Cardiac amyloidosis in the elderly
Introduction
Introduction to cardiac amyloidosis in the elderly As early as 1850, Virchow discovered that there was a deposit between human tissue cells that showed a starch-like color reaction when contacted with iodine. Virchow called it amyloid and called the amyloid deposit. Denaturation, it has been proved that the so-called amyloid is a protein composed of different components, so it is more suitable to be amyloid. basic knowledge The proportion of the disease: the incidence rate of the middle-aged and elderly people over 50 years old is about 0.001%-0.005% Susceptible people: the elderly Mode of infection: non-infectious Complications: acute left heart failure in the elderly, arrhythmia, sudden death
Cause
The cause of cardiac amyloidosis in the elderly
Primary (25%):
Due to the proliferation and malignant transformation of single plasma cells, the proportion of heavy light chain synthesis is imbalanced, resulting in excessive light chain, most of which are lambda light chains, which exceeds the catabolic capacity of macrophages and polymerize to form amyloid fibers. The mechanism of occurrence of myeloma-associated amyloid is basically the same.
Secondary (20%):
The antigenic stimulation of various primary diseases activates macrophages. Under the action of interleukin-1, hepatocytes produce a large amount of serum AA (SAA) protein, causing macrophage dysfunction, which cannot be completely degraded. The formation of poorly soluble AA protein, family heredity is represented by Mediterranean type fever, and the mechanism of AA protein production of amyloid fiber is similar.
Limitations (15%):
In some cases, the plasma cell infiltration is common. The histochemical analysis shows that the amyloid fiber is AL, so the mechanism is similar to that of the primary. In some cases, the corresponding hormone secreted by the endocrine gland, such as the medullary thyroid carcinoma, is starch. The main component of the protein fiber is procalcitonin. The deposition of amyloid protein is limited, and the mechanism is still unclear.
Senile (10%):
The pre-albumin is isolated from the myocardium in some cases. It is not produced by cardiomyocytes. It is presumed that the precursor is formed in the extracardiac tissue and is deposited in the lesion through blood circulation. In some cases, it is atrial natriuretic peptide. It is mainly produced in atrial myocytes.
Hemodialysis correlation (5%):
Normal human nucleated cells produce 2 microglobulin, 99.9% are filtered by glomerulus, reabsorbed by renal tubules and catabolized by renal tubules. Renal tubules of renal patients cannot be decomposed, resulting in a large amount of retention in the body. The copper imitation membrane or the cellulose acetate membrane cannot precipitate the 2 microglobulin, so that it is deposited in a large amount in the body, and provides conditions for the formation of its amyloid fiber.
Although pathological studies have found that amyloid lesions in primary patients generally invade the heart, there are only 1/2 to 1/3 of clinical manifestations of the heart, less than 10% of secondary patients, and fewer elderly patients. In patients with family hereditary and hemodialysis-related patients, there is only occasional clinical manifestation of the heart in the late stage of the disease, the same as amyloidosis, the frequency of violation of the heart and the difference in clinical manifestations is so great that the mechanism is unknown.
Pathology: gross examination: the heart is soft, lack of flexibility, ventricular free wall and interventricular septum are hypertrophy, which can be used for initial diagnosis at autopsy, 80% of ventricular size is normal, 20% of ventricular enlargement often combined with coronary heart disease Or chronic pulmonary heart disease, most of the bilateral atrium has moderate dilatation, 25% of the heart cavity has a wall thrombus, almost all patients with atrial brown wall, a smooth surface of amyloid deposits, and affect the valve and heart membrane.
Optical microscopy: There is an amorphous glass-like transparent substance between the cardiomyocytes, which is diffusely distributed in the ventricular muscle, resulting in myocardial atrophy, necrosis, connective tissue hyperplasia, endocardium, valve, papillary muscle, and pericardium. Invasion, Congo red staining was observed under a polarized light microscope, and the specific green birefringence was observed, which was specific.
Observation under electron microscope: Amyloid protein is mainly composed of slender and rigid fibers, each fiber is composed of subunit fibrils. X-ray crystal analysis and infrared spectrometer inspection show a special arrangement pattern called The -flap structure, in addition, there is a pentagonal substance called P component, which is very similar in nature to C-reactive protein.
Prevention
Cardiac amyloidosis prevention in the elderly
The main prevention of complications, such as the treatment of heart failure, the use of diuretics and vasodilators to improve symptoms, the treatment of amyloid protein and digitalis drugs have a certain affinity, even in small doses, can induce arrhythmia, Therefore, it is not suitable to use, especially calcium antagonists, which can further deteriorate the heart function and should also be avoided.
Complication
Cardiac amyloidosis complications in the elderly Complications, acute left heart failure, arrhythmia, sudden death
Can be complicated by atrial fibrillation, acute left heart failure, arrhythmia, and even sudden death.
