Stress tests in diseases of the cardiovascular system. Stress tests in cardiology (treadmillmetry, bicycle ergometry, stress echocardiography with physical exercise). Indications for stress testing
| Diagnosis of coronary heart disease in patients without a "coronary history", especially in middle-aged people with an intermediate probability of coronary artery disease and with an interpretable ECG |
| Angina recurrence in patients with a history of coronary artery disease, prior myocardial revascularization, and an interpretable ECG |
| Differential diagnosis of cardiac and pulmonary causes of dyspnea on exertion and/or decreased performance* |
Assessment of prognosis in patients with:
|
Assessment of the functional state of patients with:
|
When prescribing the expansion of physical activity and physical training to patients with:
|
Evaluation of the effectiveness of treatment of patients with:
|
Assessing response to heart rate exercise in patients with:
|
Examination of healthy persons:
|
Note: * - conditions/diseases in which a cardiopulmonary test should be performed.
The test is absolutely shown:
|
|
The test can be shown:
|
|
Testing is probably not shown:
|
Exercise tests can be carried out using different protocols, differing in that some provide for a gradual increase in load power, while others remain constant. The goal of gradually increasing stress tests is to achieve maximum stress on the cardiovascular system;
Among protocols with gradually increasing load, protocols in which the load increases continuously and smoothly are increasingly used, due to their advantages for both the patient (good tolerance) and the doctor (ease of interpretation of testing), they should, if possible, be given preference over protocols providing for a stepwise increase in load power.
Stress testing protocols: Among progressive loading methods, protocols in which the load is increased continuously and smoothly (A) are increasingly used, because of their advantages for both the patient (good tolerability) and the clinician (ease of interpretation of the test), they should , if possible, be given preference over protocols providing for a stepwise increase in load power (B).
For exercise tests, various types of ergometers can be used, such as a bicycle ergometer or a treadmill test, the advantages and disadvantages of which are summarized in the table.
| Characteristics | Treadmill | bicycle ergometer |
| Higher peak oxygen consumption | X | |
| Quantification of the work performed | X | |
| Better ECG recording quality | X | |
| Ease of blood sampling | X | |
| More security | X | |
| Ability to test while lying on your back | X | |
| Smaller equipment sizes | X | |
| Lower noise level | X | |
| Less cost | X | |
| Easy to move | X | |
| More familiar load pattern | X | |
| More experience in Europe | X | |
| More US experience | X |
In cases where a detailed study of O2 transport and/or efficiency of its utilization is necessary for clinical or scientific purposes, a cardiopulmonary exercise test is performed, according to the results of which the traditional indicators of exercise testing can be supplemented with an assessment of ventilation, oxygen consumption (O2in) and carbon dioxide emission (CO2e). ).
Exercise tests are widely used to diagnose obstructive coronary artery disease, the most common cause of CAD; while the most common cause of obstruction is coronary atherosclerosis, this applies both to patients without a previous history of coronary artery disease, and to patients with a progressive course of coronary artery disease due to progression of atherosclerosis of native coronary arteries or coronary bypass grafts.
Possible ECG changes during exercise in patients with coronary artery disease are shown in the figure. ST-segment changes in myocardial ischemia: downward-sloping ST-segment depression is a generally accepted indicator of stress-induced myocardial ischemia (A), it is considered diagnostically significant if it reaches at least 1 mm relative to the isoline 80 ms from the J-point of the QRS complex;
Horizontal or slanting ST segment depression at least 1 mm deep from the isoline at a distance of 80 ms from the J point of the QRS complex is a generally accepted indicator of exercise-induced myocardial ischemia. However, there are a number of reasons why a test may be false positive or false negative;
Types of Cardiac Stress Tests
The thallium stress test is used to determine how much blood is flowing into the heart and how it changes with exercise. It is also used in monitoring stress levels in patients who have had a heart attack and in determining the causes of symptoms such as chest pain and shortness of breath. Sometimes this test is done after surgery to evaluate its effectiveness. It will help determine how much blood flow is blocked in the coronary arteries.
During this test, the patient walks on the treadmill until the load is maximal. After that, thallium is injected into the patient's vein and, using a gamma camera, the movement of blood to the heart is observed. If there is impaired blood flow (as occurs with coronary artery disease), a scintigram (image of the heart) will show lesions in which the accumulation of thallium is reduced. This will be a sign of illness.
The technetium pyrophosphate scan is another stress test that uses radioactive tracers. This test is done to confirm and detect a heart attack.
2-3 hours before the test, the radioactive isotope Tc-99m (technetium pyrophosphate) is injected into the blood. Then, after some time, a series of images are taken using a gamma camera. If a heart attack occurs, then part of the heart cells necrotizes (dies off). The isotope will accumulate in these cells. This cluster will be recorded by the gamma camera.
This test is used to check how well the heart is able to pump blood. The patient, in the supine position, is connected to a heart monitor, after which 2 injections of technetium-labeled red blood cells are administered. After that, the patient experiences physical activity, the duration of which is gradually increased.
In a healthy person, the volume of blood ejected during exercise will increase, while in a sick person it may decrease. Also, there may be disturbances in the movement of the wall of the left ventricle. The same test will show a picture of the work of all four chambers of the heart.
This is another cardiac stress test. It is used to identify those areas of the heart in which blood circulation is impaired. This test is performed to diagnose coronary heart disease, to check the effectiveness of drug therapy and the operation of a heart transplant. It is identical to the technetium pyrophosphate stress test.
Physiological Basis of Tests with Gradually Increasing Cardiovascular Load
At the first stages of the stress test (up to 50% of the maximum load), cardiac output increases due to an increase in both heart rate and VR; at a higher load intensity, an increase in cardiac output is mainly due to an increase in heart rate, such an adaptation mechanism allows increasing cardiac output by 4-6 times during maximum stress.
