Hypertrophic cardiomyopathy in the elderly
Introduction
Introduction to elderly hypertrophic cardiomyopathy Hypertrophic cardiomyopathy (HCM) is characterized by asymmetry of the myocardium, uneven hypertrophy and small ventricular cavity. Unexplained heart disease, typical interventricular septum hypertrophy is much more obvious than free wall, causing left The outflow tract is narrow, so it is also called primary hypertrophic aortic stenosis (IHSS). The basic abnormal changes are left ventricular diastolic dysfunction, blood filling is blocked, and the incidence of HCM is mainly young and middle-aged. More, but in recent years, the incidence of the elderly is gradually increasing. Among the 44 patients with hypertrophic cardiomyopathy in China, 36.3% are older than 60 years old. basic knowledge The proportion of diseases: in the case of hypertension, the incidence of this disease is about 1% - 3% Susceptible people: the elderly Mode of infection: non-infectious Complications: angina, syncope, sudden death
Cause
The cause of hypertrophic cardiomyopathy in the elderly
(1) Causes of the disease
The cause of HCM is unknown, the incidence is familial, may be related to genetic factors, and other factors are involved.
Genetic theory
About 55% of HCM patients have a clear family history or a clear tendency to familial aggregation. The genetic pattern is most common with autosomal dominant inheritance, and its genetic phenotype is heterogeneous, with incidence among different families and individuals. Different from pathological manifestations, the genetic theory of HCM is thought to be closely related to the histocompatibility antigen (HLA) system. In HCM patients, the incidence of HLA-DRW4, Ag, B5, B4 antigens has increased. Important findings have been made in the study of HCM pathogenic genes. About 50% of patients are caused by mutations in the myocardial protein gene. The pathogenesis of the remaining 50% of patients is unclear. Matkins showed at least 5 in 1994 through family linkage studies. Independent sites cause HCM due to mutations on different chromosomes, and are named "hypertrophic cardiomyopathy sites 1 to 5" according to the human genome, of which 3 genes have been coded as myosin heavy chain ( -HMC) gene, troponin T gene and -troponin gene, their respective chromosomal loci are 14q1, 1q3 and 15q2, and the fourth locus is at 11q11. The fifth locus is not yet known. In different families, -MHC Because there are at least 30 separate point mutations, so this multiphase heterogeneous type of performance, not only in the same clinical symptoms and cardiac histological also have different.
The pathogenesis of pathogenic genes and HCM is still unclear. In the study of COS cell stratification devices, those with gene mutations cannot form sarcomere from COS cells, suggesting that myosin cannot bind to actin, or It is a barrier to other proteins necessary for structural integration, leading to myocardial contractility damage, and it is believed that known pathogenic genes encode myofibrillar proteins in cardiomyocytes, leading to disordered arrangement of myofibrils and myocyte abnormalities. Forming the "disordered" appearance seen in histology, thus categorizing HCM as a pathological change in myocardial myofibrillar dysgenesis, leading to damage to myocardial contractility, which is one of myocardial contractility disorders Compensatory results, which are caused by abnormal growth stimuli.
2. Catecholamine and endocrine theory
Endocrine disorders, especially catecholamines (CA) and endocrine disorders are associated with HCM. Catecholamines, angiotensin II and thyroxine play important roles in the development of cardiac hypertrophy. Not only the CA content of the heart basal part of canine experimental HCM Increased, norepinephrine can also cause HCM in dogs. Clinical application of -blockers can reverse the outflow tract pressure gradient and decrease left ventricular diastolic compliance due to adrenaline stimulation, slowing the rate of myocardial thickening. .
3. Abnormal expression of proto-oncogene
In recent years, the relationship between proto-oncogenes and cardiac hypertrophy has been emphasized. Simpson pointed out in 1988 that norepinephrine can abnormally express myc proto-oncogene in cultured cardiomyocytes and promote the formation of HCM. The activation of oncogenes is not only related to the formation of tumors, but also the occurrence and development of cardiac hypertrophy is closely related to the abnormal expression of proto-oncogenes. Proto-oncogenes are not only involved in cell transformation, but also participate in normal cell proliferation.
