Mitral valve prolapse syndrome

Introduction to mitral valve prolapse syndrome Mitral valve prolapse syndrome is also known as Barlow's syndrome, mid-systolic Karamay-systolic late murmur syndrome, balloon-like mitral valve syndrome, and valve relaxation syndrome. It is due to the left ventricular contraction, the mitral valve to the left atrium, leading to a series of clinical manifestations of left ventricular blood return to the left atrium. Often the onset is concealed, most of the disease develops slowly, and may not require treatment for life. A few cases require surgery. The disease often has complications such as progressive mitral atresia, infective endocarditis, arrhythmia, sudden cardiac death, and cerebrovascular accident. basic knowledge Sickness ratio: 0.05% Susceptible people: no special people Mode of infection: non-infectious Complications: congestive heart failure

Causes of mitral valve prolapse syndrome

(1) Causes of the disease

Clinically divided into two categories:

1. Primary (idiopathic) mitral valve prolapse: Primary mitral valve prolapse syndrome is a congenital connective tissue disease, the exact cause of which is not known, can occur in all age groups, more Occurred in women, the most women from 14 to 30 years old, one third of patients without other structural heart disease and only mitral valve prolapse as a clinical manifestation, can also be seen in Marfan syndrome, systemic lupus erythematosus, knot In patients with ganglion polyarteritis, posterior leaf prolapse is more common, most of which are sporadic (non-familial), and a few are familial morbidity, which seems to belong to autosomal dominant inheritance.

2. Secondary mitral valve prolapse: may be related to the following causes.

(1) hereditary connective tissue disease: Marfan syndrome; osteogenesis imperfecta; mucopolysaccharidosis (MPS) [Hunter syndrome (MPSII), Hurler syndrome (MPSI-H), Sanfmppo syndrome (MPSIII)]; Ehlers- Danlos syndrome (EDS); elastic pseudo-yellow tumors, etc.

(2) Rheumatic diseases: systemic lupus erythematosus (SLE); nodular polyarteritis; recurrent polychondritis.

(3) Rheumatic valvular heart disease.

(4) Viral myocarditis.

(5) Dilated cardiomyopathy, hypertrophic cardiomyopathy.

(6) coronary heart disease (papillary muscle syndrome, acute myocardial infarction, papillary muscle or chordae rupture, ventricular aneurysm.

(7) Congenital heart disease (atrial, ventricular septal defect, patent ductus arteriosus, Ebstein malformation, corrective large vessel translocation.

(8) Others: Pre-excitation syndrome, von Willebrand's disease, congenital QT prolongation syndrome, athlete's heart and straight back syndrome.

(two) pathogenesis

1. Pathological changes:

(1) Primary mitral valve prolapse: due to the increased matrix and/or mucoid degeneration of the apical fibrous layer of the leaflets, the normal fibers and elastic components are separated and ruptured, and the lobes are too long. Increased and thickened, and increased brightness, pale, lesions often involving the posterior lobe, a small number of anterior and posterior leaves are involved at the same time, due to the excessive length and enlargement of the leaflets can lead to scallops and umbrella-like deformation of the leaflets, The above changes may also involve the underlying support tissue, and the annulus may be enlarged; the chordae tendon is elongated, thinned and fragile, so that the chordae tendine is easily broken, thereby aggravating the mitral insufficiency.

(2) Secondary mitral valve prolapse lesions can have the following changes:

1 Marfan syndrome in hereditary connective tissue disease may have mitral mucoid degeneration,

2 rheumatic diseases 43% anti-nuclear antibody positive, suggesting that the disease may be associated with connective tissue disease,

3 cardiomyopathy, coronary heart disease often due to chordae, papillary muscle ischemia, inflammation, injury, causing chordae elongation, atrophy, necrosis, fracture and papillary muscle axis displacement, and left ventricular wall systolic dysfunction associated with papillary muscles , causing the mitral valve activity to lose its restraint,

4 congenital atrial septal defect may be overloaded with right ventricular diastolic, causing ventricular septal deformation, resulting in displacement of the posterior papillary muscle.

Most mitral valve prolapse had no or only mild mitral regurgitation, left ventricular end-diastolic pressure increased, ejection fraction decreased, left atrium and left ventricle increased during severe reflux.