To maintain a balance between the important diagnostic value of the test with the achievement of the maximum level of exercise and its inherent potential risk of complications, a complete list of test termination criteria was compiled.
| muscle weakness |
| Severe shortness of breath, especially disproportionate to the intensity of the load |
| Attack of angina pectoris of moderate or severe intensity |
| Horizontal or slanting ST segment depression (amp) gt; 3 mm compared to baseline ECG |
| Elevation of the ST segment (amp) gt; 1 mm from the contour in leads without pathological Q wave, with the exception of leads V 1 and aVR |
| Complex rhythm and conduction disorders (AV block II and III degree, atrial fibrillation, paroxysmal SVT and VT) |
| Exercise-induced complete BBB, especially if difficult to differentiate from VT |
| The rise in systolic blood pressure is more than 240 mm Hg, diastolic - more than 120 mm Hg. |
| Decrease in systolic blood pressure (amp) gt; 10 mm Hg. from the previous measurement, especially accompanied by other manifestations of myocardial ischemia |
| Increased atypical chest pain |
| Signs of peripheral hypoperfusion (pallor, cyanosis, cold sweat, etc.) |
| Neurological signs/symptoms (impaired motor coordination, dizziness, feeling of emptiness in the head, flashes of light before the eyes, and others) |
| Intermittent claudication |
| Restrictions associated with the pathology of the musculoskeletal system |
| Technical impossibility of continuous ECG monitoring |
| Patient's wish |
In addition, the contraindications for stress testing are clearly established and outlined in the available guidelines. It is extremely important to apply these criteria in clinical practice, as neglecting them may, if complications develop, have legal consequences.
| Absolute | relative |
|---|---|
| The most acute period of MI. Decompensation of CHF. Unstable angina. Acute myocarditis, pericarditis or endocarditis. Acute PE or deep vein thrombosis. Complex atrial or ventricular arrhythmias. Severe aortic stenosis. Severe systemic or pulmonary hypertension. Severe aneurysmal expansion of the aorta. Acute non-cardiac disease. Severe anemia. Severe load-limiting disease of the musculoskeletal system |
Moderate aortic stenosis. Severe proximal stenosis of the left coronary artery. Severe subaortic hypertrophic stenosis. Advanced AV block. electrolyte disorders. Mental disorders |
Load Test Security
Over the past decades, data on the risk-benefit ratio of exercise testing in various diseases have been systematically studied. As a result, indications and contraindications for exercise testing were clearly articulated in the recommendations of the American Heart Association and the European Society of Cardiology.
Exercise testing is seen as a valuable tool not only to detect or exclude exercise-induced myocardial ischemia, but also to determine the patient's fitness level prior to the start of an exercise program. Its implementation is necessary to determine the heart rate that provides an aerobic level of exercise, and to prevent the potential risk of developing complications during physical training such as exercise-induced arrhythmias or an excessive increase in blood pressure.
Indications for stress testing are presented above.
Large epidemiological studies have shown an association between physical endurance and mortality; exercise tests are widely used to objectify the degree of limitation of exercise tolerance due to the disease, for the risk stratification of patients with CHF.
Despite the undeniable clinical value, exercise tests with the achievement of the maximum load have a certain risk of adverse events. In the general population of patients referred for stress testing, cases of death were registered in ‹0.01% of patients, other pathological conditions - in ‹0.05% of patients.
When performing a stress test in the first 4 weeks of acute myocardial infarction, the death rate increases to 0.03%, and non-fatal myocardial infarction or the need for cardioresuscitation reaches 0.09%. In patients with a stable course of compensated CHF, an additional (relative to patients without CHF) risk of there is no test with a maximum load level; as reported in one study, when analyzing 1286 bicycle ergometry, no serious complications were identified.
The absolute risk of severe complications during exercise testing can be minimized by strict adherence to accepted patient selection criteria, careful history taking, detailed clinical examination, continuous monitoring of 12-lead ECG, blood pressure and their recording during exercise and every minute (minimum - every 3 minutes ) immediately after completion.
Although the absolute number of serious complications during exercise testing is small, it can be expected that they will occur from time to time due to the large number of studies performed. The facility where the tests are performed must have CPR supplies available, including emergency medicines, a defibrillator, and an endotracheal intubation kit.
The emergency telephone number must be available at all times. To ensure that the necessary emergency care is provided in a qualified and timely manner, regular training in cardiopulmonary resuscitation should be conducted with staff.
The concept of "stress test" in cardiology includes an assessment of the functional reserve and the state of the cardiovascular system when performing various activities. Why should stress diagnostics be carried out? The fact is that at rest the cardiovascular system can be in a state of compensation without signs of its violations. That is why a standard resting electrocardiogram (standard ECG) may not show signs of damage to certain parts of the heart, which does not exclude the presence of certain nosological forms in the patient.
Similarly, certain signs (patterns) of myocardial contractility disorders (local or global) may not be visualized on echocardiography. Therefore, to identify certain patterns, tests with physical activity (stress tests) were introduced into medical practice.
Currently, stress tests with dosed physical activity are widely used in medical practice.
Dosed physical load - the load, the power of which can be changed according to the specific tasks of the researcher. Dosing physical activity has become possible due to the emergence of special devices that allow you to change the intensity of physical activity in certain standard values. These include bicycle ergometers and treadmills (treadmills).
Bicycle ergometer - allows you to dose physical activity, expressed in Watts (W). There are 2 types of bicycle ergometers: with electromagnetic and belt load dosing mechanisms.
Treadmill - allows you to dose physical activity by changing the speed of movement and the angle of inclination of the moving canvas. The load is dosed during tredmilergometry in metabolic equivalents (MET), which reflects the energy expenditure of the body during work, while 1 MET = 1.2 cal / min or 3.5-4.0 ml of oxygen consumed per minute per 1 kg of body weight.
Bicycle ergometers and treadmills provide the so-called isotonic load, i.e. the load, during which a large muscle group is involved.
What can be diagnosed with stress tests?
1. Coronary insufficiency - initially in cardiology, exercise tests were used specifically for these purposes. Stress tests are the most informative of non-invasive methods in the diagnosis of coronary heart disease (CHD). The sensitivity of this technique reaches 98%, and the specificity is 100%. Indeed, coronary artery disease is nothing more than a mismatch in myocardial oxygen demand with its delivery. At rest, this discrepancy can be compensated due to the low energy consumption of the body, as a result of which sinus rhythm can be recorded on the resting ECG without signs of myocardial ischemia. When performing any type of activity, the energy consumption of the body increases, and as a result, the load on the myocardium increases, and its need for oxygen increases. When oxygen demand does not match with its delivery, myocardial ischemia occurs, which is manifested by certain patterns on the ECG. Depending on the degree of damage to the vascular bed, this discrepancy can manifest itself with loads of different intensity. Therefore, the use of a stepwise protocol for dosing physical activity makes it possible to assess the severity of vascular damage, and the use of certain ECG leads - to localize it anatomically.
