Arteries

23


Arteries





INTRODUCTION


Arterial disease and its management is becoming an increasingly specialized field, with training programmes accordingly recognizing this. However, all competent surgeons should be familiar with the basic principles of arterial control, repair and reconstruction.




INDICATIONS FOR OPERATION




1. Injury. This may result from sharp or blunt trauma secondary to assault or road traffic accident. Iatrogenic injuries are becoming more prevalent as a consequence of percutaneous arterial access for diagnostic procedures and treatments such as coronary interventions. Challenging self-induced injuries are also seen as a result of intravenous drug addiction.


2. Aneurysm. This is defined as a pathological, permanent dilatation of an artery. Arterial aneurysms may involve the aorta and/or peripheral arterial system. The three main sites for aneurysms are the abdominal aorta, femoral and popliteal arteries. Most vascular surgeons consider the aorta to be dilated once it is twice its normal diameter; for non-aortic vessels an arterial aneurysm is defined by an increased diameter of 50% or more. Aneurysmal disease secondary to atherosclerosis is responsible for considerable morbidity and mortality in the developed world and the prevalence of abdominal aortic aneurysm is increasing. Vascular disease is rarely localized and it is essential to exclude co-existent pathology in other vessels.


Infected (mycotic) aneurysms are much less common than those caused by degenerative disease. True mycotic aneurysms result from septic emboli of cardiac origin (endocarditis), which may result in multiple aneurysms at different sites. With an ageing population, microbial aneurysmal arteritis is seen more frequently than true mycotic aneurysms; this results from bacterial seeding into diseased arterial intima with subsequent pseudoaneurysm formation, the most common infecting organisms being the Salmonella species, Escherichia coli, Staphylococcus species and Klebsiella pneumoniae. In approximately 25% of cases no organisms are isolated.


3. Occlusion and stenosis. Most arterial occlusions result from thrombosis of a diseased vessel and are part of a generalized atherosclerotic process. Surgical intervention is not always necessary and careful assessment and management of risk factors is required before surgery is planned. Less commonly an artery is blocked by an embolus. Sudden occlusion of an otherwise normal major artery may threaten both the limb and the life of the patient and warrants emergency intervention either by embolectomy or dissolution of the occlusion. The management of acute-on-chronic limb ischaemia is quite different: this develops following thrombotic occlusion of a previously diseased vessel and cannot usually be treated effectively with thrombectomy alone.


The sections which follow assume that the patient has already been critically evaluated and the need for operation established.



GENERAL PRINCIPLES


In the United Kingdom (UK), most arterial surgery is now undertaken in specialized vascular centres with access to hybrid operating theatres able to perform combined open and endoluminal techniques. The best results are achieved with a multidisciplinary approach by a team of specialized vascular anaesthetists, vascular surgeons, interventional radiologists and vascular scientists to optimize the care of vascular patients.


In addition, facilities such as cell-saver technology to reduce blood transfusion, point-of-care coagulation testing, intra-operative monitoring and intensive care facilities are paramount to gain good outcomes in vascular patients.


There are instances where arterial surgery needs to be undertaken outwith a vascular centre, where the facilities described above may not be available. It is therefore essential for all surgeons to understand the principles of vascular operations and it is in this context and for the benefit of the generalist that this chapter is written.



EQUIPMENT


Most vascular operations can be performed with the naked eye but it is useful to become familiar with the use of magnifying loupes as they enhance clarity and may result in a technically superior anastomosis, paramount in vascular success. Loupes magnifying to x 2.5 are usually sufficient when performing an anastomosis on vessels of 2–3 mm in diameter such as tibial vessels. For smaller vessels an operating microscope should be considered and is beyond the remit of this chapter.



Instruments


In addition to a general surgical set, including a selection of fixed self-retaining retractors appropriate to the area being operated upon (for example, the Omnitract system), the following instruments are helpful:



1. Clamps. A good selection of lightweight vascular clamps is essential. The DeBakey Atraugrip range is suitable for large intra-abdominal and thoracic vessels. For smaller vessels (e.g. femoral, popliteal, subclavian, brachial and carotid arteries), miniature clamps of the Castaneda type designed for paediatric cardiac surgery are ideal. The springs should be gentle and not cause intimal damage. A selection of small ‘bulldog’ clamps is useful to control bleeding while minimizing arterial damage. Alternatively, control of small distal vessels can be gained with the use of fine nylon loops or smooth, round-ended atraumatic intraluminal catheters.


