Cardiac amyloidosis is a systemic dysproteinosis that leads to the deposition of amyloid – a specific protein-polysaccharide complex in the tissues of the heart. Cardiac amyloidosis is accompanied by myocardial hypertrophy, a violation of its contractility, the development of chronic circulatory insufficiency, arrhythmias, hypotension, valvular defects. The clinical diagnosis is established using electrocardiography, echocardiography, radiography, scintigraphy, laboratory examination of serum proteins, tissue biopsy. Treatment is aimed at inhibiting amyloidogenesis (polychemotherapy) and slowing the progression of heart failure (diuretics, cardiac glycosides, vitamins).
E85.4 Limited amyloidosis
Cardiac amyloidosis (amyloid cardiopathy) is a form of systemic protein metabolism disorder with predominant deposition of protein b-fibrillar structure (amyloid) in the myocardium, endocardium, pericardium, aorta and walls of coronary vessels. Heart damage can be observed in the following types of amyloidosis: AL – amyloidosis of the light chains, SSA – senile systemic amyloidosis, FAP – familial amyloidosis, AA – secondary amyloidosis. In generalized amyloidosis, the heart is the dominant target organ, but in some cases isolated atrial amyloidosis may occur. Among other clinical forms of the disease, along with cardiac amyloidosis, the most common are amyloidosis of the kidneys, lungs, spleen, intestines and other organs.
Causes of cardiac amyloidosis
It is not possible to talk about trigger factors of amyloidogenesis in most cases. In familial amyloidosis, there is an autosomal dominant type of transmission of the disease. Hereditary cardiac amyloidosis is more common in representatives of the Mediterranean ethnic group.
Secondary systemic amyloidosis has been studied to a greater extent, the development of which may be associated with a long course:
- rheumatoid arthritis;
- ankylosing spondylitis;
- psoriatic arthritis;
- bronchiectatic disease;
- Crohn’s disease,
Patients with chronic renal insufficiency may develop amyloidosis associated with hemodialysis.
In familial, idiopathic and advanced senile form of amyloidosis, heart damage occurs in 80-100% of patients. Most often, amyloid deposition occurs in the muscular membrane of the heart, less often – in the pericardium and endocardium. In the myocardium, amyloid accumulates between myofibrils, leading to compression of intramural arteries and arterioles.
With this disease, the myocardium thickens, becomes slightly elastic (“rubber” myocardium); the volume of the cavities of the heart usually changes slightly. Senile cardiac amyloidosis proceeds by the type of diffuse lesion of muscle fibers, which is accompanied by their atrophy; amyloid deposition is often detected in the coronary arteries and aorta. The consequence of structural changes in the myocardium are disorders of systolic and diastolic function, a decrease in cardiac output and signs of heart failure.
In the case of amyloid deposition in the area of the valves, a clinic of valvular heart disease develops; with the accumulation of fibrillar protein in the Gis bundle, sinus and atrioventricular nodes, symptoms of blockade of the cardiac conduction system come to the fore.
In the classification developed by WHO, there are 4 stages of cardiac amyloidosis, taking into account the degree of involvement of the organ in the pathological process:
- I – symptoms and signs are not detected during non-invasive examination or biopsy;
- II – heart damage is confirmed by noninvasive testing (ECG, EchoCG) or biopsy, but the course of amyloidosis is asymptomatic;
- III – compensated symptomatic;
- IV – stage of decompensated cardiomyopathy.
Symptoms of cardiac amyloidosis
Amyloid cardiopathy is often disguised as a clinic of coronary heart disease, hypertrophic cardiomyopathy, which makes it difficult to recognize it in a timely manner. In the initial stages, the development of cardiac amyloidosis occurs gradually, with little symptoms. There may be weight loss, fatigue, irritability, dizziness, swelling.
