Stress echocardiography is a method of stress echocardiography that allows you to evaluate the reaction of the heart to stress induced by pharmacological or physical agents. It is used to detect myocardial ischemia and the risk of complications of coronary heart disease, as well as for some heart defects to assess indications for cardiac surgery. In the process of stress echocardiography, echocardiographic examination and hemodynamic monitoring are performed before, during and after exercise. Bicycle ergometry, treadmill test, transesophageal electrical stimulation, pharmaceuticals can be used as stress agents. The cost takes into account the method of stimulation.
To determine myocardial ischemia in cardiology, ECG registration at rest, daily ECG monitoring, VEM, treadmill test, pharmacological tests, myocardial scintigraphy are used. Among these studies, stress echocardiography is distinguished by high sensitivity (74-97%) and specificity (64-100%). The technique combines two-dimensional echocardiography and a stress test, allowing to detect the ischemic response of the myocardium to a particular type of controlled provocation. The main criterion is the pathological kinetics of the left ventricle recorded in response to the induced load.
The grounds and necessity are established by a cardiologist. The purpose of stress EchoCG is to detect latent insufficiency of coronary circulation. In the process of stress echocardiography, the earliest lesions of the coronary arteries are recognized, since a violation of myocardial contractility precedes subsequent signs of ischemia – chest pains, ECG disorders. Stress echocardiography is indicated for ECG signs of left ventricular hypertrophy, changes in intravenous conduction, electrolyte balance disorders, etc., as well as in the case of false positive or unreliable results of stress tests.
With the help of stress echocardiography, a prognostic assessment of the stable form of angina is performed: the absence of initiated ischemia indicates a low, and detection indicates a high risk of cardiovascular complications. Dynamic monitoring of the effectiveness of rehabilitation and therapeutic tactics after myocardial infarction or CABG surgery is performed by stress EchoCG. Stress echocardiography with pharmacological tests can be performed in cases where it is impossible to conduct a treadmill test or VEM, as well as if the patient cannot achieve the required power load. This diagnostic can be useful not only for the detection of coronary artery disease, but also to assess the reserves of myocardial contractility in various heart defects – aortic stenosis, mitral insufficiency and stenosis.
The factors limiting the use of stress echocardiography are the reduced possibilities of imaging the structures of the heart in obesity, gigantomastia, hyperventilation of the lungs, subjectivity of interpretation of the results. The limited use of stress ECHO-KG with a physical test is caused by the fact that a third of patients cannot achieve the required load due to pathology of the lungs, peripheral vessels, joints, and unsatisfactory fitness. Stress echocardiography is contraindicated in acute myocardial infarction, a history of thromboembolism, congestive heart failure, aortic aneurysm dissection, severe renal, respiratory, and hepatic insufficiency.
Methodology of conducting
Stress echocardiography involves 2 doctors (a diagnostician who knows the technique of EchoCG, and a specialist in stress tests) and an assistant nurse. All personnel involved in performing stress EchoCG should have the skills to provide emergency cardiac resuscitation measures, and the office should have the necessary equipment (defibrillator) and medications. At the initial stage of stress echocardiography, a resting echocardiogram is recorded as standard in four sections – parasternal, transverse, longitudinal and apical, with the preservation of the image in the video loop format. At the same time, the initial parameters of the 12-channel ECG, heart rate, blood pressure are recorded.
The next stage of stress echocardiography includes provocation of ischemia by the chosen method (using dynamic physical activity, faramcological test, emergency EX, etc.). During the test, all changes in ECG, heart rate and blood pressure are monitored and recorded. When using horizontal bicycle ergometric tests, pharmacological tests, transesophageal electrical stimulation during stress echocardiography, echocardiographic data are monitored and stored at the stage of ischemia provocation.
The reasons for stopping stress tests during stress echocardiography may be the patient’s refusal to continue the load, the appearance of unacceptable side effects (headache, nausea, critical rise in blood pressure, etc.), as well as the registration of ischemic markers. Markers of ischemia include clinical (pain behind the sternum, decreased blood pressure, signs of peripheral or cerebral hypoperfusion), electrocardiographic (elevation or depression of the ST segment without an altered Q wave, the development of dangerous arrhythmias) and echocardiographic (determination of violations of regional LV contractility) manifestations.
In the post-loading period of the stress echocardiogram, the echocardiogram is again recorded in standard sections with video recordings preserved. At the final stage of stress echocardiography, all sequentially obtained video images are reproduced on one screen, cardiac cycles are synchronized, and the nature of the mobility of myocardial areas is compared.
Interpretation of results
The normal reaction of the myocardium in response to stress during stress echocardiography is characterized by hyperkinesis of the LV walls, an increase in the ejection fraction, the absence of violations of the kinetics of the walls, thickening of the walls during systole, a decrease in end-systolic volume. With a pathological response (a positive stress echocardiogram test), areas with impaired kinetics (akinesia, hypokinesia, dyskenesia), an increase in end-systolic LV volume, a decrease in wall thickening in the systole, a decrease in PV to 35% and below, an increase in pancreas, etc. can be determined. The severity of ischemic changes detected during stress echocardiography is judged by the number of affected LV zones, the type of asinergic changes, the time of development and disappearance of disorders.
In the process of this diagnostic, undesirable effects may develop that will be the basis for termination of the study: headache, muscle tremors, nausea, ventricular and supraventricular extrasystole. Minor complications include short episodes of paroxysms (up to 2 minutes), hemodynamically insignificant tachycardia. Threatening complications of stress echocardiography that require urgent cardiac resuscitation are acute coronary syndrome, ventricular fibrillation, and asystole.