply to these muscles can be compromised, causing valve dysfunction and regurgitation.
In rare cases, a heart attack can cause one of these papillary muscles to rupture, essentially letting one of the mitral valve leaflets hang free, leading to torrential mitral regurgitation.
Hypertrophic cardiomyopathy
In this condition there is a severe thickening of the heart muscle. This can often cause very turbulent flow in the heart that actually leads to distortion of the mitral valve with each beat and can be associated with significant mitral regurgitation.
Risk factors for mitral regurgitation
Many of the risk factors for mitral regurgitation are related to the above causes.
Age is the most obvious risk factor; the elderly are most at risk.
Those with a history of mitral valve prolapse and regurgitation are at risk for their disease to progress. The higher the degree of mitral regurgitation, the more likely it is to progress.
Normal cardiovascular risk factors, such as blood pressure and cholesterol, can be important as they can lead to coronary artery disease and heart failure, which in turn is associated with an enlarged heart that can lead to mitral regurgitation.
Intravenous drug use increases the risk of endocarditis, an infection in the heart that can damage the valve and lead to regurgitation.
Certain genetic diseases, such as congenital heart disease, in which people can be born with defective mitral valves or hypertrophic cardiomyopathy, can increase the chances of significant mitral regurgitation.
How does the heart handle mitral regurgitation?
In mitral regurgitation, blood leaks from the lower chamber of the heart into the upper chamber of the heart.
It is important to realize that all of this blood has yet to advance to the bottom of the heart with the next beat. So basically in mitral regurgitation the heart has to handle more blood.
We call this volume overload. The way the heart handles this extra blood is to get bigger to handle the increased blood volume. The enlargement process is known as adaptive remodeling.
This is good and bad. It’s good because it allows the heart to handle the extra blood, so despite the leak, enough blood moves into the body where it is needed.
Unfortunately, in the process of enlargement, the heart muscle weakens over time and eventually fails if it is not treated in time.
That becomes more important in the treatment of severe mitral regurgitation. To further complicate matters, filtration allows the heart’s pumping function to appear higher than it actually is.
For this reason, it is important to keep a close eye on how the heart is pumping when there is moderate or greater amounts of mitral regurgitation.
Symptoms of mitral regurgitation
Acute mitral regurgitation
Rarely, people present with severe mitral regurgitation that occurs suddenly. Such as in the rupture of the cord or the rupture of the papillary muscle. This is known as severe acute mitral regurgitation and is a medical emergency.
Patients with severe acute mitral regurgitation will present:
- Low blood pressure .
- Short of breath.
- Dizziness.
- Fainting.
Acute acute mitral regurgitation is life threatening and should be treated almost immediately.
Chronic severe mitral regurgitation
This is much more common and basically means that the disease is present for years and generally progresses slowly. Valve disease is usually clinically silent for many years and can only be detected by the presence of a murmur.
This is because, as described above, the heart adapts to mitral regurgitation as it grows.
Ultimately, however, in severe disease, the heart fails and the following symptoms may be present.
- Fatigue.
- Short of breath.
- Decreased tolerance to exercise.
- Swelling of the leg
- Irregular heartbeat
Testing and Diagnosis of Mitral Regurgitation
Auscultation
This is listening with a stethoscope. In mitral regurgitation, there will be a murmur that lasts for the entire pumping phase. This is the noise that blood leaking back makes. It is known as a pan-systolic murmur or sometimes a late systolic murmur.
This is not the best test for the diagnosis of mitral regurgitation, but it may give some clues about the effect on the heart.
In severe mitral regurgitation, there may be an irregular heart rhythm known as atrial fibrillation; this can be picked up on the EKG.
Enlargement of the upper and lower chambers of the heart can be seen in chronic severe mitral regurgitation. Up to 50% of patients will have ECG evidence of left ventricular chamber enlargement known as hypertrophy.
Chest x-ray
This is not particularly helpful, however a chest X-ray may show signs of congestion and signs of enlargement of the heart chamber.