4. Calcium regulation is abnormal
Some authors have suggested that HCM patients have biological defects, abnormal calcium ion mediation in cardiomyocytes, intracellular calcium overload, clinical high blood calcium and HCM at the same time, experimental calcium overload can cause ventricular diastolic dysfunction, clinically The use of calcium antagonists can improve the symptoms of HCM, indicating abnormalities in the regulation mechanism of intracellular calcium, and may be involved in the pathogenesis of HCM.
(two) pathogenesis
There are three main aspects:
Left ventricular systolic outflow obstruction
The main hemodynamic characteristics of HCM are the systolic left ventricular outflow tract obstruction and the pressure gradient across the outflow tract. Due to the unevenness of the interventricular septum and left ventricular wall, different (upper, middle, lower) internal obstruction is formed. The main cause of obstruction of the outflow tract is the hypertrophy of the nipple muscle. The moving and systolic mitral leaflets are subjected to the forward movement (SAM) by the jet flow effect of the high velocity blood flow (SAM), resulting in the mitral valve. "leaflet-septal contact" phenomenon, when the outflow pressure is reduced and the pressure in the humane and apex increases, resulting in a pressure gradient, if at rest, the pressure difference between the two phases is > At 4.0kPa, both ventricular endoscopic obstruction is considered. The greater the pressure difference, the more serious the obstruction is. In order to overcome the indoor resistance, the left ventricular contractility is strengthened, the pressure difference is larger, the myocardium is modern and compensatory, and the oxygen supply is long-term. Damaged hypertrophic myocardium becomes a harmful energy-consuming mechanical stimulus, while mitral valve leaflet leaf closure is not strict, blood reflux, and possible mitral valve prolapse, leaflet fibrosis, annulus calcification.
The outflow obstruction of HCM is often dynamic, and some physical and pharmacological factors can change it. Any factor that reduces the volume of left ventricular cavity can increase the pressure gradient and increase the obstruction; otherwise, reduce and reduce, such as the lack of movement At the end of inhalation, standing suddenly from the lower jaw, compensatory interval after pre-systolic contraction, tachycardia, digitalis preparation, isoproterenol, nitrates, diuretics, etc., can increase the pressure gradient, obstruction Increase, and the lack of movement to hold the breath, supine or chin fist, -blockers, -receptor stimulants, etc., can reduce the pressure gradient.
2. Myocardial diastolic dysfunction
Another feature of HCM is that early myocardial volume increases, chamber stiffness increases, ventricular compliance decreases, diastolic phase increases due to pressure, and the ratio of diastolic capacity (dp/dv) increases, followed by contraction due to internal obstruction Diastolic load is impaired, myocardial relaxation loses normal load dependence, myocardial cell sarcoplasmic reticulum calcium regulation disorder, increased muscle tone, abnormal electromechanical activity, myocardial relaxation and contraction in space and time, due to these three myocardial There are obstacles in the relaxation regulation factors, which can make the diastolic function more impaired. The filling rate and amount of the rapid filling period (REP) in the early diastolic period are decreased, the left atrial systolic filling is increased, the left atrium is enlarged or there is atrial fibrillation, and the high frequency is often present. The fourth heart sound, pulmonary vein congestion, clinical fatigue, fatigue, dyspnea and angina, and even syncope.
In the case of left ventricular load constant, the rate of decongestion is the main determinant of myocardial slowness, and myocardial ischemia and excessive calcium overload are the main determinants of decompression activity, HCM from pathology, hemodynamics and Clinically, it has been proven to have the presence of myocardial ischemia. Myocardial ischemia hinders the reabsorption of calcium by the sarcoplasmic reticulum, overloading the cytoplasmic calcium, thereby hindering the contraction activity and soothing, so this is due to the biochemical process of the heart muscle. Due to the loss, myocardial load and deconstriction activity are asymmetrical, and unevenness also impairs the slow process.
The left ventricular systolic function of HCM patients is mostly normal or supernormal, and LVEF is increased, but 8% to 17% of HCM patients have left ventricular diastolic and systolic dysfunction.
