Possible consequences of coronary artery bypass surgery

Coronary artery bypass grafting (CABG) is one of the most complex operations in cardiovascular surgery, requiring a complex rehabilitation activities aimed at preventing complications, adapting the patient and his speedy recovery.

Let's take a closer look at why rehabilitation is important after CABG surgery?

Bypass surgery is performed when a vessel or duct does not function functionally in the body. This method creates an additional path bypassing the affected area using shunts. Most often they talk about bypassing blood vessels, but the operation can be performed on the ducts gastrointestinal tract and (very rarely) in the ventricular system of the brain.

During blood vessel bypass, the artery's patency for blood flow is restored. The operation should be distinguished from vascular stenting - in this method, the vessel is restored by implanting a tubular structure into its walls.

Vascular bypass surgery

When is bypass surgery performed?

This surgical intervention is indicated for the following conditions:

1. myocardial infarction;
2. coronary insufficiency;
3. cardiac ischemia;
4. refractory angina;
5. unstable angina;
6. stenosis of the left main coronary artery;
7. as a concomitant operation during surgical interventions on heart valves and coronary arteries.

Coronary artery bypass grafting is prescribed for coronary insufficiency, which is the basis of coronary heart disease. The condition is characterized by the fact that the coronary vessels (feeding the heart muscle) are affected by atherosclerosis. Atherosclerotic plaques are deposited on the inner wall of the artery; as they increase, they close the lumen of the bloodstream, which disrupts the nutrition of a certain area of ​​the myocardium. In the future, this can lead to necrosis - tissue death with complete disruption of functioning.

Coronary insufficiency leads to ischemic heart disease. The pathology represents a disruption of the activity of the heart muscle due to a sharp decrease in the supply of oxygen to blood cells. Coronary heart disease can occur in the acute phase (myocardial infarction) or in the chronic phase (angina pectoris attacks acute pain behind the sternum or in the region of the heart).

What is the essence of the operation?

Before the intervention, the patient is prescribed coronography (analysis of the state of myocardial vessels), complex ultrasound examination and angiography (X-ray scanning of arteries and veins) in order to take into account the individual characteristics of the person in the upcoming operation.

Coronary is performed under general anesthesia. The material for the shunt is usually chosen from the area of ​​the saphenous veins of the thigh, since removal of part of this vessel does not affect the functioning lower limbs. The veins of the thigh have a large diameter and are less susceptible to atherosclerotic changes. The second option is a section of the radial artery of a person’s non-dominant arm. In surgical practice, artificial shunts made of synthetic materials are also used.

Carrying out the operation

The operation is performed on an open heart, sometimes on a beating one, using an artificial circulation system, and lasts 3-4 hours. The surgeon decides how to perform the operation. Depends on the degree of vascular damage and possible aggravating factors (need to replace valves, aneurysm).

Why is rehabilitation so important after CABG surgery?

There are several important reasons for this:

• Heart bypass surgery is a traumatic operation, performed on patients (most often elderly) with poor health and therefore recovery is difficult.
• After coronary bypass surgery, complications are possible, most often - sticking of the shunts. Almost 90% of shunts stick together within 8-10 years and require repeated surgery.
• The presence of comorbidities in older people may reduce the effectiveness of recovery.

Recovery after surgery is an important stage

Rehabilitation after coronary artery bypass surgery

The leading principles of recovery in the postoperative period are phasing and continuity.

First stage

Lasts 10-14 days from the date of surgery.

At first, the patient is on a ventilator. When the patient begins to breathe on his own, the supervising physician must ensure that there is no congestion left in the lungs.

The next step is dressing and treating wounds on the arm or thigh, depending on where the material for the shunt was taken from, and wounds on the sternum. In open heart surgery, an incision is made in the breastbone, which is then held together with metal sutures. The sternum is a hard-to-heal bone, full recovery may take up to 6 months. To ensure rest and strengthen the bones, special medical bandages (corsets) are used. Postoperative bandage is a special belt made of elastic material with ties and fasteners. Protects the seams from divergence, fixes the chest, minimizes pain; By tightly grasping the intercostal muscles, the corset reduces the physiological load on them and fixes the organs of the mediastinum and chest.

Bandage is a prerequisite after surgery with sternum incision

There are men's and women's corsets. When selecting a bandage, it is necessary to take into account the individual characteristics of the patient. Select the appropriate width to postoperative suture was completely covered, and the girth of the corset was equal to the girth of the patient's chest. The material of the bandage should be natural, breathable, moisture-wicking and hypoallergenic. The corset is put on in a supine position, over the patient’s clothes. The chest bandage must be worn for up to 4-6 months, in some cases longer.

