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Coronary artery stenting: indications, technique of conducting
The number of cases of the development of cardiovascular diseases is increasing every year, and with it the statistics of deaths related to heart failure, myocardial infarction and other pathologies of the heart are corrected. All the same it is a question of the organ providing a blood supply of all human body, and failures in its work necessarily affect the condition of other organs and systems. But it happens that the heart itself suffers from a lack of nutrients. And the reason for this can be a narrowing of the vessels that feed the organ. Effective methods to restore the blood supply to the heart, improving the patency of the affected vessel, is not so much, and one of them is coronary stenting.
Pathogenesis of arterial stenosis
Heart is not in vain compared with the pump, because thanks to him, the blood gets the opportunity to move along the vessels. Rhythmic contractions of the heart muscle provide the movement of a physiological fluid that contains the substances necessary for the nourishment and respiration of organs and oxygen, and then everything depends on the state of the vessels.
Blood vessels are hollow organs, bounded by a strong and elastic wall. Normally, inside the arteries, veins and small capillaries, nothing should stop the blood from moving at a heart rate. But the narrowing of the lumen of blood vessels, the formation on their walls of blood clots and cholesterol plaques is an obstacle to the movement of physiological fluid.
Such obstacles inhibit the flow of blood, and this affects the organs for the blood supply which corresponded to the stenotic vessel, because they now do not receive enough nutrients and oxygen, necessary for normal life.
Comparing the human heart with the pump, one can understand that to exercise its important function this body also needs energy. And her heart gives blood, providing food and breathing myocardium. Blood to heart, in turn, feeds the coronary artery network, any changes in the state of which, including stenosis of blood vessels, negatively affect blood supply and cardiac efficiency, provoking myocardial ischemia, heart failure, heart attack.
What are the reasons for narrowing the lumen of the coronary arteries? The most common cause of this condition is considered by doctors to be atherosclerosis of the vessels, i.e. Formation on the inner layer of their walls of cholesterol deposits, which gradually increase, leaving less and less free space for blood.
Other common causes include coronary artery thrombosis (thrombosis) or spasm of the heart vessels due to GI diseases, infectious-allergic pathologies, rheumatoid and syphilitic lesions.
Risk factors for such problems are hypodynamia (sedentary lifestyle), overweight (obesity), bad habits (eg, smoking), age over 50 years, frequent stresses, taking certain medications, hereditary predisposition and national characteristics.
The appearance of foci of abnormal vasoconstriction, in the treatment of which coronary stenting is practiced, can cause some diseases, besides the above. These include metabolic diseases, endocrine diseases, blood and vascular diseases (for example, vasculitis), body intoxication, arterial hypertension, anemia, congenital malformations of the heart and blood vessels (for example, slowly progressive heart disease with predominance of stenosis).
Since our heart is divided into two parts, to the ventricles of which the blood vessels are brought, the doctors distinguish stenosis of the left and right coronary artery trunk. In the first case almost whole organ of the person gets under attack, in fact the left cardiac ventricle provides with a blood the big circle of a circulation. The most common cause of stenosis of the left artery of the heart is atherosclerosis, in which a gradual decrease in the lumen of the vessel occurs.
If it is a question of the cavity of the artery occupying less than 30% of the initial lumen, one speaks of a critical stenosis that is fraught with cardiac arrest or the development of a myocardial infarction.
With stenosis of the right heart artery, the organ itself suffers, first of all, because the blood supply of the sinus node is disturbed, which leads to cardiac rhythm failure.
In some cases, doctors diagnose concurrently narrowing the right and left coronary arteries (so-called tandem stenosis). If the compensatory mechanism worked during unilateral stenosis and the main part of the work was taken by an intact ventricle, then with tandem narrowing this is impossible. To save a person's life in this case will only help surgical treatment, a more gentle option of which is considered stenting.
The concept of treating vasoconstriction by expanding the stenotic site of arteries with a special framework was proposed more than half a century ago by the American radiologist Charles Dotter, but the first successful operation was carried out only a year after his death. But the evidence base for the effectiveness of stenting was obtained only 7 years after the first experiment. Now this method helps save the life of many patients without resorting to a traumatic abdominal operation.
Indications for the procedure
Usually, with heart disease, patients come to the doctor with complaints of pain behind the sternum. If this symptom is aggravated by physical exertion, a specialist may suspect narrowing of the coronary arteries, as a result of which the blood supply of the heart is disturbed. In this case, the smaller the lumen of the vessel, the more often a person will experience discomfort in the chest and the more pronounced will be pain sensations.