2. Dissecting instruments. Handle arteries gently, and only with non-toothed forceps such as the DeBakey Atraugrip range. Following an initial arteriotomy with an appropriate-sized scalpel blade (a No. 15 for infrainguinal surgery), Pott’s scissors angles in two planes are required for lengthening the arterial incisions. For dissection within the vessel, in order to remove adherent thrombus or elevate the plaque in an endarterectomy, Watson-Cheyne and James MacDonald’s dissectors are ideal. Long tunnelling instruments are necessary for conveying grafts between unconnected incisions.


3. Catheters and shunts. Atraumatic (umbilical) catheters ranging from 3F to 6F in size are useful for intraluminal irrigation and to control small vessels. In addition, a range of the Pruitt type catheters are helpful as they have dual ports to irrigate and occlude vessels. These catheters are particularly useful where heavily calcified vessels may preclude the use of traditional vascular clamps, which may cause iatrogenic injury. A similar size range of Fogarty embolectomy catheters is also required. Catheters with a central lumen allow their introduction over a guidewire under fluoroscopic control, to facilitate intra-operative radiological imaging as well as the instillation of anticoagulant solutions, for example heparinized saline or tissue plasminogen activator (tPA).


It is sometimes necessary to employ an intraluminal shunt as a temporary bypass during reconstruction of a vessel, most commonly in carotid endarterectomy or during arterial and venous reconstruction following trauma. There are two basic types: the Javid and Pruitt-Inihara. A Javid shunt is a tapered plastic tube with a bulbous expansion at each end; these allow large and small ring clamps to be applied to the outside of the vessel once the shunt has been introduced into the artery (see Fig. 23.35).



The second type is a modification of the Pruitt catheter described above, with a balloon at each end to retain it in place and to control bleeding, and a side-arm for withdrawal of blood or air from the lumen.


4. Endovascular equipment. For the most part, percutaneous procedures are the remit of the interventionalist and/or the vascular specialist. Procedures may involve both open and endoluminal techniques. It is paramount that procedures involving radiation and contrast medium are undertaken by appropriately trained staff with the requisite certification. For the non-specialist a basic understanding of the guidewires (variety of diameters, thickness, lengths and coatings as well as stiffness, depending on usage, tip shapes and steering capabilities), catheters and sheaths available is all that is required. It is not recommended that surgeons lacking the requisite training and skills undertake these techniques.


5. Sutures, needle-holders and suture clamps. Arteries are always sewn with non-absorbable stitches. There are three types:



image Fine monofilament material such as polypropylene (Prolene) has the advantage of being very smooth and slipping easily through the tissues so that a loose suture can be drawn tight. The material possesses a slight ‘memory’ which can easily be compensated for with familiarity of use. Its main disadvantage is that it has a tendency to fracture with direct handling with metal instruments.


image Braided materials are coated with an outer layer of polyester to render them smooth, for example Ethiflex and Ethibond. Sutures of this type do not slip so easily through the arterial wall but are pleasantly floppy to handle and knot easily.


image PTFE (polytetrafluoroethylene; Gore-Tex) sutures are designed specifically for use with PTFE grafts. PTFE is non-compliant: thus holes in the graft made by the passage of a needle result in more bleeding than occurs with other types of grafts. In PTFE sutures the diameter of the needle is smaller than that of the suture itself, thereby reducing bleeding. This is at the expense of some loss of strength, and the fragility of these needles precludes their use in tough or calcified arteries. The suture material itself is extremely strong and has excellent handling properties.


In general, use the finest suture appropriate for the job; as a rough guide, 3/0 for the aorta, 4/0 for the iliacs, 5/0 for the femoral, 6/0 for the popliteal and 7/0 for the tibial arteries. For very fine work a monofilament stitch is always necessary.


Vascular sutures are usually double-ended sutures and are used accordingly. The end of the suture not being used for the anastomosis is usually attached to a ‘rubber shod’ clamp-a mosquito or similar clamp with fine tubing cushioning the jaws to prevent damage to the suture. Unprotected clamps should never be applied to monofilament sutures.


To complement the range of sutures a wide selection of needle-holders varying in length should be available; likewise, the tips should reflect the degree of delicacy of the anastomosis being performed.