Drug therapy after CABG initial stage is aimed at preventing the consequences of anemia due to blood loss and stimulating cardiac activity.

The following groups of drugs are used:

• aspirin;
• anaprilin, metoprolol, bisoprolol, carvedilol, nadolol - reduce heart rate and blood pressure, protecting the heart weakened after surgery from the stress of adrenaline;
• captopril, enalapril, ramipril, fosinopril - reduce heart pressure by dilating blood vessels, act similarly to vasodilators;
• statins (simvastatin, lovastatin, atorvastatin, rosuvastatin) - inhibit the formation of cholesterol and have become indispensable aids in atherosclerosis, which is a prerequisite for the development of coronary heart disease.

Particularly important physical rehabilitation sick. In the first days after the operation, the patient is allowed to get out of bed, move around the hospital room, and do basic exercises for the arms and legs. After a few days, the patient can take walks along the corridor, accompanied by relatives or a nurse. Then light gymnastics is prescribed.

Walking gradually increases, after a week the patient walks about 100 meters. The person’s condition must be noted: heart rate and blood pressure are measured at rest, during exercise and after rest. Physical activity must be alternated with periods of rest.

Moderate walking on stairs is helpful. After this type of physical education, functional tests are carried out and the patient’s well-being is monitored.

Therapy is accompanied laboratory tests:

• regular electrocardiograms;
• daily measurements blood pressure and heart rate;
• control of components of the blood-coagulation system, bleeding time and coagulation;
• general blood analysis;
• general urine analysis.

Second phase

The patient independently carries out a complex of physical therapy.

The procedures include therapeutic massage, laser therapy, magnetic therapy, the action of therapeutic electric currents on the heart area and postoperative scars; electrophoresis.

Monitoring the patient’s condition, conducting tests, clinical tests, wearing a bandage - as in the first period after heart surgery.

Third stage

The third stage of rehabilitation begins 21-24 days after surgery.

The patient is transferred to exercise equipment to perform cardio training. Physical activity gradually increases. The choice of exercise regimen and the degree of increase in intensity depends on the person’s fitness level, how recovery proceeds, and the condition of postoperative scars.

Therapeutic massage continues, laser therapy, electrotherapy, and electrophoresis of medications are used.

The course lasts 15-20 days.

Rehabilitation on exercise bikes after bypass surgery

Fourth stage

The fourth stage of rehabilitation takes place within 1-2 months from the moment surgical intervention.

It is recommended to carry out this stage of recovery in sanatoriums, health resorts and other resort and preventive institutions. The sanatorium regime is aimed at speedy recovery of patients, treatment of concomitant diseases, and improvement of the overall quality of life. Walking in the fresh air and a specially selected diet help improve the condition and help you quickly return to your previous active life.

Physical therapy and cardio training continue on specially selected equipment, and individual sets of exercises are being developed for patients so that those recovering can do them at home.

Specialists from medical institutions carry out constant monitoring of the progress of recovery, measures to prevent complications and the development of atherosclerosis, restore the functional activity of the heart and its compensatory mechanisms, consolidate the results of the treatment, prepare patients for everyday life and their former life (psychological, social and labor rehabilitation).

Diet is important: nitrogen-rich foods are excluded from the diet of people who have undergone CABG surgery; meat, poultry and fish are steamed, limit consumption simple carbohydrates(flour and confectionery, sugar, honey). It is recommended to eat more fresh fruits and vegetables, especially those containing potassium. Eggs, milk and fermented milk products are healthy. And it is especially important to exclude foods rich in cholesterol.

Rehabilitation after cardiac bypass surgery is a long and labor-intensive process, but step-by-step implementation of recommendations and competent assistance from specialists returns almost all patients after CABG to active life.

It is carried out for medical reasons for the treatment of coronary artery disease and improving the performance of the heart muscle. An intervention is prescribed for poor blood supply to the heart, when the operating surgeon creates a bypass arterial pathway (shunt) instead of a natural analogue clogged with atherosclerotic plaques. Since the operation requires a serious approach and significant tissue damage, rehabilitation after CABG takes a long time. Nowadays, the technologies for performing coronary artery bypass surgery have been enriched, and surgical methods have been replenished with new practices. This made it possible to significantly shorten the recovery period. After CABG surgery performed in the clinic, rehabilitation requires a short period of time. If the patient feels well after the intervention, activity is allowed from the first days. On the second day, with the help of doctors, the patient begins to sit up in bed, and the ability to move, breathe and eat independently returns to him.