The most unpleasant thing is that the appearance of the first signs of stenosis is not evidence of the onset of the disease, which for a long time could have been hidden. Discomfort during physical exertion occurs when the lumen of the vessel becomes significantly less than normal and the myocardium begins to experience oxygen starvation at a time when it requires active work.
Symptoms that are also worth paying attention to are shortness of breath and attacks of angina (symptomatic complex, which includes: rapid heartbeat, chest pain, hyperhidrosis, nausea, sensation of lack of oxygen, dizziness). All these signs may indicate coronary artery stenosis
It must be said that this pathology, regardless of the causes that cause it, does not have a very good prognosis. If we are talking about coronary artery atherosclerosis, then conservative treatment with statins that correct blood cholesterol level and drugs that reduce myocardial oxygen demand is prescribed only at the initial stages of the disease, when a person actually does not complain about anything. When there are symptoms of stenosis, traditional treatment can not produce results, and then doctors resort to surgical intervention.
A strong constriction of the vessels causes the onset of angina attacks, and the more the vessels are affected, the more obvious the disease is. Attacks of angina usually can be stopped with drugs, but if improvement does not occur, then there is no other way out, how to resort to coronary bypass or less traumatic stenting.
Coronary bypass surgery is the creation of a bypass for the flow of blood, if the blood vessel narrows so much that it can no longer cover the needs of the myocardium. To perform such an operation, a sternum opening is required and all manipulations are performed on the open heart, which is considered very dangerous.
At the same time, if a safer, less invasive operation called stenting, which does not require large incisions and a long recovery period. It is not surprising that the latter doctors have recently resorted much more often.
In this case, stenting can be successfully performed both with a single stenosis, and with narrowing of several arteries.
With a narrowing of the vessels by more than 70%, or a complete overlap of blood flow (occlusion), the risk of developing acute myocardial infarction is high. If the symptoms indicate a pre-infarcted condition, and a patient's examination indicates acute tissue hypoxia associated with a violation of blood flow in the coronary vessels, the doctor can refer the patient to an operation to restore the patency of the arteries, one of which is arterial stenting.
The operation of coronary stenting can also be performed during the treatment of a heart attack or in the post-infarction period, when an emergency is given to a person, and the activity of the heart is restored, i. The patient's condition can be called stable.
Stenting after a heart attack is prescribed in the first hours after the attack (maximum 6 hours), otherwise such an operation will not be of particular benefit. It is best, if no more than 2 hours pass from the appearance of the first symptoms of the infarction before the beginning of the operative intervention. Such treatment helps to prevent the attack itself and reduce the area of ischemic necrosis of the myocardial tissue, which will allow for early recovery and reduce the risk of recurrence of the disease.
Restoration of vascular patency within 2-6 hours after a heart attack will only prevent the recurrence. But this is also important, because every subsequent attack is more severe and at any time can put an end to the patient's life. In addition, aortocoronary stenting helps to restore normal breathing and nutrition of the heart muscle, which gives it the strength to recover more quickly after damage, since normal blood supply to tissues speeds up their regeneration.
The operation of stenting vessels in atherosclerosis can be performed both as prevention of heart failure and myocardial ischemia, and for therapeutic purposes. So, in chronic forms of IHD, when the vessels are half blocked by cholesterol deposits, stenting can help preserve healthy heart tissue and prolong the life of the patient.
Coronary stenting is prescribed in the case of frequent recurrences of angina at the slightest physical exertion, what to say about the violation of the patency of the coronary vessels. But you need to understand that severe cases of coronary heart disease (unstable or decompensated stress angina) can not be cured in this way. The operation only facilitates the patient's condition and improves the prognosis of the disease.
Preparation
Any operation, even the least traumatic, is considered a serious interference in the functioning of the body, and what can we say about heart surgery, which are considered potentially dangerous for human life. It is clear that a cardiac surgeon should have good reasons for carrying out such manipulations. One desire of the patient is not enough.
At first the patient should be examined by a cardiologist. After a physical examination, examination of anamnesis and patient complaints, auscultation (listening) of the patient, measurement of heart rate and blood pressure in case of suspected coronary artery stenosis, the doctor may prescribe the following studies:
- general and biochemical analysis of blood,
- ECG and EchoCG-study of heart activity by recording the electrical impulses passing through it (at rest and with load),
- radiography or ultrasound of the chest, which allow you to fix the location of the heart and blood vessels, their size and shape changes,
But the most informative in this case is the study, called coronary angiography (coronary angiography), implying the study of the lumen of blood vessels that feed the heart myocardium, with the determination of the severity of coronary heart disease. It is this diagnostic study that makes it possible to evaluate the appropriateness of performing heart surgery and choose the appropriate technique, as well as to determine the areas on which the stents will be installed.