A sharp deterioration in well-being is usually preceded by an intercurrent disease, including respiratory infection, stress, emotional overstrain. In the advanced stage of cardiac amyloidosis, attention is drawn to low blood pressure with the phenomena of orthostatic hypotension; pain in the heart area, having angina pectoris; syncopal states, arrhythmias. Signs of developing chronic heart failure are shortness of breath, hepatomegaly, edema. A distinctive feature of heart failure in cardiac amyloidosis is its rapid progression and resistance to therapy with cardiac glycosides.
Quite often, patients with cardiac amyloidosis have pericardial effusion and ascites. Due to amyloid infiltration, sinus node weakness syndrome develops, which is accompanied by bradycardia and can lead to sudden cardiac death.
In the event that cardiac amyloidosis is one of the manifestations of systemic amyloidosis, patients may experience renal failure, dysphagia, diarrhea, macroglossia, cutaneous hemorrhages, periorbital purpura, damage to the nervous system. Generalized amyloidosis is characterized by the sequential addition of more and more new symptoms, creating a motley clinical picture with multiple organ manifestations.
Diagnosis of cardiac amyloidosis
The absence of pathognomonic symptoms complicates the lifetime diagnosis of cardiac amyloidosis. Often, reliable data for amyloid cardiopathy are detected only on autopsy. During auscultation of the heart in patients with amyloidosis, deafness of heart tones, systolic noise of regurgitation on the atrioventricular valves are heard.
- Electrocardiography. The ECG shows a decrease in the voltage of QRS complexes, various kinds of disorders of excitability and conduction of the myocardium.
- Ultrasound of the heart. EchoCG signs of cardiac amyloidosis include thickening of the interventricular and atrial septa, ventricular walls, heart valves, atrial dilation, myocardial hypokinesia. Functional changes are characterized by a sharp decrease in the ejection fraction of the left ventricle, a violation of diastolic filling, valvular regurgitation. Sometimes it is possible to identify echopositive inclusions in the myocardium in the form of small granules representing amyloid deposits.
- X-ray and tomography. An increase in the shadow of the heart, exudative pleurisy can be determined on an X-ray of the chest organs. Myocardial scintigraphy and cardiac MRI are more highly sensitive and specific methods of lifetime diagnosis of cardiac amyloidosis
- Biopsy. Morphological confirmation of cardiac amyloidosis can be obtained by biopsy of the myocardium or other affected organs (tongue, gums, subcutaneous fat, lymph nodes, kidney, rectum, etc.).
- Laboratory tests. In laboratory tests of urine and blood with cardiac amyloidosis, proteinuria, hypoproteinemia, hyperglobulinemia and hypoalbuminemia are detected.
Differential diagnosis of cardiac amyloidosis is performed with hereditary dystonic lipidosis (Fabry’s disease), myxedematous cardiomyopathy in hypothyroidism, hypertopic cardiomyopathy, idiopathic restrictive cardiomyopathy, pulmonary heart, hemochromatosis, aortic stenosis, sarcoidosis, glycogenoses.
Treatment of cardiac amyloidosis
Treatment of patients with this disease presents significant difficulties. In order to suppress amyloidogenesis, various schemes of polychemotherapy, immunosuppressive drugs are used. In most cases, the treatment of cardiac amyloidosis is reduced to slowing the progression of heart failure. Symptomatic medications are prescribed – diuretics, cardiac glycosides, vitamins, anticoagulants.
With sinus node weakness syndrome, implantation of an artificial pacemaker can be used. Currently, in cardiology, transplantation of affected organs, including the heart, is beginning to be used for the treatment of amyloidosis. After diagnosis, patients with cardiac amyloidosis should be under the systematic supervision of a cardiologist, hematologist, neurologist, nephrologist, and other specialists.
The prognosis of cardiac amyloidosis is unfavorable: heart failure is prone to steady progression. The death of patients occurs on average 1.5-2.5 years after the appearance of signs of heart damage from heart failure or from extracardial complications.