Arterial hypertension - until now, arterial hypertension was diagnosed by one main criterion, namely, a persistent rise in blood pressure (BP). The severity of arterial hypertension (AH) was assessed by the presence of certain changes in the "target organs" - the heart (left ventricular hypertrophy), brain (hypertensive encephalopathy), kidneys (hypertensive nephropathy). However, a patient with normal resting BP does not rule out hypertension. In addition, most patients with hypertension receive antihypertensive therapy and there are problems with determining the severity of the disease. In this regard, stress tests are of high diagnostic value, since when performing work, the load increases not only on the heart, but also on the entire cardiovascular system, which is manifested by an increase in heart rate (HR) and blood pressure levels. If, when performing work of a certain intensity, an excessive increase in blood pressure occurs, then this serves as a “diagnostic key” in the setting of hypertension. Depending on the intensity of the load, at which a pathological increase in blood pressure occurred, the severity of hypertension can also be assessed.
Heart (myocardial) insufficiency is also well verified during stress tests. When performing work of a certain intensity in patients with heart failure (HF), there is a depletion of the functional reserve, which is subjectively expressed in the appearance of severe shortness of breath. Using the gas analysis of exhaled air on special gas analyzer attachments, it is possible to objectify the appearance of myocardial dysfunction, which increases the diagnostic value of stress tests in the diagnosis of heart failure.
Arterial insufficiency of the vessels of the lower extremities is currently underused due to the fact that stress tests have recently begun to be used to assess this criterion. By analogy with coronary insufficiency, with an increase in the intensity of the load, the need for oxygen increases in the working muscles. If there is a discrepancy between the need for oxygen and its delivery (which occurs with obliterating atherosclerosis of the vessels of the lower extremities), then there are subjective complaints of pain in the legs. Recently, it has become possible to objectify ischemia of the lower extremities, which allows for a more accurate diagnosis even before the appearance of subjective complaints of the patient. Depending on the intensity of the load, at which arterial insufficiency manifested itself, it is possible to assess the severity of the disease.
So, we have considered the diagnostic possibilities of stress tests. Thus, based on them, patients are sent to verify the diagnosis or determine the severity of the verified disease.
Stress tests are a serious diagnostic study, so it is necessary to take into account contraindications to their conduct.
ABSOLUTE CONTRAINDICATIONS.
- * Congestive heart failure
- * Recent (current) myocardial infarction
- * Unstable or progressive angina
- * Dissecting aneurysm
- * Polytopic extrasystole
- * Severe aortic stenosis
- * Recent (current) thromboembolism
- * Recent (current) thrombophlebitis
- * Acute infectious disease
RELATIVE CONTRAINDICATIONS.
- * Frequent (1:10 or more) ventricular extrasystoles
- * Untreated severe arterial or pulmonary hypertension
- * Aneurysm of the ventricle of the heart
- * Moderate aortic stenosis
- * Poorly treatable metabolic diseases (diabetes, thyrotoxicosis, etc.)
So, for carrying out load tests, the protocol of isotonic load with a continuous stepwise increase in its level has become most widespread.
What is the best way to do a stress test? In Western countries, treadmill ergometry is widely used, while in Europe bicycle ergometry (VEM) is used. From a physiological point of view, tredmilergometry is the most suitable, however, due to the high cost of the equipment, VEM is widespread in our country.
For stress tests, regardless of the method of dosing the load, there are general principles:
Load uniformity - the load from stage to stage should not be dosed randomly, but increase evenly to ensure proper adaptation of the cardiovascular system at each stage, which will allow for accurate diagnosis.
Fixed duration of each step. It is generally accepted throughout the world to have a load step duration of 3 minutes.
You need to start the test with a minimum load - for VEM this is a value equal to 20-40 W, and for treadmill ergometry - 1.8-2.0 MET.
After the stress test has been carried out, it is necessary to proceed with the evaluation of the obtained data, which includes:
- * assessment of coronary insufficiency with the definition of a functional class
- * evaluation of exercise tolerance
- * recommendations for correction of therapy and motor regimen
ASSESSMENT OF CORONARY INSUFFICIENCY
In total, the sample is evaluated according to three criteria: positive, negative and doubtful.
A positive sample is set if during the study there were ECG signs of myocardial ischemia. When signs of myocardial ischemia appear without an attack of angina pectoris (anginal pain), painless myocardial ischemia is indicated.
A negative test is placed on the basis of the absence of ischemia criteria, provided that the required level of load is reached (submaximal heart rate or load corresponding to 10 METs or more).
A questionable sample is placed if:
- 1. the patient had an attack of angina pectoris, but no ischemic changes were detected on the ECG;
- 2. the required level of load has not been reached (submaximal heart rate or load
If a positive test is set, then it is necessary to determine the functional class and topical localization of ischemia.
It should be noted that today the international metabolic scale is used to assess the functional class. The use of the metabolic scale makes it possible to accurately determine the functional class, while in the traditionally used in our country assessment of the functional class according to the threshold load power criterion (in Watts), we received a discrepancy between the severity of the disease and the objective state of the patient, determined according to coronary angiography. This is due to the fact that the value of MET (metabolic load equivalent) depends on many factors (age, weight, gender), while the value of Watts is “stationary” and depends only on the degree of fitness of the body.
For example, the same load of 60 W for a 55-year-old man with a body weight of 90 kg “costs” 3.0 METs, and with a smaller weight at 40 years old - 5.0 METs. If this critical load provoked myocardial ischemia (according to ECG data), then in the first patient it corresponds to the 3rd functional class, and in the second it corresponds to the 2nd functional class.
When blood pressure rises at any level above the threshold value of 190/100 mm Hg, a hypertensive response to physical activity is indicated.
If during the test, rhythm and / or conduction disturbances occur, it is also necessary to indicate in the conclusion with a description of the level of load at which they appeared and their nature.
