Hemodynamic and Immunological Risk Factors of Occlusive-Stenotic Lesions of Vascular Anastomoses in Patients with Obliterating Atherosclerosis of the Arteries of the Lower Extremities

The research is dedicated to developing a comprehensive diagnostic methodology for predicting the development of vascular anastomosis stenosis in the postoperative period in patients with obliterating atherosclerosis of the arteries of the lower extremities. The relevance of the work is due to the high frequency of reocclusions of reconstructed arteries, occurring in more than 60% of operated patients, which leads to limb loss in many cases. For the first time, a comprehensive assessment of local immunity indicators in vivo was conducted, the dynamics of local blood flow in the zones of arterial anastomoses was analyzed, and reliable immunological and hemodynamic factors were identified as prognostic criteria for the development of delayed stenoses.

Despite all the advances in surgical techniques for the treatment of patients with obliterating atherosclerosis of the arteries of the lower extremities, associated with the use of high-tech materials and endovascular minimally invasive methods, the results of treatment of patients with atherosclerotic lesions of the main arteries of the extremities still require significant improvement, since none of the minimally invasive treatment methods currently proposed allows achieving optimal long-term results (130). This is associated with a large number of complications occurring both immediately after surgery and in a later period. The most common of them is reocclusion of the reconstructed artery, developing in more than 60% of all operated patients (22,86). It is fair to call reocclusion a complication rather than a consequence of regression of the underlying disease, since its development is associated with a relatively rapid return of limb ischemia and its worsening in most patients to a level exceeding the preoperative one, which in many cases leads to limb loss.

In the literature it is customary to divide restenoses and reocclusions by the time of their occurrence into early ones, forming within two weeks after surgery, intermediate ones, developing within up to 1 year, and late ones, manifesting themselves a year or more after surgery (6,22). This division is primarily justified by the fact that it reflects the etiology of repeated impairment of vessel patency.

The main causes of early reocclusion are considered to be errors in surgical technique, disturbances of the coagulation system balance, inadequate outflow or inflow in the anastomosis zone due to hemodynamically significant stenoses of the distal or proximal vascular bed. The main cause of reocclusion in the late postoperative period is progression of the underlying disease — atherosclerosis, while intermediate or so-called delayed restenoses arise, in the opinion of most authors, as a result of excessive proliferation of the intima in the zones of vascular anastomoses, occluding their lumen (52). Restenoses forming in the intermediate postoperative period are the most common and the most dramatic in their outcomes group of complications (Ш). This is due to the fact that in a adequately operated patient with a good effect in the early postoperative period in the reconstructed arterial segment, changes arise that not only return it to the original level of ischemia but in many cases lead to the development of more severe disturbances of limb blood circulation (6).

Modern data revealing the mechanisms of their development, the appearance of new methods of diagnosis and treatment do not allow solving this problem. This is due not only to insufficient understanding of the pathogenesis of this pathology, but also to the absence of reliable prognostic criteria and schemes that could allow identifying patients at high risk of restenosis development in a separate group for timely implementation of therapeutic and preventive measures both in the preoperative and postoperative periods. This can contribute to a significant reduction in the frequency of occurrence of this complication and reduce clinical manifestations. The presence of such acute problems prompted the formulation of the goal and objectives of the present study:

To develop a comprehensive diagnostic methodology allowing to predict the development of stenosis of vascular anastomoses in the postoperative period in patients with obliterating atherosclerosis,

Within the framework of the study goal, the following specific tasks were identified:

1) To assess the characteristics of local cellular and humoral immunity, cytokine status in patients with obliterating atherosclerosis of the arteries of the lower extremities before surgery and after reconstructive vascular interventions.

2) To investigate the dynamics of local blood flow parameters in the zones of arterial anastomoses in the early and delayed postoperative period, to determine based on the obtained data the degree of narrowing of the anastomosis lines.

3) To identify reliable prognostically significant immunological factors of occurrence of delayed anastomotic stenoses in patients with obliterating atherosclerosis.

4) To develop a pathogenetically justified prognostic algorithm for the development of stenosis of vascular anastomoses in the delayed postoperative period in patients with obliterating atherosclerosis.

Scientific novelty of the work

For the first time, a comprehensive assessment of local immunity indicators in vivo was conducted in patients with obliterating atherosclerosis in the preoperative and postoperative periods. Parameters of arterial blood flow and concentrations of immunological factors in patients with obliterating atherosclerosis were compared. An in vivo study of the dynamics of concentration, activity, and degree of influence of immunological factors on the formation of restenosis was performed in patients with obliterating atherosclerosis. Previously, similar studies were conducted only in vitro on animal models. For the first time, a pathogenetically justified methodology for identifying patients suffering from obliterating atherosclerosis with a high risk of developing arterial anastomosis stenosis in the postoperative period was proposed.

Practical significance of the work

A systematic comprehensive assessment of a large volume of clinical, immunological, biochemical, and rheological indicators was conducted. The obtained data were compared with parameters of local blood flow in the arterial and venous bed of the lower extremities in patients with obliterating atherosclerosis, characteristics of the functional adequacy of arterial anastomoses evaluated in dynamics. Features of velocity and volumetric characteristics of blood flow in the zones of arterial anastomoses at various postoperative periods in patients with obliterating atherosclerosis of the arteries of the lower extremities were studied. A detailed assessment of local immunity parameters and cytokine status in patients with obliterating atherosclerosis of the lower extremities before surgery and after reconstructive arterial interventions was conducted. The degree of influence of a large number of immunological and hemodynamic factors on the degree of narrowing of arterial anastomoses and the degree of their functional adequacy in the early and late postoperative periods was evaluated. Immunological and hemodynamic factors were identified as reliable prognostic criteria for the development of vascular anastomosis stenosis and, as a consequence, its functional insufficiency within 6 to 12 months after surgery.

Implementation

Methods for examining patients with obliterating atherosclerosis of the arteries of the lower extremities have been implemented in the practice of the clinic of faculty surgery named after S.I. Spasokucoksky of the Russian State Medical University, specifically in the I surgical departments of the First City Clinical Hospital named after N.I. Pirogov and the Moscow City Clinical Hospital named after St. Alexius.

Dissertation defense

The main provisions of the dissertation were reported at the I Interregional Scientific and Practical Conference "Actual Problems of Emergency Medical Care" (Yakutsk, December 10-12, 2003), the XI All-Russian Congress of Cardiovascular Surgeons (Moscow, October 23-26, 2005), and the educational-departmental conference of the Department of Faculty Surgery named after S.I. Spasokucoksky jointly with laboratories of angiology, anesthesiology and resuscitation, endoscopy, biochemistry, intracardiac and contrast radiography methods of investigation of the Russian State Medical University and staff of the First City Clinical Hospital named after N.I. Pirogov of Moscow.

Publications

Based on the dissertation materials, 9 works were published, 4 of them in the central medical press, and 1 Russian Federation invention patent No. 2266711 dated December 27, 2005 was obtained.

Structure of the dissertation

The dissertation consists of an introduction, 5 chapters, conclusion, conclusions, practical recommendations, and a bibliography including 14 domestic and 117 foreign sources, illustrated with 15 tables, 19 figures, and photographs.