2. Pathophysiology: mitral valve prolapse most often involves the posterior valve leaflet, occasionally affecting the anterior and posterior leaflets, when the ventricle contracts, the normal mitral valve is closed, but the long valve leaflets make the valve further upward and protrude In the left atrium, the mid-systolic period is suddenly tightened due to the long chordae when the mitral valve prolapses to the extreme point, causing the valve activity to suddenly stop, resulting in a click sound. When the mitral leaflet is obviously displaced beyond the annulus plane, it is not normal. When closed, it can lead to contraction, late-stage reflux murmur, which can produce hemodynamic changes similar to mitral regurgitation. In severe cases, large-area prolapse of mitral leaflets may not occur with clicks and murmurs, and a small number of patients Progressive degenerative changes in the valve or chordae rupture, or both, can cause severe mitral regurgitation.

3. Pathogenesis: Some patients with mitral valve prolapse often show syncope. If the episode is frequent, it may be one of the risk factors for sudden death. The mechanism of its occurrence is related to the following aspects:

(1) Arrhythmia: Continuous eccentric monitoring in patients with mitral valve prolapse shows that the mechanism of various types of ventricular arrhythmias in patients with mitral valve prolapse is unclear. Barlow et al believe that ventricular arrhythmia may It is caused by ischemia caused by the pulling of the papillary muscle. Wit classifies the mechanism of mechanical stimulation according to the experimental results, which is caused by the sudden contraction of the papillary muscles and the sudden drop of the diastolic papillary muscles.

Some scholars have found that many patients with syncope are based on a tortuosity-type ventricular tachycardia that occurs on the basis of prolonged QT interval, and found that:

1 Many symptoms of patients with mitral valve prolapse suggest autonomic dysfunction or increased adrenergic neurological tone;

2 The urinary catecholamine excretion in patients with symptomatic mitral valve prolapse was greater than normal;

3 Infusion of isoproterenol in patients with symptomatic mitral valve prolapse increased heart rate and QT interval, suggesting an adrenergic-dependent atypical long QT syndrome.

(2) outflow obstruction: patients with mitral valve prolapse often have left ventricular outflow infarction:

1 during systole, the anterior motion of the anterior mitral valve and the ventricular septum can cause hemodynamic obstruction;

2Barlow et al reported that mitral valve prolapse often coexists with hypertrophic cardiomyopathy. Sophyst et al.'s study of 190 cases of mitral valve prolapse showed that about 8% of patients had asymmetric ventricular septal hypertrophy, and 50% of such patients Atrial fibrillation can occur.

(3) Paroxysmal ischemic attack (TIA): Barnett et al found that 40% of patients with transient ischemic attack under 45 years of age were associated with mitral valve prolapse.

(4) Bacterial endocarditis (IE): Macmahon et al. showed that the relative risk of mitral valve prolapse with infective endocarditis was 2.9% to 8.2%, which was normal compared with no mitral valve prolapse. The population is 52 times higher. If the mitral valve prolapse has obvious systolic murmur, the risk of infective endocarditis is higher. Macmahon et al found that mitral valve prolapse with systolic murmur has an infectious heart. Endometritis is 13 times higher than mitral valve prolapse without systolic murmur. Patients with mitral valve prolapse over 45 years of age have a higher risk of infective endocarditis than those with age less than 45 years old. Patients with valvular prolapse are large, and male mitral valve prolapse is 2 times higher than that of female patients with infective endocarditis. Clinically, 89% of mitral valve prolapse has systolic murmur.

(5) valvular regurgitation: Many researchers have found that where rheumatic fever has disappeared, mitral valve prolapse is the most common cause of mitral regurgitation, a group of 97 patients with severe mitral regurgitation and two In patients with cuspidal replacement, mitral valve prolapse is 2%. Rheumatic heart disease is still a common and frequently-occurring disease in China, so it needs to be identified.

The mechanism of mitral valve prolapse with mitral regurgitation is mainly caused by the elongation of the mitral chordae when the heart is enlarged.

Mitral valve prolapse syndrome prevention

The preventive measures taken against this disease are mainly to prevent infective endocarditis, such as tooth extraction, surgery, skin infection, urinary tract infection, upper respiratory tract infection, etc., using antibiotics for preventive treatment, mitral valve prolapse is due to the second tip The prolapse of the valve into the left atrium, the main complications are infective endocarditis, progressive mitral regurgitation, chordae rupture, arrhythmia, systemic embolism and sudden death, but early mortality is not common, ultrasound Cardiogram examination is most meaningful. For patients with arrhythmia, ECG examination and dynamic ECG examination should be performed. The treatment can be performed with drugs such as propranolol and betaloc. For those with systolic murmur, the changes of murmur should be observed regularly. Pay attention to whether mitral insufficiency is gradually aggravated, and should limit physical activity and avoid infection, prevent heart failure and infective endocarditis, for characteristic systolic snoring, murmur accompanied by progressive bacterial blood Patients with a disease process should be given antibiotics to prevent endocarditis.