3. Myocardial ischemia
201Ti perfusion scan defect, increased myocardial lactic acid production and electron diffusion scanning (PET) observation confirmed the existence of myocardial ischemia in HCM patients, the exact mechanism of myocardial ischemia is still unclear, may be due to hypertrophic myocardial bridging in the myocardium Intima and medial thickening of small coronary arteries, stenosis of the lumen, decreased capillary density in hypertrophic myocardium, impaired coronary reserve, increased sensitivity to subendocardial myocardial ischemia, poor left ventricular diastolic, increased filling pressure, and filling Decreased, coronary filling and perfusion damage and ventricular septal coronary artery permeation or coronary vasospasm and other factors, clinically common HCM patients have angina pectoris, and coronary artery no abnormalities.
The heart of HCM patients has different degrees of increase, from the normal upper limit to more than 100%, older patients are more obvious, the most important is 675g, mainly left ventricular hypertrophy, normal or reduced ventricular volume, most lesions Involved in interventricular septum, mostly asymmetrical hypertrophy, occasionally symmetrical hypertrophy, hypertrophic myocardial distribution is not uniform, both in the upper part of the interventricular septum, but also in the middle of the interval or apex, pure heart tip hypertrophy, known as apical HCM In Japan, it became a special subtype of HCM, accounting for 51% of the total HCM. The maximum wall thickness of the interventricular septum was 52 mm. When the patient was 55-60 years old, the hypertrophy rarely exceeded 25 mm. The interventricular septum hypertrophy was more obvious than that of the left ventricle. Sometimes more than 3 times, hypertrophy can also be seen in the right ventricle, bilateral ventricles, papillary muscles and left ventricular wall, posterior wall and other parts, mitral and aortic valve often thickened, about 32.4% of patients in the main A special marginal endocardial cord-like fibrous thickening zone can be seen in the upper part of the interventricular septum. The anterior systolic anterior motion of the anterior mitral valve is close to the upper part of the septum. Long-term stimulation makes the endocardium Fiber hyperplasia It has characteristic pathological changes and has diagnostic value. HCM histology is characterized by disordered myocardial fibers in hypertrophic sites. The myofibrils in myocardial cells are stretched in various directions, arranged, and each muscle cell is widened under light microscope. It deforms and travels around the central foci of the connective tissue. This is a special and specific manifestation of HCM. The structure of the myocardial cell bundle is disordered, intersecting each other or showing the bone-like arrangement of the carp. At the same time, the nucleus is huge, strange, mitochondria increase, and the nucleus often There is a "halo" around it, and histochemistry is determined to be glycogen accumulation. This specific phenomenon, together with myocardial alignment disorder and fibrosis, becomes the hallmark of defining the ventricular thickening segment, the endocardium is thickened, and the extracardiac coronary artery is mostly normal.
Prevention
Elderly hypertrophic cardiomyopathy prevention
1, lose weight. Obese people have a much higher proportion of heart disease than normal weight, especially those with "apple-shaped" body (waist-hip obesity). As long as the elderly lose 3-5 kilograms, the heart condition will be greatly improved. At the same time, experts warn the fatter old man, do not expect to become a super model at once, to gradually achieve the purpose of weight loss through balanced diet and exercise.
2, eat less egg yolk. A normal-sized egg yolk contains about 200 mg of cholesterol. If the elderly have higher cholesterol, they can only eat up to two egg yolks a week.
3. More exercise. A moderate exercise for 20 minutes a day can reduce the risk of heart disease by 30%, and the quickest effect is best.
4. Quit smoking. Smokers are twice as likely to suffer from heart disease as non-smokers. The study found that after 2-3 years of smoking cessation, the risk of heart disease fell to the same level as non-smokers.
5, pay attention to diet. In normal life, insist on eating low-fat foods, such as lean meat and low-fat dairy products.
6, the right amount of drinking. Drinking 3-9 glasses of wine a week is appropriate for the heart. But be careful not to be greedy, because excessive drinking can cause heart disease.