To get a consultation

Rehabilitation after CABG in the intensive care unit

Major heart surgery eliminates a number of specific problems that prevent a person from living a normal life. But after CABG, the patient faces a period of recovery, when it is necessary to be patient in order to regain the lost shape. The rehabilitation period for each person is unique, much depends on the patient’s age, general health, the presence of concomitant diseases, and the individual characteristics of the body. Rehabilitation after coronary artery bypass surgery begins with the department intensive care, after which the patient remains in the hospital for three to five days. After discharge, it will take another six weeks of recovery at home to get back to normal shape. At this time, you must strictly follow the rules and regulations recommended by your doctor so as not to provoke complications.

Intensive care unit - a specially equipped box with vital monitoring equipment important organs. Medical staff underwent specialized training to provide assistance to seriously ill people who end up here after complex operations. Anesthesia continues to affect the body for two to four hours after surgery. During this period, breathing is supported by a tube that provides artificial ventilation lungs. The equipment creates air movement into the lungs and back, which forms a full-fledged respiratory process without the participation of the patient. The equipment provides deep breaths, allowing you to breathe without complications and delays, which can have a detrimental effect on the life of the operated person.

Once the condition after CABG has stabilized and the patient can breathe on his own, the tube is disconnected. Most patients, after anesthesia, try to remove the interfering tube from their mouth. This is counteracted by special clamps on the hands. When the doctor is convinced that the patient soberly assesses the situation, the artificial ventilation equipment is turned off.

In the intensive care unit of the Assuta clinic, short visits with relatives and loved ones are allowed. The doctor agrees to allow visitors a few hours after the intervention. At this time, the tube is still in the mouth and interferes with speaking. The only thing the patient can do is communicate with his eyes and small movements of his head. Equipment and other life-support systems are turned off the day after the operation. These include:

• A tube inserted through the nose into the stomach - the action is aimed at eliminating the feeling of nausea due to bloating. Painful sensations the tube does not deliver. Discomfort manifests itself in the sensation of rhinitis, when fluid seems to be running from the nose.
• A catheter in the bladder to monitor urine levels. When the catheter is connected, the patient experiences a normal urge to urinate, but urine is discharged through the tube. When it is removed, the patient goes to the toilet independently. In this case, a burning sensation is felt during urination for a short period.
• Drainage - tubes that remove accumulated fluid from the chest cavity, which prevents its accumulation and the development of complications.
• Arterial system - controls blood pressure levels. With its help, doctors also draw blood.
• Droppers for supplying fluids and medications that nourish the body.

On the second day, recovery after CABG on the heart with normal indications includes the activation of the patient in the rehabilitation processes. Doctors allow you to take clear liquids the day after surgery. If the body is ready to accept solid food, then the products are carefully included in the diet. The broths are followed by puree-like gruels, approved by the cardiologist. If the patient’s strength allows him to sit down, doctors agree to gently bring the body into a semi-sitting position on the bed, leaning on a pillow or with the help of nurses.

Practicing breathing exercises which the patient was taught before surgery. The patient begins to breathe independently and cough in order to remove the fluid accumulating in the lungs and prevent it from stagnating, which provokes complications. If the patient feels normal, he is transferred to a regular ward, where doctors tirelessly monitor him, monitoring his condition. For convenience, the patient after coronary artery bypass surgery should carry a portable device with which the heart rate is monitored. The telemetry monitor displays data that is easy for the patient and the doctors monitoring his condition to monitor.

The next day the patient needs to start eating solid food. It is recommended to walk short distances. But in total, fluid intake is still limited so as not to provoke swelling. Up to six to eight cups are allowed per day, after meals you need to sit in a chair at rest. The patient spends three to five days in the hospital, each time increasing the load in order to quickly return to the usual rhythm of life. If coronary artery bypass surgery is behind you, rehabilitation in a hospital setting is completed, and if the patient feels normal, the patient is discharged home, where a strict regimen and periodic monitoring by the attending physician are still recommended.