Grafts and stents


The best arterial substitute is the patient’s own blood vessel, usually vein. However, quite often there is no suitable vein available because it is either absent, too small, varicose or damaged by thrombophlebitis. In these circumstances a prosthetic graft has to be chosen:



1. Dacron. This is an inert polymer that is spun into a thread and then either woven or knitted; it is available as straight or bifurcated grafts measuring from 5 to 40 mm in diameter. In general, the knitted variety with a velour lining is preferred as its porosity leads to better anchoring of the internal ‘neointimal’ surface. The original knitted grafts needed to be carefully preclotted with blood taken from the patient prior to the administration of heparin and in an emergency such as a ruptured aneurysm it was necessary to use a woven graft, which leaks less. However, most vascular surgeons now use knitted grafts that have been presealed with bovine collagen, gelatin or albumin. These grafts have very low porosity at the time of insertion and so do not require preclotting. Dacron grafts perform well when used to bypass large arteries with a high flow-rate (e.g. the aorta and iliac arteries) and are the conduit of choice in these situations provided there is no obvious infection present. In general, Dacron grafts are used above the groin and PTFE below the groin. Dacron grafts are available with external ring supports to prevent compression or kinking.


2. Expanded polytetrafluoroethylene (PTFE) is more expensive than Dacron, but its performance is superior for reconstruction of small arteries. PTFE grafts are again available with an external polypropylene ring support to prevent compression or kinking of the graft. It is essential to use this type of graft when traversing a joint (for example the knee joint). Further developments in this field include preshaped grafts which are manufactured from PTFE to reproduce an anastomosis of ‘ideal’ configuration without the need to form a vein cuff at the distal anastomosis. The long-term patency rate is inferior to that of vein grafts.


3. Biological. The first arterial substitutes tried were arterial or venous allografts or xenografts but these degraded and were abandoned. Grafts from cryopreserved human umbilical veins have been advocated for bypass procedures in the presence of infection; however they are prone to aneurysmal dilatation and therefore their use is limited.


4. Compliant grafts. Prosthetic grafts are stiff and non-compliant and hence their patency is inferior to that of human vessels. Newer grafts developed using nanotechnology have an excellent compliance profile; they are currently in clinical trials and may prove to be a significant new material in the armamentarium of the vascular surgeon.


5. Stents and stent-grafts. Metallic stents made from either stainless steel or nitinol may be used as an adjunct to balloon angioplasty in order to maintain patency of a vessel. There are two types: balloon expandable (e.g. Palmaz stent) and self-expanding (e.g. Wallstent). Stent-grafts are used for endovascular aneurysm repair and are made of polyester/PTFE attached to a metal stent (either stainless steel or nitinol, which is a nickel–titanium alloy). The metal stent provides both radial and longitudinal support, with the aneurysm being excluded from the circulation by the graft material. Endografts are usually self-expanding but balloon expandable devices have been made. All endoluminal stent-grafts rely on being oversized by 10–15% relative to the normal diameter of the artery in which they are placed. One further variable is the proximal fixation method, which usually consists of hooks or barbs which secure the device to the proximal aortic wall to minimize distal migration. Most stent-grafts are either bifurcated aortoiliac or uni-iliac devices and are either one piece or modular in design. If a uni-iliac device is deployed, the contralateral iliac artery has to be occluded, usually with a radiological plug, and a femoro-femoral crossover graft performed to allow perfusion of the contralateral lower limb.



GENERAL CONSIDERATIONS





BASIC TECHNIQUES OF ARTERIAL REPAIR, ANASTOMOSIS AND TRANSLUMINAL ANGIOPLASTY




Simple suture




1. Longitudinal arteriotomies in large or medium-sized arteries can usually be closed by simple suture (Fig. 23.1).



2. Use the finest suture material compatible with the thickness and quality of the arterial wall. The aim is to produce an everted suture line that is leak-proof, with apposition of the intima. This is quite different from bowel anastomosis, where the mucosa is deliberately inverted into the lumen and tension on the sutures is minimal to prevent necrosis of the edges. There is no need to use everting mattress sutures which would narrow the lumen: a simple over-and-over stitch is adequate provided that care is taken to ensure that the intima turns outwards. The needle must pass through all layers of the arterial wall with every stitch. The inner layers must be included to ensure good intimal apposition and to prevent flap dissection, and the outer layers must be included since the main strength of the arterial wall resides in its adventitia. A good surgical assistant who follows your stitches and maintains firm, even tension on the suture at all times is important. Experience is required in order to judge the spacing and size of each bite, and this varies with the size and nature of the artery. Occasionally, for example in aortic aneurysm repair, large irregular stitches may be required but in general evenly spaced regular stitching is best.