7, beware of diabetes. People with diabetes have four times more heart disease than others. Therefore, the elderly should have regular physical examinations and early detection and early treatment of diabetes.
8, control emotions. Grumpy, unable to control themselves in the event of an emergency, it is also easy to induce heart disease.
Complication
Complications of hypertrophic cardiomyopathy in the elderly Complications, angina, syncope
Can be complicated by angina, syncope, sudden cardiac death.
Symptom
Symptoms of hypertrophic cardiomyopathy in the elderly Common symptoms: Sudden sudden death, arrhythmia, hepatomegaly, congestion, edema, pulmonary congestion, cardiac output, and acute heart failure
Symptom
The deciding factor of clinical manifestation of HCM patients is the size and presence or absence of pressure gradient across the outflow tract. Most patients are asymptomatic or only mild, non-obstructive symptoms are mild, latent obstruction is heavier, obstructive The symptoms are the heaviest.
(1) Labor dyspnea: Most of the most common complaints of HCM patients, 90% of patients are tired, shortness of breath after exercise, older patients are more obvious, 31% of patients have nocturnal paroxysmal dyspnea, and left Room compliance decreased, end-diastolic pressure and left atrial pressure increased, pulmonary congestion related, advanced patients may have sitting breathing, fatigue, palpitations and other symptoms.
(2) angina pectoris: 70% to 80% of patients often have atypical angina, but the duration is longer, to a lesser extent, nitroglycerin can not be alleviated, may be due to increased myocardial oxygen demand, coronary artery blood supply is relatively insufficient, The long-term existence of myocardial ischemia results.
(3) syncope: 30% to 35% of patients may have sudden standing or syncope after exercise, can be relieved by themselves, can be the only complaint of the patient, about 1/3 of patients have frequent syncope or syncope, which lasts for a while. Relief, physical activity or emotional excitement can often be induced, probably due to sympathetic excitation, increased left ventricular contractility, worsening diastolic filling, increased pressure gradient across the outflow tract, decreased cardiac output, systemic circulation, cerebral arterial blood supply Insufficient fainting, in addition, complex ventricular premature contraction, ventricular tachycardia, rapid atrial fibrillation, etc., rapid changes in hemodynamics, can also lead to syncope.
(4) Sudden death: HCM patients have a higher rate of sudden death, patients are usually asymptomatic, and suddenly die after a calm state or a slight activity, or sudden cardiac arrest after strenuous activity. The cause of sudden death is considered to be mainly outflow obstruction. In recent years, sudden death is closely related to severe ventricular arrhythmia. Sudden death is mainly caused by ventricular tachycardia and ventricular fibrillation. The high risk factors of sudden death are: family history of syncope and sudden death, ventricular hypertrophy is obvious and diffuse, electrophysiological examination can induce Ventricular velocities or room velocities.
(5) Heart failure: late stage of HCM due to myocardial fibrosis, infarction and systolic and diastolic dysfunction, 7% to 15% of patients may have heart failure, shortness of breath, palpitations, not lying, liver enlargement, lower extremity edema, etc. Symptoms and signs of congestive heart failure.
2. Signs
The middle and late stage of the anterior and posterior systolic murmur is the most common. It is located in the 3 to 5 intercostal zone or interventricular zone of the sternal border and is accompanied by tremor. It is released to the sternal border, abdomen and apex. The loudness and duration of the murmur. , varies with different conditions: 1 in standing position, exertion of breath holding, digitalis, isoproterenol, nitroglycerin and premature beats, myocardial contractility is enhanced, afterload is reduced, so that when the pressure difference increases, the noise is enhanced, 2 In the supine position, squat, when applying norepinephrine and beta blockers, the myocardial contractility is weakened. When the front and rear loads increase, the pressure difference in the room decreases, the noise is weakened, and the apex beats due to the left atrium, left. The enlargement of the chamber to the left and the left, together with the subsequent systolic blood obstruction, can form a "double" or "triple" pulsation, the heart is obviously enlarged, and the third and fourth heart sounds can be heard, about 1/3 of the patients There is a second tone splitting, half of the patients with apex can be heard and mitral regurgitation systolic murmur, a small number of patients due to left ventricular diastolic dysfunction, increased diastolic blood pressure caused by mitral valve openness, mid-diastolic murmur, due to room interval Thick, inclined aortic annulus, some patients early diastolic murmur can be heard in the aortic valve area.