Ask a question to the doctor

Rehabilitation after CABG at home

Recovery takes on average six weeks. Depending on the individual characteristics of the patient’s body and other third-party factors, the period can range from four to twelve weeks. Much depends on strictly following the recommendations of doctors. Upon discharge from the Assuta clinic, the patient is handed over to an accompanying person, with whom the doctor first talks about caring for the patient. Personnel from the rehabilitation center can also accompany the patient if an appropriate agreement has been drawn up. Specially trained nurse provides care, adheres to the schedule for taking medications and attending specialized procedures.

Strict control requires a chest incision, which must be monitored in order to timely record symptoms of infection when they appear. You should be alert to a feverish state, rapid heartbeat, increased bleeding from the wound, intense pain that does not go away after taking painkillers. Previously, the cardiologist talks with the patient’s companion, warns him about crisis moments, which he must immediately report to the attending physician.

It is important to take care of the incision in the chest area and the wound where the vessel was removed for bypass surgery. The incision can be extensive or minimal if the bypass is performed in a minimally invasive way using punctures in the chest. CABG rehabilitation includes the following recommendations for incision care:

1. You cannot swim, visit the pool, or take a hot shower for the first few weeks. Let's take a warm shower, but avoid direct contact of the jet under pressure into the wound area. The incision should be treated delicately with mild soap and water, and then blot the wound with a dry, moisture-absorbing towel. Permission to take water procedures is given by a doctor.
2. Do not use lotions, oils, or powders when treating wounds. The doctor prescribes an antiseptic.
3. Avoid sudden movements and excessive loads that can lead to separation of the edges of the wound. It is necessary to use a bandage after CABG to prevent careless movements from worsening the incision.
4. Itching, mild burning, numbness or tingling sensations are acceptable during recovery.
5. A special silicone-based gel will improve the appearance of the scar and give it a cosmetic effect. You cannot purchase the product yourself; permission to use is issued by a doctor.
6. It is worth consulting with a cardiologist about the use of sunscreens and other products that protect the scar from exposure to intense sunlight during the summer season.

It is important to follow the recommendations after CABG for the leg where the vein was removed so that the wound heals faster and does not leave a mark. Will be required compression stockings, washing the wound with warm water and soap. The legs should be kept elevated more often to reduce swelling. Wounds in diabetic patients are especially difficult to heal. Doctors' recommendations should be carefully followed to shorten the recovery period.

If you have any doubts about taking medications, you should not stop treatment after CABG on your own. It is important to discuss this issue with your doctor, otherwise there is a high risk of complications. The cardiologist will determine the period after which it will be possible to return to to the usual way life. For people with intellectual work, the rehabilitation period is shorter than for representatives of professions that require the use of physical force.

Cardiac rehabilitation after CABG

Recovery from bypass surgery is similar to recovery from any heart surgery. The attending physician draws up an individual exercise program to improve health. Training begins in the hospital and continues at home. The duration of the program is several months. The patient’s condition is strictly monitored by doctors: a cardiologist, a therapist, a nutritionist, and a psychologist.

When breathing exercises after CABG are mastered, physical activity increases every day. Walking, physical therapy, and an exercise bike are practiced. Applicable special diet, which excludes harmful products. It has been scientifically proven that undergoing cardiac rehabilitation gives positive results. In most cases, strict adherence to the program avoids the risks of complications and prolongs the life of patients who have undergone a complex procedure.

It is important to remember that bypass surgery corrects blockages in the blood vessels that supply the heart muscle. However, surgery does not treat the underlying heart disease. For long-term results, it is necessary to follow a recovery program and combat risk factors for coronary heart disease. Not all of them can be corrected. The genetic factor and heredity will remain unchanged. But the patient can reduce the risk by changing his diet, developing a competent approach to physical activity, and eliminating bad habits from his life.

It is necessary to exclude fatty foods, sweets, fried and smoked foods, and large amounts of salt from the diet. It is necessary to give up cigarettes and alcohol-containing drinks. After the operation performed at the Assuta clinic, you will receive carefully developed instructions on how to recovery period in the first months of rehabilitation, as well as a long-term program of restoration and health support. By following individual indications, you can extend your life by decades, restoring the ability to enjoy every day.

Send a request

Already for a long time the leading cause of mortality is occupied by cardiovascular diseases. Poor nutrition, sedentary lifestyle, bad habits - all this negatively affects the health of the heart and blood vessels. Cases of strokes and heart attacks have become not uncommon among young people; elevated cholesterol levels, and therefore atherosclerotic vascular damage, are found in almost every second person. In this regard, cardiac surgeons have a lot of work.

