Apical Hypertrophic Cardiomyopathy
Introduction
Introduction to apical hypertrophic cardiomyopathy Atrial hypertrophic cardiomyopathy (AHCM) is a special type of primary hypertrophic cardiomyopathy, first reported by the Japanese scholar Yamaguchi in 1976. It is different from classic hypertrophic cardiomyopathy, often without left ventricular outflow tract dynamic obstruction and pressure gradient. The hypertrophic myocardium is mainly located at the apex of the anterior wall, while the base of the ventricular septum is mostly free of hypertrophy. In recent years, due to the wide application of echocardiography, especially two-dimensional echocardiography, it is not uncommon to find this disease. basic knowledge The proportion of illness: 0.012% Susceptible people: no specific population Mode of infection: non-infectious Complications: arrhythmia, arterial embolism, infective endocarditis, sudden death
Cause
Etiology of apical hypertrophic cardiomyopathy
Myocardium during fetal development has an abnormal response to catecholamines in the circulation (20%):
To date, Perloff believes that hypertrophic cardiomyopathy is caused by abnormal myocardial response to catecholamines in the circulation of the fetus, or improper placement of fetal norepinephrine and myocardial receptors, resulting in disordered and asymmetrical myocardial fibers. Sexual hypertrophy.
Genetic factors (20%):
Some people think that it is related to excessive secretion of catecholamines or excessive sensitivity of the heart to catecholamines. It has been confirmed that hypertrophic cardiomyopathy has a family-like tendency and is autosomal dominant, possibly related to histocompatibility antigen (HLA-A, B) system. However, some sporadic cases are not associated with HLA antigens, and most of the apical hypertrophic cardiomyopathy occurs in men, possibly through recessive inheritance.
Strenuous exercise, chronic hypoxia and other factors have long-term stimulation of the myocardium (25%):
Yamaguchi et al believe that the disease progresses slowly and often shows typical performance in middle age, so it may be a combination of multiple factors, including hypertension, strenuous exercise, chronic hypoxia, alcohol abuse, catecholamines and other factors that cause long-term stimulation of the myocardium. Cardiac hypertrophy can be expressed in the same family as apical hypertrophy or classic asymmetric ventricular septal hypertrophic cardiomyopathy. According to statistics, there are no clear family history in 1/3 to 1/2 cases of this disease. It is sporadic.
Pathogenesis
Cardiac hypertrophy is particularly evident at the apex of the heart, and can be as thick as 15 to 35 mm (average 25 mm). The ventricular cavity is not enlarged or deformed, and the apex can be occluded. In the advanced case, the heart chamber can be enlarged occasionally due to repeated heart failure. The mitral valve Position advance, may be associated with papillary muscle hypertrophy, some cases may be combined with mitral regurgitation, microscopic examination of myocardial fibrosis, myocardial cell arrangement disorder, myocardial cells and nuclear abnormal hypertrophy, deformation, may be associated with focal fibrosis and plaque Block-like hyperplasia, endometrial thickening of the apex, etc., the pathophysiological abnormalities of this disease are mainly left ventricular diastolic compliance decreased, diastolic dysfunction and filling obstruction, and some cases may lead to left ventricular end-diastolic pressure as the disease progresses ( LVEDP) is elevated, followed by signs of pulmonary congestion and left and right cardiac insufficiency.
Prevention
Apical hypertrophic cardiomyopathy prevention
Among the prognostic factors of hypertrophic cardiomyopathy, reasonable life guidance is a favorable factor. Patients with this disease should avoid strenuous activities, avoid using positive inotropic drugs and dilating vascular drugs, pay attention to bathing time should not be too long, prohibit alcohol and tobacco, To prevent and treat infections, to improve the prognosis, the prevention requirements are as follows:
1. Once the hypertrophic cardiomyopathy is diagnosed, it can not participate in strenuous activities regardless of whether there is left ventricular outflow obstruction.
2. Patients with this disease may be complicated by infective endocarditis. Therefore, prophylactic antibiotics can prevent such complications in the case of tooth extraction and cardiac catheterization, which may increase the chance of infection.
Complication
Apical hypertrophic cardiomyopathy Complications, arrhythmia, arterial embolism, infective endocarditis, sudden death
The complications are the same as hypertrophic cardiomyopathy, complications such as arrhythmia, arterial embolism and infective endocarditis, but less sudden cardiac death and heart failure.
Symptom
Symptoms of apical hypertrophic cardiomyopathy Common symptoms Angina pectoris palpitations Chest pain Chest tightness Dizziness and sudden death
1. Symptoms Although the disease has a genetic predisposition, the age of onset is mostly 30 to 50 years old. Men are more common than women. About 1/3 to 1/2 patients have a family history of cardiomyopathy, and 1/3 to 1/2 patients. There may be hypertension, long-term strenuous exercise or alcohol abuse history. Because there is no left ventricular outflow obstruction and pressure gradient in this disease, the impact on cardiac hemodynamics is less than that of classic hypertrophic cardiomyopathy, so most patients are not conscious. Symptoms, only found during physical examination or echocardiography.
The onset of the disease is concealed, and the development is slow. Some cases may have chest pain, chest tightness, palpitations and other symptoms. Chest pain may resemble coronary heart disease angina pectoris, but generally lasts for a long time. Sublingual nitroglycerin is often ineffective. In addition, there may be dizziness and fatigue. Wait, late signs of cardiac dysfunction can occur, and occasionally sudden death.