Closure with a patch




1. Close vessels of less than 4 mm in diameter with a patch in order to avoid narrowing of the lumen (Fig. 23.2).



2. This technique may also be used to widen the lumen of a vessel that has become stenosed by disease (e.g. the profunda femoris artery). For small vessels use a patch of autologous vein. Do not use the proximal end of the long saphenous vein for this purpose. Use either a segment taken from the ankle, a tributary or a piece of vein from another site (e.g. an arm vein). For larger vessels prosthetic material (either Dacron or PTFE) or bovine or equine patches may be used. When cutting the patch to shape, always ensure that the ends are rounded rather than tapered to a sharp point: this prevents narrowing of the lumen caused by clustering of sutures at the pointed end. After shaping the patch use a single double-ended stitch commencing close to one end and working around each side. Do not finish the stitching at the apex as knots here are at risk of causing significant narrowing: carry one of the sutures around to the other side to complete the closure and tie the knot a short distance to one side. This technique permits direct vision of the internal suture line and allows final trimming of the patch to be delayed until closure is nearly complete in order to ensure a perfect match for size.



End-to-end anastomosis




1. For small delicate arteries this is accomplished most safely by applying the principles of the triangulation technique originally described by Carrel.1 Join the vessels with a suture placed in the centre of the back or deepest aspect of the anastomosis (Fig. 23.3). Be sure to tie the knot on the outside. Place two more sutures so as to divide the circumference of the vessels equally into three. Any disparity in calibre can be compensated for at this stage. If the vessel is small it is better to insert interrupted sutures to prevent narrowing. Use the three original stay sutures to apply gentle traction and to rotate the vessel and facilitate exposure of each segment of the anastomosis in turn. Complete the back two segments first, leaving the easiest segment at the front to be finished last.



2. For larger vessels it is permissible to use continuous sutures. Cut the ends of the vessels to be joined obliquely then make a short incision longitudinally to create a spatulated shape and reduce the risk of narrowing at the anastomosis.


3. A different technique of end-to-end anastomosis, the inlay technique, is routinely used in open operations for aneurysms (see below).



End-to-side anastomosis




1. This is the standard form of anastomosis for bypass operations. It should be oblique and its length should be 2–2.5 times the diameter of the lumen of the graft. To avoid narrowing the lumen, it is important that the end of the graft is fashioned into a spatulated shape, which on completion of the anastomosis has a smooth curved ‘cobra-head’ appearance rather than an angulated ‘V’ appearance. The end of the anastomosis in the angle with the native vessel is referred to as the ‘heel’ and the other end as the ‘toe’. Place a double-ended stitch at the heel and another at the toe and run sutures along each margin, ending with a knot at the halfway point on each side. Alternatively, start with a double-ended suture at the heel and leave the toe free. Run the suture up each side to beyond the midpoint and then place the suture in a ‘rubber-shod’ clamp to prevent damage. Take a new double-ended suture and start at the toe end and suture around the apex towards the midpoint on either side and then tie to the previously retained threads. This is sometimes known as the ‘four-quadrant technique’ (Fig. 23.4), and has the advantage of keeping the inside of the suture line in view as much as possible.



The ‘toe’ and ‘heel’ are the most crucial points of an end-to-side anastomosis. To ensure that the toe is completed as smoothly as possible, offset the starting point of the ‘toe’, suturing a few millimetres to one side or the other of the apex. In order to further reduce the risk of causing a stricture at this point, some surgeons prefer to place a few interrupted sutures around the toe. It is essential that this end of the anastomosis is performed under direct vision and to ensure that each stitch is placed carefully without causing narrowing.


2. A stricture of the heel may be avoided by stenting the vessel with an intraluminal catheter of appropriate size until this portion of the anastomosis is complete. An alternative method is the ‘parachute’ technique (Fig. 23.5). This is particularly useful where access is difficult and good visualization of the anastomosis is impaired, but it is applicable to most situations. With the graft and the recipient artery separated, place a series of running sutures between them at what will become the heel of the anastomosis. These sutures are then pulled tight as the vessels are approximated.





Transluminal angioplasty (Fig. 23.6)





1. Angioplasty is performed by appropriately trained vascular interventionalists. Most patients with symptoms secondary to peripheral arterial occlusion are now treated with endoluminal techniques rather than open surgery. Prior to offering patients transluminal angioplasty, optimize the patient’s risk factors with best medical therapy, cessation of smoking and a supervised exercise programme.2


It is paramount to consider these patients in the context of a multidisciplinary meeting. Most surgeons and radiologists will not offer angioplasty to patients with calf claudication as the risks may outweigh the benefits. Angioplasty and, if required, placement of a stent may be warranted in patients with buttock claudication with iliac stenosis, as the risks of emboli and consequent limb loss are lower. Patients with critical ischaemia and tissue loss should be considered for an endoluminal approach.