Examine
Examination of hypertrophic cardiomyopathy in the elderly
Abnormal liver function in advanced hepatic congestion.
Electrocardiogram
Most patients with HCM have abnormal electrocardiogram. The most common manifestations are left ventricular hypertrophy and strain, ST-T changes obviously, T wave is sometimes similar to "coronal T", and the pre-cardiac lead V5 appears wide and inverted T wave ( >10mm) may be an indication of apical hypertrophy. About 30% to 50% of patients have abnormal Q waves, which are common in II, III, aVF, V1, V2, V5, and V6 leads. The Q wave is deep and narrow. Often <0.03 to 0.04 s, the same lead T wave in the presence of Q wave is erect, sometimes difficult to distinguish from myocardial infarction, the mechanism of abnormal Q wave may be related to myocardial disorder, fibrosis and abnormal conduction pathway of ECG. Sometimes P-wave changes can be seen, and the left atrium is enlarged. In addition, various arrhythmias, such as supraventricular tachycardia, polymorphic ventricular tachycardia, atrial fibrillation, left and right bundle branch block, and intraventricular conduction resistance can be seen. Stagnation.
2. Echocardiography
Echocardiography is the best method for non-invasive diagnosis of HCM. It can not only determine the diagnosis, but also can classify HCM. The main positive manifestations are:
(1) ventricular septal hypertrophy and abnormal movement: mostly asymmetrical hypertrophy, adult thickness is more than 15mm, the ratio of ventricular septum to left ventricular thickness > 1.3 ~ 1.5 (normal = 1.03 ± 0.07), ventricular septal motion amplitude and contraction The period of thickening rate is reduced, the ventricular cavity becomes smaller, and the middle interval hypertrophy can be seen in the middle left ventricular systolic atresia, while the long axis of the cardiac cavity is shortened, and the apical atresia is characteristic of the apical HCM. The normal part of the myocardial movement is normal or compensated. Sexual enhancement.
(2) Left ventricular outflow tract stenosis: the width of the normal left ventricular outflow tract is 2.0 to 2.5 cm. Due to the hypertrophy of the interventricular septum, the anterior systolic systolic movement of the anterior mitral valve body makes the left ventricular outflow tract stenosis <2.0 cm.
(3) mitral systolic anterior movement: due to asymmetry hypertrophy of the interventricular septum, especially under the aortic valve, the heart chamber becomes smaller, the position of the papillary muscle is close to the interventricular septum, making the mitral leaflets relatively long, the ventricle During systole, blood flow rapidly passes through the narrow outflow tract, forming a relatively low-pressure zone, causing the anterior mitral valvular bulge to the low-pressure left ventricular outflow tract, resulting in stenosis or obstruction of the outflow tract, and mitral annulus calcification is seen in elderly patients.
(4) Aortic valve systolic mid-term closure: systolic mitral valve opening, ventricular isovolumic relaxation time prolonged, EF slope decreased significantly, response ventricular muscle compliance decreased.
(5) Early diastolic mitral valve opening: the anterior lobe is again in contact with the ventricular septum, and the distance between the anterior mitral anterior lobe and the ventricular septum is smaller than that of normal people.
Echocardiography showed that the mitral E peak decreased, the EF slope decreased, and the CD segment of the anterior mitral systole showed an arched bulge to the ventricular septum, called the SAM sign. The method of reducing the amount of blood return or increasing the contractility of the heart muscle is as follows: Both nitroglycerin and dobutamine can significantly enhance the SAM sign.
3. X-ray inspection
Most of the chest radiographs have obvious heart enlargement, mainly left ventricle, and left atrial and right ventricular enlargement are not uncommon. Sometimes intracardiac calcification is seen, the aortic widening is not obvious, and pulmonary congestion can be seen in heart failure. Interstitial pulmonary edema.
