SHUNTING of BLOOD VESSELS — surgery on creation by means of various vascular transplants of a new way of a blood-groove bypassing the segment of an arterial or venous vessel struck with pathological process at partial or full disturbance of its passability. Unlike prosthetics of blood vessels at their shunting patholologically the changed sites of a vessel do not resect and an anastomosis of a transplant with the shunted vessel imposes on a way the end sideways. During the shunting create a new way of a blood-groove, to-ry does not correspond to an anatomic circulatory bed, but it is quite full in the hemodynamic and functional relation.
For the first time Sh. to. the page in an experiment was executed by Eger (E. Jeger) in 1913, and in clinic — J. Kunlin in 1949.
Indications to Sh. to. pages are thrombosis and a stenosis of arteries and veins of various etiology when extensiveness of defeat, technical difficulties or the general condition of the patient do not allow to recover a blood stream on a natural anatomic way.
Operations on Sh. to. pages carry out in a planned and emergency order. Aortocoronary shunting can be an example of an immediate surgery (see Arterialization of a myocardium) at a preinfarction angina for the purpose of the prevention of development of a myocardial infarction. At a myocardial infarction this operation promotes restriction of distribution of a necrosis and accelerates process of scarring of a myocardium (see the Myocardial infarction, surgical treatment). The emergency Sh. to. pages make also at the suppuration in the field of earlier implanted transplant or a prosthesis of a vessel complicated by arrosive bleeding at acute thrombosis and injuries of large vessels.
III. to. pages carry out by means of autografts, allotransplants or heterografts (see the Transplant). As an autograft use veins of the patient, is more often a big saphena of a leg in the form of a free transplant or a transplant «on a leg». E.g., at occlusion of subnodal and femoral veins impose an anastomosis between a distal part of a big saphena of a leg and deep veins of a shin. At unilateral occlusion of ileal veins it is possible to use the method offered in 1960. Palma and Esperon (E. Palma, V. Es-regop), being that the distal end of a big saphena of a healthy leg is moved on the opposite side through a tunnel in hypodermic cellulose over a pubic joint and anastomose with a femoral vein of a sore leg. Movement of a big saphena «on a leg» sometimes is applied also at a gipertenzionny syndrome of an upper vena cava (see Venas cava), napr, at her fibrinferment or a prelum a malignant tumor. In this case the big saphena of a leg after mobilization of its distal department is carried out through a tunnel in hypodermic cellulose of a perednebokovy surface of belly and chest walls and connected to a jugular or subclavial vein.
For creation of shunts «on a leg» use also small saphena of a leg, an outside jugular vein, lateral and medial veins of a shoulder, and also an internal chest artery at podklyuchichnokoronarny shunting. The listed veins apply also as free shuntov-transplan-
SHUNTING of VEINS 503
of Fig. 1. The diagrammatic representation of separate stages of operation of removal of sacculate aneurism of an aortic arch using temporary shunting: and — the synthetic shunt (1) via which the blood stream bypassing the ascending part of an aorta which is disconnected by means of clips is carried out is imposed; removal of sacculate
aneurism (2) \b_ is begun stitches on a wall of an aorta in the field of the excised sacculate aneurism
and v'mesta of connection of the temporary shunt are put, the usual blood stream on an aorta is recovered.
Tats at the most various occlusal defeats of the main venous trunks of system top and bottom venas cava, in particular at Pedzhet's disease — Schröter (see Pedzhet — Schröter a syndrome), at unilateral occlusions of ileal veins, occlusions of femoral, subnodal veins and deep veins of a shin.
Autovenozny shunting is widely applied at reconstructive operations on arteries of top and bottom extremities. This operation is method of the choice at obstruction of rather small arteries of a forearm and shin. During the formation of a vascular anastomosis in these cases it is desirable to use the microsurgical equipment (see Microsurgery).
At stenoses and occlusions celiac, upper mesenteric, renal arteries make Sh. to. page directly with belly department of an aorta. For shunting of arteries of small diameter, except autoven, use allotransplants and heterografts, e.g. the vein of an umbilical cord of the person processed by glutaric dialdehyde for the purpose of decrease in antigenic properties. Similar processing promotes weakening of neutrophylic and macrophagic reaction and improves results of operation. Sometimes outside the umbilical vein is strengthened a mesh synthetic framework. Highway to. pages carry out also transplants from bull and pork vessels (heterografts). They for the purpose of removal of foreign proteins are previously processed proteolytic enzymes (ficin, papain, chymotrypsin, Terrilytinum, etc.), and then tanned glutaraldegidy and dial of starch.
