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INVENTION
Russian Federation Patent RU2233614

A method for diagnosing coronary artery disease

A method for diagnosing coronary artery disease

Name of the inventor: Savvateev KL (RU); Shevchenko OP
The name of the patentee: Russian State Medical University
Address for correspondence: 117997, Moscow, ul. Ostrovityanova 1, SMU, patent department, SV Pyzhevu
Starting date of the patent: 2002.06.28

The invention relates to medicine, cardiology. The patient is carried out stepwise increasing load on the cycle ergometer. ECG recorded during loading. Since the beginning of veloergometry conducted transesophageal atrial electrical stimulation. Impose your heart rate in the range of 120-180 beats per minute. The method is a sensitive non-invasive method of diagnosis and verification of latent coronary insufficiency.

DESCRIPTION OF THE INVENTION

The invention relates to medicine, namely to methods of functional diagnostics in cardiology.

Known methods of verification of coronary heart disease (CHD) are based on the idea of ​​induction of clinical (angina attack) and electrocardiography (ST depression) symptoms of transient myocardial ischemia by means of an artificial increase in myocardial oxygen demand.

The most common way to increase myocardial oxygen demand is increasing step by step exercise on the cycle ergometer or treadmill (Aronov DM Manual of Cardiology / Edited Chazova EI - M., 1982, Volume 2, s.587-605) . The sensitivity of the known method in the diagnosis of coronary heart disease is in the range 40-80% (range is due mainly to differences in the cohort of subjects). The diagnostic potential of the stress tests is limited by the physical failure subjects, especially women, and related conditions, such as high blood pressure, vascular atherosclerosis of the lower limbs and so forth.

Other ways to increase myocardial oxygen demand are as artificial effects on hemodynamic factors (heart rate, total peripheral vascular resistance, myocardial contractility), defining this need. The diagnostic sensitivity of this approach to verification IBS usually lower than that of a standard exercise test.

Known method of increasing the demand for oxygen by increasing the heart rate by means of increasing the electrical atrial stimulation (Diseases of the circulatory system / Edited Chazova EI - Moscow, 1997, p.147 and 148). In most cases, this method does not induce significant signs of myocardial ischaemia or for the blockade of II AV extent necessary to impose or ultrahigh frequency stimulation conjugate with the risk of complications.

Known sample and dosed with intravenous administration of dopamine, where myocardial oxygen demand increases, using cardiotonic and hypertensive effect of the drug (Aronov DM Functional tests in cardiology Part I. -. Cardiology, 1995, №3, s.74-82) . Diagnostic value of the sample is constrained by excess dopamine increase in blood pressure, the risk of arrhythmias and poor individual tolerability.

Another approach to the verification of CAD modeling uses the idea of ​​"steal syndrome" pharmacological reduction of blood flow in the affected coronary arteries. For this purpose, the sample used intravenous dipyridamole. However, the probability of induction of myocardial ischemia using this method proved to be, at least not higher than that of a standard sample with a dosed physical load (Diseases of the circulatory system / Edited Chazova EI - Moscow, 1997, p.147 and 148).

A combination of technique and transesophageal atrial electrical stimulation with dipyridamole breakdown. Here, in order to improve the diagnostic sensitivity of measures of influence aimed at the induction of "steal syndrome", complemented by an attempt to increase myocardial oxygen demand by artificially increasing the heart rate (Upnitsky AA Mazaev VP Combined, dipyridamole + TEES atria, electrocardiographic test in the diagnosis of coronary atherosclerosis minimum -. Cardiology 1992, number 9, 10, s.50-53). The advantage of this method is its implementation without the active participation of the patient, which allows survey of disabled patients. At the same time, the use as a component of the sample with the known method dipyridamole preclude accurate evaluation of the functional status of the cardiovascular system. This technique is not widely used in practice.

The aim of the invention to provide a sensitive non-invasive methods of diagnosis and verification of latent coronary insufficiency.

The object is achieved by the fact that according to the method of diagnosis of coronary heart disease by detecting the electrocardiogram during stepwise increasing load on the cycle ergometer bicycle stress test is carried out in conjunction with the regulation of heart rate, imposed by means of transesophageal atrial electrical stimulation in the range of 120-180 beats per minute.

