Stress echocardiography: what is it?
Stress echocardiography (Stress Echocardiography) is a method of stress echocardiography that allows to evaluate the reaction of the heart to the stress effect induced by pharmacological or physical agents.
Stress Echocardiogram is used mainly to detect myocardial ischemia and the risk of complications of coronary artery disease, as well as with certain heart defects to assess indications for cardiac surgery. In the process of Stress Echo-CG, echocardiography and hemodynamic monitoring are performed before, during and after exercise.
As stress agents, bicycle ergometry (on a horizontal or vertical simulator), treadmill test, trans-esophageal electrostimulation, pharmaceutical preparations can be used.
To determine myocardial ischemia in cardiology, ECG registration at rest, daily ECG monitoring, VEM, treadmill test, pharmacological tests, myocardial scintigraphy are used. In a number of these studies, stress-echocardiography is characterized by high sensitivity (74-97%) and specificity (64-100%).
The stress-echocardiography technique combines a two-dimensional EchoCG and a stress test, allowing the detection of an ischemic myocardial response to a particular type of controlled provocation. The main criterion of stress echocardiography is the pathological kinetics of the left ventricle that is registered in response to the induced load.
In the process of carrying out stress EchoCG, various load options are used: physical (vertical or horizontal VEM, walking along the treadmill, isometric loading, etc.), electrostimulation of the atria (direct or transesophageal), pharmaceutical tests (with ATP, arbutamine, dobutamine, adenosine, ergonovine, dipyridamole) and others (hyperventilation, cold).
The diagnostic advantages of stress echocardiography include the possibility of visualizing the heart in multiple sections and a detailed study of the segments of the left ventricle; excellent spatial resolution; the admissibility of assessing the overall and regional contractility of the heart.
Stress echocardiography is a non-invasive, safe procedure that can be repeated many times and has a relatively low cost compared with coronary angiography and perfusion scintigraphy of the myocardium.
Indications for heart echo stress test
The basis and necessity of carrying out stress echocardiography is established by the cardiologist. The purpose of stress echocardiography is the detection of latent deficiency of coronary circulation. In the process of stress echocardiography, the earliest lesions of the coronary arteries are recognized, as a violation of myocardial contractility precedes the subsequent signs of ischemia – chest pains, ECG disorders. Stress echocardiography is indicated for ECG signs of left ventricular hypertrophy, changes in intraventricular conduction, electrolyte balance disorders, etc., and also in case of false positive or unreliable results of stress tests.
With the help of stress echocardiography, a prognostic evaluation of the stable form of angina is made: the absence of initiated ischemia indicates a low, and the detection of a high risk of complications of cardiovascular nature. By stress EchoCG, a dynamic control of the effectiveness of rehabilitation and treatment tactics after myocardial infarction or CABG surgery is performed.
Stress echocardiography with pharmacological tests can be performed in cases where it is not possible to conduct a treadmill test or a BEM, and if the patient does not reach the required load.
Stress echocardiography can be useful not only for the identification of IHD, but also for the purpose of assessing the reserves of myocardial contractility for various heart defects – aortic stenosis, mitral insufficiency and stenosis.
Contraindications for stress echo
Factors limiting the use of stress echocardiography are reduced possibilities for imaging heart structures in obesity, gigantomastia, hyperventilation of the lungs, subjectivism of interpretation of results.
The limited use of stress ECHO-CG with physical breakdown is caused by the fact that one third of patients can not achieve the required load due to pathology of the lungs, peripheral vessels, joints, and poor fitness.
Stress echocardiography is contraindicated in acute myocardial infarction, history of thromboembolism, congestive heart failure, dissection of the aortic aneurysm, marked renal, respiratory, liver failure.
Echo heart test: Method of conducting
In carrying out stress echocardiography, 2 physicians (a diagnostician who owns the EchoCG technique, and a stress tests expert) and an assistant sister participate.
All personnel involved in the implementation of stress echocardiography should have the skills to provide emergency cardio-reanimation activities, and the office must have the necessary equipment (defibrillator) and medicines.
At the initial stage of stress echocardiography, an echocardiogram of rest in four sections – parasternal, transverse, longitudinal and apex, with preservation of the image in video-tape format – is registered as standard.
Simultaneously, fixation of the baseline parameters of 12-channel ECG, heart rate, blood pressure is performed.
The next stage of stress echocardiography involves provocation of ischemia by the chosen method (with the help of dynamic physical exertion, a pharamcological test, PE ENC, etc.).
During the test, all changes in the ECG, heart rate and blood pressure are monitored and recorded. When using a horizontal bicycle ergometric test, pharmacological tests, transesophageal electrostimulation during the stage of provocation of ischemia, echocardiographic data are monitored and stored.
The reasons for stopping the stress tests during stress echocardiography include the patient’s refusal to continue the workload, the appearance of unacceptable side effects (headache, nausea, critical BP elevation, etc.), as well as the registration of ischemic markers.
Ischemia markers include clinical (pain behind the sternum, lowering blood pressure, signs of peripheral or cerebral hypoperfusion), electrocardiographic (elevation or depression of the ST segment without altered Q wave, development of dangerous arrhythmias) and echocardiographic (determining violations of LV regional contractility).
In the postnagruzochnom period stress-echocardiography again recorded an echocardiogram in standard sections with preservation of the video loop. At the final stage of stress echocardiography, all the video images consecutively obtained are reproduced on one screen, the cardiac cycles are synchronized, and the character of the mobility of the myocardium is compared.
Normal myocardial response in response to stress in the process of stress echocardiography is characterized by hyperkinesia of the LV wall, an increase in the ejection fraction, no violations of wall kinetics, thickening of the walls during systole, and a decrease in the end-systolic volume.
With a pathological response (a positive stress-echoCG sample), zones with kinetics disorders (akinesia, hypokinesia, discenezia), an increase in the end-systolic volume of the left ventricle, a decrease in the thickening of the walls in the systole, a decrease in the EF up to 35% or lower, an increase in the RV, etc. can be determined.
The severity of the ischemic changes revealed during stress echocardiography is judged by the number of affected LV zones, the type of asynergic changes, the time of development and the disappearance of disturbances.
Complications after stress echocardiogram
In the process of stress echocardiography, unwanted effects can develop that will be the basis for stopping the research: headache, muscle tremor, nausea, ventricular and supraventricular extrasystole. Small complications of stress EchoCG include short episodes of paroxysms (up to 2 minutes), hemodynamically insignificant tachycardia.
Threatening complications of stress echocardiography, which require urgent cardio-reanimation measures, are acute coronary syndrome, ventricular fibrillation, asystole.
Cost of stress echocardiography in the United States
The cost of the study varies depending on the type of stress tests. When pricing takes into account the duration and laboriousness of the test for a specialist, as well as the need for additional costs (for example, when carrying out samples with drugs).
In addition, the price of stress echocardiography in USA is determined by the type of medical-diagnostic institution (public or private), the urgency of the diagnostic procedure and the level of specialist training.
If the patient wishes to undergo Stress Echocardiogram without queue, the cost of the procedure may be increased during the procedure by a doctor of the highest category, a candidate or a doctor of medical sciences.