Radiation heart damage
Introduction
Introduction to radiation heart damage Radioactive heart damage refers to myocardial lesions that are produced by radiation from radioactive materials. The heart of humans and animals exposed to radiation has varying degrees of pathological changes. The damaged parts, including the pericardium, epicardium, endocardium, and even heart valves, as well as the conduction system and coronary artery damage, are prone to cause radioactive heart. damage. basic knowledge The proportion of illness: 0.006% Susceptible people: no special people Mode of infection: non-infectious Complications: radiation pneumonitis, constrictive pericarditis, arrhythmia
Cause
Cause of radiation heart damage
(1) Causes of the disease
Radiation therapy (18%):
Radiation therapy for malignant tumors such as breast cancer, esophageal cancer, lung cancer, mediastinal tumor, Hodgkin's disease, etc.
Long-term X-ray (18%):
Long-term radiofrequency or interventional treatment under X-ray irradiation, and improper protection, due to the above reasons, causing pericardium, epicardium, myocardium, endocardium and even heart valves, as well as conduction system and coronary artery damage.
Nuclear leakage (18%):
The release of atomic bombs during the war, the leakage of nuclear reactors, and the misuse of radioactive materials.
(two) pathogenesis
1. Pathogenesis:
Although the heart is not a sensitive organ of radiation damage, the large dose of radiation therapy can still cause a series of changes in the heart. It is generally believed that the damage is directly related to the area irradiated, the irradiation plan and the dose of the irradiation: the dose is up to 4~ 6Gy or cumulative dose of 40 ~ 60Gy can cause heart damage, the most common damage is pericarditis and myocarditis, the incidence is also positively correlated with the dose of radiation therapy, the person observed that the larger the dose, the shorter the interval, The incidence of myocardial damage is higher, and the lower the incidence is, the two are in a dose-dependent manner. The direct damage of radiation is the most important cause of the disease. The radiation can directly cause tissue ionization, causing local sterility. Inflammatory reaction can also inhibit the growth of heart cells, causing cell lysis, destruction, apoptosis, and even necrosis. Early inflammatory infiltration is a manifestation of stress myocarditis. Repeated radiation damage can inhibit local fiber solubilization, so in cells The large amount of cellulose deposited inside can not be reduced or exuded, resulting in damage to the vascular endothelium, leading to vascular permeability. Alterations, intravascular microthrombus formation and vascular bed reduction, which are the basis for later cardiac delayed dysfunction and electrical activity disorders, in addition to the biological effects of radiation may cause secondary damage to the heart, such as tissue caused by radiation Cell autoimmune changes, trigger gene mutations or gene expression abnormalities, as well as capillary and lymphatic drainage disorders, etc., which can aggravate or initiate persistent myocardial damage, accelerate myocardial fibrosis, aggravate myocardial, pericardial exudation and increase Thickness changes, however, due to the lack of consistency between pericardial effusion and cardiac function decline due to radiation therapy, it is believed that the mechanism of response of the pericardium to the myocardium may be different or focused. In addition, experiments have confirmed that after radiation exposure Some factors, such as high-fat diet, high blood pressure, etc., have a synergistic effect on the promotion of radiation atherosclerosis. If patients receive radiation therapy without paying attention to diet and blood pressure, they can accelerate platelet aggregation and cellulose deposition. Thereby greatly aggravating the proliferation of atherosclerotic plaques and stenosis of the lumen, and Often eating animals and humans have not yet found these changes.
2. Pathology:
It has been shown that the human and animal hearts exposed to radiation have varying degrees of pathological changes, including pericardium, epicardium, endocardium, and even heart valves, as well as conduction systems and coronary arteries. It is closely related to the area of radiation therapy, with pericardial and myocardial damage being the most common.
(1) gross anatomy: pericardial exudation and thickening can be seen in patients with radioactive heart damage, endocardium and outer membrane are also thickened, and myocardial fibrosis is manifested in all layers of ventricular wall. The changes seen can be diffuse or Focal distribution, but the right or right ventricle is more obvious, which may be related to the right ventricle being closer to the chest wall. Some people have left ventricular systolic in the late stage of the disease, which may be accompanied by thickening of one or more valves. The incidence of tricuspid and aortic valves is high, and mitral atresia and wall thrombosis are rare. About 40% of the coronary arteries can be found to have severe stenosis. The main cause is atherosclerotic plaque formation. The block is mainly fibrous lesions, and the proximal end is significantly more distant.