At III. to. pages widely apply transplants from synthetics (lavsan, a Dacron, poly-
tetrafluorethylene, etc.). These transplants apply to shunting at occlusions of branches of an aortic arch and subclavial arteries. At occlusions of ileal arteries and belly department of an aorta became standard aortoiliac and aortobedrenny Sh. to. page. Use of synthetics allows to create shunts of necessary length and a configuration (see Atherosclerosis, surgical treatment of occlusal defeats).
Distinguish temporary and constant III. to. page. Temporary Sh. to. pages usually apply to creation of a bypass way of a blood-groove only for the period of the main stage of operation demanding full overlapping of a blood-groove in a segment of a large vessel. E.g., at operations for aneurisms of an arch and the descending part of chest department of an aorta (see the Aortic aneurysm) resort to imposing of the temporary shunt (fig. 1). Temporary shunting can be performed not only by means of vascular transplants. Sometimes for this purpose use the special cannulas or needles connected among themselves by a polyethylene or silicon drainage tube. Cannulas (needle) enter into a vessel use-simalnee and distalny places of its reconstruction. At the same time blood from the central segment of the pressed artery on a connecting tube comes to its peripheral department. Advantage of a kanyulny method of temporary shunting consists in its simplicity. The small openings remaining in a vascular wall after removal of cannulas take in one-two seams. However a serious lack of the specified method is that rather small caliber of cannulas and needles not always provides the necessary volume of a blood-groove through their gleam. Temporary III. to. the page by means of cannulas and silicon drainage tubes is shown also at an acute
injury of the main vessels for preservation of a blood-groove in them for the period of transportation of the wounded in specialized to lay down. establishment.
The greatest distribution in cardiovascular surgery was gained by constant Sh. to. page. In nek-ry cases it is less traumatic, and technically simpler operation, chekhm prosthetics of vessels. Basic value at constant Sh. to. the page has preservation of collateral circulation (see Collaterals vascular). Constant III. to. pages most often apply at obliterations or stenoses of an aorta of various nature, napr, at Lerish's syndrome (see Lerish a syndrome), and also at obliterating diseases of the main arteries of pi of veins.
For constant Sh. to. pages depending on type of a vessel (an artery or a vein), and also its diameter apply various transplants (see). During the shunting of venous trunks, as a rule, use autovena.
III. to. pages one linear transplant (fig. 2) call single, or linear, shunting. If apply a bifurcation transplant, shunting call bifurcation (e.g., bifurcation aortobedrenny shunting). If several vessels are shunted at the same time, then speak about double, triple or multiple shunting (e.g., multiple aortocoronary shunting). Recently began to use so-called consecutive shunting. Carry out its hl. obr. at aortocoronary shunting and reconstruction of arteries of a shin. The principle of this operation consists in formation of several consecutive anastomosis of one
Fig. 2. Aortogramma of the patient with the stenosing atherosclerosis of ileal arteries after right-hand linear aortobedrenny shunting: the blood stream is carried out at the same time on the shunt (2) and on stenosed by the general (2) and to internal (3) ileal arteries.
a transplant with two or three nearby arteries or passable segments of one artery.
At Sh. to. the page needs to consider nek-ry technical features. The channel, carry out a transplant to Krom, shall be rather wide to warn a prelum of the shunt surrounding fabrics. During the use of the long shunt during its carrying out it is necessary to avoid twisting of the last on a longitudinal axis. Excess length of the shunt can lead to its excess and the subsequent thrombosis (see). The shunt shall be in slightly tense state. Diameter of a transplant shall be more than diameter of the shunted vessels in 1V2 — 2 of time. Connection of a transplant with vessels shall be carried out under the most acute angle, no more than 15 are desirable °. In this case the hemodynamic characteristic of an anastomosis is almost similar that at connection of vessels the end in the end. It is desirable that length of an anastomosis (the end sideways) in I/2 — 2 times exceeded diameter of the shunt. It is especially important when the shunt and the shunted vessels have approximately identical caliber. For imposing of an anastomosis choose usually not changed sites of walls of vessels. If the wall of an aorta or artery is condensed, it is necessary to excise economically before imposing of an anastomosis the site of a vascular wall that in it the oval opening was formed. During the shunting of veins this reception should be carried out whenever possible always.
Sewing together of a transplant with the shunted vessel is usually made a blanket atraumatic seam between two seams handles which are previously imposed on top and bottom corners of an anastomosis. Before turning on of the shunt in a blood stream delete the pristenochny blood clots formed in it and air.
At Sh. to. pages are of great importance morfol. the features of system of again created vascular anastomosis connected with many reasons including with the applied transplants. The vascular transplant (shunt) quite often causes an aseptic inflammation in surrounding fabrics. Around it granulyatsionny fabric is formed (see), edges during 2 — 3 weeks turns into the outside fibrous (connective tissue) capsule. Further the outside capsule changes a little, only its thinning, and sometimes a hyalinosis (see) and petrification is observed (see Petri-fikat).
