Vascular anastomoses
General rules
In operations on blood-vessels certain general rules must be followed.These rules have been adopted with the view of eliminating the complications which are especially liable to occur after vascular sutures，namely，stenosis，haemorrhage，and thrombosis.A rigid asepsis is absolutely essential.Sutures of blood-vessels must never be performed in infected wounds.It seems that the degree of asepsis under which general surgical operations can safely be made may be insticient for the success of a vascular[8]operation.It is possible that a slight non-suppurative infection，which does not prevent the union of tissues“per primam intentionem”，may yet be sufficient to cause thrombosis[9].The obliteration of the vessel also follows injuries to its walls.The arteries and veins can be freely handled with the fingers without being injured，but it is often harmful to use forceps[10]or other instruments.If a forceps be used，it must take between its jaws nothing but the external sheath[11].When temporary haemostasis[12]is obtained by means of forceps or clamps，these instruments must be smooth-jawed and their pressure carefully regulated.The dessication of the endothelium[13]may also lead to the formation of a thrombus[14].Therefore，during the operation the wall of the vessels must be humidified with Ringer's solution or be covered with Vaseline.The presence of coagulated blood[15]，of fibrin[16]ferment，or of foreign tissues or tissue juices on the intima[17]can determine the production of a thrombus.It is，therefore，necessary to resect or to remove the external sheath from the edges of the vessels，for if，during the suture，it gets between the edges of the vessels or around the silk threads，it very quickly leads to a deposit of fibrin，and possibly to an obliterative thrombus.By washing the vessel carefully with Ringer's solution and coating it and the surrounding parts of the operating-field with Vaseline，we can efficiently protect the endothelium against coagulating blood and the juices of tissues.Vaseline also prevents the fingers of the operators and the threads from becoming soiled by fibrin ferment.As perforating stitches are always used，the endothelial layer is necessarily wounded by the needle.These wounds，however，are rendered as harmless as possible by the use of very fine and sharp round needles.Extremely small wounds are made.The threads are sterilized in vaseline and kept heavily coated with it during the suture，thus preventing the wounded tissue and the foreign material from coming into actual contact with the blood.Stenosis is very liable to occur at the point of anastomosis，therefore the suture must be performed while the wall is under tension.The tension can easily be ob-tained by traction on retaining stitches properly located.Great care is taken to obtain a smooth union and approximation of the internal coats，in order to produce as small a scar as possible.When these general rules are observed the operation can be safely performed.
Technique
The instruments employed are very simple.Temporary haemostasis in the case of small vessels is secured by an ordinary serrefine，the spring of which is carefully regulated，and in the case of large vessels by Crile clamps or smoothjawed Gentile forceps.These instruments are all smoothjawed and are applied to the vessel without a cover of rubber.The vessel is washed in Ringer's solution by means of a Gentile syringe[18]，which is composed of a rubber bulb and a glass-tube narrowed at its end.The anastomosis is performed with round，straight Kirby needles.No.16 is used for the small vessels and No.12 for the large ones.Short，curved needles can also be used，but the straight ones are always preferable.The needles are threaded and the thread is rolled on cardboard，after which the needles and threads are placed in a hermetically closed jar，which is put in the sterilizer under fifteen or eighteen pounds'pressure.The needles and thread are removed from the jar whilst the Vaseline is still warm and deposited on a black towel.During the operation the threads are fixed by means of small Gentile haemostatic[19]forceps.The operating-field is circumscribed by a black Japanese silk towel on which the fine threads can easily be seen.
（1）Temporary haemostasis and preparation of the vessels.The vessels are exposed by a large incision and they are freely dissected.The dissection of a very long segment of artery or vein is not dangerous.Careful haemostasis of the wound is made，because during the suture the operatingfield must be free from blood.The temporary haemostasis is secured by clamps placed at a few centimeters'distance from the location of the suture.If there are collateral branches between the forceps and the point of section，they are ligated or clamped.Then the vessels are cut and the external sheath is resected from the ends of the vessels.The end of the syringe is introduced into the lumen of the vessel and the blood is washed out of the vessel and from the operating-field.The fluid is removed with dry gauze[20]sponges.Then the vessels and the surrounding parts are covered with vaseline[21]and a black Japanese silk towel is placed around the ends of the vessels.
