Gamification Friday - Flashcards
Mitral Valve General Anatomy
The valvar complex comprises the annulus, the leaflets, the tendinous cords, and the papillary muscles. Also important for its functioning is the left atrial musculature inserting to the leaflets and the myocardium to which the papillary muscles are inserted. The valve is obliquely located in the heart and has a close relation to the aortic valve. Unlike the tricuspid valve which is separated by muscle from its counterpart, the pulmonary valve, the mitral valve is immediately adjacent to the aortic valve.
Mitral annulus
The annulus marking the hingeline of the valvar leaflets is more D shaped than the circular shape portrayed by prosthetic valves. The straight border accommodates the aortic valve allowing the latter to be wedged between the ventricular septum and the mitral valve. In this region, the aortic valve is in fibrous continuity with one of the two leaflets of the mitral valve. Expansions of fibrous tissues at either extreme of the area of continuity form the right and left fibrous trigones. The atrioventricular conduction bundle passes through the right fibrous trigone.
Mitral Leaflets
Distinctly different from the tricuspid valve, the mitral valve has two leaflets although some may argue that it has four leaflets. These are notably different in shape and circumferential length. Owing to the oblique location of the valve, strictly speaking, its two leaflets do not occupy anterior/posterior positions nor is one of the leaflets “septal”. The septal leaflet is characteristic of the tricuspid valve whereas neither of the mitral leaflets is attached to the septum. The corresponding terms for anterior and posterior are “aortic” and “mural”. It is the aortic leaflet that is in fibrous continuity with the aortic valve. The aortic leaflet has a rounded free edge and occupies a third of the annular circumference, whereas the other leaflet is long and narrow, lining the remainder of the circumference. The aortic leaflet hangs like a curtain between the left ventricular inflow and outflow tracts . When the valve is closed, this leaflet appears to form the greater part of the atrial floor but is approximately equal in area to the mural leaflet.9 It meets the mural leaflet to form an arc shaped closure line, or zone of apposition, that is obliquely situated relative to the orthogonal planes of the body. With the leaflets meeting, the view of the valve from the atrium resembles a smile. Each end of the closure line is referred to as a commissure. These are designated the anterolateral and posteromedial commissures. It is worth noting, however, that the indentations between leaflets do not reach the annulus but end about 5 mm short in the adult heart. Therefore, there are no clear cut divisions between the two leaflets. Furthermore, the free edge of the mural leaflet is often divided into three or more scallops or segments described as lateral, middle, and medial or assigned terms like P1, P2, and P3. Although three scallops are most common, the scallops are not equal in size.
Tendinous cords
The tendinous cords are string-like structures that attach the ventricular surface or the free edge of the leaflets to the papillary muscles. Characteristically, the tricuspid valve has cordal attachments to the ventricular septum allowing it to be distinguished from the mitral valve on cross sectional echocardiography. The tendinous cords of the mitral valve are attached to two groups of papillary muscles or directly to the postero-inferior ventricular wall to form the tensor apparatus of the valve. Cords that arise from the apices of the papillary muscles attach to both aortic and mural leaflets of the valve. Since cords usually branch distal to their muscular origins, there are five times as many cords attached to the leaflets as to the papillary muscles.
Papillary muscles and left ventricular wall
These are the muscular components of the mitral apparatus. As a functional unit, the papillary muscle includes a portion of the adjacent left ventricular wall. Tendinous cords arise from the tips of the papillary muscles. Alterations in the size and shape of the left ventricle can distort the locations of the papillary muscles, resulting in valvar function being disturbed. The papillary muscles normally arise from the apical and middle thirds of the left ventricular wall. Described in most textbooks as two in number, however, there are usually groups of papillary muscles arranged fairly close together. At their bases, the muscles sometimes fuse or have bridges of muscular or fibrous continuity before attaching to the ventricular wall. Extreme fusion results in parachute malformation with potential for valvar stenosis).
Viewed from the atrial aspect, the two groups are located beneath the commissures, occupying anterolateral and posteromedial positions.
SECTIONAL ANATOMY OF THE MITRAL VALVE
Since the mitral valve is a complex with a unique arrangement of its component parts within the left ventricle, cross sectional imaging techniques including four dimensional echocardiography allow it to be visualised in its entirety by building up whole series of planes. The valve can be demonstrated in each of the orthogonal planes of the left ventricle, as well as in the orthogonal planes of the body.