During the use for III. to. pages autoven in their wall in the first days are noted partial desquamation of an endothelium, reksis kernels of smooth muscle cells, swelled also moderate neutrophylic infiltration that is connected with disturbance of blood circulation and metabolism of a venous wall. Then there is a proliferation of an endothelium, smooth muscle cells and fibroblasts to synthesis of collagen and glikozamino-glycanes that causes a reparation of a vascular wall. In late terms after Sh. to. the page occurs a thickening of a wall of a vein at the expense of fibrosis and a hyperelastosis of all its layers, especially adventitias. At patients of advanced age in several years after shunting perivascular fibrosis, a thickening of an internal cover of a vessel and atherosclerosis can develop (see). Narrowing or obliteration of a gleam of peripheral autovenozny shunts is caused.
Morfol. changes of a transplant of a vein from an umbilical cord of the person are less expressed. The internal cover of a transplantirovanny vein becomes covered by a pellicle of fibrin (see), in the field of an anastomosis the layer is formed of cells of an endothelium, neutrophils and macrophages that creates favorable conditions for functioning of a transplant. As a result of a tissue incompatibility (see Incompatibility immunological) the endothelium, unstriated muscles and partially elastic fibers collapse macrophagic, limfoplazmokletochny and neutrophylic infiltrate. Dystrophic changes conduct to an ulceration, late fibrinferments, calcification (see), to reduction of durability, formation of aneurisms (see Aneurism) and to ruptures of a wall of a transplant.
During the use of tinned heterografts (bull, pork vessels, etc.) morfol. changes are not essential, and neutrophylic and limfoplazmokletochny reactions to change of such vessels are minimum.
Morfol. changes in synthetic transplants are especially expressed on an inner surface, edges becomes covered by a fibrinny vystilka with formation of a so-called neointima. A source of its education are the fibroblasts and capillaries burgeoning through a time of a synthetic framework, and also the cells of a vascular wall migrating through an anastomosis (usually on the distance which is not exceeding 2 — 3 cm). It is impossible to exclude also participations in this process of predecessors of the fibroblasts which are in a blood-groove. At the person of a full endotelization of a new vascular bed often does not occur.
Functioning of shunts depends on diameter of the shunted vessels, character of the used plastic material, etc. The more diameter of the shunted vessel and is shorter a transplant, the remote result of operation is better. The long-term results of shunting of an artery of alny vessels depend on many factors, in particular the etiology of damage of an aorta and arteries (atherosclerosis, an aortitis, arteritis) matters. The most adverse results are observed after operation at a nonspecific aortitis (see) and arteritis (see). Progressing of a basic disease is the main reason for the adverse long-term results during the shunting of arterial trunks. Therefore after different types of shunting constant dispensary observation for patients and treatment of a basic disease is necessary.
The long-term results of shunting of the main veins it is much worse, than during the shunting of the main arterial trunks. However recently there were messages on long-term functioning of the autovenozny shunts created concerning occlusion of veins of the most various localization. It is connected with development of the therapy improving rheological properties of blood and implementation of the microsurgical equipment.
See also Blood vessels, operations; Obliterating defeats of vessels of extremities.
Bibliography: Vedeno A. N. Plastic and reconstructive surgeries on the main veins, D., 1979; Knyazev M. D., Belarusians O. S. and Savchenko A. H. Surgery of aortoiliac occlusions, Minsk, 1980; L e-
e d e in L. V., Plotkin L. L. and Smirnov A. D. Prostheses of blood vessels, L., 1975, bibliogr.; Petrovsky B. V., Belichenko I. A. and Krylov B.C. Surgery of branches of an arch, M., 1970; Sychen and - to about in I. A. Seam and plastics of arteries, M., 1980; E sato K., Shintani K. Yasutake S. Modification and morphology of human umbilical cord vein as canine arterial bypass grafts, Ann. Surg., v. 191, p. 443, 1980; Leu H. J. u. Brunner U. Zur Pathogenese der degenerati ven Veranderungen an autologen des Venetransplantaten, Dtsch. med. Wschr., S. 2433, 1973; Palma E. E s p e-r o n R. Vein transplants and grafts in the surgical treatment of the postphlebitic syndrome, J. cardiovasc. Surg., v*. 1, p. 94, 1960; S z i 1 a g y i D. E. a. o. The laws of fluid flow and arterial grafting, Surgery, v. 47, p. 55, 1960; We so low A. The healing of arterial prosthesis, Thorac. cardiovasc. Surg., v. 30, p. 196, 1982.
O. S. Belorusov; A. B. Shekhter (stalemate. An.).