Features of the State of Peripheral Circulation in Patients with Chronic Critical Limb Ischemia and Pathways to Improving the Results of Reconstructive Operations

The research is devoted to the study of the features of peripheral circulation in patients with chronic critical limb ischemia caused by atherosclerotic occlusion of the main arteries below the inguinal ligament, as well as the development of approaches to improving the results of reconstructive surgical operations. The work addresses diagnostic and surgical problems associated with widespread atherosclerotic occlusions of the femoropopliteal-tibial segment, with particular attention to the state of the distal arterial bed and the microcirculatory system. During the research, clinico-angiographic variants of damage were developed, prognostic criteria for a favorable outcome of reconstruction were determined, and indications for the placement of a decompressive arteriovenous fistula were established.

Obstructive atherosclerosis of the main arteries of the lower extremities affects 2–3% of the population and 35–50% of individuals over the age of 65 [74,115]. Damage to the femoropopliteal segment is observed in no less than 80% of these patients [57,100,107,127]. According to European statistics (Berlin, 1989), critical ischemia occurs in 500–1,000 patients per one million population per year [243]. The therapeutic prognosis for the majority of patients with chronic critical ischemia is unfavorable [242,254]. The annual level of amputations remains high, and even in developed countries it stays at the level of 30 per 100,000 population [167,199]. Conservative treatment of critical lower extremity ischemia is effective only in 10–30% of patients [56,173]. Within the first year from the moment of diagnosis, 25–40% of patients require major amputation [14,74], and hospital mortality after amputation reaches 40–45% [14,83].

Performance of a reconstructive operation in individuals with widespread atherosclerotic damage of the main arteries below the inguinal ligament at the stage of decompensation of collateral circulation is the only chance of limb preservation [13,44,157]. Surgical treatment of these patients represents a very difficult and far from resolved problem in modern angiosurgery. The gold standard of reconstructive surgery in atherosclerotic damage of the femoropopliteal segment remains femoropopliteal shunting below the joint fissure using a reversed autologous great saphenous vein of the thigh [5,157]. However, the results of autogenous venofemoral shunting are far from optimistic [45,84,112]. According to literature data [9,36,44,35,51,55], damage to the distal arterial bed has a great influence on the results of the reconstructive operation. The most important aspect of preoperative diagnosis is the determination of the state of the main arteries at the level of «leg-foot», the plantar arch. According to the views of a number of authors, in 15–20% of patients with atherosclerotic damage to the arteries of the lower extremities, the development of critical ischemia is caused by impairment of tissue microcirculation [98,159]. However, these questions have not found worthy reflection in modern literature.

In recent years, the most effective operation in damage to the main arteries of the femoropopliteal-tibial segment of III–IV degree of chronic ischemia is distal femorotibial shunting with the great saphenous vein by the in situ technique [6,88,120,172]. According to data from a number of angiosurgeons, formation of a decompressive arteriovenous fistula in the area of the distal anastomosis significantly improves the results of the intervention [7,28,29,34,35,56,172,231]. However, objective criteria for the placement of an arteriovenous fistula have not been developed.

Thus, the most complex, socially significant, and far from resolved problem of surgery is improving the treatment outcomes of patients in the stage of critical ischemia. The goal of the work: to improve the results of reconstructive operations in patients with atherosclerotic occlusion of the main arteries below the inguinal ligament with critical ischemia.

Research tasks:

1. To study the features of peripheral circulation and develop prognostically significant clinico-angiographic variants of atherosclerotic damage to the main arteries at the level of «leg-foot» in patients with atherosclerotic occlusion of the main arteries below the inguinal ligament of III–IV degree ischemia.

2. To study the state of the microcirculatory bed in patients with atherosclerotic occlusion of the main arteries below the inguinal ligament at the stage of decompensation of collateral circulation and to identify prognostically significant criteria.

3. On the basis of a comprehensive comparative study of the state of peripheral circulation (clinical picture, angiography data, duplex scanning) to develop criteria for a favorable prognosis of femorotibial shunting in patients with critical ischemia of the lower extremities.

4. To clarify the causes of thrombosis of distal femorotibial shunts in the early postoperative period in patients with chronic critical ischemia.