If the patient's condition allows the doctor to prescribe a planned operation and tells how to properly prepare for it. Preparing for an operation involves:
- Refusal to take certain medications:
- non-steroidal anti-inflammatory drugs and anticoagulants (warfarin, etc.) that affect blood coagulability, it is undesirable to take within a week before surgery (or at least a couple of days),
- for a couple of days before the operation you will need to refuse to take hypoglycemic medications or change the time of their intake (these questions should be discussed with the endocrinologist),
- with ischemia of the heart and heart failure, patients should regularly take aspirin-based medications, they do not need to change their regimen. Moreover, 3 days before surgery, a patient may be prescribed antithrombotic agents (eg, clopidogrel). Less often it is administered in high doses directly in the preoperative, which is fraught with problems from the stomach.
- On the eve of the operation, eating is not prohibited, but it should be a light supper. After 12 o'clock in the morning, a complete refusal to eat and drink is required. The operation is performed on an empty stomach.
- Before the procedure of coronary stenting, it is advisable to take a shower with the use of antibacterial agents and shave off the vegetation in the groin area (usually the stent is inserted on the femoral artery in the pelvic area, because access through the groin is considered more reliable and safe than the puncture of the large artery in the arm).
In severe cases with the development of acute coronary insufficiency and myocardial infarction, when there is no time for a full examination and preparation for the operation, the patient simply takes necessary tests and proceeds to an urgent operation, during which the cardiac surgeon decides to stent or shunt the vessels.
Technique of the coronary artery stenting
The most important diagnostic method, which allows not only to reveal the fact of stenosis, but also to determine the exact size and location of the affected area, is coronography. This is a variant of X-ray examination of blood vessels with the help of contrast, which allows visualizing any changes in the structure of the arteries of the heart. The pictures are taken from different angles and archived on the computer screen to make it easier for the doctor to navigate during the operation, because the human eye is not able to see what is happening inside the body.
Coronary stenting, unlike shunting, is performed without large incisions of the body tissues and implies percutaneous insertion of a thin tube, through which all the necessary instruments are delivered to the surgical site (as in endoscopy). It turns out that the cardiac surgeon works blindly and can not see the result of his work. That is why such operations are carried out under the control of radiography or ultrasound.
Ideally, in streaming operations, a diagnostic study should be conducted on the eve of the procedure, but in severe cases requiring urgent care, coronagraphy and coronary stenting can be performed simultaneously. Thus, doctors do not have to spend precious time on diagnostics and at the same time they get the opportunity to actively monitor the progress of the operation.
The essence of the operation of coronary stenting is to expand the stenotic vessel with a special flexible metal frame resembling a mesh. The stent is inserted in the folded form, but at the site of narrowing the artery expands and then remains in the straightened inside the vessel, preventing further narrowing of the lumen.
For the introduction of a stent, it is required to make a puncture in a large artery passing in the groin or arm region. Anesthesia is carried out by means of local anesthesia, but sedatives can also be added (the patient remains conscious and can see the manipulations of the surgeon, so this does not fit) and anesthetics. First, the puncture site is treated with an antiseptic, then an anesthetic is injected. Usually use novocaine or lidocaine.
During the operation, the cardiac function is continuously monitored by ECG, for which the electrodes are placed on the upper and lower limbs of the patient.
Most often a puncture is done in the femoral artery, which is more convenient and avoids various complications . At the puncture site, a plastic tube, called an introducer, is introduced into the artery, which will be a kind of tunnel for the delivery of instruments to the site of the vessel's lesion. Inside the introducer insert another flexible tube (catheter), which is advanced to the site of stenosis, and already along this tube is fed a folded stent.
When carrying out coronagraphography and stenting simultaneously before the stent is delivered to the catheter, iodine preparations are administered, which are used as a contrast captured by X-rays. The information is displayed on the computer monitor. This allows you to control the location of the catheter and bring it exactly to the site of vessel stenosis.
After the catheter is installed, a stent is inserted into it. Inside the stent is pre-placed a blown out special balloon, used for angioplasty. Even before the beginning of development in the field of stenting, the expansion of stenotic vessels was carried out by means of balloon angioplasty, when a balloon was introduced into the vessel, and then by patency it was restored the patency of the artery. True, such an operation was effective usually within six months, after which restenosis was diagnosed, i.e. Repeated narrowing of the lumen of the vessel.
Coronary angioplasty with stenting can reduce the risk of such a complication, because the necessary in this case, repeated operations a person may not survive. The balloon is placed in the stent. Moving it to the place of narrowing of the vessel, the balloon is inflated, and the stent, which after removal of the balloon and tubes remains inside the artery, does not allow it to narrow.