POSSIBILITIES OF STRESS TESTS IN PATIENTS WITH ARTERIAL HYPERTENSION
Currently, arterial hypertension has a large share in the structure of diseases of the cardiovascular system. Most patients are taking antihypertensive therapy and are in the so-called “normotensive zone”, which significantly complicates the determination of the degree of hypertension, since normal blood pressure values in hypertensive patients are not the criteria for “cured”. In patients with hypertension, a false impression is created that they do not have hypertension, which is the reason for refusing to take antihypertensive drugs.
In a comprehensive assessment of the severity of hypertension, load tests are of great importance, which simulate loads of different power. This makes it possible to assess the relationship between blood pressure and load in this group of patients, which is important in the examination of working capacity.
We have studied the response to physical activity in patients with arterial hypertension. The “peak” value of blood pressure was revealed, i.e. the value of blood pressure, which is achieved at the peak of physical activity. If the value of the “peak” level of blood pressure corresponded to 190/100 mm Hg. and more, then a hypertensive reaction to physical activity was diagnosed. The functional class of the hypertensive response was determined depending on the stage of the load at which the peak BP level was reached, i.e., the metabolic “cost” of the load (in METs).
Thus, the relationship between an increase in blood pressure above the threshold value (“hypertensive reaction”) and physical activity allows us to establish the “functional class” of hypertension and helps to decide on the correction of antihypertensive drugs, as well as expert questions regarding the ability of patients to work.
ASSESSMENT OF TOLERANCE TO PHYSICAL LOAD
If the duration of the last step is less than three minutes, then the performance is calculated by the formula:
W =Wstart + (Wlast-Wstart)t/3
W - general performance;
Wnach - power of the previous load stage;
Wposl - power of the last load stage;
t is the time of work at the last stage.
For survivors of myocardial infarction and patients with coronary artery disease, exercise tolerance is assessed as “high” if W> 100 W; “medium” - at W = 50-100 W; “low” if W< 50 Вт.
According to the tolerance to physical activity, recommendations on the motor regimen are given.
If coronary insufficiency is detected during the exercise test, then recommendations are given for correcting antianginal therapy and coronary angiography.
If a hypertensive response to physical activity occurs, it is necessary to indicate the correction of antihypertensive therapy and repeated stress testing to assess its adequacy.
If during the stress test complaints such as dizziness and pain in the calf muscles occur, then it is necessary to recommend a Doppler examination of the vessels of the brain and lower extremities, since this indirectly indicates cerebrovascular insufficiency and arterial insufficiency of the lower extremities.
HOLTER MONITORING
The method of long-term ECG recording, proposed in 1961 by Norman Holter, is now firmly established in cardiological practice. Indeed, a standard ECG allows you to register only fragments from a few seconds to several minutes, while the study is carried out at rest, as a result of which the signs of myocardial ischemia and various arrhythmias may not appear on the ECG. These shortcomings are deprived of the method of long-term ECG recording (Holter-ECG), which is called “ambulatory ECG monitoring” abroad. Indeed, as the name implies, ECG registration can be carried out in the usual “domestic” conditions for the patient, while maintaining normal daily activities. It is this fact that makes it possible to identify the genesis of changes on the ECG with the patient's complaints: during the recording of the Holter ECG, the patient keeps a diary of daily activity, where he indicates at what time and what load was performed, notes all the complaints that bothered him during the entire registration period .
Our department uses the Hoter system “Custo-Med”, Germany. ECG recording is carried out on the solid-state memory of the sensor (in contrast to the “cassette” recording methods, which gave a large number of hardware artifacts). The device is attached using a special case on the patient's belt. Disposable sticky electrodes are used. The device is powered by an alkaline battery. The procedure is safe for the patient and does not interfere with the patient's normal activities.
Fields of application of Holter ECG monitoring:
1. Diagnosis of rhythm and conduction disturbances is the most common indication. The Holter method can determine the type of arrhythmia, its circadian activity (day, morning, night), as well as determine the possible factors of its provocation (physical activity, food intake, emotional stress, etc.).
Indications:
- 1) Patient's complaints about frequent heartbeats;
- 2) Extrasystole (to identify their total number per day and circadian activity, connection with various activities);
- 3) Ventricular preexcitation syndrome (WPW-syndrome) - both manifest and latent forms;
- 4) Dysfunction of the sinus node (to exclude the syndrome of weakness of the sinus node) - with heart rate at rest 50 per minute or less;
- 5) Syncope - are subject to 100% ECG monitoring to exclude their arrhythmogenic nature.
- 6) Transient and permanent form of atrial fibrillation.
- 2. Ischemic heart disease - is the method of choice in the diagnosis of coronary artery disease. If the patient complains of pain in the region of the heart - for their differential diagnosis and verification of coronary artery disease. To verify the ischemic heart disease, it is recommended that the patient be given loads of various intensity per day, especially those in which he experiences subjective complaints with their mandatory registration in the patient's diary.
- 1) Angina pectoris - is used, as a rule, in patients who cannot perform stress tests (non-training, joint disease, thrombophlebitis, etc.).
- 2) Vasospastic angina (Prinzmetal's angina) - is a 100% indication for daily ECG recording. Vasospastic angina tends to occur in young patients, predominantly men. An attack of angina pectoris is not associated with atherosclerotic lesions of the coronary vessels, but with their spasm (“angina pectoris on unchanged coronaries”). As a rule, an attack of angina pectoris is not associated with physical activity and occurs in the early morning hours, accompanied by ST segment elevation on the ECG (ECG changes according to the type of damage) - lasts a few seconds, sometimes minutes. After an attack, the ECG returns to baseline (“sinus rhythm”).
- 3) Postinfarction period.
Let us consider some features of the conclusions based on the results of Holter ECG monitoring.
So, the long-term registration method allows you to evaluate:
- 1) Pacemaker activity of the sinus node (normally not disturbed).
- 2) Ectopic activity of the myocardium (normally not expressed).
- 3) Paroxysmal arrhythmias.
- 4) Conduction disorders (transient blockade, etc.).
- 5) Fluctuations of the ST segment - in the diagnosis of coronary artery disease. Normally, no significant fluctuations in the ST segment are recorded on the daily ECG.