5. To develop indications for the placement of a decompressive arteriovenous fistula during distal femorotibial shunting in patients with critical ischemia.

Scientific novelty of the research.

A comprehensive study of the features of damage to the distal arterial bed at the level of «leg-foot» made it possible to identify groups of patients with different prognoses for femorotibial reconstruction. Prognostically significant clinico-angiographic variants of damage have been developed in patients with atherosclerotic occlusion of the main arteries below the inguinal ligament, III–IV degree ischemia.

It has been first established that in patients with occlusion of the femoropopliteal segment in the stage of critical ischemia, an insufficient plantar arch is diagnosed in 25% of cases. It has been proven that in patients with chronic critical ischemia, in the collateral circulation of the foot, distal interosseous anastomoses play a significant role, which provide collateral flow between the functioning peroneal artery and the anterior and posterior tibial arteries.

It has been first proven that the state of microcirculation plays an important prognostically significant role in the performance of a distal femorotibial shunting operation. A test with «Vazoprostan» allows the most reliable assessment of the reserve capabilities of the microcirculatory bed.

The causes of early thromboses during distal femorotibial shunting with an autogenous vein in situ in patients with decompensation of collateral circulation have been clarified. A direct connection between the frequency of thromboses of distal femorotibial shunts and the severity of damage to the main arteries at the level of «leg-foot» (II–H2 clinico-angiographic variants of damage) has been first established. Indications for the placement of a decompressive arteriovenous fistula in the area of the distal anastomosis during distal femorotibial shunting with an autogenous vein in situ have been developed for the first time.

Practical significance.

For the first time, clinico-angiographic variants of damage have been developed in patients with atherosclerotic occlusion of the femoropopliteal-tibial segment with critical ischemia, which have important prognostic significance.

It has been proven that the choice of the optimal type of reconstructive operation must be based on a comprehensive assessment of the following factors: anatomical variants of damage, state of microcirculation, functioning of interosseous anastomoses and arteries of the foot, quantitative determination of the state of total peripheral resistance according to Rutherford, intraoperative flowmetry data.

Criteria for predicting the early results of distal femorotibial shunting have been determined. A «favorable prognosis» of distal reconstruction is observed in patients with patent arteries in the lower third of the leg and foot, with an intact plantar arch (I–I2 clinico-angiographic variants of damage); a «relatively favorable» prognosis is observed in patients with severe damage to the main arteries of the leg, foot, and dysfunction of the plantar arch (II–H2 variants).

It has been proven that the main causes of early thromboses of autogenous venofemorotibial shunts are severe occlusive-stenotic damage to the main arteries of the leg and foot with dysfunction of the plantar arch, and ineffective valvulotomy of the great saphenous vein.

It has been proven that distal femorotibial shunting with an autogenous vein by the in situ technique is the operation of choice in patients with critical ischemia of the lower extremities. Placement of a decompressive arteriovenous fistula in patients with severe damage to the main arteries of the leg and foot and critical state of microcirculation (II–P2 variants of damage) is an effective method for preventing early thromboses of autogenous venofemorotibial shunts.

Implementation of the results.

The results of the research and practical recommendations have been implemented in clinical practice and are applied in the department of cardiovascular surgery of the regional clinical hospital of the city of Tver.

Validation of the work.

The main materials and provisions of the work were reported and discussed at the annual session of the Bakulev Scientific Center of Cardiovascular Surgery RAMN (Moscow, 2006), at the All-Russian Congress of Cardiovascular Surgeons (Moscow, 2006); at the jubilee scientific-practical conference «Actual Problems of Clinical and Experimental Medicine» (Tver, 2006), at the VI annual interregional conference «Differential Diagnosis of Oncological and Vascular Diseases» (Chelyabinsk, 2006), at a meeting of the regional surgical society named after N.I. Pirogov (Tver, 2006); at a joint meeting of the surgical departments of the Tver State Medical Academy.

Volume and structure of the work. The dissertation is presented in 165 pages. It consists of an introduction, three chapters, a conclusion, conclusions, and practical recommendations. Illustrated with 21 figures and 17 tables. The bibliography includes 130 domestic and 126 foreign sources. Publications.