Perhaps the most common is coronary artery bypass surgery. Its essence is to restore blood supply to the heart muscle, bypassing the affected vessels, and the saphenous vein of the thigh or artery are used for this purpose chest wall and shoulder. Such an operation can significantly improve the patient’s well-being and significantly prolong his life.

Any operation, especially on the heart, has certain difficulties, both in the technique of execution and in the prevention and treatment of complications, and coronary artery bypass grafting is no exception. The operation, although it has been carried out for a long time and on a large scale, is quite difficult and complications after it, unfortunately, are not such a rare occurrence.

The highest percentage of complications is in elderly patients, with many concomitant pathology. They can be divided into early ones, which arose during the perioperative period (immediately during or within a few days after surgery) and late ones, which appeared during the rehabilitation period. Postoperative complications can be divided into two categories: from the side of the heart and blood vessels and from the side of the surgical wound.

Complications of the heart and blood vessels

Myocardial infarction during the perioperative period - severe complication, which often becomes the reason fatal outcome. Women are more often affected. This is due to the fact that representatives of the fair sex come to the surgeon’s table with cardiac pathology approximately 10 years later than men, due to hormonal characteristics, and the age factor plays an important role here.

Stroke occurs due to microthrombosis of blood vessels during surgery.

Atrial fibrillation is a fairly common complication. This is a condition when the full contraction of the ventricles is replaced by their frequent fluttering movements, as a result of which hemodynamics are sharply disrupted, which increases the risk of thrombosis. To prevent this condition, patients are prescribed b-blockers, both preoperatively and during postoperative period.

Pericarditis- inflammation of the serous membrane of the heart. Occurs due to the addition of a secondary infection, more often in elderly, weakened patients.

Bleeding due to a blood clotting disorder. From 2-5% of patients who have undergone coronary artery bypass surgery undergo re-operation due to bleeding.

Read about the consequences of cardiac bypass surgery of a specific and nonspecific nature in the corresponding publication.

Complications from the postoperative suture

Mediastinitis and suture failure occur for the same reason as pericarditis, in approximately 1% of those operated on. More often, such complications occur in people suffering from diabetes.

Other complications are: suppuration of the surgical suture, incomplete fusion of the sternum, formation of a keloid scar .

Mention should also be made of complications of a neurological nature, such as encephalopathy, ophthalmological disorders, damage to the peripheral nervous system etc.

Despite all these risks, the number of lives saved and grateful patients suffered disproportionately from complications.

Prevention

It must be remembered that coronary artery bypass surgery does not get rid of the main problem, does not cure atherosclerosis, but only gives a second chance to think about your lifestyle, draw the right conclusions and start new life after bypass surgery.

Continuing to smoke, eat fast food and other harmful products, you will very quickly damage the implants and waste the chance given to you. Read more about diet after heart bypass surgery.

After discharge from the hospital, the doctor will definitely give you a long list of recommendations, do not neglect them, follow all the doctor’s instructions and enjoy the gift of life!

After CABG surgery: complications and possible consequences

After bypass the condition of most patients improves in the first month, which allows them to return to normal life. But any operation, including coronary artery bypass surgery. can lead to certain complications, especially in a weakened body. The most serious complication can be considered the occurrence of heart attacks after surgery (in 5-7% of patients) and the associated likelihood of death; in some patients, bleeding may occur, which will require additional diagnostic surgery. The likelihood of complications and death is increased in elderly patients, patients with chronic diseases lungs, diabetes, renal failure and weak contraction of the heart muscle.

The nature of complications and their likelihood are different for men and women of different ages. Women are characterized by the development of coronary heart disease at a later age than men, due to a different hormonal background, respectively, and according to statistics, CABG surgery is performed in patients 7-10 years older than in men. But at the same time, the risk of complications increases precisely due to advanced age. In cases where patients have bad habits (smoking), when lipid spectrum or have diabetes, the likelihood of developing coronary artery disease at a young age and the likelihood of undergoing heart bypass surgery increases. In these cases, concomitant diseases can also lead to postoperative complications.

Complications after CABG

The main goal of CABG surgery is to qualitatively change the patient’s life, improve his condition, and reduce the risks of complications. For this purpose, the postoperative period is divided into stages of intensive care in the first days after CABG surgery (up to 5 days) and the subsequent rehabilitation stage (the first weeks after surgery, until the patient is discharged).