Mitral valve prolapse syndrome complications Complications, congestive heart failure

(1) Congestive heart failure:

Severe mitral regurgitation leads to congestive heart failure, expansion of the annulus and gradual elongation of the chordae, and mitral regurgitation gradually worsens; it can also occur acutely, mostly in the chordae rupture or infective heart Appears when endometritis occurs.

(2) Infective endocarditis:

More common in men and those over 45 years old, the incidence rate is 1% to 10%. Infected endocarditis should be considered in patients with isolated snoring murmurs or murmurs with prolonged time and unexplained fever. Probably, bacterial endocarditis mitral valve prolapse as a basic cause is easy to be combined with endocarditis (11%), pathological common leaflet thickening, deformation, neoplasm formation, valve rupture, perforation, partial chordae can be broken, there are Cardiac pathological murmurs are 35 times more likely to have endocarditis than those without cardiac pathological murmurs. Therefore, patients with mitral valve prolapse should be actively treated with antibiotics for device examination, surgical treatment or concurrent infection.

(3) Arrhythmia and sudden death:

Patients with mitral valve prolapse are prone to arrhythmia, 85% of patients with dynamic electrocardiogram can detect frequent ventricular premature contraction, 50% have short ventricular tachycardia, and about 1/3 of patients have rapid or excessive Mild supraventricular arrhythmia, generally have no effect on health, the most common ventricular arrhythmia, the incidence rate is more than 50%, paroxysmal supraventricular tachycardia is also more common, the mechanism is unknown, and may be related to mitral valve Leaf, papillary muscle chordae traction, or increased sympathetic nerve activity, blood catecholamine concentration increased.

Mitral valve prolapse is one of the important causes of sudden death in young people. It occurs in 1% to 2% of patients. The risk of sudden death is greater in the following cases: severe mitral valve prolapse with decompensation of left ventricular function; Complex ventricular arrhythmia; QT interval significantly prolonged; ventricular late potential positive; atrial flutter or tremor with pre-excitation syndrome; young women with black Mongolian, syncope history with difficulty breathing.

(D) transient cerebral ischemia and embolism:

Due to cerebral embolism, the incidence of mitral valve prolapse in patients under 45 years old can reach 40%. Studies have shown that patients with mitral valve prolapse often have increased platelet activity, in addition, mitral atrial surface and chordae Left endocardial fibrosis caused by friction with the left ventricular wall, easy to cause thrombosis, thrombus shedding can cause cerebral embolism, retinal artery embolization, and systemic circulation (coronary, renal artery, splenic artery, mesenteric artery, etc.) embolism, burst Atrial fibrillation is often a precursor to cerebral embolism. It is reported that the detection rate of mitral valve prolapse syndrome in non-stroke patients is 0% to 8.4%. The mitral valve prolapse syndrome in patients with ischemic cerebrovascular disease The outbreak rate is 1% to 61%, among which the incidence of patients under 45 years old is the highest, especially in stroke patients under 45 years of age, the detection rate of mitral valve prolapse is as high as 20% to 61%, higher than 4 times the normal population.

(5) mitral regurgitation:

Mitral valve prolapse is complicated by mitral regurgitation. When mitral valve prolapse syndrome is present, hemorrhage may occur when the annulus is enlarged, the chordae tendine is prolonged, and the valve is ruptured (endocarditis). The significance of mitral regurgitation should be considered for surgical treatment of severe mitral regurgitation. A small number of patients may experience progressive mitral regurgitation, which is more common in men and may be related to the following reasons:

1 Mucoid degeneration of the chordae can cause spontaneous rupture, or infective endocarditis causes chordae lesions, fracture;

2 mucus-like degeneration of the valve can cause spontaneous rupture, or invasive endocarditis causes valve tissue destruction;

3 The increase of the circumference of the annulus and the elongation of the chordae tend to increase the prolapse of the valve leaflets, causing an increase in the mitral regurgitation. The most important measure to prevent the valve, chordae damage or fracture is to actively prevent and treat infective endocarditis.