(2) Microscopic observation: microscopic observation of granulocyte infiltration and edema around the blood vessels in the acute phase of radiation-induced cardiac damage can be observed. Cardiomyocyte edema, hyaline degeneration and steatosis can be seen later. The lesions are spotted or spotted. Flaky fibrotic lesions and necrotic foci are scattered, fibrous hyperplasia occurs around the interstitial and blood vessels, and the number of smooth muscle cells in the blood vessels is reduced.
(3) Observation by electron microscopy: under the electron microscope, the arrangement of myocardial cells was disordered, muscle fibers were broken, atrophy, nuclear deformation, mitochondrial sarcoplasmic reticulum and nuclear structure destruction, high-density particle deposition under the cell membrane, and the continuity of the membrane was interrupted, but not all Cases have the above changes, because the liquid exudation in the pericardium is mainly caused by aseptic inflammation, so it is mostly pale yellow non-specific exudate, occasionally bloody, the amount is more or less, generally 50 ~ 200ml, the most Up to 700ml or more, the cytological examination of the exudate is mostly negative, but sometimes the protein content can be high, so the exudate caused by the malignant tumor is difficult to identify.
Prevention
Radioactive heart damage prevention
In the course of radiotherapy for breast cancer, Hodgkin's disease and non-Hodgkin's lymphoma, attention should be paid to the dose, frequency and time of radiotherapy. The dose should not be too large, and the time should not be too long. The volume of the heart should be as small as possible. In the process of radiotherapy, attention should be paid to the protection of the heart and lungs. If necessary, protect the heart with a protective pad under the bulge, which can reduce the damage to the heart.
Complication
Radioactive heart damage complications Complications, radiation pneumonitis, constrictive pericarditis, arrhythmia
Radioactive heart damage can lead to complications such as radiation pneumonitis, constrictive pericarditis, and arrhythmia.
Symptom
Radioactive heart damage symptoms Common symptoms Conduction block fatigue ECG abnormal atherosclerosis Heart penetrating injury Pericardial effusion dyspnea Electrophysiological abnormalities
The heart of the patient can develop an acute reaction within 24 hours after exposure. The delayed response occurs about 6 months or more after the irradiation. The acute damage of the animal model heart occurs within 6 to 58 hours after the irradiation. The reaction occurred 2 to 3 months later, and autopsy found that after 7 to 10 years of radiation therapy, patients can still detect the presence of pathological changes in the heart muscle. The performance of radiation-induced heart damage can be divided into the following main types. Patients can start with one or more of the symptoms and run through the main clinical process.
Pericarditis
It is divided into acute pericarditis and delayed pericarditis. It may also occur in the form of acute episodes of delayed pericarditis, or in the form of recurrent pericarditis. The main clinical manifestations are fever, chest pain, fatigue and other symptoms. When there is little, it can be asymptomatic or shortness of breath after mild activity. When it is exuded for a long time, it can be manifested as progressive chest tightness, dyspnea and other symptoms of cardiac tamponade. Physical examination can reveal that the patient has a fast heart rate, far heart sound, pulse breakdown, breathing Difficulties and other signs, the sitting position is obvious, the lying position is aggravated; occasionally the odd pulse, in the anterior region can be heard and pericardial friction sound, such as accompanied by pleural effusion can also hear pleural friction sound; cardiac tamponade with obvious jugular vein filling or anger The heart can be enlarged, showing a large or spherical shape; both ultrasound and X-ray have evidence of pericardial effusion. According to Ruckdeschel et al, there were 25 cases of pericardial effusion after radiation treatment of 81 cases of Hodgkin's disease, accounting for 31 cases. %, of which 86% of patients developed after 1 year of treatment, about half of them were persistent pericardial effusions.