During the procedure the patient can communicate with the doctor, follow his instructions and report unpleasant sensations. Usually discomfort in the chest appears during the approach to the stenotic area, which is a variant of the norm. When the balloon is inflated and the stent is pressed into the vessel walls, the patient may experience pain associated with a blood flow disorder (the same angina attack). A little to reduce the unpleasant sensations possible by holding your breath, which the doctor can ask for.
Currently, doctors successfully perform stenting of the left and right coronary arteries, as well as treatment of tandems and multiple stenoses. The effectiveness of such operations is much higher than in balloon angioplasty or aortocoronary shunting. The least complication occurs when using drug-eluting stents.
Contraindications to the procedure
Coronary stenting is an operation that helps to save a person's life under threatening pathologies. And since it is no longer possible to be worse than death, there are no absolute contraindications to the procedure. Especially if stenting is indicated with myocardial infarction. Serious problems can arise only in the event that there is no possibility to conduct antiplatelet treatment, because the risk of blood clots after the operation increases.
The procedure has some relative contraindications, which are risk factors for the development of complications after or during surgery. At the same time, some violations can be temporary, and after successful treatment the operation becomes possible. Such violations include:
- febrile state, high body temperature,
- infectious diseases in the active stage,
- gastrointestinal bleeding,
- acute form of stroke,
- a severe neuropsychic state, in which the patient can not contact the doctor,
- poisoning with cardiac glycosides,
- severe anemia, etc.
In this case, it is recommended to postpone the operation date as much as possible until the patient's condition stabilizes. But there is another part of the diseases that can affect the outcome of the operation:
- severe acute and chronic renal failure,
- insufficiency of respiratory function,
- the pathology of the blood, in which its clotting is impaired,
- intolerance of contrast, used for coronography,
- arterial hypertension, not amenable to correction,
- serious violations of electrolyte metabolism,
- heart failure in the stage of decompensation,
- diabetes,
- pulmonary edema,
- Concomitant disease, which may have complications after coronary examination,
- inflammation of the inner membrane of the heart and its valves (endocarditis).
In these cases, the decision to perform the operation is decided by the attending physician, who makes certain adjustments to the course of the procedure taking into account possible complications (for example, the study of vessels is carried out without contrast or other substances with similar properties are used instead of iodine).
Another obstacle to the operation is the unwillingness of the patient to undergo further treatment, if required. Still, the stenting of the heart vessels is a serious intervention, requiring the surgeon to expend energy, nerves, forces, so if the patient is not currently at risk of death, and he does not want to care about his future, should the doctor experience it? After all at the same time the surgeon can render help to the patient who seriously needs it.
Care after the procedure
After the end of the operation, which usually takes about 1-2 hours, the patient is transferred to the intensive care unit. In this case, the introducer remains for some time in the artery. Within a few hours after the procedure, the patient is constantly monitored for blood, blood pressure, heart function, monitoring the place of insertion of the catheter. If everything is normal, the tube is removed, and a pressure bandage is applied to the puncture site. No stitches can be done, a small wound usually lasts for several days.
Take the food and water the patient can immediately after the end of the operation. This will not affect his condition in any way. Carrying out coronagraphography with coronary stenting involves the introduction of a contrast agent. To quickly remove it from the body it is recommended to use mineral water in a volume of not less than 1 liter.
For the introduction of a stent, which will subsequently maintain a sufficient lumen of the vessel, it is not necessary to open the sternum and large incisions on the body, which heal for a long time, limiting the physical activity of the patient. A small puncture does not impose such restrictions, and yet on the day of surgery the patient can not bend his leg.
The next day, after the patient is transferred to a regular ward, he will be allowed to walk and serve himself. But from active physical activity, which provides for a greater load on legs and vessels, for some time it will be necessary to abstain.
Usually after a couple of days with normal health the patient is discharged home. Restoration of the body in everyone happens in different ways. Someone is quite a few days old, and the lives of others are established 3-4 months later. During this period, you should avoid fatigue, hypothermia or overheating of the body, adhere to a balanced diet (preferably fractional), try to worry less and avoid stressful situations.
If before the operation the patient was prescribed some drugs, the doctor can cancel this appointment, leaving only means that reduce the viscosity of blood and prevent the formation of blood clots. Further, the patient will have regular visits to the cardiologist with the necessary studies: a cardiogram, a stress test, the delivery of tests, etc. How will the recovery of the body after the operation , largely depends on the patient's implementation of the doctor's recommendations.