Patients with diabetes mellitus may present with challenging long occlusions extending from superficial femoral to crural vessels in tandem with significant co-morbidites. In these patients an endoluminal approach may be offered in isolation or in conjunction with surgical revascularization: subintimal angioplasty may be preferred to a transluminal approach; however, this should not be undertaken without due consideration and by an experienced endovascular specialist. Specialist equipment such as the ‘Outback’ catheter and ‘Ree kross’ balloon can achieve endoluminal revascularization of long occlusions and may result in a successful outcome in patients with critical limb ischaemia or tissue loss who may not be candidates for traditional surgery.


2. Essential requirements are fluoroscopy with ‘subtraction’ and ‘road-mapping’ functions and skilled radiographic assistance. Use a radiolucent operating table.


3. Ensure all operating theatre staff are properly protected against radiation.


4. In the case of elective procedures ensure that patients are prescribed antiplatelet therapy at least 48 hours prior to the procedure. Minimize contrast-induced renal damage by ensuring adequate rehydration with intravenous fluids pre and post procedure.


5. Consider giving mild sedation and oxygen; ensure regular non-invasive monitoring of blood pressure, heart rate and oxygen saturation. Well-chosen music in the operating room may help patients to relax.


6. Transluminal angioplasty can be undertaken percutaneously or using an open technique to expose the relevant artery. Be aware that this technique may be used concurrently with open arterial reconstruction (for example, iliac angioplasty and femorodistal bypass).


7. If the chosen entry vessel cannot easily be palpated consider using ultrasound to locate the vessel, allowing accurate single puncture entry. An introducer sheath is always used and permits repeated endovascular access with minimal trauma to the vessel. The size of sheath required is determined by the procedure to follow – balloon angioplasty usually requires a 4–7F sheath; stent placement may require a larger catheter. All manufacturers recommend the appropriate sheaths on their instructions and packaging.


8. The common femoral artery is the access vessel for most endovascular procedures and it is important to be familiar with its position with reference to surface landmarks (see Exposure of the common femoral artery, below).


9. For percutaneous access, clean the skin and apply drapes as for an open procedure. Inject a small amount of local anaesthetic at the chosen puncture site and make a nick in the skin with a no. 11 scalpel blade. While palpating the common femoral artery with the fingers of one hand introduce a Potts-Cournand or similar needle. These needles have a central trocar that allows blood to ‘flashback’ into a chamber on the hub when the lumen of the vessel is entered. Angle the needle to facilitate access of the guide wire in the direction required and to avoid puncture of the back wall or creation of a false lumen and dissection. For infrainguinal procedures, puncture the artery just distal to the inguinal ligament, allowing room to manoeuvre the tip of the needle within the lumen of the common femoral artery whilst negotiating the guide wire into the superficial femoral artery. Note that the inguinal ligament lies approximately 2 cm proximal to the groin crease. Care should be taken to identify the landmarks accurately in all patients: do not be misled in obese patients whose groin crease will be significantly lower than the inguinal ligament. For access to the upstream iliac arteries the puncture site may be a little lower, but take care to avoid unintended puncture of the superficial or profunda femoris arteries. When no pulse is palpable or percutaneous access is difficult use an ultrasound-guided arterial puncture technique. Alternatively, ‘cut-down’ onto the common femoral artery under local infiltration anaesthesia.


10. When ‘flashback’ occurs you should observe strong pulsatile flow from the needle. Unless there is severe inflow obstruction, the absence of pulsatile flow from the needle indicates that the tip is not properly positioned within the lumen. Do not attempt to advance a guide wire, but re-position the needle to gain access to the arterial lumen.


11. When satisfied with the position of the needle, advance a short J guide-wire down the trocar (normally a suitable wire is packaged as a part of the introducer set) and check with fluoroscopy. A guide-wire that is within the lumen passes without resistance: if resistance is encountered do not apply force as this is likely to result in dissection of the subintimal plane. Stop, withdraw the guide-wire and readjust the position of the needle. For downstream procedures the guide-wire must be manipulated into the superficial femoral artery by adjusting the angle of the needle. This requires that stiff metallic rather than soft plastic or Silastic needles are used. Simple fluoroscopy without contrast is usually sufficient to guide this manoeuvre, but if persistent difficulty is encountered obtain a road-map by injection of contrast through the needle. Never pass a hydrophilic guide-wire through a metallic needle: the hydrophilic coating will be stripped off by the needle when the wire is withdrawn, with potentially dire consequences.