WPW syndrome or ventricular pre-excitation syndrome is known to be associated with the presence of accessory conduction pathways between the atria and ventricles, which causes characteristic resting ECG changes. The prevalence of WPW syndrome in the population is relatively low - from 0.01-0.3%, however, it can be combined with other cardiovascular pathologies, including coronary heart disease (CHD). Stress tests, in particular bicycle ergometry and treadmill test, are widely used in the diagnosis of coronary artery disease. From the literature it is known about the possibility of false positive results of ECG tests in WPW syndrome. However, in practice, these tests are often used in this group of patients. The choice of the type of exercise test and the correct interpretation of its results in WPW syndrome, for this reason, remains an important task.
We present a clinical case of diagnosing coronary artery disease using various types of exercise tests in an asymptomatic woman with ventricular preexcitation syndrome.
Patient K., 43 years old, was hospitalized for examination with a diagnosis of coronary artery disease, postinfarction cardiosclerosis. On admission, she did not have any specific complaints. From the anamnesis it is known that the diagnosis was established retrospectively on the basis of ECG changes. There were no indications of a prolonged anginal attack in the anamnesis. The patient did not describe the clinic of angina pectoris, did not note increases in blood pressure and cardiac arrhythmias. Previously, repeated biochemical blood tests in the patient revealed an increase in total cholesterol from 6.0-6.5 mmol/l. The woman smoked for several years, but stopped smoking shortly before hospitalization and had a preserved menstrual function. Resting ECG changes were detected for the first time by accident during examination in a sanatorium. As can be seen from the presented ECG (Fig. 1), in the right chest leads, the ventricular complex had a QS shape, which was preserved during the ECG recording during inspiration, which at the prehospital stage was interpreted as cicatricial changes in the anterior septal region. In addition, there was a shortening of the P-Q interval to 0.10 s. and changes in the initial part of the QRS complex in the form of a weakly expressed "delta" wave.
At the outpatient stage, in order to detect episodes of myocardial ischemia, the patient underwent 24-hour ECG monitoring, as a result of which no ischemic changes and significant arrhythmias were recorded. An objective examination did not reveal any features of the cardiovascular system, blood pressure was 130/80 mm Hg. Art., heart rate - 70 bpm.
Rice. 1. Resting ECG of patient K., 43 years old.
In the clinic, the patient underwent echocardiography (EchoCG) and a dosed exercise test according to the R.Bruce protocol (treadmill test with ECG and EchoCG). Echocardiography at rest showed no pathological changes in the size of the heart chambers, wall thickness, systolic and diastolic function. No zones of impaired local contractility were identified. Stress echocardiography showed no ST segment changes on the resting ECG. Against the background of the maximum load at the 4th minute (HR 164 beats/min, BP 140/90 mm Hg, performed load - 4.8 METS), the appearance of ST segment depression was noted (Fig. 2). Maximum horizontal ST segment depression of more than 2 mm was observed in leads II, III, aVF, up to 2 mm in leads V4-V6. According to echocardiography, in the first 2 minutes after the end of the load, no zones of impaired local contractility were found. There were no clinical manifestations of angina pectoris in the form of pain or discomfort in the chest, and no rhythm disturbances were recorded.
Rice. Fig. 2. ECG dynamics during the exercise test of patient K., 43 years old.
Given the risk factors for coronary artery disease and the ambiguous results of the stress test, the patient underwent single photon emission computed tomography of the myocardium with an assessment of perfusion at rest and during the exercise test (Fig. 3 - see 1st cover page). 99mTc-technetrile was used as a radiopharmaceutical, VEM was performed according to the standard R. Bruce protocol. During the test, a heart rate of 170 beats/min was achieved, no clinical signs of acute myocardial ischemia were found. On perfusion tomoscintigrams in the study at rest and under conditions of a stress test, regional perfusion defects were not determined, and there were no violations of local contractility of the left ventricle. Thus, despite the existing risk factors, good exercise tolerance, as well as the absence of perfusion defects and local myocardial contractility disorders, both at rest and under exercise conditions, made it possible to regard the results of the ECG stress test as false positive, and the patient as having a low risk of coronary heart disease. Changes in the QRS complex were interpreted as characteristic of the WPW syndrome, type B (shortening of the P-Q interval to 0.10, a negative "delta" wave in leads V1-V3, a positive one in leads V5-V6), which caused a specific "pseudo-infarction" resting ECG picture. During the 5-year follow-up, the patient continues to be asymptomatic, while following dietary recommendations, blood lipid levels are normalized (total cholesterol - 4.0-4.5 mmol/l, low-density lipoprotein - less than 2.5 mmol/l).
Rice. 3. Results of single photon emission computed tomography at rest and under exercise
DISCUSSION
The high frequency of false positive results of the stress test with ECG in the syndrome of premature ventricular excitation has been repeatedly described in the literature. Thus, according to M.R. Jezior et al. who analyzed 8 stress testing studies for WPW syndrome, with a total of 176 patients, false positive results were reported in 49% of patients (Table 1). In this number of cases, against the background of the load, the "delta" wave disappeared with simultaneous normalization of the ST segment. At the same time, ST segment changes in some cases persisted despite the disappearance of the “delta” wave, which the authors explain by the “cardiac memory” phenomenon, which causes the persistence of repolarization disorders, for example, after cessation of stimulation or after tachycardia. In some cases, ST segment depression was very pronounced (greater than 4 mm) in angiographically normal coronary arteries.
Table 1. False-positive results of the exercise ECG test in patients with WPW syndrome according to M.R. Jezior et al.
| Study | ST type | Patients with ST segment depression, n | Patients with IS, n | Patients with abnormal IS results, n |
| Gazes (n=23) | T | 20 | ||
| Poyatos and others (n=58) | T | 31 | 18 | 9 |
| Strasberg and others (n=54) | T | 19 | ||
| Paquet and others (n=1) | T | 1 | 1 | 1 |
| Archer and others (n=8) | B | 7 | 8 | 2 |
| Tawarahara and others (n=20) | WITH | 20 | 2 | |
| Pattoneri and others (n=11) | B | 7 | ||
| Greenland and others (n=1) | T | 1 | ||
| Total (n=176) | 86 (49%) | 47 | 14 (30%) |
where, ST - stress test, AI - isotope study, T - treadmill; B - bicycle ergometry; C - myocardial scintigraphy (thallium) with loading.