2. Myocardial fibrosis or whole heart disease
The latter includes pericardial fibrosis, clinical manifestations similar to constrictive pericarditis, patients with chest tightness, shortness of breath, fatigue, etc., accompanied by jugular vein engorgement and peripheral edema, liver, kidney and other organ congestion, mainly due to myocardial After a large area of fibrosis, the contraction and relaxation of the heart are restricted. This change affects the right heart. The examination may have a weakened first heart sound, systolic murmur, and galloping. The ultrasound may reveal a reduction in the left ventricle. Left ventricular shortening score decreased, abnormal ratio of ejection time to ejection time, and decreased wall activity and compliance, but no significant specific changes, difficult to distinguish from constrictive pericarditis, mainly pericardial fibrosis Patients with pericardial dissection can be treated, the symptoms can be significantly improved, but the efficacy of myocardial fibrosis is not good, the patient's treatment effect and prognosis are poor.
3. Asymptomatic cardiac dysfunction
There were no obvious symptoms in the patients for several years or even decades after receiving radiotherapy. However, after radionuclide and echocardiographic follow-up, the ejection fraction decreased gradually, and selective right ventricular dysfunction could also occur. Hemodynamic examination can detect elevated right ventricular pressure, and this change has nothing to do with age. It is reported that the incidence of myocardial damage can account for more than 50% of the follow-up patients, but it has not received much attention due to its little impact on patients. .
4. Angina pectoris and myocardial infarction
This is a complication caused by radiation therapy for coronary atherosclerosis and severe stenosis. The clinical manifestations are the same as coronary heart disease, and there may be repeated episodes of angina. Pearson et al. have also reported myocardial infarction. These patients are often younger. However, the symptoms of myocardial ischemia occur after radiotherapy. With the increase of age, the degree of ischemia can be significantly aggravated or accelerated. Coronary angiography has vascular stenosis, and autopsy confirms. Coronary artery and aorta have outer scar and thickening of the intimal fibers. Especially in the death autopsy report within 1 year of radiotherapy, the rate of coronary lesions is quite high. Therefore, special attention should be paid to those who receive radiation therapy for a long time. Control of diet and blood pressure, if chest pain occurs during treatment, should be alert to the occurrence of ischemic heart disease and myocardial infarction.
5. ECG abnormalities
Such patients with ST-T changes and bundle branch and atrioventricular block more common, can also occur pre-contraction, individual reports of A-S syndrome, radiation damage myocardial and conduction system performance, according to statistics After radiotherapy, ECG changes account for about half of the total, which may be acute reactions, or may occur repeatedly in the future. Generally, they do not exist alone, and often coexist with other manifestations.
6. Valve dysfunction
Radiation therapy can cause valve thickening, but abnormal valvular dysfunction is rare. Sometimes, systolic murmurs can be heard during auscultation, and echocardiography shows slowing of valve closure. The incidence of the elderly is higher than that of young people. As with ECG abnormalities, they often coexist with other manifestations. Those who have radiation therapy or who are exposed to radiation doses may consider radioactive heart damage if they have cardiac symptoms. Even if they are asymptomatic, they should follow up and evaluate their cardiac function. Common methods of cardiac examination: such as electrocardiogram, echocardiography, myocardial radionuclide examination, exercise test, etc., can be used to evaluate the electrical activity, cardiac function, cardiac morphology and ejection fraction of the heart; To evaluate the pathological changes of myocardium and the degree of fibrosis. If combined with cardiac catheterization and pericardial puncture, the constrictive pericarditis and cardiac tamponade can be evaluated. However, all these tests lack specificity, especially for the diagnosis of pericardial effusion. Infiltration or radiation damage is quite difficult, at the same time, due to myocardial fibers The lack of homogeneity in the location and extent of occurrence, it is difficult to assess the exact range of occurrence in the myocardium and pericardial lesions, so that the accuracy will be lost in the choice of treatment plan or predicting the outcome of the disease, so many clinical occurrences For radioactive heart damage, the diagnosis is more retrospective or confirmed by autopsy.
Examine
Radioactive heart damage examination
1. X-ray chest: heart shadow increased.
2. Electrocardiogram: ST-T changes, abnormal conduction function (atrioventricular or bundle branch block, etc.).
3. Echocardiography: The heart shadow is enlarged, and the dark area of the liquid is visible when there is a pericarditis.
Diagnosis
Diagnosis and diagnosis of radiation heart damage
Radioactive myocardial damage is often confused with various clinical cardiomyopathy, but patients with this disease often have experience with radiation therapy or a large dose of exposure to radiation, and now have cardiac symptoms that can be differentiated from other myocardial diseases.