Echocardiogram
This is basically the test of choice in the diagnosis of mitral regurgitation and is essential.
Echocardiography can be used to determine the underlying cause of mitral regurgitation and provide important information about the size of the heart’s chamber and the integrity of the valve leaflets, as well as the structures that hold the valve together.
Echocardiography is generally considered the most accurate way to determine the severity of mitral regurgitation.
Transesophageal echocardiogram – TEE
TEE is the most accurate test to evaluate mitral regurgitation.
This is an ultrasound of the heart that requires a small tube to be passed into the food pipe to get close to the images of the heart. The advantage is that it shows the structures in greater detail.
A TEE can be performed to assess mitral regurgitation which is questionable and can identify the exact cause of mitral regurgitation.
Most people would have a TEE before considering surgery, and a TEE is almost always done in surgery to ensure the valve is repaired.
Heart catheterization
In this procedure, small tubes are passed into the heart to obtain information about the pressures in the heart and also to view the coronary arteries.
A cardiac catheterization may be done to see the effect mitral regurgitation has on the heart.
Cardiac catheterization is almost always done before surgery for mitral regurgitation to ensure that there are no arterial blockages that need to be repaired at the same time.
Magnetic resonance imaging
Although it is not used mainstream, it is used by some expert centers to monitor the progression of mitral regurgitation and the effect it has on the heart, as it provides superior information on the structure and function of the heart.
One of the advantages is that it is highly reproducible and therefore can be useful in cases where close monitoring is important.
Complications of mitral regurgitation
Heart failure
As the heart enlarges to cope with the increased blood volume that eventually fails, this usually only occurs in the setting of severe MR.
One of the keys to treatment is to repair the valve before heart failure begins and prevent irreversible damage.
Atrial fibrillation
The large volume of blood that leaks into the upper chamber of the heart in mitral regurgitation can lead to an irregular heart rhythm originating in the upper chamber known as atrial fibrillation. If left unchecked, it is known as Afib with RVR.
Pulmonary hypertension
The pulmonary hypertension is the term for increasing the pressure in the arteries of the lungs. It can occur in mitral regurgitation from the posterior transmission of pressure from the left chambers of the heart that are dealing with increased blood volume.
Medical treatment of mitral regurgitation
For severe mitral regurgitation, especially if it is primary and symptomatic, then fixing the valve is the only way to alleviate the problem.
There are currently no medications that can completely reverse the condition. Some medical treatments can be beneficial, as explained below.
Primary mitral regurgitation
In primary mitral regurgitation, where there is a problem with the valve itself, such as mitral valve prolapse, there is no drug that will reverse the disease and no specific drug recommended by the guidelines.
There is some evidence that beta-blocker medications, such as metoprolol, may have a beneficial effect in terms of preserving cardiac function, however the evidence for this is not strong enough to be a strong recommendation.
Steps should be taken to ensure adequate blood pressure control, as increased blood pressure can lead to increased severity of mitral regurgitation.
Basically, the mainstay of medical management is surveillance, monitoring the stability of the disease with clinic visits, and echocardiography, ensuring that the disease does not progress too far before valve surgery is considered.
Secondary mitral regurgitation
In secondary mitral regurgitation, the problem is not with the valve itself, but with the structures that hold the valve in place and keep it working.
Unlike primary mitral regurgitation, medications can have a significant impact on secondary mitral regurgitation.
Some cases of secondary mitral regurgitation are caused by coronary artery disease that causes certain areas of the heart to not pump as well, leading to valve dysfunction.
In these cases, repair of the coronary artery disease, whether through medication, stents, or surgery, can be beneficial.
Secondary mitral regurgitation is often due to an enlarged heart, whereby the heart becomes too large for the valve leading to the leak.
In these cases, medications that can possibly reverse this process in some way will allow the heart to become smaller and possibly restore the capacity of the valve.
Steps should be taken to ensure adequate blood pressure control, as increased blood pressure can lead to increased severity of mitral regurgitation.