This case also demonstrates the possible difficulties in assessing the results of a stress test in the presence of ventricular preexcitation syndrome. ECG stress testing for WPW syndrome is a class III indication according to ACC recommendations. Therefore, first of all, the correct diagnosis of the WPW syndrome is important, since the choice of the method of functional diagnostics depends on this. As is known, in WPW syndrome, excitation from the atria to the ventricles is transmitted both through the atrioventricular node and through an additional pathway (Kent's bundle), which causes a shortening of the P-Q interval and an expansion of the QRS complex with the appearance of a "delta" wave.
In the presented case, despite the shortening of the P-Q interval, the weak severity of the "delta" wave can lead to the problem of recognizing the syndrome of premature ventricular excitation and erroneous interpretation of ECG changes as cicatricial post-infarction. This conclusion can also be supported by the data of myocardial scintigraphy, where attenuation by the breast tissue can simulate hypoperfusion in the anterior-apical region (Fig. 3). At the same time, the absence of zones of impaired local contractility according to both echocardiography and scintigraphy makes it possible to exclude cicatricial damage to the myocardium.
Disturbances in repolarization processes in the form of ST segment depression during a stress test could be regarded as evidence of ischemia in the lower lateral wall of the left ventricle. However, the absence of zones of hypokinesia during exercise according to scintigraphy and echocardiography, as well as stress-induced perfusion disorders, make it possible to exclude transient myocardial ischemia. Thus, the diagnosis of coronary artery disease in individuals with WPW syndrome should be carried out on the same principles as in other patients, and be based on risk assessment, pretest probability of coronary artery disease and clinical data, but with the obligatory consideration of the presence of initial ECG changes. The correct choice of the method of functional diagnostics helps to avoid false positive results, which, in turn, can lead to unreasonable prescription of invasive diagnostic methods.
LITERATURE
- Kushakovsky M.S. Arrhythmias of the heart. - St. Petersburg: Foliant Publishing LLC, 2004. - 672 p.
- Jezior MR, Kent SM, Atwood JE. Exercise Testing in Wolff-Parkinson-White Syndrome // Chest 2005; 127: 1454-1457.
- Gaze PC. False positive exercise test in the presence of the Wolff-Parkinson-White syndrome // Am J Cardiol 1969; 78:13-15.
- Poyatos ME, Suarez L, Lerman J, et al. Exercise testing and thallium-201 myocardial perfusion scintigraphy in the clinical evaluation of patients with Wolff Parkinson White syndrome // J Electrocardiol 1986; 19:319-326.
- Strasberg B, Ashley WW, Wyndham CRC et al. Treadmill exercise testing in the Wolff-Parkinson-White syndrome // Am J Cardiol 1980; 45:742-747.
- Paquet N, Verreault J, Lepage S et al. False-positive 201 thallium study in Wolff-Parkinson-White syndrome // Can J Cardiol 1996; 12:499-502.
- Archer S, Gornick C, Grund F. et al. Exercise thallium testing in ventricular preexcitation // Am J Cardiol 1987; 59:1103-1106.
- Tawarahara K, Kurata C, Taguchi T, et al. Exercise testing and thallium-201 emission computed tomographic in patients with intraventricular conduction disturbances // Am J Cardiol 1992; 69:97-102.
- Pattoneri P, Astorri E, Calbiani B, et al. Thallium-201 myocardial scintigraphy inpatients with Wolff-Parkinson-White syndrome // Minerva Cardioangiol 2003; 51:87-93.
- Greenland P, Kauffman R, Weir KE. Profound exercise-induced ST segment depression in patients with Wolff-Parkinson-White syndrome and normal coronary arteriograms // Thorax 1980; 35:559-560.
- Gibbons J, Balady GJ, Bricker JT, et al. ACC/AHA 2002 Guideline Update for Exercise Testing: Summary Article: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Update the 1997 Exercise Testing Guidelines) // Circulation 2002; 106: 1883-1892.
Treadmill, a stress test with walking under ECG control, is carried out on a Case stress system complete with a treadmill and a bicycle ergometer with the ability to automatically measure blood pressure from GE, USA. A person on the track makes a walk corresponding to the speed of the track, which is regulated over a wide range. The load can be increased by creating a graduated slope (imitation of walking uphill). Each patient is given a load according to one of the available protocols, the choice of which depends on the purpose of the study and the initial capabilities of the patient. Throughout the stress test and in the recovery period, the patient's condition is constantly monitored (continuous monitoring of the ECG, heart rate and blood pressure).
Functional stress tests are used to:
- diagnosis of hidden manifestations of coronary insufficiency (ischemic heart disease);
- evaluation of the effectiveness of treatment and rehabilitation measures, including after myocardial infarction;
- determining the nature of the reaction of the functional systems of the body to the load (excessive rise or decrease in blood pressure, the degree of increase in heart rate, violation of heart rhythm and conduction);
- determining the prognosis of the disease.
Before the test, if necessary, depending on the purpose of the study, cancel the drugs; the patient should not smoke on the day of the study; the study is carried out on an empty stomach or 2 hours after eating; the patient must have sports or comfortable shoes and trousers with him. It is desirable to have the results of previous studies (ECG at rest and during exercise, echocardiography, discharge from the hospital or outpatient card, laboratory results).
Stress echocardiography is a method of studying the heart that allows you to evaluate hidden disorders of the coronary circulation during exercise (walking, drug exposure, TPE stimulation, etc.) under the control of echocardiography and obtain objective signs of insufficiency of the coronary blood supply in the form of impaired contractility of certain areas of the myocardium. In our hospital, stress echocardiography is currently performed with various types of physical activity (bicycle ergometer in the supine position and treadmill); In addition, in 2014, 2 new techniques were introduced in our department: stress echocardiography with transesophageal atrial stimulation and with dobutamine, which made it possible to conduct the test primarily in patients who, for some reason, are not able to perform physical activity.