The state of shunts and the native coronary bed at various times after coronary artery bypass surgery

Section contains:

• Condition of mammary coronary shunts at various times after surgery
• Changes in autovenous shunts at various times after surgery
• The influence of shunt patency on the state of the native coronary bed

Condition of mammary coronary bypass grafts at various times after coronary artery bypass surgery

Thus, as the analysis of the studies shows, the use of stenting in the endovascular treatment of multivascular lesions can reduce the incidence of acute complications in the hospital period. In contrast to balloon angioplasty, multivessel stenting, according to published randomized trials, is not associated with a higher incidence of in-hospital complications compared to coronary artery bypass graft surgery.

However, in the long term after treatment, relapse of angina, according to the results of most studies, is more often observed after endovascular implantation of stents than after bypass surgery. In the largest BARI study, angina recurrence in the long-term period after angioplasty was 54%; the use of stents in the Dynamic Registry (continuation of the study) reduced the rate of angina recurrence to 21%. However, this indicator was still significantly different from the operated patients - 8% (p< 0.001).

The paucity of information accumulated to date on the results of stenting of multivascular lesions determines the relevance of studying this problem. To date, two large studies have been published in the foreign literature to study the comparative effectiveness of stenting and coronary bypass surgery in patients with multivessel disease. The disadvantages of the work carried out include the lack of a comparative analysis of the dynamics of tolerance to physical activity after treatment, and the need for taking antianginal drugs at different times after the intervention. To date, there are no studies in the domestic literature on the comparative effectiveness of endovascular and surgical methods of treating multivascular lesions. In our opinion, in addition to studying the clinical results of endovascular and surgical interventions, an urgent problem is to study the cost-effectiveness of treatment: analysis of the comparative cost of both methods and the length of the patient’s hospital stay.

The state of shunts and the native coronary bed at various times after coronary artery bypass surgery.

Condition of mammary coronary bypass grafts at various times after coronary artery bypass surgery

Today the problem optimal choice autografts still remain relevant in cardiovascular surgery. The limited viability of shunts can lead to the resumption of the clinical picture of coronary heart disease in operated patients. Secondary intervention, whether repeat coronary artery bypass surgery or endovascular angioplasty, generally carries an increased risk compared with the primary revascularization procedure. Therefore, determining preoperative risk factors for damage to coronary artery bypass grafts remains an important practical task. In turn, the formation of artificial coronary anastomoses leads to significant changes in hemodynamics in the coronary bed. The influence of working shunts on the state of the native bed, the frequency of appearance of new atherosclerotic lesions has not been fully studied and many specialists in the field of cardiac surgery are dealing with this problem.

Large studies have demonstrated significantly better viability of arterial autografts both in the immediate and long term after surgery compared to venous autografts. According to E. D. Loop et al. 3 years after surgery, the rate of occlusion of mammary shunts is about 0.6%; after 1 year and 10 years, 95% of shunts remain patent. According to some randomized studies, the use of the internal mammary artery improves the long-term prognosis of operated patients compared with autovenous bypass. Such results may be due to both the high resistance of the internal mammary artery to the development of atherosclerotic changes, and the fact that this artery is primarily used for bypassing the anterior descending coronary artery, which itself largely determines the prognosis.

The resistance of the internal mammary artery to the development of atherosclerosis is due to both its anatomical and functional features. IAV - artery muscular type with a jagged membrane that prevents the growth of smooth muscle cells from the media into the intima. This structure largely determines the resistance to intimal thickening and the appearance of atherosclerotic lesions. In addition, the tissues of the internal mammary artery produce large amounts of prostacyclin, which plays a role in its athrombogenicity. Histological and functional studies have shown that the intima and media are supplied with blood from the lumen of the artery, which preserves the normal trophism of the vessel wall when used as a shunt.

Changes in autovenous shunts at different times after coronary artery bypass surgery

The effectiveness of the internal mammary artery has been established both in patients with normal myocardial contractility and in patients with poor left ventricular function. When analyzing the life expectancy of patients after operations, E. D. Loop et al. demonstrated that patients who used only autologous veins for coronary reconstructions had a 1.6 times greater risk of dying over a 10-year period compared with the group of patients using a mammary artery.

Despite the proven effectiveness of the use of the internal mammary artery in coronary surgery, a significant number of opponents of this technique still remain. Some authors do not recommend using the artery in following cases: the vessel is less than 2 mm in diameter, the caliber of the shunt is less than the caliber of the recipient vessel. However, a number of studies have proven the good ability of the internal mammary artery to physiological adaptation in various hemodynamic conditions: in the long-term period, an increase in the diameter of mammary shunts and blood flow through them was observed with an increase in the need for blood supply in the area of ​​the shunted vessel.