Symptoms of mitral valve prolapse syndrome Common symptoms Mitral valve prolapse heartbeat leakage nervous anxiety dizziness fatigue dyspnea chordae rupture fatigue migraine

(a) symptoms

Most patients have no obvious symptoms, only systolic click sound without concomitant middle and late murmur, that is, mitral valve prolapse without reflux, the natural development history is as follows: mitral valve prolapse without reflux mitral valve Mild reflux with prolapse moderate regurgitation of mitral valve prolapse severe regurgitation of mitral valve prolapse. When mitral valve prolapse with moderate to severe reflux, the following characteristic symptoms may occur and symptoms may appear Intermittent, repetitive and transient characteristics:

1. Atypical chest pain: the incidence rate is 60% to 70%, which can occur in the chest. The pain is different. The heavy ones are like tingling or knife cutting. It has nothing to do with fatigue and mental stress. The attack can be instantaneous or continuous. Hours, in the lying position can be reduced, and coronary heart disease is different from angina pectoris, the latter is exacerbated in the supine position, the sitting position is reduced, the nitroglycerin effect is different, the disease can not be relieved by taking nitroglycerin.

2. palpitations: in 50% of patients, the cause is unknown, may be related to arrhythmia such as frequent ventricular premature beats, paroxysmal supraventricular tachycardia or ventricular tachycardia, but dynamic electrocardiogram monitoring and atrioventricular bundle Electrogram examination found that some patients had a low correlation between palpitations and arrhythmia.

3. Dyspnea and fatigue: 40% of patients complain of shortness of breath, fatigue, often initial symptoms, some patients without heart failure, exercise endurance decreased, severe mitral regurgitation may occur left ventricular dysfunction which performed.

4. Autonomous (plant) neurological dysfunction: including anxiety, emotional stress and irritability, fatigue, excessive ventilation, etc., reflecting vagal tone and increased sympathetic tone.

5. Others: may have dizziness, fainting, vascular migraine, transient cerebral ischemia and so on.

(two) signs

1. The disease is more common in women: accompanied by body lengthening and thoracic deformity, such as funnel chest, straight back (small and anterior chest diameter, normal thoracic kyphosis disappeared) and vertebral scoliosis, etc., have certain reference value for diagnosis.

2. 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, for the sudden withdrawal of the chordae or the prolapse of the leaflet suddenly Due to the suspension, the sound of squeaking in the late stage of contraction can be heard, often in the form of increasing gradation, and a few can be full systolic murmurs, and cover the squeaky sound. When there is a click and murmur, the mitral valve is reversed. The degree of flow is generally mild to moderate, and no regurgitation does not produce systolic murmur. Sometimes, high-pitched loud-sounding systolic late murmurs can be heard in the apical region, similar to pertussis or geese-like, and the systolic murmur appears earlier. The longer the appearance time, the more severe the mitral regurgitation is. The physiological or drug measures that can reduce the left ventricular blood flow resistance, reduce venous return, enhance myocardial contractility, and reduce the left ventricular end diastolic volume, such as deep inhalation, Sitting or standing position, inhalation of isoamyl nitrite, Valsalva action period can cause left ventricular end-diastolic volume reduction, mitral valve prolapse is increased, the click sound is advanced, the murmur becomes longer and louder; Increase left ventricle Blood resistance, increased venous return, weakened myocardial contractility and physiological or drug factors that increase left ventricular end-diastolic volume such as deep exhalation, diarrhea, left lateral position, relaxation of Valsalva action, etc. may cause left ventricular end-diastolic volume Increase, the mitral valve prolapse is relieved, the click sound is delayed, the murmur is shortened and reduced, and a few patients with mitral valve prolapse have neither systolic mid-term click sound nor contraction middle or late murmur, relying only on echocardiography Or left ventricular angiography can be diagnosed, clinically known as "dumb mitral valve prolapse."

3. Other signs: more apex beats occasionally in the left lateral position, the pulsation of the apex can be suddenly retracted in the mid-systolic phase consistent with the mid-systolic click, forming a double-peak apex beat, in the middle of the contraction and At the same time as the sound of the sound appeared, the sudden withdrawal of the heart caused the heart to pulsate outward.

Examination of mitral valve prolapse syndrome

1. X-ray examination: most patients have no obvious abnormal heart shadow, severe left ventricular and left ventricle in patients with severe mitral regurgitation, chest skeletal abnormalities are the most common, left ventricular angiography shows mitral valve prolapse and reflux, right front In the oblique position, the posterior mitral valvular flap protruded into the left atrium; the left ventricle contracted asymmetrically, and the basal or middle part of the ventricle contracted strongly, showing an inwardly concave "ballet foot"-like change.