Stress-ECHOCG with physical activity is a method for examining the heart, which allows to evaluate hidden disorders of the coronary circulation during exercise (walking, drug exposure, TEE stimulation, etc.) under the control of echocardiography and to obtain objective signs of coronary blood supply insufficiency in the form of impaired contractility of certain zones myocardium. In our hospital, it is now possible to perform stress echocardiography with different types of physical activity (bicycle ergometer in the supine position and treadmill). Depending on the time of registration of echocardiographic positions during exercise, there are several options for conducting stress echocardiography. The most informative variant of the stress echocardiogram is the one that allows you to constantly monitor the echocardiographic positions. In our department there is such an opportunity, because. a bicycle ergometer is available for testing in the horizontal position of the patient and turning it to the left side. Thus, the maximum sensitivity of the sample is achieved.
Stress echocardiography does not replace the methods of CAD diagnostics available in the department, such as the ECG-guided treadmill test, but expands the diagnostic capabilities for patients with an initially pathological ECG and for those who cannot exercise.
Stress echocardiography with transesophageal electrical atrial stimulation.
Advantages of transesophageal stimulation compared to exercise:
This test can be performed in patients who are unable to exercise;
- the patient does not move during the examination (image of better quality is possible);
- the test is safer than physical activity (heart rate returns to baseline immediately after cessation of stimulation, local contractility of the left ventricle is well controlled during the test, the likelihood of ventricular arrhythmias is significantly less);
- the test is not accompanied by a hypertonic reaction.
Disadvantages of transesophageal stimulation:
Non-physiological sample;
Some patients may experience discomfort during the procedure;
In 1/3 of patients, the development of AV blockade of the 2nd degree occurs, which requires intravenous
administration of atropine.
Dobutamine stress echocardiography.
One of the types of stress during stress echocardiography are pharmacological tests. These include:
Test with adenosine;
- test with dipyridamole;
- test with dobutamine.
Dobutamine stress echocardiography has been introduced in our department. Patients with CAD have a two-stage response to dobutamine administration:
Small doses - an increase in LV myocardial contractility, incl. segments with initially impaired contractility, if they contain a viable myocardium;
- then, against the background of medium and high doses, there are violations of contractility of the LV myocardium, which is supplied with blood by stenotic coronary arteries.
Features of the myocardial reaction to the introduction of dobutamine make it possible to use this test for:
1) detection of myocardial viability, i.e. determining the cause of myocardial dysfunction, which can be caused by both irreversible components (necrosis, fibrosis, remodeling as a result of transferred myocardium) and reversible components (stunned or hibernating myocardium);
2) determination of operational risk.
Indications for stress echocardiography:
1. Diagnosis of coronary artery disease:
- in persons with significant initial ECG changes (complete left bundle branch block, ventricular pacing, severe left ventricular hypertrophy with changes in the terminal part of the ventricular complex, WPW syndrome, etc.);
- with painless myocardial ischemia;
- with a doubtful result of a stress test according to ECG criteria for myocardial ischemia;
- with a negative result of the stress ECG test and strong clinical suspicion of the presence of angina pectoris.
2. Evaluation of the functional significance of lesions in the main coronary arteries in patients with coronary artery disease.
3. Evaluation of myocardial viability in patients with extensive disorders of left ventricular contractility:
- after myocardial infarction and acute coronary syndrome;
- in chronic forms of coronary artery disease;
- before cardiac revascularization procedures.
4. Evaluation of the effectiveness of myocardial revascularization (bypass surgery, angioplasty, stenting of the coronary arteries).
5. Evaluation of the effectiveness of drug therapy.
6. Assessment of the prognosis of the course of coronary artery disease:
- in chronic forms of coronary artery disease;
- after uncomplicated myocardial infarction and acute coronary syndrome.
7. Assessment of the degree of risk of complications:
- during operations on the heart, aorta and lungs;
- during major non-cardiac surgery.
8. To address issues of examination of disability.
The advantages of stress echocardiography are more reliable visualization of the manifestations of myocardial ischemia, expanding the range of patients who can undergo a stress study.
Statistics inexorably reports: people sharply reduce their physical activity by the age of 30. Afterwards, things usually get worse. Excessive body fat, shortness of breath even with slight physical exertion, awkward, constrained movements ... This is how premature aging of the body begins. What if we dig deeper? "Rust" on the vessels, limitation of movements in the joints, diseases begin to "stick" ...
Unfortunately, in our society, many are accustomed to such an age-related turn of events and even attribute these changes to peculiar manifestations of well-being.
Stop! This allegedly “natural” reaction of the body, associated with a sedentary lifestyle, can and should be slowed down. It is enough just to increase the amount of physical activity and the time allocated to them - in comparison with the amount and time that you have observed within the last 10 years. I emphasize: increase the volume and time, but not the intensity.
Heart and motor. Score 6:1
The heart is a hollow muscular organ, the main task of which is to pump blood through contractions and deliver it to all cells of the body. In a minute, an adult has 60-80 such contractions. There are 80 × 60 = 4800 contractions per hour of life, 4800 × 24 = 115200 per day, 115200 × 365 = 4 204 8000 per year. That is, by the age of 70, the number of heart contractions is gaining about 3 billion.
Compare with a car engine. Usually, he allows the car to go 120 thousand km without major repairs - three round-the-world trips, just in case. At a speed of 60 km / h, the life of the motor will be only 2 thousand hours, which is 480 million cycles.
Let's compare the results for our heart and car engine. 6:1! Even with the most modest estimates, the advantage is striking. Now you understand what a colossal work our little heart does?
It has been scientifically proven that the heart has enormous adaptive capabilities. They are based on its ability to significantly increase both the frequency of contractions and the amount of blood ejected into the vessels with each contraction.
Under the influence of physical activity, the efficiency of a healthy untrained heart increases by 2.5–3 times compared to the state of rest.
Think about the wonders that regular exercise can do!
What amount of physical activity is needed for a person who does not aspire to participate in the Olympic Games, but is engaged only in order to keep himself in normal conditions, allowing not to reduce the quality of life?
The main goal of health training is to increase the efficiency of the heart and blood vessels.