Conducting tests with physical activity, together with the regulation of heart rate allows by artificially increasing the heart rate to reduce power load needed to induce significant clinical and electrocardiographic manifestations of coronary artery disease. This eliminates the most common reason for the ineffectiveness of standard stress tests - physical de-conditioning of the patient.

The process is carried out as follows:

Record 12-lead electrocardiogram, set electrode for transesophageal electrical stimulation of the heart, the patient is placed for veloergometry in a horizontal position. Then give a bicycle stress load that start with power 0 W and that stepwise increases of 25-30 W every 3 minutes load. Since the start of the veloergometry impose stimulation of the atria. Choosing the frequency of stimulation is carried out individually depending on the data previously held ordinary exercise test on a bicycle ergometer or a treadmill. At the same time based on the fact that the increase in heart rate of 15-20 per minute is equivalent to increasing the load capacity of 25-30 watts. In cases when initially selected cardiac pacing rate was insufficient to obtain reliable diagnostic criteria for coronary heart disease, it increases (up to 180 per minute) without interrupting the execution of bicycle exercise load.

Despite the seeming simplicity of the proposed method is not obvious to specialists working in the field of functional diagnostics of diseases of the cardiovascular system.

The sample with exercise stress and heart TEES widely used as an independent method of verification of coronary heart disease. Appropriate to combine their use is not obvious, as is commonly believed that if individual methods do not produce results, it is unlikely that they will give the combined application. It does not take into account a number of circumstances.

There are at least two reasons for this low sensitivity in the diagnosis of heart TEES coronary heart disease.

Firstly, the use TEES associated with exposure to only one, and not the main factor that determines myocardial oxygen demand - heart rate.

Secondly, the significance of heart rate as a factor determining myocardial oxygen demand, is further reduced when the frequency is increasing the rate artificially and in a state of physical rest. In these conditions the blood flow to the heart remains substantially constant and systematic building up of heart pacing rate accompanied by a parallel reduction in the volume of the left ventricular cavity and wall voltage reduction that is equivalent to a decrease in myocardial oxygen demand.

Taking into consideration that provision on the main wall voltage has to flow (at least 40%) oxygen coronary, total myocardial oxygen demand capacity under artificial beat frequency increases slightly. This is the main reason for the low diagnostic value of TEES. If on the background to stimulation peak exercise load that is proposed in this method, the concomitant increase in blood flow to the heart increases the voltage of the left ventricular wall and thus myocardial oxygen demand.

Another reason of non-obviousness of the proposed method lies in the fact that previously ignored the possibility of preventing the development of a functional AV blockade II degree with the help of exercise. And it was premature achievement Wenckebach point, preventing further increase heart rate, is a common cause of inefficiency TEES heart in the diagnosis of CHD. Exercise removes the moderating influence of the vagus on the atrioventricular connection that allows you to bring the pacing rate to the maximum allowable, without resorting to the introduction of atropine and without fear of a functional AV block.

Finally, the vast majority of women are not trained and elderly patients is able to still carry out small and medium power load. And this is usually quite sufficient for CHD verification using the proposed method.

Thanks to the artificial regulation of heart rate frequency of the proposed methodology for the first time allows the researcher to induce myocardial ischemia at much lower power bicycle stress load than with ordinary stress test. In addition, it provides an opportunity to carry out individual selection of safe and unhindered execution mode bicycle stress load without prejudice to its information content.

The method is illustrated by the following examples.

example 1

Patient S., 57 years old. Diagnosis: arterial hypertension, II stage. Cardiac ischemia.

3 diagnostic tests in order to verify angina patient is carried out:

Standard bicycle stress test: at a power of 90 W load is stopped because of the high level of blood pressure 240/115 mm Hg. Art. The maximum heart rate is 114 min -1. On the electrocardiographic signs of ischemia induction, no infarction. The sample could not be brought to the diagnostically relevant criteria.

Increasing heart TEES: initial pacing rate to 90 min-1. At the end of each minute stimulation turned off is recorded on ECG complexes 5-6 spontaneous rhythm, the pacing rate is then increased to 10 min -1. When the stimulation frequency of 140 min -1 developed atrioventricular block II degree. Maximum blood pressure was 145/100 mm Hg. Art. Electrocardiographic signs of myocardial ischemia are absent.

