What Is Cardiac Amyloidosis?

As early as 1850, Virchow discovered a deposit between human tissue cells that exhibited a starch-like color response when exposed to iodine. Virchow calls it amyloid and calls the tissue in which it is deposited amyloid degeneration. It has been proven that the so-called amyloid is actually a protein composed of different components, so it is more appropriate to call it amyloid.

Basic Information

English name

Heart Amyloidosis

Visiting department

Cardiology

Common locations

heart

Common symptoms

Jugular vein irritation, weakened apical pulsation, decreased heart sounds, and increased heart rate; arrhythmia, decreased systolic blood pressure, and angina; macroglossia, carpal tunnel syndrome, etc.

Causes of cardiac amyloidosis

Because this disease includes different types of amyloidosis to the heart, the etiology also includes different types of related causes.

Primary

Due to the proliferation and malignant transformation of individual plasma cells, the proportion of heavy and light chain synthesis is unbalanced, resulting in excessive light chains, most of which are lambda-type light chains, which exceed the catabolic capacity of macrophages and aggregate to form amyloid fibers. The mechanism of myeloma-associated amyloid is basically the same.

Secondary

Antigen stimulation of various primary diseases activates macrophages. Under the action of interleukin-1, liver cells produce a large amount of serum AA (SAA) protein, causing macrophage dysfunction, which cannot be completely degraded, resulting in the formation of Insoluble AA protein. Familial heredity is represented by Mediterranean fever, and the mechanism of AA protein formation of its amyloid fiber is similar to this.

3. Limitations

Plasma cell infiltration is common in the lesions of some cases, and histochemical analysis indicates that the amyloid fiber is AL, so the mechanism is similar to the primary. In some cases, the corresponding hormone secreted by the endocrine gland such as the amyloid fiber of medullary thyroid carcinoma, the main component is procalcitonin. The limitation of this type of amyloid deposition is unknown, and the mechanism is unknown.

4. Senile

Pre-albumin was isolated from myocardium in some cases. It is not generated by myocardial cells, and it is presumed to generate its precursor in extracardiac tissue, which is deposited on the lesion by blood circulation. In some cases, it is atrial natriuretic peptide, which is mainly produced in atrial muscle cells.

5. Hemodialysis correlation

The long-term use of copper-like membranes or cellulose acetate membranes in hemodialysis patients can not precipitate 2 microglobulin, resulting in a large amount of deposition in the body, which provides conditions for the formation of amyloid fibers.

Clinical manifestations of cardiac amyloidosis

Cardiovascular performance

Compensation period often has no clinical manifestations, or only dizziness, fatigue, palpitations after exertion, and shortness of breath. After entering the decompensation period, the main performances are as follows.

(1) Right ventricular insufficiency, jugular venous irritation, apical pulsation weakened, heart sounds reduced, heart rate increased, fourth heart sound or gallop rhythm can be heard. Most are murmur-free or have only systolic murmur in the mitral valve area. The mind has not been significantly enlarged. Hepatomegaly, palpable, mild to moderate ascites, sunken edema in the limbs. Left heart failure may also appear in later stages, but acute pulmonary edema rarely occurs.

(2) Arrhythmia can show various arrhythmias, especially atrial fibrillation. Sinus syndrome or atrioventricular and bundle branch block to varying degrees can also occur. Sudden death can occur due to the occurrence of malignant ventricular tachyarrhythmias.

(3) Decreased systolic blood pressure Due to the decrease in cardiac output, systolic blood pressure is often reduced, resulting in a decrease in pulse pressure. About 10% of patients develop orthostatic hypotension. The systolic blood pressure gradually decreases in elderly patients with hypertension without treatment, which leads to the return to normal. The disease should be suspected.

(4) Angina Pectoris Due to reduced cardiac output, coronary arteries are invaded or co-existing coronary heart disease, patients often have chest tightness, anterior heart pain or typical angina pectoris.

2. Whole body performance

Due to the deposition of amyloid in tissues, the following specific symptoms can be caused.

(1) Giant Tongue Signs The tongue becomes large and stiff, resulting in vague language, difficulty chewing and swallowing, and loud snoring sounds during sleep.

(2) Carpal tunnel syndrome Carpal tunnel tissue hypertrophy, hyperplasia, adhesion, compression of the median nerve, resulting in finger flexion disorders, sensory disturbances in the distribution area of the median nerve, and atrophy of the great intermuscular muscles.

(3) Amyloid arthropathy joint pain, swelling, stiffness, and movement disorders, but local inflammation is not obvious. If the finger joint is violated, it is easy to be misdiagnosed as rheumatoid arthritis; if the tissue around the shoulder joint is violated, a "shoulder pad sign" can be presented.

(4) Skin damage usually occurs in folds such as the groin, underarms, anus, eye area, and neck. Skin lesions can be pimples, plaques, or purpura higher than the skin, cluster-like, without itching. Can also be scleroderma-like infiltration. About 55% of primary patients have skin damage.

(5) Bone damage Occasionally , bone damage can be seen, and X-rays show a puncture-like defect, and even cause pathological fractures.

Cardiac amyloidosis test

Chest x-ray

The heart is mostly slightly enlarged, disproportionate to the severity of right heart failure. It can be seen that the heart beat is obviously weakened under the perspective, and some scholars call it "quiet heart". Pulmonary congestion and pleural effusion are common.

2. ECG examination

ST-T anomalies are common, and most of them show QRS low voltage and abnormal Q waves. Although left ventricular hypertrophy was found on echocardiogram, there was no manifestation of ECG. Various arrhythmias can occur.

3. Echocardiography

It is of great significance for the diagnosis of this disease. The main features are: the left ventricle is symmetrically hypertrophic, and the interventricular septum is also thickened; the heart enlarges lightly and the ventricular cavity becomes smaller; the rigid wall of the chamber and hypertrophic light spots can be seen in the myocardium; Ventricular ejection fraction decreased; 50% of patients had pericardial effusion.

4. Biopsy

Is the most reliable diagnosis of this disease. Biopsy should be performed on suspicious tissue or organs outside the heart. In recent years, it has been reported that the abdominal subcutaneous adipose tissue biopsy is obtained by puncture, and the positive rates of AL and AA can reach 95% and 67%, respectively, and the operation is safe and simple. If extracardiac tissue biopsy does not confirm the diagnosis, an endocardial myocardial biopsy should be performed.

Diagnosis of cardiac amyloidosis

Positive extracardiac biopsy, combined with clinical conditions, can basically confirm the diagnosis. If in doubt, an endocardial myocardial biopsy is feasible. When the result is negative and clinical suspicion is still high, the disease should not be easily denied. Because of its lesions can be focally distributed.

Cardiac amyloidosis treatment

1. Treatment of heart failure

There is currently no satisfactory method. Diuretics and vasodilators, such as angiotensin-converting enzyme inhibitors and nitrates, can be given cautiously to improve symptoms. However, it should be prevented that the ventricular filling pressure is inappropriately reduced to cause hypotension.

2. Management of arrhythmia

For symptomatic severe cardiac conduction disorders or malignant ventricular tachyarrhythmias, they should be treated with a pacemaker or an embedded automatic defibrillator whenever possible. For benign arrhythmias, try to avoid the use of antiarrhythmic drugs, because the negative muscle strength of these drugs may aggravate cardiac dysfunction. For those who may have malignant arrhythmias, it is advisable to choose antiarrhythmic drugs with less negative muscle strength.