2. Signs
(1) The apex beats to the left and down, and is pulsating with a lifting sensation, sometimes with a triple apex pulsation. There are two systolic swells after the systolic pre-lift, and the second appears in the late systole.
(2) The first heart sound (S1) is normal, often audible and the third, fourth heart sound, the apical region may have a systolic period of 1/6 to 2/6 level murmur, and the individual is 3/6 or 3/6 Above, it is often suggested to merge mitral regurgitation;
(3) In most cases, the proportion of cardiothoracic is normal, the heart does not increase significantly, and the proportion of cardiothorax in about 1/3 patients is >51%;
(4) Patients with advanced disease may have signs of heart failure.
Examine
Examination of apical hypertrophic cardiomyopathy
Endomyocardial biopsy: Fluorescence immunoassay found that the content of catecholamine in hypertrophic myocardium was increased, and histologically found hypertrophic cardiomyocytes with hypertrophic myocardial arrangement.
1. Echocardiography is the most clinically diagnostic test. The characteristic change of two-dimensional echocardiography is that the left ventricular long axis view shows the apical compartment and the left ventricular posterior wall is thickened. The thickest part can reach 20 ~35mm, the apical ventricular cavity is narrow, observed in real time, in the systolic phase, the hypertrophic myocardium is a tumor-like protrusion, resulting in occlusion of the left ventricular cavity and ventricular cavity in the apex. In addition, the apex can also be seen in the right anterior oblique position of the left ventricle. The interventricular septum and the posterior wall of the left ventricle are abnormally hypertrophied; the apical four-chamber view still has left ventricular anterior wall hypertrophy, and the M-mode echocardiogram is a one-dimensional image. If the apex is not detected, the disease is easily missed. Therefore, For suspected and present disease, in addition to scanning in the conventional exploration area, the apical area should be scanned, when the M-type probe is along the long axis of the heart from the II area [mitral anterior and posterior leaf group (IIB area), mitral chord level ( IIA area)] When scanning the I area (ventricular group) and apical area, it is often found that the left ventricular posterior wall and interventricular septum are significantly thickened at the apex, and the left ventricular apical cavity is obviously narrow and has a diagnostic value.
2. Electrocardiogram and heart vector map The patients have abnormal electrocardiogram and heart vector map. The abnormal electrocardiogram includes: 1 left ventricular high voltage and left chest lead (V4 ~ 6) ST segment depression; 2 deep tip inverted T wave ( GNT); 380% of patients with ventricular septal depolarization Q wave disappeared, half of patients may have mitral-type P wave, while aVL lead occasionally has a narrow Q wave, in addition, there may be various arrhythmia, ECG exercise load test Good tolerance, 24h dynamic ECG monitoring, individual cases with short ventricular tachycardia or atrial fibrillation, the former may be an important cause of sudden death of the disease, the heart vector map shows the frontal QRS ring counterclockwise operation, ring body Located at the lower left and lower, the starting vector is often pointing forward, slightly to the left, and the frontal and horizontal planes are narrow and long, located in the right rear quadrant.
3. Cardiovascular angiography Most patients with this disease can establish a diagnosis based on clinical manifestations, combined with echocardiography and electrocardiogram. Very few need to do cardiovascular angiography. The coronary angiography of this disease often shows no coronary stenosis, left ventricular angiography. The characteristic change is a left ventricular end-diastolic angiography in the right anterior oblique position with a "spades"-like change. The systolic left ventricular apex has a strong symmetrical contraction. The left anterior oblique biventricular angiography shows a thickening of the lower part of the ventricular septum. Triangle" performance.
Diagnosis
Diagnosis and diagnosis of apical hypertrophic cardiomyopathy
The diagnosis of this disease is not difficult, the key is to be vigilant, clinically suspected and the disease should be used for echocardiography (preferably two-dimensional echocardiography) and electrocardiogram examination, all of the above typical changes can be In the diagnosis, only a very small number of patients need further left ventricular angiography.
The disease should be differentiated from angina pectoris, aortic valve stenosis and other diseases.
1. Angina pectoris coronary heart disease This cause may have angina pectoris and ST-T changes and abnormal Q wave, need to be differentiated from angina pectoris coronary heart disease:
1 The age of onset of coronary heart disease is mostly in middle age.
2 There are many typical features of pain in the precordial area, but the chest pain time of apical hypertrophic cardiomyopathy is longer than that of coronary heart disease, and nitroglycerin is often ineffective.
3 more with increased blood lipids, increased blood pressure, increased blood sugar, etc., according to the characteristics of the disease and typical ultrasound images can be diagnosed, if necessary, left ventricular angiography can be clearly diagnosed.
2. The main points of identification of aortic stenosis are:
1 The aortic stenosis has a higher systolic murmur position, with the second intercostal space on the right sternal border and the 2 to 4 intercostal space on the left sternal border. The murmur is transmitted to the neck, and measures to change the contractility of the heart muscle and the surrounding resistance are used. It has little effect on the change of miscellaneous sound. The apical hypertrophic cardiomyopathy generally has a mild systolic murmur.
The 2X line shows ascending aorta dilatation, and the aortic valve may have calcification.
3 Aortic valve stenosis echocardiography can be found in aortic valve disease, while apical hypertrophic cardiomyopathy left ventricular long axis view of the apical ventricular septum and left ventricular posterior inferior wall thickening, apical ventricular cavity narrow, during systole It can be seen that the hypertrophic myocardium is a tumor-like protrusion, which leads to more specific echocardiographic changes such as occlusion of the left ventricular cavity and significant reduction of the ventricular cavity.