The proposed method: removed 12-lead electrocardiogram, set electrode for transesophageal electrical stimulation of the heart, the patient is placed for veloergometry in the horizontal position. To impose a rhythm with a frequency of 120 min -1, given load power 0 Watt. A minute later, the stimulation is turned off is recorded on an electrocardiogram spontaneous rhythm, there is no change. The frequency of stimulation bring to 140 min -1, giving a load of 30 watts. A minute later, the stimulation is turned off, the ECG is recorded. In leads V 5 -V 6 noted the appearance of the horizontal segment of the value of ST depression of 1 mm. It was decided to increase the pacing rate of 150 min -1, and the load capacity of the previous leave. A minute later the stimulation stopped, blood pressure tests at a height 180/105 mm Hg. Art., on an electrocardiogram in leads V 5 -V 6 registered ST-segment depression magnitude 2.0-2.5 mm, the patient complains of the appearance of unpleasant sensations in the sternum. Bicycle exercise load and electrical stimulation of the heart stopped. After 2 minutes of rest electrocardiogram recovered discomfort behind the breastbone passed 30 seconds after the end of the sample.

Conclusion: only the result of a study on the proposed method clearly confirms the presence of a female patient of moderate stenosis in the coronary arteries of the process.

example 2

Patient S., 46 years old. Diagnosis: coronary heart disease. Myocardial infarction.

In this patient the diagnosis of coronary heart disease is no doubt a history of myocardial infarction. Hospitalized in the cardiology department about the pain in the left side of the chest at rest and during exercise with suspected resistance to anti-anginal therapy. It was necessary to resolve the question of further treatment, possibly surgery. For this purpose it was necessary to establish whether the complaints of chest pain of angina manifestation, and if the load causes the development of transient myocardial ischemia?

Standard bicycle stress test: at a load of 60 watts, heart rate of 107 min-1 and BP = 150/90 mm Hg. Art. the patient complains of pain in the left side of the chest, forcing to stop the load, although the electrocardiogram remained unchanged. This result of the sample is regarded as doubtful.

Increasing heart TEES: stimulation at a frequency of 130 min -1 achieved Wenckebach point, ECG remained unchanged. The result of the study indefinitely.

The proposed method: forced upon stimulation with a frequency of 110 min -1, given bicycle stress load of 30 watts. A minute later recorded on an electrocardiogram spontaneous rhythm, there is no change. Dana load capacity of 60 watts, the rhythm brought to 120 and then to 130 (min -1). A minute later, the ECG recorded on spontaneous rhythm - no changes. Dana load capacity of 90 watts, the pacing rate is brought up to 140 min -1. A minute later, spontaneous ECG rhythm unchanged. Dana load capacity of 120 watts, the pacing rate is brought up to 150 min -1. A minute later recorded on an electrocardiogram spontaneous rhythm - no changes. The patient complains of pain in the legs. Therefore, the load power is reduced from 120 to 100 (W), and the pacing rate is first increased to 160 min -1, and a moment load of 100 W to 180 min -1. A minute later the load on the rhythm of 180 min -1 and a blood pressure level of 210/80 mm Hg. Art. over load. Electrocardiogram at the time of termination exercise test without changes.

Conclusion. None of the three applied methods of the stress test did not cause the patient Sh development electrocardiographic manifestations of transient myocardial ischemia. However, only the proposed method allowed to establish in the patient a high level of coronary flow reserve (maximum heart rate of 180 per minute and systolic blood pressure of 210 mm Hg. Art., Double product 378 USD), which indicates a very low probability of relevant stenoses of the coronary arteries. This means that the patient S., despite the myocardial infarction in the past, in the antianginal therapy is not needed, it is not shown in surgery, complaints of pain in the left chest are not a manifestation of angina pectoris, and a different nature to be installed . It is possible, though unlikely, variant angina.

example 3

Patient A., 44 years old. Diagnosis: coronary heart disease. Angina II FC? Hospitalized for diagnosis and selection of therapy.