Surgeries for mitral regurgitation
When to have surgery for primary mitral regurgitation?
Primary mitral regurgitation is when the valve is affected, as in mitral valve prolapse. There is no proven medical therapy to improve the valve and the only way to get rid of mitral regurgitation is through mitral valve surgery.
The options are mitral valve repair and mitral valve replacement, which are explained in detail later. The timing of mitral valve surgery for mitral regurgitation has been the subject of much debate over the years.
When deciding to send someone for valve surgery, we must consider the following.
We don’t want to send someone too soon because heart surgery is a big deal, and if they don’t need it, it’s hard to justify the risk, no matter how small.
On the other hand, we do not want to send someone too late because there is a possibility that any damage caused will be irreversible.
Years ago, patients with severe mitral regurgitation would be sent for surgery only when the heart showed clear evidence of failure.
It was then discovered that many patients would never regain function and remain symptomatic. So the valve was being repaired too late.
The problem is that due to the nature of the condition, it is often difficult to tell when the heart is reaching that point of failure.
Unlike other conditions, we cannot simply rely on the pumping function of the heart to tell us what is happening because in mitral regurgitation it initially appears normal and often we only find it abnormal after the valve has repaired! !
For this reason, in severe mitral regurgitation, if the pumping function of the heart is reduced, even minimally, the valve must be operated.
Many expert centers are now moving toward mitral valve surgery in patients who have severe mitral regurgitation, even if the heart is pumping normally and the patient has no symptoms. The reasons for this are:
- Surgery is done before heart failure is established to prevent any irreversible damage.
- The modern risk of mitral valve surgery in skilled hands is minimal.
- In expert hands, it is almost always possible to repair the valve rather than having to replace it.
Some centers still prefer what is called a watchful waiting strategy in which they closely observe patients with severe mitral regurgitation for the development of symptoms or subtle evidence of cardiac dysfunction.
In addition to the development of symptoms of evidence of cardiac dysfunction, there are a number of other factors associated with worse outcomes in patients with severe MRI. Generally, if any of these appear, it is time to trade.
These are an irregular heart rhythm known as atrial fibrillation and increase the pressure in the pulmonary arteries known as pulmonary hypertension.
Surgery in primary mitral regurgitation
Before considering surgery, it is important to ensure that mitral regurgitation is serious in nature.
In expert centers, it is reasonable to consider surgery for severe mitral regurgitation, even if there are no symptoms and the heart appears to be working normally, provided there is a certainty that the valve can be repaired rather than replaced.
In general, patients with severe mitral regurgitation should be closely monitored and surgery should be performed if there is a development of symptoms or if there is even subtle evidence of cardiac dysfunction.
Other indicators that should suggest the need for surgery in severe mitral regurgitation include the development of an irregular heart rhythm called atrial fibrillation or the development of high pressures in the pulmonary arteries known as pulmonary hypertension.
When to have surgery for secondary mitral regurgitation?
In secondary mitral regurgitation, the main problem is not the valve itself, but the structures that hold the valve in place. The prime example of this is in people with very enlarged hearts, where essentially the heart is too big for the valve.
Unlike primary mitral regurgitation, medications can be very helpful in people with secondary mitral regurgitation. Before considering surgery for secondary mitral regurgitation, there should be an effort to maximize medical therapy.
Often, those with secondary mitral regurgitation have severely reduced pumping function and therefore any operation is high risk compared to the generally healthier population with primary mitral regurgitation.
It is not clear whether surgery for secondary mitral regurgitation has any effect on the long-term prognosis. The goal of surgery for severe secondary mitral regurgitation is to reduce symptoms, so surgery is generally reserved for symptomatic patients.
Surgery in secondary mitral regurgitation
Before considering surgery for secondary mitral regurgitation, it is important to ensure maximum use of medications to see if they can improve mitral regurgitation.
Surgery for secondary mitral regurgitation is generally reserved for those who remain symptomatic despite medical therapy.