Changes in autovenous shunts at different times after coronary artery bypass surgery

Venous autografts are less resistant to development pathological changes in conditions of arterial circulation compared to the internal mammary artery. According to various studies, the patency of autovenous shunts from v. saphena one year after surgery is 80%. Within 2-3 years after surgery, the frequency of occlusions of autovenous shunts stabilizes at 16-2.2% per year, however, then it increases again to 4% per year. By 10 years after surgery, only 45% of autovenous shunts remain patent, and more than half of them have hemodynamically significant stenoses.

Most studies examining the patency of venous shunts after surgery indicate that if the shunt is damaged in the first year after surgery, thrombotic occlusion occurs. And since in the first year after surgery the largest number of autovenous shunts are affected, this mechanism can be considered the leading one among the reasons leading to the failure of coronary bypass grafts of this type.

The reasons for the high incidence of thrombosis, according to R. T. Lee et al. , lie in the specific structure of the venous wall. Its lower elasticity compared to the arterial one does not allow it to adapt to conditions of high blood pressure and ensure the optimal speed of blood flow through the shunt, which creates a tendency to slow blood flow and increased thrombus formation. Many research works have been devoted to studying the causes of the high incidence of thrombosis in the first year after surgery. As evidenced by major research on this topic, the main reason for early failure of vein grafts is the inability in many cases to maintain optimal blood flow through the graft. This feature is due to insufficient adaptation mechanisms when placing a venous vessel in the arterial bed. As is known, the venous circulatory system functions under conditions low pressure and the main force providing blood flow through the veins is the work of skeletal muscles and the pumping function of the heart. The middle layer of the venous wall, representing the smooth muscle layer, is poorly developed compared to the arterial wall, which, under conditions of arterial blood supply, plays an important role in regulating blood pressure by changing vascular tone and, thereby, peripheral resistance. A venous vessel placed in the arterial bed experiences increased load, which under conditions high pressure and the lack of regulatory mechanisms can lead to impaired tone, pathological expansion and, ultimately, slowing of blood flow and thrombosis.

In the case of thrombotic occlusion, the entire shunt is usually filled with thrombotic masses. This type of lesion represents an unpromising area for endovascular treatment. Firstly, the probability of recanalization of an extended occlusion is negligible, and secondly, even with successful recanalization, a large volume of thrombotic masses poses a threat to distal embolization when performing balloon angioplasty.

Factors influencing the condition of shunts after coronary artery bypass surgery.

Due to the current lack of effective therapeutic measures to eliminate occlusion of venous shunts in the first year after surgery, measures to avoid or reduce the risk of thrombosis of this type of shunt after coronary artery bypass grafting are of greatest importance. As the time after surgery increases, the so-called “arterialization” of the venous shunt and hyperplasia of its intima occurs. The shunt acquires the adaptation mechanisms necessary for proper blood flow, however, as long-term observations show, it becomes susceptible to atherosclerotic damage to no less extent than the native arterial bed. According to autopsy data, typical atherosclerotic changes of varying severity are observed after 3 years in 73% of autovenous shunts.

Factors influencing the condition of shunts after coronary artery bypass surgery.

Various studies devoted to the prevention of pathological changes in autovenous shunts after CABG indicate that the influence of various factors on the incidence of shunt damage varies at different times after surgery. Most of the studies have been devoted to the study of clinical risk factors for closure of autovenous shunts. Studies conducted to determine clinical predictors of shunt occlusions in the immediate postoperative period did not reveal clinical factors (diabetes mellitus, smoking, hypertension) that negatively affect the frequency of occlusions in the early postoperative period. At the same time, in the long term after surgery, clinical factors that contribute to the progression of atherosclerosis in the native course also accelerate the development of pathological changes in autovenous shunts. A study conducted in the Department of Cardiovascular Surgery examined the relationship between blood cholesterol levels and the number of occlusions of vein grafts at different times after surgery. When analyzing shuntography data, there was no correlation between high cholesterol levels and a higher incidence of shunt lesions in the first year after coronary artery bypass grafting. At the same time, in the long term, when a morphological restructuring of the venous bed occurred, a significantly higher incidence of shunt lesions was observed in patients with hypercholesterolemia. Prescribing lipid-lowering therapy with statins to patients in this study did not change the number of shunt occlusions in the immediate period, but led to a significant decrease in lesions in the long term.