And since the heart is the most vulnerable link in the trained body, monitoring its condition is especially important. Why? Firstly, knowing the reserve capacity of the heart allows you to make your loads safe and effective. Secondly, monitoring the changes in the cardiovascular system that develop during training allows you to assess how successfully you “digest” loads.
Before the start of systematic training, we, cardiologists, check the initial level of fitness of the cardiovascular and respiratory systems. To do this, there are certain tests for assessing the pulse, pressure, breathing rate, and even control of emotions.
Below are stress tests that anyone can apply on their own at home.
Samples with pulse control. Squat, jump, walk up the stairs
Let's start with the pulse as the main indicator of the heart's performance. The norms for men of working age are 50-60 beats / min in a calm state, for women, oddly enough, the value is less.
Before I go into the description of the samples, a warning for people with heart problems. A small indulgence for you: you can immediately do only half of the squats (jumps) and only then, subject to an increase in heart rate by no more than 50%, continue to the generally recommended load.
Stair test.
We rise to the 4th floor, slowly, without stopping and immediately count the pulse. If the heart rate (HR):
- < 100 уд./мин – всё отлично,
- < 120 – хорошо,
- < 140 – удовлетворительно.
- But if > 140 - beat the drum, it's bad.
The next stage of testing. Rise to the 7th floor - already taking into account the time. First, we rise in 2 minutes and count the pulse:
- if heart rate > 140 bpm, this is your limit for now. Start working on yourself.
- if heart rate< 140 уд./мин, считаем пульс еще раз через 2 мин. За 2 мин пульс должен вернуться к исходному – при хорошем уровне тренированности. Если же все-таки не вернется – у вас есть повод работать над собой.
Squat test.
We stand up straight and count the pulse. Then, slowly, we squat 20 times, stretching our arms forward, keeping the torso straight and widely spreading our knees to the sides. Again, we consider the pulse, or rather, the percentage of its growth:
- an increase in heart rate after exercise by 25% or less indicates an excellent state of the body;
- an increase of 25-50% is also not bad, but it is already considered simply
- values of 50-65% (satisfactory) and > 75% (poor) indicate your lack of training.
Another version of the test with squats.
We count the pulse at rest for 10 seconds, for the next 30 seconds we squat 20 times and count the pulse again. So we repeat every 10 seconds until the moment when the heart rate returns to its original value.
If you are trained, the increase in heart rate in the first 10 seconds will be no more than 5-7 beats, and the return to the original numbers will occur within 1.5-2.5 minutes, with excellent fitness, 40-60 seconds will be enough. If you missed these time frames, you have work to do.
Jump test.
Immediately consider the pulse, then stand straight, hands on the belt. Your task is to do 60 small jumps on your toes in 30 seconds. Then count the pulse again. We evaluate the values in the same way as in the previous sample.
Samples with pulse control. We lie down - we get up. We stand - we lie down
The role of the nervous system, as a regulator of the work of the heart and blood vessels, is reflected in tests with a change in body position.
Orthostatic test (first lie down, then get up).
We count the pulse in the prone position for 10 seconds, multiply by 6, we get the initial pulse. Slowly get up, count the pulse in a standing position.
We focus on the difference - no more than 10-14 beats / min. If your result< 20 уд./мин, вы уложились в общепринятый норматив, и ваш организм хорошо восстанавливается после физической нагрузки. Если разница >20 bpm is bad.
Clinostatic test (first we stand, then we lie down).
The test is based on the body's feedback: when the body position changes from vertical to horizontal. The recommended difference is no more than 4-10 bpm. The evaluation of the result is similar to the evaluation in the previous sample.
Pressure controlled samples
The second important indicator that you can measure when training at home is blood pressure (BP).
We measure before training, after training, another 20-30 minutes later, plus if you feel worse.
minute volume of blood.
Knowing the numbers of blood pressure and pulse, you can approximately calculate the minute volume of blood ejected by the heart. To do this, we multiply the difference between the maximum and minimum values of blood pressure by the heart rate.
We focus on the level of 2600. If the value is exceeded, think about whether you have gone too far with the loads.
Even the coefficient of endurance can be determined at home! Just multiply your heart rate by 10 and then divide by the difference between your maximum and minimum BP. The permissible norm is 16. An increase in the indicator indicates a weakening of the work of the heart and blood vessels.
Breathing rate
In the process of physical exercise, it is important to monitor the frequency of breathing. This is especially true for people who have shortness of breath during physical activity. I recommend keeping this indicator at 16 times per minute. Just don't take it for granted. You can measure the respiratory rate 1-2 times a week as an addition to other tests.
12-minute test (Cooper test)
Assuming a healthy heart - to assess the training role of walking, a 12-minute test or Cooper test is suitable.
Running track in the stadium. Photo: deborahrodriguez.net When it is done, you can walk, or you can run. The important thing is what distance you have mastered in 12 minutes. The actions performed should not cause severe shortness of breath, otherwise stop and restore breathing. Evaluate the result according to the table.
What is required for the test? A pedometer and a treadmill, ideally a stadium one. In the absence of a pedometer, a pre-count of the number of steps in 100 m or 200 m will help.
The most important thing in performing the test is to evaluate the strength. If you have a heart condition, it's best to take the 6-minute walk test (see Heart Attack First Steps). If the heart is healthy, but you want to be sure of this for sure, be examined by a therapist the day before. If you think that both are not about you, then it’s better to practice first, and then start testing.
Emotion control
Equally important are the emotional criteria for proper training of the body. Here we include a feeling of cheerfulness, sound sleep, a good appetite, a desire to continue in the same spirit.
Cheerful and well-rested - this is a person who regularly loads himself and feels a desire to continue exercising.
It is logical that any physical activity leads to fatigue and muscle pain. At the same time, the preservation of cheerfulness, as an indicator of getting used to unusual loads, may indicate normal fitness. On the contrary, a decline in strength, increased fatigue, the appearance of indifference and apathy signal overwork.
Changing the motor mode will require you to have a fairly high level of self-organization. Of course, just lying on the couch, using the elevator whenever possible and driving up in transport every time you need to overcome 300 meters is much easier than encouraging yourself to be physically active regularly. To start or not to start training - the decision is yours. And if you decide, immediately learn to enjoy the movement, listening to how the body reacts. Then compliance with the regularity of training will never become a burden.
