Radioisotope study of the heart - Causes, Symptoms and Treatment .MF .
In the early 70 - ies of the last century in the practice of physicians, new methods of research, called radioisotope (radionuclide).The principle of this research is based on the introduction of the blood to the patient substances with affinity for certain tissues, that is, the ability to attach and penetrate into certain cells.Also these materials are capable of radiation, which is detected by gamma - camera is processed on a computer and displayed on the monitor device in the form of two-dimensional images in different projections.In the Cardiology such methods include radioisotope ventriculography, radioangiokardiografiyu, myocardial perfusion scintigraphy .Last used more frequently than others.
General The method consists in the following - in the blood of a patient is administered one of the drugs, tropic to red blood cells or the cells of the myocardium and in a few minutes, a picture of the passage of blood through the chambers of the heart or blood supply to the myocardium.
For example, in the diagnosis of acute myocardial infarction patient intravenously a solution containing one of the following radioactive substances - technetium - 99, thallium - 201, indium, pyrophosphate, labeled with technetium, potassium - 43, etc. Due to the binding drug molecules to the membranes.cardiac muscle cells is a gradual accumulation of it in the cells themselves.Drugs produce radiation that is detected by the camera is processed and displayed on a computer or a luminous image of the heart with the accumulation of defects ( "cold" spots) or with excess ( "hot" spots).When
ischemia, myocardial infarction or cicatricial substitution (myocardial infarction), when disturbed blood supply to the heart muscle, thallium can not penetrate from the blood into the cells, which leads to the formation of cold spots.When using pyrophosphate labeled technetium appearance of hot spots caused by contrast, increased permeability of the membranes of damaged cells to the drug.
At heart diseases, cardiomyopathies injected technetium, evenly distributed over the bloodstream and binds to red blood cells.Blood from the drug flows through the chambers of the heart, and its movement is recorded series of images that reveal the violation of systolic and diastolic function of the atria and ventricles, the blood from flowing back into the atria or the ventricles, as well as the mixing of blood with a patient such vices as ASD andventricular septal.
Despite the fact that some drugs are derived from long-term heart muscle, that is, the method allows the study again in a few hours, and sometimes even through the night, the survey method in modern institutions have not found a fairly wide application.
First, work with radioactive drugs requires great precautions.
Second, using this technique in combination with clinical symptoms can not find out the true antiquity of the process, since the absence of the drug in the affected area may be indicative of the development and acute myocardial infarction, and ischemia without infarction, and myocardial infarction, as blood flow disturbancespreparation and delivery to cells occur in all these disorders.
Third, in recent years, massively used other diagnostic methods, such as ultrasound of the heart with Doppler, allows to visualize the movement of blood through the heart chambers or coronary angiography, able to provide full information on the patency of the coronary arteries.Still, radionuclide studies can be used diagnostically ambiguous cases where other methods (ECG, ultrasound of the heart) can not either confirm or refute the diagnosis.
Indications for radioisotope study heart
survey can be shown in such diseases as:
- acute myocardial
infarction - chronic ischemic
heart disease - hypertrophic and dilated cardiomyopathy
- defects in walls between the atria or ventricles
infarction - monitoring the effectiveness of thrombolytic therapy in myocardial infarction (a series of shots before and after administration of streptokinase - preparation, dissolving the blood clot that is causing the blockage of the coronary arteries)
This method may be appointed under the following conditions:
- pain in thethe heart is not stopped by nitroglycerine, failed to find confirmation on the ECG
- dyspnea at rest or while walking
- dry cough with episodes of breathlessness
- episodes "gurgling" cough with choking, especially when lying down at night - symptoms "of heart"asthma or pulmonary edema
- the presence of a heart murmur, identifying doctors by using
auscultation - conducting stress tests (on bicycle) in patients with documented coronary heart disease with research before and after exercise to assess disorders of myocardial perfusion
Contraindications for radioisotope methodsresearch
contraindications include fever, sepsis, allergy radiopharmaceuticals, installed previously, acute illness and exacerbation of chronic diseases of other organs and systems.
complications do not develop during this procedure.Despite the use of radioactive substances, the probability of radiological risk is negligible, since the total radiation dose received during one study less than during the X-ray or CT scan, especially since most drugs are rapidly cleared from the body.
Decoding results heart radioisotope studies
It looks scintigraphy before and after exercise.In the upper row of arrows Set perfusion defect, that the evidence in favor of myocardial ischemia provoked by stress tests.
After receiving the images is carried out analysis of the data using a computer.As a result of research you can find out whether a patient has ischemia, acute or myocardial infarction, the presence of shunts (connections) between the chambers of the heart, which normally should not be, and to assess blood ejection function of the ventricles, such as stroke volume,ejection fraction, blood flow rate of the atria and ventricles.The indicators are calculated according to the amount of isotope analysis, traveled with blood by the heart chambers for each heartbeat and the number of isotopes absorbed by the cells of the heart muscle.
GP Sazykina OJ