4. Cardioangiography
HCM can show the left ventricular cavity shrinkage deformation, S-shaped stenosis under the aortic valve, thickening of the ventricular wall, thickening of the time interval into the heart chamber, the left atrium can also be developed at the same time, the papillary muscle can be hypertrophied.
5. Magnetic resonance imaging (MRI)
Magnetic resonance imaging can diagnose the disease in terms of morphology, function, tissue characteristics and metabolism. MRI can clearly distinguish the left ventricular endocardial surface, epicardial surface, pericardial cavity and surrounding adipose tissue. The myocardial thickness and the distribution range and location of the thickened myocardium were measured, and the degree of myocardial systolic thickening was observed.
6. Endomyocardial biopsy
Fluorescence immunoassay found that the content of catecholamine in hypertrophic myocardium increased, histological examination of hypertrophic myocardial arrangement disorder can be seen in the singular hypertrophic cardiomyocytes, and there are typical signs of disorder.
7. Genetic analysis
Genetic testing of members of the familial HCM family, such as the analysis of the -MHC mutant gene, may reveal a recessive patient with familial HCM, which is also beneficial to the patient's own diagnosis.
8. Echocardiography typing
(1) According to hemodynamic classification:
1 Obstruction type: the ventricular septum is obviously thickened, especially the anterior superior part of the ventricular septum obstructs the left ventricular outflow tract, the left ventricular posterior wall often has compensatory hypertrophy, and the blood flow velocity between the left ventricular cavity and the aortic valve increases. The pressure gradient increases and reaches the highest peak at the end of the contraction.
2 non-obstructive type: the ventricular septum was obviously hypertrophic, but the left ventricular outflow tract was not significantly narrow, there was no pressure gradient between the left ventricular outflow tract and the ventricular cavity, and the left ventricular posterior wall was not compensatory thickening.
(2) According to the type of hypertrophy:
1 asymmetry ventricular septal hypertrophy: except for interventricular septal hypertrophy, no outflow tract stenosis, no compensatory thickening of the left ventricular posterior wall, left ventricular wall and other parts of the left ventricular wall thickness and movement normal, or compensatory Enhanced, the movement of the hypertrophic part is obviously weakened or disappeared.
2 aortic subvalvular hypertrophy: ventricular septal hypertrophy, basal thickening into the left ventricular outflow tract, resulting in left ventricular outflow tract stenosis or obstruction, left ventricular posterior wall compensatory thickening.
3 apex hypertrophy: the 1/3 apex of the ventricular wall is obviously hypertrophy, the base of the ventricular septum may be normal, the apex of the apex becomes smaller, cleft or even occluded, and the posterior wall of the left ventricle and the posterior wall of the left ventricle are seen. Thick, and protruding into the heart chamber, the wall motion is not coordinated.
Diagnosis
Diagnosis and diagnosis of hypertrophic cardiomyopathy in the elderly
diagnosis
According to the patient's clinical symptoms, physical signs combined with electrocardiogram and echocardiography, HCM is generally not difficult to diagnose. If the above examination is still not diagnosed, cardiovascular angiography and cardiac catheter hemodynamics are feasible. The elderly are relatively rare. Should pay attention to missed diagnosis and misdiagnosis.
Differential diagnosis
The differential diagnosis of HCM, the elderly should focus on hypertension and coronary heart disease, hypertensive heart disease has a history of long-term hypertension, in addition to the heart can have other organ damage, ultrasound is mainly left ventricular wall thickening , the ratio of ventricular septum to left ventricular posterior wall thickness is less than 1.3, etc., the aortic valve or subvalvular stenosis, or mitral valve prolapse sign in senile degenerative heart valve disease, according to the systolic murmur position In the right sternal border of 2 to 4, not affected by myocardial contractility or changes in anterior and posterior load, and no asymmetry of myocardial hypertrophy, etc., elderly patients with coronary heart disease often have typical angina pectoris, clinical evolution during myocardial infarction Characteristic, accompanied by papillary muscle dysfunction or ventricular septal perforation, sternal rim systolic murmur, but ECG can have ischemic ST-T changes, and site abnormal Q waves.