（2）Suture.We shall now proceed to describe the technique of the suture，selecting as our type the termino-terminal anastomosis.Then we will point out the modifications which take place in the termino-lateral and latero-lateral anastomoses.
The termino-terminal anastomosis is effected by bringing the extremities of the vessels into contact，no traction being necessary.The ends are united by three retaining stitches located in three equidistant points of their circumference.By traction on the threads the circumference of the artery can be transformed into a triangle，and the perimeter can be dilated at will.Then the edges of each side of the tri-angle are united by a continuous suture whilst they are under tension.During the suture great care is taken to approximate exactly the surfaces of section of the wall.Before the last stitch is made，the remaining Vaseline is removed by pressure from the lumen of the vessel.In venous[22]anastomoses[23]the ends of the veins are also united by three retaining stitches.A venous suture，however，requires more stitches than an arterial[24]suture，on account of the thinness of the walls.The union of the extremities is made by eversion of the edges，which are united not by their surface of section，but by their endothelial surfaces.An inversion of the edges would be very dangerous and would provoke the formation of a thrombus.In arterio-venous sutures the vein is generally larger than the artery.After the ends of both vessels have been united by the retaining stitches each side of the venous triangle is longer than the corresponding side of the artery.By traction on the retaining stitches the arterial lumen can be greatly dilated and be brought nearer to the size of the vein.Each stitch of the continuous suture is made larger on the vein than on the artery，and the size of the vein is thus progressively reduced and a good union ensured.During the suture the venous wall is turned outward and its endothelial surface is applied to the surface of section of the arterial wall.
The termino-lateral anastomosis consists in implanting the end of one vessel on to the wall of another vessel.A triangular or elliptic incision is made in the wall of one vessel，whereupon the edges of the opening are united to the extremity of the second vessel by three or four retaining stitches，and the operation finally concluded by a continuous suture.If the vessel is of small caliber[25]it is better to perform the termino-lateral anastomosis by the patching method.This consists in dissecting the small vessel to the level of its implantation in a larger trunk and in resecting the patch of the wall of this trunk which surrounds the mouth of the small artery.This patch must be elliptic in shape and its edges as regular as possible in order that a smooth anastomosis can be made.The patch is then inserted into an opening made through the wall of the larger vessel and fixed by four retaining stitches and a continuous suture.This method is safer than the direct implantation，for the formation of a slight thrombus on the line of suture would not impede the circulation of the large vessel，whereas the lumen[26]of the smaller vessel would be obliterated if the thrombus were formed at its mouth.
The latero-lateral anastomosis is performed by placing two vessels parallel to one another and opening them longitudinally by incision or resection of an elliptic flap.The ends of the openings are united by two posterior retaining stitches and by a continuous suture performed on the interior of the vessels whilst their walls are under tension.A third retaining stitch unites the middle points of the anterior edges，the posterior line of suture being still stretched by traction on the two retaining stitches.Finally by traction on the posterior and anterior retaining stitches the opening is transformed into a triangle and the anastomosis is completed by a continuous suture running along both anterior sides.
（3）Reestablishment of the circulation.Before the circulation is reestablished the line of suture must be carefully examined，and if a gap is found between two stitches it is immediately closed.Next，gauze sponges are placed on the line of suture and the clamps are removed，while a gentle pressure is exercised on the sponges.There is almost always some leakage during the first minutes.After two or three minutes the sponges are removed，and if the haemorrhage persists one or two complementary stitches are added.It is of fundamental importance that the wound be not closed before complete haemostasis of the anastomosis has been obtained.Finally，the vessels and the operating-field are washed in Ringer's solution and the wound closed without drainage.
Results
A great number of vascular sutures and anastomoses were performed by this method on dogs and cats，and some on man.The operations were made on arteries and veins of both large and small caliber.The simplicity of the technique makes it readily adaptable to all vessels.It is as easy to make a circular suture of the delicate renal vein of a small-sized dog as of the thoracic[27]artery of a large dog，or even of the femoral[28]artery of man.In aortic sutures，where the walls are very friable，the edges of the vessel are jointed by ushaped stitches，instead of by a continuous suture.If it is necessary not to interrupt the circulation during the suturing，a diversion of the flow can be practised by means of a paraffined tube，which is inserted into the lumen of the vessel and afterwards removed by means of an incision in the wall.But in nearly all cases it is possible to interrupt the circulation for the space of a few minutes.Even during the operation of the Eck fistula or the circular suture of the thoracic aorta，the circulation in the portal vein or in the aorta was completely interrupted.The operation is always simple，except in those cases in which the region to be operated upon is deeply situated.It is possible to perform the suture of the carotid artery of a medium-sized dog in two and a half minutes，and of the aorta of a dog or of the femoral artery of a man in five or six minutes.Generally there is nothing to be gained by hastening the operations，as they could last 10 or 20 minutes without any harm resulting.