During the first year after surgery, an extremely important role is played by factors that influence the speed of blood flow through the shunt (the condition of the distal bed, the quality of the anastomosis with the coronary artery, the diameter of the bypassed artery). These factors significantly influence the quality of outflow and, thus, determine the speed of blood flow through the shunt. In this regard, the work of Koyama J et al is interesting, where the degree of influence of a defect in the distal anastomosis on the speed of blood flow in mammary and venous shunts is assessed. It was revealed that the pathology of the distal anastomosis of the mammary shunt practically does not change the speed characteristics of blood flow compared to a shunt without an anastomotic defect. At the same time, a defect in the distal anastomosis of an autovenous shunt significantly slows down blood flow, which is explained by the unsatisfactory ability of the venous wall to change tone in the presence of increased resistance, which in this case is caused by the pathology of the anastomosis.

Most authors identify the diameter of the shunted vessel as the most important of all the local factors influencing the patency of shunts in the first year after surgery. A number of studies have shown a significant decrease in the percentage of shunt patency in the early and late postoperative periods with autovenous bypass of arteries less than 1.5 mm. Also important issue in indications for surgical treatment The degree of stenosis of the coronary arteries is considered. There is disagreement in the literature regarding the need for bypass surgery for “borderline” stenoses of 50-75%. A number of studies have noted low patency of shunts during interventions on such lesions (17% according to Wertheimer et al.). The concept of competitive blood flow is most often put forward as the reason for unsatisfactory results: the shunted bed distal to the anastomosis is supplied with blood from two sources and, with good filling in the native bed, conditions are created for a reduction in blood flow through the shunt with subsequent thrombosis. Other studies using a significant amount of material have shown that there are no differences in the patency of shunts to vessels with critical and non-critical stenoses. There are also reports in the literature about the dependence of the condition of shunts on the vascular area in which revascularization is performed. Thus, in the work of Crosby et al. indicate worse patency of shunts to the circumflex artery compared to other arteries.

Factors influencing the condition of shunts after coronary artery bypass surgery

Thus, there remains disagreement among researchers regarding the influence of various morphological characteristics on the condition of shunts. From a practical point of view, it is interesting to study the influence of morphological factors on the condition of shunts both in the immediate and long-term period, when morphological restructuring of the shunts occurs and adaptation to hemodynamic conditions is completed.

The influence of shunt patency on the state of the native coronary bed.

Literary information regarding the impact of working shunts on the dynamics of atherosclerosis in the shunt bed is scarce and contradictory. Among researchers studying the condition of coronary artery bypass grafts, there is no consensus on how functioning shunts influence the course of atherosclerosis in the native coronary bed. There are reports in the literature about negative impact functioning shunts on the course of atherosclerosis in segments proximal to the anastomosis. Thus, in the work of Carrel T. et al. It has been shown that in stenotic segments of the coronary arteries, bypassing which the myocardium is supplied with blood, rapid progression of atherosclerotic changes occurs with the development of occlusion of their lumen. An explanation for this is found in the high competitive blood flow through coronary artery bypass grafts, which leads to a reduction in blood flow through stenotic arteries, thrombus formation in the area of ​​atherosclerotic plaques and complete closure of the lumen of blood vessels. In other works devoted to this problem, this point of view is not confirmed and there is no report of provoking the aggressive course of atherosclerosis in bypassed arteries. . The above-mentioned studies address the problem of progression of atherosclerosis in segments that have hemodynamically significant lesions before surgery. At the same time, the question of whether functioning shunts can provoke the development of new atherosclerotic plaques in unaffected segments remains open. In modern literature, there are no reports on studying the effect of functioning shunts on the appearance of new atherosclerotic lesions that were absent before coronary artery bypass surgery.

To summarize the above, it should be noted that determining the anatomical features of the coronary bed that affect the prognosis of shunt performance is as important as studying the clinical risk factors for shunt occlusion. In our opinion, the study of the following issues remains relevant today: determination of the morphological characteristics of coronary artery lesions that affect the condition of shunts in the immediate and long-term periods after coronary bypass surgery; determination of the influence of shunt patency on the severity of the disease coronary atherosclerosis in segments affected before surgery; study of the effect of shunt patency on the incidence of new atherosclerotic changes in the immediate and long-term periods. Analysis of these issues, in our opinion, would help predict the course of coronary artery disease in operated patients and differentiate the treatment of patients with different morphological characteristics.