Current Problems in Surgical Treatment of Patients with Myocardial Infarction and Ischemic Cardiomyopathy

The study is dedicated to the analysis of current problems in surgical treatment of patients with myocardial infarction and ischemic cardiomyopathy. The work examines the etiology and pathogenesis of these diseases, the state of the coronary circulation, cardiodynamics and myocardial perfusion, as well as the clinical course of myocardial infarction of various types. Special attention is given to the comparative evaluation of the effectiveness of medical and surgical treatment methods, including coronary artery bypass grafting, at various stages of the disease. The research substantiates indications for surgical treatment and develops optimal approaches to anesthetic support of cardiac surgical interventions.

Relevance of the Topic. More than two centuries have passed since the English therapist W. Heberden (1772) first described one of the most common forms of coronary insufficiency — angina pectoris. In 1878, surgeon A. Hammer identified a special form of coronary insufficiency — myocardial infarction. Despite the numerous publications since then dedicated to the problems of coronary heart disease, questions of treatment of the "chest strangler" remain relevant to this day. Possessing the properties of a kind of non-infectious epidemic (Lisitsin Yu.P., 1987; Ogанов R.G., 1990), coronary heart disease affects people regardless of race, profession, and sex. The disease is characterized by evolution from one clinical form to another, generally more severe, often with a hard-to-predict prognosis, sudden death, which in some cases is the first and only manifestation of the disease (Mazur N.A., 1985; Belov Yu.V., 1988). To date, high morbidity, disability, and mortality rates are characteristic of CHD.

Thanks to the wide introduction into clinical practice of operations of direct myocardial revascularization and percutaneous transluminal coronary angioplasty, over the last decade it has been possible to make a significant "breakthrough" in the treatment of CHD. Mortality and the frequency of development of acute coronary syndromes in CHD patients during the remote observation period have decreased, and accordingly, the quality of life has improved and life expectancy has increased. The accumulated surgical experience, together with improvements in the quality of extracorporeal perfusion and anesthetic support, have made it possible to reduce mortality after coronary artery bypass grafting surgery, which currently in most domestic cardiac surgery clinics ranges from 1 to 4%. Nevertheless, there are groups of CHD patients in whom relatively high operative mortality and frequency of perioperative complications remain. One such group is patients who have had one or more myocardial infarctions. Such patients are characterized by initially reduced contractile function of the myocardium, caused by both Rubinstein changes of cardiac muscle and the presence of hibernating myocardium in the paranecrotic zone and in the basins of other affected coronary arteries. Operative mortality in this group of patients, according to various authors, depending on the severity of the initial condition, reaches 10-12%. The frequency of such postoperative complications as perioperative myocardial infarction and acute heart failure is high. Part of such patients are altogether excluded from selection for surgical treatment due to the high risk of fatal outcome and development of complications and are condemned to "a life of disability" and sudden death.

Despite the large number of publications in domestic literature dedicated to surgical treatment of CHD, no unified approach to the treatment of patients who have had one or more myocardial infarctions has been developed. To date, there are no clear criteria for determining the treatment strategy either in the subacute period of infarction or in the stage of scarring and cardiostenosis. On the one hand, the surgical method in treatment — continuing attacks of angina after infarction (so-called early postinfarction angina), persistent myocardial ischemia, insignificant disturbances of contractile function of the myocardium, caused by postischemic dysfunction. On the other hand, against such a strategy — disappearance of angina attacks after infarction, stability of the ECG picture, as well as pronounced disturbances of contractile function of the myocardium, generally caused by scar dysfunction of cardiac muscle. Based on the above, it can be summarized that today there is a necessity for clear differentiation of indications for interventional and surgical treatment in patients who have had myocardial infarction. The criteria for such division should be: 1) type of transferred myocardial infarction; 2) time since its development; 3) state of the coronary circulation, degree of impairment of contractile function of the myocardium and its perfusion; 4) immediate and remote results of this or that method of treatment based on their retrospective evaluation and from the standpoint of quality of life.

The present study is dedicated to these questions.

Goal of the work: to improve the results of treatment of CHD patients who have had one or more myocardial infarctions, as well as its complicated forms, by optimizing the approach to the treatment strategy depending on the type of transferred myocardial infarction, the time since its development, the state of the coronary circulation, the degree of impairment of contractile function of the myocardium, and the severity of clinical manifestations of angina.

Tasks of the investigation:

1. To evaluate the effectiveness of isolated medication treatment of patients with postinfarction cardiostenosis and ischemic cardiomyopathy.

2. To prove the advantages of direct myocardial revascularization in the treatment of patients with postinfarction cardiostenosis and ischemic cardiomyopathy compared with conservative methods.

3. To reveal the character of damage to the coronary arteries and the possibility of surgical treatment of patients with non-transmural myocardial infarction.

4. To prove the effectiveness of surgical treatment of patients who have had transmural myocardial infarction, based on investigation of the coronary arteries and functional capabilities of the myocardium.