Short axis planes through the ventricle
Short axis planes through the ventricle display from apex to the cardiac base the oblique arrangement of the two groups of papillary muscles, the tendinous cords, the fish mouth appearance of the valvar opening, and the aortic outflow tract sandwiched between the ventricular septum and the mitral leaflet . This view allows assessment of the area of the valvar orifice. At right angles to the short axis plane, the long axis plane such as that obtained from the parasternal window produces the so-called two chamber plane. In this view, the mode of closure of the leaflets and the level of the closure line relative to the atrioventricular junction is seen to best advantage. The aortic and mural leaflets are readily distinguished, allowing detection of hooding, overshoot, or prolapse of each leaflet. The normal valve in closed position shows the aortic leaflet at an angle to the long axis of the ventricle but the mural leaflet is perpendicular. It should be noted that in some normal valves the leaflets may balloon slightly past the plane of the atrioventricular junction during systole, but the zone of coaptation remains below the plane. In valvar opening, the mural leaflet becomes nearly parallel to the inferior wall while the aortic leaflet parallels the ventricular septum.
Four and five chamber planes
The second series of long axis sections through the left ventricle, the so-called four and five chamber planes, allow distinction between tricuspid and mitral valves. Being more or less parallel to the zone of apposition between leaflets, it is poor for detecting problems of coaptation. The series of two chamber sections obtainable from the apical window cuts the leaflets obliquely, distorting the true leaflet length and motion. Views of the mitral valve through the transgastric and transoesophageal windows enable more detailed studies of the entire length of the zone of apposition, revealing the arrangement of cordal supports at all segments of the leaflets
What is the Marfan’s syndrome?
Marfan syndrome is a genetic condition that affects a protein in the body that helps build healthy connective tissues. Connective tissues support the bones, muscles, and organs in your body and allow your skin, blood vessels, and ligaments to stretch.
Marfan syndrome symptoms
Some people who have Marfan syndrome have few or no signs or symptoms, while others experience serious symptoms or life-threatening complications. Symptoms of Marfan syndrome depend on which parts of the body are affected and the severity of the condition. People who have Marfan syndrome may be tall and thin with long arms, legs, fingers, and toes, as well as flexible joints. The most serious complications are problems in the heart and blood vessels, such as weakening or bulging of the aorta.
Marfan syndrome causes
Marfan syndrome is a genetic condition caused by a mutation, or change, in one of your genes, called the fibrillin-1 (FBN1) gene. The FBN1 gene makes fibrillin-1, which is a protein that forms elastic fibers within connective tissue. Fibrillin-1 also affects levels of another protein that helps control how you grow.
Most people who have Marfan syndrome inherit it from their parents. Sometimes, the mutation that causes Marfan syndrome is not passed down from a parent but happens by chance while the unborn baby is developing in the womb.
Marfan syndrome Risk Factors
Marfan syndrome affects people of all races and ethnicities and men and women equally.
Your risk for Marfan syndrome is higher if one or both parents have the condition. Learn how Marfan syndrome is inherited and the risk of passing the condition on to a child in our Causes section.
Your doctor may recommend one or more of the following tests to help diagnose Marfan syndrome:
Chest CT scan to check your heart valves and aorta and possibly the connective tissue around your spinal cord
Chest MRI to create detailed pictures of the organs in your chest, including your heart, lungs, and blood vessels
Echocardiography (echo) to view and measure the size of your aorta or check the heart’s valves
Genetic testing to detect mutated FBN1 genes. Genetic testing involves blood tests to detect mutations in the FBN1 genes. Many different mutations within the FBN1 gene can cause Marfan syndrome, so no single blood test can diagnose the condition. Sometimes testing for an abnormal FBN1 gene can help tell whether you have Marfan syndrome if you have other signs and symptoms.
Slit-lamp exam to find out whether you have an eye lens that is out of place, cataracts, or a detached retina. An eye specialist or ophthalmologist uses a slit lamp, a microscope with a light, to check your eyes.
What is the most common cause of mitral regurgitation?
It is caused by disruption in any part of the mitral valve (MV) apparatus. The most common etiologies of MR include MV prolapse (MVP), rheumatic heart disease, infective endocarditis, annular calcification, cardiomyopathy, and ischemic heart disease.
Can mild mitral regurgitation go away?
When the mitral valve doesn’t close all the way, blood flows backward into the upper heart chamber (atrium) from the lower chamber as it contracts. … Mitral regurgitation may begin suddenly. This often occurs after a heart attack. When the regurgitation does not go away, it becomes long-term (chronic).
How do you treat mild mitral regurgitation?
Medications may include:
Diuretics. These medications can relieve fluid accumulation in your lungs or legs, which can accompany mitral valve regurgitation.
Blood thinners. These medications can help prevent blood clots and may be used if you have atrial fibrillation.
High blood pressure medications.