Mitral valve repair vs. mitral valve replacement
When undergoing surgery for mitral regurgitation there are two main options: mitral valve repair and mitral valve replacement.
Mitral valve repair involves making modifications to the existing valve that result in the elimination of mitral regurgitation and reestablish the competence of the valve.
These modifications include the addition of artificial strings to stabilize the valve and also the addition of a band around the valve to allow it to function normally.
In some cases, when the valve is thick and flexible as in mitral valve prolapse, some of the redundant valve tissue may be cut away.
The other option is mitral valve replacement, either using a metal valve or a tissue valve. A metal valve will generally last a lifetime, although it will require the use of a blood-thinning drug, such as Coumadin, for life.
A tissue valve does not require the use of a blood thinning drug, however it will be subject to wear and tear and therefore will have a limited lifespan, perhaps up to 10 years, after which additional procedures may be required .
When possible, mitral valve repair is the preferred course of action if it can last into a lasting repair. Skilled mitral valve surgeons will usually be able to tell if a valve can be repaired based on the echocardiogram performed before surgery.
Mitral valve repair is considered superior, when possible, because it can result in better results and greater preservation of cardiac function.
Unfortunately, many patients end up with a mitral valve replacement simply because they were referred to surgeons who are inexperienced in repair.
This is unacceptable and is one of the reasons to ensure that your mitral valve disease is managed in a truly expert facility.
Robotics vs. Open surgery for mitral regurgitation
The standard way to repair the mitral valve is to do it through a sternotomy, which is the term for cutting the sternum. Mitral valve repair is complex, and an advantage to an open surgical approach is that the entire valve can be visualized and a complex repair can be performed.
Some people would say that the open approach allows the highest chance of success in a high-quality repair. A minimally invasive approach that involves a smaller incision may also be an option.
A few specialized centers offer a robotic approach to mitral valve surgery. Some very skilled and experienced robotic surgeons, of which there are not many, can perform even complex repairs.
The advantage of a robotic approach would be that the incisions are much smaller than those of standard open surgery. If you opt for a robotic approach, it is important to know that the surgeon is very experienced with this and has a good history of mitral valve repair.
Keyhole Catheter-Based Treatment of Mitral Regurgitation
Incredible advances in technology in recent years have led to the development of a way to repair some mitral valves without having to perform open heart surgery.
This is called percutaneous mitral regurgitation repair and involves the use of small tubes that pass into the heart from the groin.
The most widely studied method of percutaneous mitral valve repair is known as Mitraclip.
In the Mitraclip procedure there is a clip that is applied to the mitral valve leaflets (as you can see in the video below) that can reduce the amount of mitral regurgitation.
The advantages of this procedure include minimal recovery time and avoiding surgical risk in those patients who have been at high risk for surgery.
Although the Mitraclip procedure is considered effective in reducing mitral regurgitation, it is not as effective as standard surgical approaches.
Currently in the US, the Mitraclip is limited to subsets of high-risk mitral regurgitation, basically those patients who are considered to be at prohibitively high risk of surgery.
It is also reserved for primary mitral regurgitation, and not secondary at this time. Evidence is ongoing that will establish the role of the clip in broader subsets of mitral regurgitation.
One of the greatest revolutions in cardiology has been the development of a catheter-based treatment for aortic valve disease. This involves implanting a new valve through a small tube and has been very successful.
Excitingly, progress is being made in catheter-based mitral valve implantation and this is likely to change the field significantly over the next decade.
Can a pacemaker help mitral regurgitation?
In some cases of secondary mitral regurgitation, different areas of the heart that pale in synchronization cause the regurgitation. This can be diagnosed using a combination of a cardiac EKG tracing and an ultrasound of the heart.
In these cases, it has been shown that the use of a particular type of pacemaker known as cardiac resynchronization therapy (CRT) can improve mitral regurgitation both at rest and during exercise. This will not be effective for primary mitral regurgitation.