5. To evaluate the effectiveness of coronary bypass surgery in patients with ischemic cardiomyopathy.

6. To develop a complex of anesthetic support for cardiac surgical interventions that allow reducing operative mortality and the frequency of perioperative complications in the studied category of patients.

Scientific Novelty

For the first time, a comparative evaluation of the effectiveness of medication and surgical methods of treatment of CHD patients who have had one or more myocardial infarctions was conducted. It has been proven that medication treatment of patients with postinfarction cardiostenosis and ischemic cardiomyopathy is characterized by an extremely unfavorable prognosis, accompanied by high mortality and unsatisfactory quality of life.

We have confirmed that myocardial revascularization is a highly effective method of treatment of patients with postinfarction cardiostenosis and ischemic cardiomyopathy and provides a more favorable prognosis compared with medication therapy.

An evaluation of the character of damage to the coronary arteries and contractile function of the myocardium in patients with transmural and non-transmural myocardial infarction has been given, and the necessity and advisability of performing direct myocardial revascularization have been substantiated. For the first time, the possibility of successful performance of direct myocardial revascularization surgery in patients with ischemic cardiomyopathy has been demonstrated. This ensures a significant increase in two-year survival compared with the conservative method of treatment.

For the first time, it has been proven that more effective results of surgical treatment of patients with postinfarction cardiostenosis and ischemic cardiomyopathy in the intra- and immediate postoperative periods are achieved under conditions of application of a complex of anesthetic support, including the use of combined epidural anesthesia, normothermic perfusion, normovolemic hemodilution, and cold cardioplegia based on autologous blood.

Practical Significance of the Investigation

The practical significance of the work lies in the introduction into clinical practice of an integral system of approach to the choice of method for correction of impaired coronary blood flow and improvement of contractile function of the myocardium in patients with postinfarction cardiostenosis and ischemic cardiomyopathy. Indications for the surgical method of treatment of patients with postinfarction cardiostenosis and ischemic cardiomyopathy have been determined based on comprehensive examination with mandatory coronary angiography and evaluation of contractile function of the myocardium.

Surgical treatment has made it possible to increase the level of quality of life and five-year survival in patients with postinfarction cardiostenosis and ischemic cardiomyopathy compared with conservative methods of treatment.

An optimal method of anesthetic support for performing coronary bypass surgery in patients with myocardial infarction and ischemic cardiomyopathy has been developed, including the use of combined epidural anesthesia, artificial blood circulation under conditions of normothermia and normovolemic hemodilution with application of cardioplegia based on autologous blood.

Basic Provisions of the Dissertation for Defense

Medication treatment of patients with postinfarction cardiostenosis and ischemic cardiomyopathy is characterized by an extremely unfavorable prognosis accompanied by high mortality and unsatisfactory quality of life.

Myocardial revascularization is a highly effective method of treatment of patients with postinfarction cardiostenosis and complicated forms of myocardial infarction and provides a more favorable prognosis compared with medication therapy.

The possibility of successful performance of revascularization operations in patients with ischemic cardiomyopathy has been proven, which ensures a significant increase in two-year survival compared with conservative treatment.

The application of an original technique for ensuring surgical myocardial revascularization, including combined epidural anesthesia, normovolemic hemodilution, normothermic perfusion, cardioplegia based on autologous blood, makes it possible to improve the results of surgical treatment of patients with postinfarction cardiostenosis with significantly reduced contractile function of the myocardium.

Implementation of the Work

Ten printed works on the dissertation topic have been published in central medical journals and collections of scientific works. The results of the investigation have been introduced into the practice of the cardiac surgery center of CVKG named after A. A. Vishnevsky, the clinic of cardiovascular surgery named after P. A. Kupriyanov of S. M. Kirov Moscow Medical Academy, and the regional clinical hospital of the city of Orenburg. They may be recommended for wide application in other cardiac surgery clinics. Methodological recommendations "Tactics of Treatment of Patients with Acute Coronary Syndrome" have been developed and published.

Defense of the Work

The dissertation work was defended at a meeting of the Scientific-Methodological Bureau of CVKG named after A. A. Vishnevsky. The main materials of the dissertation were reported at the IV All-Russian Congress of Cardiovascular Surgeons (Moscow, 1998), V All-Russian Congress of Cardiovascular Surgeons (Novosibirsk, 1999), III and IV annual sessions of the NCSSS named after A. N. Bakulev RAMN (Moscow, 1999, 2000), the international scientific-practical conference "Bloodless Surgery on the Threshold of the XXI Century" (Moscow, 1999), and the XIX World Congress of the International Union of Angiology (Ghent, Belgium, 2000).

Volume and Structure of the Work

The dissertation is presented on 249 pages of typed text and consists of an introduction, literature review, eight chapters characterizing the materials and methods of investigation and the results of own observations, conclusion, conclusions, and practical recommendations. The bibliography includes 454 sources (91 in Russian and 363 in foreign languages). The work is illustrated with 36 tables and 57 figures.