(1) Most patients have a straight back, funnel chest or thoracic vertebrae.

(2) mitral valve prolapse without concomitant mitral insufficiency, normal heart shadow.

(3) patients with severe mitral insufficiency show left atrium, left ventricular enlargement, pulmonary congestion, lung texture thickening, etc., left ventricular enlargement, the heart is pear-shaped.

2. Electrocardiogram examination: Most patients have normal ECG, some patients show II, III, aVF lead T wave biphasic or inverted, and non-specific ST segment changes, this change in the inhalation of isoamyl nitrite or exercise obvious.

(1) T wave: the lower wall (II, III, aVF) and the left chest lead (V4 ~ 5) T wave is inverted or bidirectional, with light inversion being the most common, T wave inverted in standing position, after exercise or Appear or aggravate when inhaling isoamyl nitrite, suggesting that it may be associated with excessive traction of the papillary muscles.

(2) ST segment: ST segment rarely changes at rest, but there is obvious ST segment depression after exercise test, but ST segment tends to return to normal at the peak of exercise, and coronary angiography is normal, ST-T wave Changes may be related to papillary muscle ischemia, increased left ventricular tone after valve prolapse, and hypersympathetic hyperfunction.

(3) QT interval prolongation: uncommon, but one of the characteristics may be related to sudden death. Paddu et al found that the increase of blood catecholamine concentration is closely related to QTc prolongation, and may also be electrophysiology of severe ventricular tachyarrhythmia. basis.

(4) arrhythmia: ventricular premature contraction is the most common, followed by ventricular tachycardia, supraventricular tachycardia, atrial premature contraction and atrial fibrillation, etc., a few may have ventricular fibrillation or severe sinus cardiac Too slow, even sinus arrest.

3. Echocardiography: It is of special significance for the diagnosis of mitral valve prolapse. M-mode ultrasound can be seen in the late systolic mitral leaf closure line (CD segment) with posteriorly moved ultrasound 2mm and full systolic posterior ultrasound 3mm. During the systole, the leaflets or the anterior and posterior lobes were hammock-like changes, and the amplitude of the anterior mitral valve was increased. The two-dimensional UCG showed systolic mitral occlusion when the anterior and posterior lobes were closed or their lobes were to the left atrium. The top of the mitral valve exceeds the line of the mitral annulus, and the mitral valve has a significantly increased range of motion. When the chordae ruptures, the leaflets are swinging like a scorpion, the chordae tend to grow, relax, and break at the broken end. The ventricle, the left atrium is enlarged.

Doppler UCG can be used in the left atrial exploration and systolic reflux spectrum and colorful mosaic reflux beam, two-dimensional echocardiogram apical four-cavity position diagram:

a. The posterior lobe of the mitral valve slightly exceeds the annulus;

b. The anterior mitral lobes are slightly beyond the annulus;

a and b. the valve in the figure is in the left chamber;

c. Before the mitral valve, the posterior leaf is moderately beyond the annulus, and the mating point is on the annulus;

d. Before the mitral valve, the posterior lobes are severe beyond the annulus with the collateral beyond the annulus.

LA is the left atrium and LV is the left ventricle.

4. Left ventricular angiography: contribute to the diagnosis of mitral valve prolapse, not only can clear the prolapse of the leaflet, but also semi-quantitative mitral regurgitation, the right anterior oblique position for the posterior lobe prolapse is clear, while the left front The oblique position is suitable for anterior leaf prolapse.

Diagnosis and diagnosis of mitral valve prolapse syndrome

diagnosis

The clinical diagnosis of mitral valve prolapse is mainly based on typical auscultation characteristics of mid-term snoring and contraction, late murmur, drug and motion effects on murmur, combined with echocardiography, if necessary, left ventricular angiography, generally more diagnosed Primary mitral valve prolapse can only be considered after the exclusion of mitral valve prolapse caused by various cardiovascular diseases or systemic diseases.

Differential diagnosis

It is generally believed that mitral valve prolapse is not a heart disease, but a lesion of the mitral valve, which can be normal mitral valve prolapse or pathological mitral valve prolapse, so 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, including echocardiography after 10 mg 15 min after treatment, left ventricular long axis, and four-chamber view. Both showed different degrees of anterior and posterior lobe prolapse. In some cases, conventional echocardiography revealed unclear mitral valve prolapse. Ultrasound examination clearly showed anterior lobe 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.

3, mitral valve prolapse should be distinguished from the flap sound of the valve.

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