Symptom
Symptoms of cardiac amyloidosis in the elderly Common symptoms Hepatic enlargement, palpitations, amyloidosis, sensory disturbance, dysphagia, increased heart rate, muscle atrophy, conduction block, dizziness
1. Cardiovascular performance often has no clinical manifestations during the compensation period, or only dizziness, fatigue, nausea after tiring, shortness of breath, etc. After entering the decompensation period, the following performances are mainly observed.
(1) Right heart dysfunction: jugular vein engorgement, apical beat weakened, heart sound is reduced, heart rate is increased, fourth heart sound or galloping can be heard, most of them have no murmur or only mild systolic murmur in mitral valve area. There is no obvious enlargement of the heart, the liver is swollen, the beat can be touched, mild to moderate ascites, depression and edema of the extremities, and left heart failure can also occur in the later stage, but acute pulmonary edema rarely occurs.
(2) arrhythmia: can present a variety of arrhythmia, especially atrial fibrillation, can also occur sick sinus syndrome or varying degrees of atrioventricular and bundle branch block, due to malignant ventricular tachyarrhythmia, sudden death can occur .
(3) systolic blood pressure reduction: due to decreased cardiac output, systolic blood pressure is often reduced, resulting in small pulse pressure, about 10% of patients with orthostatic hypotension, elderly hypertensive patients without treatment and systolic blood pressure gradually decreased, resulting in Return to normal, the disease should be suspected.
(4) angina pectoris: due to decreased cardiac output, coronary artery invasion or coexisting coronary heart disease, patients often have chest tightness, pain in the anterior region or typical angina.
2. Systemic manifestations Due to the deposition of amyloid in tissues, the following specific symptoms can be caused.
(1) Giant tongue sign: The tongue becomes bigger and stiffer, so that the language is vague, chewing and swallowing is difficult, and there is a loud snoring when sleeping.
(2) carpal tunnel syndrome: carpal tunnel tissue hypertrophy, hyperplasia, adhesion, median nerve compression, resulting in finger flexion disorder, median nerve distribution area sensory disturbance and large fish muscle atrophy.
(3) amyloidosis arthrosis: joint pain, swelling, hard, activity disorder, but local inflammation is not obvious, if the finger joints are invaded, it is easy to be misdiagnosed as rheumatoid arthritis; if it violates the tissue around the shoulder joint, it can be presented "Shoulder levy."
(4) Skin damage: mostly occurs in the groin, underarm, anus, eye, neck and other wrinkles, skin lesions can be higher than the skin of the papules, plaque or purpura, clustered distribution, no itching It can also be a scleroderma-like infiltration, and about 55% of the primary patients have skin damage.
(5) Bone damage: Occasionally visible bone damage, X-ray image showed a chisel-like defect, and even caused pathological fracture, the characteristics of different clinical types of amyloidosis.
Examine
Examination of cardiac amyloidosis in the elderly
Blood calcium, urinary calcium is generally normal.
1. Chest X-ray examination: The heart is slightly enlarged, which is not proportional to the severity of right heart failure. Under the fluoroscopy, the heart beat is obviously weakened. Some scholars call it quiet heart, common pulmonary congestion, pleural effusion. .
2. Electrocardiogram examination: ST-T abnormalities are common. Most of them have QRS low voltage and abnormal Q wave. Although echocardiography shows left ventricular hypertrophy, ECG has no manifestation, and various arrhythmia can occur. Roberts et al. The 40 prenatal records in the autopsy report were: low voltage accounted for 63%, abnormal Q wave accounted for 83%; QRS wave axis offset accounted for 73%, most of which was left axis deviation; origin arrhythmia accounted for 73%, including Atrial fibrillation, atrial and borderline tachycardia, early room; 45% of different degrees of atrioventricular block, complete bundle branch block accounted for 18%.
3. Echocardiography: It is of great significance for the diagnosis of this disease. Its main features are: 1 left ventricular symmetry hypertrophy, thickening of interventricular septum; 2 lighter heart enlargement, small lumen; 3 chamber wall In the stiff, hypertrophic myocardium, a particle-like enhancement spot was observed; in most patients, the ventricular ejection fraction decreased; 550% of patients had pericardial effusion.
4. Biopsy: It is the most reliable diagnostic method for this disease. Firstly, biopsy should be performed on suspicious tissues or organs outside the heart. In recent years, biopsy of abdominal subcutaneous adipose tissue was taken by puncture method, and the positive rates of AL and AA were respectively reached. 95% and 67%, and the operation is safe and simple, the positive rate of different extracardiac biopsy (Table 4), if the extracardiac biopsy can not be clearly diagnosed, endocardial myocardial biopsy should be performed.
