Mitral valve prolapse

Introduction Mitral valve prolapse refers to abnormal detachment of the valve into the left atrium during systole due to abnormalities of the mitral valve device. This sign was first described by Barlow in 1963, so it is also known as Barlow syndrome. There have been many names used, including "systolic snoring syndrome", "mitral valve prolapse syndrome", "soft valve syndrome" and so on.

Cause

Primary mitral valve prolapse syndrome is a congenital connective tissue disease whose exact cause is not known. Can occur in all age groups, more often in women, with the largest number of women between the ages of 14 and 30. One third of patients have no other structural heart disease and only have mitral valve prolapse as a clinical manifestation. They can also be seen in patients with Marfan syndrome, systemic lupus erythematosus, nodular polyarteritis, and later leaf prolapse. More common. In some patients, hereditary collagen tissue is abnormal. Under electron microscope, the formation and loss of type III collagen fibers are reduced, the collagen fibers in the center of connective tissue are progressively degenerated, cellulose is deposited, and elastic fibers are broken and dissolved. The pathological features of mitral valve prolapse are mitral valve mucoid degeneration, the sponge layer proliferates and invades the fibrous layer, the sponge layer is thickened with proteoglycan accumulation, the atrial surface of the valve leaflets is thickened, and the surface has cellulose and platelet deposition. . The prolapsed mitral valve leaflets partially swelled, and the leaflet bulging toward the left atrium bulged in a hemispherical bulge, and the leaflet became longer and longer, and the mitral annulus expanded in severe cases. At the same time, the tendon becomes thinner, longer, twisted, and then thickened by fibrosis. The abnormality of the chordae tendine is marked by the most important part of the valve leaf. Due to the abnormal chordae tendine, the mitral valve stress is uneven, resulting in the mucus degeneration of the leaflet stretch and exfoliation tissue, and the chordae tendon rupture can occur. The papillary muscles and the surrounding myocardium can cause ischemia and fibrosis due to excessive pulling and friction. The enlargement of the annulus and calcification further aggravate the degree of prolapse.

Partial mitral valve prolapse may be secondary to inflammation of rheumatism or viral infection, and prolapse of the previous leaf is more common. In addition, it can also be seen in coronary heart disease, cardiomyopathy, congenital heart disease, hyperthyroidism patients often combined with mitral valve prolapse.

an examination

Related inspection

Two-dimensional echocardiogram electrocardiogram

(1) Physical examination

1. Cardiac auscultation: apical area or its inner side can be heard and contracted in the middle and late stage of non-jet-like click sound, this sound appears more than 0.14 seconds after the first heart sound, suddenly the sling is suddenly tightened or the prolapse of the leaflet suddenly Suspension. Immediately after the click, you can hear the murmur of the late contraction, which is often incremental, and a few can be full systolic murmurs, and cover up the clicks. Sometimes in the apex area, you can hear the high-pitched loud-sounding gradual late-stage murmur, similar to whooping cough or geese. The earlier the systolic murmur appears, the longer it appears, indicating the more severe the mitral regurgitation. Physiological or medical measures such as standing position, breath holding, tachycardia, inhalation of isoamyl nitrite, etc., which can reduce left ventricular blood flow resistance, reduce venous return, enhance myocardial contractility, and reduce left ventricular end diastolic volume Make the systolic clicks and noises advance. Conversely, any physiological or pharmaceutical factors that increase left ventricular blood flow resistance, increase venous return, reduce myocardial contractility, and increase left ventricular end diastolic volume are as follows: bradycardia, bradycardia, beta blockers, pressors, etc. Both can delay the systolic clicks and noises.

2. Other signs: The heart beats in a double nature. At the same time as the mid-systolic and the appearance of the click, the heart suddenly retreats and the heart's outward beat suddenly stops. The patient's body shape is mostly weak, and can be accompanied by straight back, scoliosis or lordosis, funnel chest and so on.

(B) X-ray examination: most patients have no obvious abnormalities in the heart shadow. The left atrium and left ventricle were significantly enlarged in patients with severe mitral regurgitation. Chest skeletal abnormalities are the most common. Left ventricular angiography showed mitral valve prolapse and reflux, right anterior oblique projection showed systolic mitral posterior valvular lobes into the left atrium, left ventricular contraction asymmetry, ventricular basal or central ventricular contraction, inward The "ballet foot" of the depression changes.

(C) ECG examination: most patients' ECG can be normal. Some patients presented with T-wave biphasic or inversion of II, III, aVF leads, and changes in non-specific ST segments, which were more pronounced after inhalation of isoamyl nitrite or exercise. ST-T wave changes may be related to papillary muscle ischemia, increased left ventricular tone after valve prolapse, and hypersympathetic hyperfunction. It can be seen that the QT interval is prolonged. Common arrhythmias, including atrial premature beats, premature ventricular contractions, supraventricular or ventricular tachycardia, sinus node dysfunction and various degrees of atrioventricular block. Pre-excitation syndrome can also be seen.

(4) Echocardiography: It has special significance for the diagnosis of mitral valve prolapse. Two-dimensional echocardiography showed that the systolic mitral anterior and posterior lobes protruded to the left atrium and exceeded the annulus level. In addition, the mitral valve showed a balloon-like change, the leaflets became thicker, longer, the annulus expanded, the left atrium and left ventricle expanded, and the chordae became thinner or prolonged. M-mode ultrasound showed an advanced systolic mitral leaf closure line (CD segment) with an arched posterior ultrasound 2 mm and a full systolic posterior ultrasound 3 mm. At the same time, a segment of the leaflet or the anterior and posterior leaflets in the systolic phase showed hammock-like changes

Differential diagnosis

It is generally believed that mitral valve prolapse is not a heart condition, but a lesion of the mitral valve. It can be a normal mitral valve prolapse or a pathological mitral valve prolapse. Therefore, it is divided into physiological and pathological. Most physiological patients have no typical symptoms, so the physiological and pathological mitral valve prolapse should be identified clinically:

1. In patients with physiological mitral valve prolapse, the conventional echocardiography showed partial anterior and posterior lobe prolapse, and echocardiography was performed after 10 mg and 15 min of treatment of heart failure. Left ventricular long axis and four-chamber view were performed. For different degrees of anterior and posterior leaf prolapse. In some cases, conventional echocardiography for mitral valve prolapse is unclear. Ultrasonography can clearly show anterior leaf prolapse or posterior lobe prolapse, accompanied by thoracic deformity.

2, pathological mitral valve prolapse syndrome, accompanied by rheumatic heart disease mitral regurgitation, ultrasound examination, in addition to mitral regurgitation, also showed mitral anterior and posterior lobe prolapse.

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