The results were as simple as the technique.No haemorrhage was ever observed and no stenosis[29]was ever produced at the location of the anastomosis，provided a proper tension was made on the retaining stitches during the suture.Occasionally I noticed in the Eck fistulas a reduction in the size of the vascular opening，which was due，doubtless，to deposits of fibrin.The commonest complication which was apt to take place in connection with vascular sutures，viz.thrombosis，never occurred when this method was properly employed.In sutures of vessels of the caliber of the carotid of a middle-sized dog，as well as in those of smaller vessels，it may be said that an obliteration occurred in hardly five out of one hundred cases.In the sutures of arteries or veins of larger caliber deposits of fibrin could sometimes be detected on the line of the suture，but never an obliterative thrombosis.In short，we can say that thrombosis has become an altogether unusual complication in cases of vascular operations.
The anatomical[30]evolution of vascular sutures was studied during a period of time varying from several days to over four years.One week after the operation all the stitches could still be seen on the endothelial surface of the vessel.In certain cases the line of suture was covered by a very fine layer of fibrin.Little by little the threads became invisible and at the end of some months no trace of the suture could be perceived except a more or less indistinct transverse line.Sometimes this line was slightly depressed，but there was never any trace of dilatation or of stenosis at the location of the suture.Sometimes，again，the line of juncture became entirely invisible，and this occurred in the case of the suturing of the renal artery，for，six months after the operation，it was impossible to locate the place where the anastomosis had taken place.Careful examination disclosed the place where the wall of the vessel had become slightly thicker，but no signs of the operation could be detected on the inner surface.Similarly，after the extirpation and replantation of the spleen，performed with a circular suture of the splenic vessels，an examination of the endothelial surface of the vessels，conducted twenty-two months after the operation，likewise failed to show where the anastomosis had taken place.It was only after the vessel had been placed in formalin，that two faint whitish lines began to appear，indicating the place where the suture had been performed.In the case of veins，where the walls are thinner，the marks of the operation remain for a longer time.Nearly all the stitches of a suture of a renal vein could still be seen as long as ten months after the kidney had been replanted.Certain animals on which circular sutures of the thoracic or abdominal aortas or of the carotid artery had been performed，and which we had retained in health two，three，and even four years afterwards，showed the same results.A histological examination of the sutured vessels readily explains the perfection of the clinical results obtained.The union produced by the suture is so exact that the scar resulting from the junction of the extremities of the vessels is in consequence very slight，and in some cases the medias become directly united without the interposition of any fibrous tissue.A longitudinal section of the anastomosis of the abdominal aorta of a cat，to which a segment of the aorta from another cat had been transplanted，showed that the wall at one of the extremities was slightly everted and had united with the surface of the section of the intima at the other extremity，without the interposition of fibrous tissue.At a short distance from the line of suture the elastic tunic was seen to be interrupted，because the section had encroached[31]upon one of the silk threads surrounded by fibrous tissue.This result was exceptionally good.In most cases the elastic tunic was interrupted by a faint scar at the place of the anastomosis.The faintness of the scar explains why there was never any stenosis or dilatation[32]at the level of the suture lines.
By means of this technique I have been able to successfully perform sutures of incisions made on the ascending part of the aortic arch，and likewise to perform circular anastomoses of the thoracic[33]aorta[34]，of the abdominal aorta，of the vena cava，and of the majority of the vessels of the organism.Lateral anastomoses were employed in arterio-venous sutures and in the operation of the Eck fistula[35].Fi-nally，by applying this technique to operations on the human body，I have shown it to be equally simple and efficacious as in the case of animals.It has made possible the successful transplantation of arterial and venous segments，of organs and members.