What is Double Orifice Mitral Valve?
A double-orifice mitral valve is a rare condition that can be either present at birth (congenital) or develop over time (acquired). This condition features a single, fibrous ring, or “annulus,” in the heart’s mitral valve, creating two openings, or “orifices.” First identified by British scientist William Smith Greenfield in 1876, there isn’t much information available about double-orifice mitral valves because it’s mostly limited to specific case reports and collections of facts gathered from autopsies.
Usually, those with a double-orifice mitral valve don’t show any symptoms; the abnormality allows the blood to flow normally between the two left chambers of the heart. However, certain complications like mitral valve dysfunction could arise. In such cases, there could be a narrowing (stenosis) or backflow (regurgitation) of blood which may lead to the development of symptoms.
What Causes Double Orifice Mitral Valve?
A double-orifice mitral valve is a rare heart defect often present at birth and could also be associated with other heart problems like a narrowing of the aorta, an open ductus arteriosus, and a two-leaflet aortic valve. This suggests that the underlying problem might be a defect in the endocardial cushion, a developmental tissue in the heart.
An autopsy study found the most common heart defect associated with a double-orifice mitral valve to be a defect in the septum, which is the wall dividing the two chambers of the heart. However, acquired cases of this condition due to calcification, or hardening because of calcium buildup, or because of mitral valve repair procedures have also been documented.
Imaging studies have shown that there are three different forms of the congenital double-orifice mitral valve: eccentric, central, and duplicate mitral valve. The eccentric type, which is the most common and is found in approximately 85% of cases, has a larger main opening and a smaller secondary one located at the back middle or front side of the heart. Central, present in 15% of cases, is characterized by a fibrous tissue in the middle connecting the two sections of the mitral valve. The orifices in this case can be the same size or different. Lastly, the duplicate type consists of two separate mitral valves, each with its own leaflets, junctions, muscles, and chords.
Risk Factors and Frequency for Double Orifice Mitral Valve
Double-orifice mitral valves are quite rare, and there isn’t a lot of data about how frequently they occur. One study of 2,733 autopsy cases at Boston Children’s Hospital found 28 instances of this condition, or about 1% of all cases. Another study looking at ultrasound heart data in adults estimated that this condition occurs in about 0.06% of cases. Internationally, information is scarce too. For example, a study in Poland found an incidence of 0.01% from analyzing ultrasound heart studies of 79,919 patients between 1993 and 2006. Currently, there’s no evidence to suggest that one gender is more likely to have this condition than the other.
Signs and Symptoms of Double Orifice Mitral Valve
Double-orifice mitral valves, a type of heart valve abnormality, usually don’t cause any symptoms unless they’re paired with other heart conditions or defects. If a person has a heart defect along with a double-orifice mitral valve, any symptoms they experience will most likely be due to the heart defect, and not the double-orifice mitral valve itself. In isolated cases of a double-orifice mitral valve (meaning there are no other heart conditions present), any symptoms would be a result of changes in blood flow and pressure in the left atrium of the heart, leading to a condition called pulmonary congestion.
When this condition occurs in children, it mainly leads to decreased cardiac output, which can result in a range of symptoms. These include:
- Fast breathing or tachypnea
- Difficulty breathing or dyspnea
- Wheezing
- Poor feeding
- Failure to thrive or poor growth
Patients who don’t exhibit any symptoms might have totally normal physical examination results, as the double-orifice mitral valve alone doesn’t typically cause any noticeable issues, even during a heart-related examination.
However, if there’s also mitral stenosis, a type of heart valve disease, present with the double-orifice mitral valve, it may produce a unique sound that doctors can hear during a checkup. Similarly, if a double-orifice mitral valve is paired with mitral regurgitation, another type of valve disorder, it could result in a specific type of sound or murmuring heard at the heart’s apex. As the condition worsens, the signs of heart failure might become evident. These can include:
- Increase in the work of breathing
- Bluish coloration of skin on extremities or peripheral cyanosis
- Raised pressure in the neck veins or elevated jugular venous pressure
- Feeling of a strong, forceful heartbeat or parasternal heave
- Pulmonary crackles heard on examination
- Swelling of the extremities or peripheral edema
Testing for Double Orifice Mitral Valve
Transthoracic echocardiography, which can be two-dimensional (2-D) or three-dimensional (3-D), is the main technique used for evaluating a heart condition known as a double-orifice mitral valve. This is a situation where there are two openings in the mitral valve of the heart. The double openings can be best studied using a view known as the parasternal short-axis, while the best way to see the area beneath the mitral valve with clear imagery is by using views known as the apical and subcostal 4-chamber views.
Adding a third dimension to the echocardiogram supports and improves the analysis of the mitral valve’s structure and function. 3-D TTE effectively measures the mitral valve’s proportions, and its connections within the heart, allowing a detailed examination of the chordal attachments and abnormalities in the area beneath the valve.
Color Doppler enhancement provides valuable insights into blood flow through the mitral valve, which helps in assessing whether the valve is leaking (regurgitating) or narrowed (stenotic). Normally, a pre-surgery procedure called transesophageal echocardiography is not needed, but confirming what has been found on the pre-surgery electrocardiogram during the surgery is a common procedure. Although cardiac magnetic resonance imaging is usually not needed, an x-ray of the chest and an electrocardiogram can provide additional information.