Diagnosis
Diagnosis and differentiation of cardiac amyloidosis in the elderly
Diagnostic criteria
Twenty years ago, in developed countries, only 25% of the patients were diagnosed before the disease, and late, due to the increased awareness and wide application of biopsy methods, most patients have been able to confirm the diagnosis before birth.
1. Suspected conditions: The elderly should be suspected of the following conditions:
1 refractory heart failure, no common cause of heart disease;
2 echocardiography found hypertrophy, ECG showed low voltage and abnormal Q wave;
3 refractory nephrotic syndrome, blood pressure is not high or the original hypertension has not been treated with drugs and gradually returned to normal;
4 with abnormal cardiac manifestations, and there are giant tongue signs or carpal tunnel syndrome unexplained;
5 There is a primary disease that induces the disease, and there is a manifestation of cardiac involvement;
6 chest penetration revealed that the heart did not increase significantly, but the beat was significantly weakened, and echocardiography found hypertrophy;
7 has a family history of hereditary family, and there are cases of abnormal cardiac manifestations without other causes.
2. Diagnosis conditions: Once the disease is suspected, biopsy should be performed, and the extracardiac biopsy should be positive. Combined with the clinical situation, the diagnosis can be basically confirmed. If there is still doubt, the endocardial biopsy can be performed, the result is negative and the clinical still highly suspected. The disease should not be easily denied, because the lesions can be focally distributed.
Differential diagnosis
1. Constrictive pericarditis: The clinical manifestations and hemodynamic characteristics of this disease are very similar to cardiac amyloidosis, but the disease has the following characteristics, which can be differentiated from cardiac amyloidosis:
1X line examination 50% ~ 75% visible pericardial calcification;
2 echocardiography showed that the pericardium was thickened and the myocardium was not thickened, and there was no enhanced particle-like spot in the myocardium;
3 extracardiac manifestations without cardiac amyloidosis;
4CT or magnetic resonance examination can clearly show that the lesion exists in the pericardium without myocardial thickening.
2. Coronary heart disease: This disease is the first cause of heart failure in the elderly, and it is often necessary to identify it. Its characteristics are:
1 There are risk factors, atherosclerosis and a history of coronary heart disease for many years;
2 early ischemic changes in ECG are often regional;
3 echocardiography often showed a segmental motor attenuated, after heart failure, often left heart dilatation changes;
4 coronary angiography showed abnormal changes in the coronary arteries.
3. Dilated cardiomyopathy: This disease is more easily differentiated from cardiac amyloidosis, but in the case of domestic amyloidosis, there are many cases of misdiagnosis of this disease. The disease has the following characteristics, and can be related to heart starch. Identification of the disease:
1 mainly manifested as left heart failure, not right heart failure;
2 physical examination of the heart significantly expanded;
3 echocardiography showed an increase in left ventricular diameter, ventricular septum, thinning of the posterior wall of the left ventricle, rather than thickening;
4 no extracardiac symptoms of cardiac amyloidosis.
4. Hypertrophic cardiomyopathy: The disease has the following characteristics, which can be differentiated from cardiac amyloidosis:
1 apex beats enhanced, sometimes lifted;
2 heart sound enhancement, the third to fifth intercostal space of the left sternal border or the apex of the apex can be heard in the middle and late murmur of rough jet contraction, and the lower jaw is relieved;
3 ECG often shows left ventricular hypertrophy and strain, and R wave increases in the right anterior region lead;
4 echocardiography often shows asymmetrical cardiac hypertrophy, especially in the ventricular septal hypertrophy, while the right ventricular anterior wall is often not thickened.
5. Restricted cardiomyopathy: This disease first refers to endocardial myocardium fibrosis, which is not well defined, and can be differentiated from cardiac amyloidosis by means of the following points:
1Echocardiogram shows mainly enhancement and thickening of endocardial reflex, rather than myocardial thickening;
2 extracardiac symptoms without cardiac amyloidosis;
3 endomyocardial biopsy is characterized by interstitial fibrosis, without amyloid deposition, followed by systemic scleroderma invasion of the heart, can also show the performance of restrictive cardiomyopathy characterized by myocardial interstitial fibrosis, but It has systemic manifestations of scleroderma, especially skin hardening and pigmentation, which is easier to distinguish from cardiac amyloidosis.
6. Cardiac sarcoidosis: The clinical manifestations of this disease can be similar to cardiac amyloidosis, but the disease has the following characteristics, which is helpful for identification of cardiac amyloidosis:
1 chest radiograph showed bilateral hilar lymphadenopathy, nodular or cord-like infiltrating shadow in the lung field;
2 visible nodular erythema on the skin;
3 blood calcium, elevated urinary calcium;
4 sarcoidosis antigen skin test (Kviem-Siltzbaih test) positive;
5 endocardial myocardium or extracardiac suspicious tissue biopsy can be seen by the accumulation of granuloma formed by epithelial cells.