Standard bicycle stress test: performed threshold power load is 175 watts. At the height of the sample heart rate was 142 min -1 BP = 182/95 mm Hg. Art. In leads V 5 ST-segment depression of 1 mm. Attack was not angina. The patient refused to continue the load due to physical exhaustion. The sample for occult coronary insufficiency questionable.

Increasing heart TEES: stimulation frequency increased to 165 min -1, achieved Wenckebach point. Changes in the electrocardiogram, and there was no attack of angina. The result regarding the availability of latent coronary insufficiency negative.

The proposed method: the imposed rhythm with a frequency of 100 min -1, given bicycle stress load of 30 watts. After 3 minutes, the load capacity is increased to 60 W, the stimulation of the heart rate up to 140 min -1. Electrocardiogram normal. Dana load capacity of 90 watts, and the pacing rate is brought up to 160 min -1. After 2 minutes of ECG recording in the spontaneous rhythm in lead V 5 recorded segment depression ST = 2 mm. In the absence of angina attack stimulation frequency is increased to 175 min -1, and given 120 watt load. After 1 minutes, there was a pain in the chest, blood pressure = 165/90 mm Hg. Art. The ECG when disconnecting the stimulation of ST segment depression has reached 4 mm. Load aborted. The attack of angina was alone after 25 seconds, ECG recovered in 3.5 minutes of rest.

Conclusion. The result of diagnostic tests for the proposed method allows to confirm the patient A. coronary heart disease and angina at high coronary reserve. The case is the most commonly encountered in diagnostic tests: TEES was insensitive to verify latent coronary insufficiency; bicycle stress test failed to bring to the diagnostically relevant criteria because of the physical exhaustion of the patient. Using the proposed method, thanks to an artificial increase in myocardial oxygen demand by bringing the heart rate to 175 min -1 (recall that at the trial bicycle exercise maximum heart rate was 142 min -1) yielded unambiguous diagnostic criteria for coronary insufficiency with a load capacity 120 watts. Of course, the implementation of bicycle stress load of 120 watts is not as burdensome as the 175-watt load, which was also ineffective at veloergometry.

The proposed method was tested on 32 patients with typical angina II-IV functional class, confirmed by the data of selective coronary angiography in 23 patients. A comparative evaluation of the sensitivity of three methods: a standard bicycle ergometry (BEM), increasing transesophageal electrical stimulation of the heart (TEES), and the proposed method. Each patient had a 3 all diagnostic tests. The result was considered significant sample, subject to ST segment depression in lead V 5 by 2 mm or more. The results are shown in the table.

The table shows that the TEES heart as an independent CHD diagnostic method has the lowest sensitivity in the diagnosis of coronary artery disease (37.4%). Standard bicycle stress test is more informative, its sensitivity was 62.5%. The proposed method of the stress test was the most effective, its sensitivity has exceeded 90%.

It is important to note that when using the proposed method is objective evidence of coronary disease in the average received power at a low load of the heart (43 ± 5 W), and close to normal blood pressure level (138 ± 8 mm Hg. V.). Thus, the proposed technique really allows you to load burdensome, and blood pressure levels be maintained at an acceptable level.

The proposed method of the stress test with the regulation of heart rate by means of transesophageal atrial electrical stimulation significantly increases the sensitivity of the exercise test in the diagnosis of atherosclerotic lesions of the coronary arteries. In this diagnostically significant electrocardiographic criteria are achieved at substantially lower load power and the level of blood pressure as compared, for example, with an ordinary bicycle stress breakdown, which allows virtually eliminate the influence of physical disability and excessive increase in blood pressure in the patient samples for sensitivity in the diagnosis of coronary heart disease.

The proposed method can be used in cardiology departments of hospitals and clinics, laboratories and offices of functional diagnostics of cardiovascular profile. For carrying out the process necessary ECG, ergometer (preferably horizontal) equipment TEES heart of global standards. The research can be done in two specially trained professionals who possess techniques of cardiopulmonary resuscitation.

CLAIM

A method of diagnosing coronary heart disease by recording the electrocardiogram while stepwise increasing load, characterized in that from the start of veloergometry impose heart rate in the range 120-180 beats per minute using transesophageal electrostimulation.

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Publication date 05.04.2007gg