For example, a chest x-ray may display the condition of left atrial enlargement which is an increase in the size of the left upper chamber of the heart, and signs of pulomonary congestion, like upper lobe diversion, increased markings between tissues, and Kerley B lines. An electrocardiogram is usually normal in cases of a standalone double-orifice mitral valve. However, some possible indications include P mitrale if left atrial enlargement is present, and signs of an enlarged left ventricle (left ventricular hypertrophy) if the mitral valve is severely incompetent.
Treatment Options for Double Orifice Mitral Valve
The approach to managing a double-orifice mitral valve, a rare condition where the heart’s mitral valve has two openings, depends on the patient’s symptoms and the level of valve dysfunction present. Patients with no symptoms are typically advised to have regular echocardiograms (heart scans)—although current guidelines do not specify exactly how often these should occur. If a patient is exhibiting symptoms, the management of the double-orifice mitral valve may include heart medication, non-surgical procedures, or surgery.
For symptoms linked to heart failure and lung congestion, medication can be used. This is particularly important in young patients, where managing symptoms of heart failure is critical until they are older and can undergo specific valve treatments. When a double-orifice mitral valve causes mitral stenosis (an abnormal narrowing of the valve), a non-surgical procedure, called percutaneous transcatheter balloon dilation, can help to relieve the blockage. If this procedure isn’t a practical option or does not work, mitral valvuloplasty, which reshapes the valve, or valve replacement surgery are other alternatives.
Patients who have symptoms and a leaky (regurgitant) valve should be assessed for surgical repair. Surgery might include reshaping the valve flaps or possibly dividing the bridging tissue. One potential surgical treatment for double-orifice mitral valves is to surgically close one of the openings. However, this can cause the valve area to suddenly get smaller, leading to stenotic flow, a condition where blood flow through the valve is restricted.
When operating on a double-orifice mitral valve, surgeons need to be very careful to avoid accidentally cutting the strip of tissue between the two openings as this can lead to substantial leakage of the valve. This can make repair challenging due to the lack of supportive cords (chordae tendineae) in the middle part of the valve. In cases where double-orifice valves show stenosis, addressing any underlying causes, such as blockages in the heart muscle, can help alleviate constriction.
There may be occasions where a split appears in the larger of the two valve openings. Using expert judgment to evaluate whether surgical correction is needed is key. It’s important to weigh up the potential impact of repairing the split, which could cause stenosis, against the level of valve leakage if left untreated.
What else can Double Orifice Mitral Valve be?
A double-orifice mitral valve is a unique condition that doesn’t have specific symptoms. The symptoms that do appear are related to how well the mitral valve functions, the pressure in the left part of the heart, and how congested the lungs’ blood vessels are. In adults, it’s important to check for other possible causes of mitral valve problems. These can include heart disease caused by rheumatism, issues with mitral valve function, lack of blood flow to the heart, calcium buildup in elderly individuals, disorders affecting the body’s connective tissues, changes in the valve due to a type of noncancerous tumor, and heart infection.
In children, if there’s another heart defect present (like narrowing of the aorta, blood flow between the lung artery and the aorta, having only two parts to the aortic valve, or issues with the walls between the heart’s chambers), doctors should consider the possibility of a double-orifice mitral valve.
What to expect with Double Orifice Mitral Valve
If a patient who has a double-orifice mitral valve shows no symptoms and has no issues with their mitral valve, their health outlook is generally positive. Nonetheless, there aren’t any current studies that can pinpoint exactly when this type of mitral valve might start to cause problems. Some patients may start to experience problems early in infancy, while others may not have issues until they’re adults.
Progress in medical technology has also improved survival rates. With non-invasive methods, treating mitral valve problems can be much safer than replacing the valve through surgery.
Possible Complications When Diagnosed with Double Orifice Mitral Valve
Having a double-orifice mitral valve can lead to several complications. These include problems with the mitral valve, such as narrowing (mitral stenosis) and leaking (mitral regurgitation). This can result in fluid build-up in the lungs (pulmonary edema) and heart failure. Other issues that can arise include irregular heart rhythms like atrial fibrillation and atrial flutter directly because of the double-orifice mitral valve. This could potentially cause clots to form and lead to strokes in certain patients.
Common Complications:
- Mitral valve dysfunction (mitral stenosis and mitral regurgitation)
- Pulmonary edema (fluid buildup in the lungs)
- Congestive Heart Failure
- Irregular heart rhythms (atrial fibrillation and atrial flutter)
- Possibility of clots leading to strokes
Preventing Double Orifice Mitral Valve
Double-orifice mitral valve, a heart condition, is often discovered unintentionally during investigations for other heart-related issues. This condition doesn’t usually cause symptoms by itself, but it can lead to problems with the mitral valve function, that might need treatment. This treatment may involve medication or non-invasive or surgical procedures on the valve.
After detecting this condition, patients should see a heart specialist (cardiologist) and a heart and lung surgeon (cardiothoracic surgeon) for regular checks using an echocardiogram (TTE). For patients experiencing symptoms, it’s suggested that they limit physical activity and seek medical help if they notice heart failure signs like breathlessness, coughing, swelling in the legs, or weight gain. In such cases, medication might be provided to manage heart failure symptoms until the faulty mitral valve is repaired.