12. If angioplasty is to be performed through the exposed common femoral artery (see Exposure of the common femoral artery, below), do not clamp and open the artery. Place a purse-string suture of 5/0 polypropylene (Prolene) around the artery before puncturing the vessel directly with a Potts-Cournand needle. Then proceed in the same way as for a percutaneous procedure.


13. When you are satisfied that the guide-wire is in place, withdraw the needle and insert the introducer sheath with its dilator. Remove the dilator. Flush the sheath with heparinized saline through the side channel, which is fitted with a tap. This channel can also be used for injection of contrast medium in order to obtain an angiographic image of the lesion.


14. Withdraw the short guide-wire and replace it with the wire chosen to navigate the lesion to be treated. The size of guide-wire required is indicated on the packaging of the balloon catheter – most often 0.035 inches in diameter for peripheral arterial procedures. Introduce it through the sheath floppy end first, using the small plastic introducer cone that comes with the wire to penetrate the valve. If difficulty is encountered in crossing the lesion use a hydrophilic guide-wire. Always wipe the guide-wire with a swab soaked in heparinized saline after removing a catheter as dried blood on the surface obstructs the smooth passage of a subsequent catheter.


15. If navigation of the guide-wire has been difficult, pass an appropriately sized catheter across the lesion and obtain an angiogram to ensure that the natural lumen has been entered beyond the lesion before passing a balloon catheter. If a subintimal space has been entered consider abandoning the procedure.


16. For most applications select a balloon catheter of 4 cm in length. For accurate sizing of the balloon obtain an angiogram using a measuring catheter with 1 cm markings. Match the size of the balloon to the diameter of the unstenosed artery. However, this degree of precision is not normally necessary: for lesions in the superficial femoral artery balloons with a diameter of 6 mm, and for iliac lesions 8 mm, are usually appropriate. Be cautious when selecting catheters for female patients with small arteries.


17. Use a hand-operated syringe driver to inflate the balloon to a pressure of 5–10 atmospheres with a 50/50 mixture of contrast medium and saline. Observe the shape of the balloon as it inflates; ‘popping’ of the ‘waist’ caused by the stenosis indicates that the plaque has given way and, usually, a satisfactory outcome. It is not necessary to maintain inflation of the balloon for more than a few seconds but a second inflation helps smooth the irregularities of the flow surface that result from splitting and fissuring of the plaque.


18. Obtain a completion angiogram to assess the final result. Remember that some irregularity of the flow surface at the site of angioplasty is usual. This tends to remodel naturally within a few weeks. Also, dilatation may continue to occur at the angioplasty site for a short time. If a significant stenosis remains, or if a large intimal flap has developed following iliac artery angioplasty, consider the use of an intraluminal stent. Stents do not perform well in arteries below the groin and should only be used in exceptional circumstances.


19. Following withdrawal of the introducer sheath apply digital pressure to the puncture site for a minimum of 10 minutes, and longer if needed, before applying a dressing and moving the patient. Give clear instructions to the nursing staff regarding duration of bed rest prior to mobilization to minimize haematoma and pseudoaneurysm formation. If the artery has been exposed, tie the purse-string suture to secure haemostasis or apply clamps and proceed with the open procedure.


20. Unless contraindicated, prescribe subcutaneous heparin or low-molecular-weight heparin postoperatively. Monitor peripheral perfusion and the groin for signs of haematoma or formation of a false aneurysm. Ensure post procedure antiplatelet therapy is continued indefinitely.




EXPOSURE OF THE MAJOR PERIPHERAL ARTERIES




Common femoral artery




1. The common femoral artery needs to be exposed more frequently than any other vessel in the body and it is important to know how to do this swiftly and correctly (Fig. 23.7).




2. The position of the groin crease does not correspond to that of the inguinal ligament, but lies distal to it by 2–3 cm.


3. The midpoint of the incision should roughly correspond to the groin crease. Inexperienced surgeons tend to make the incision too low. When limited exposure of the common femoral artery is required (e.g. access for an endovascular intervention), it is permissible to use a transverse incision, which heals better and less painfully than a vertical incision crossing the groin crease. Position a transverse incision two fingers breadth above the groin crease.


4. Deepen the incision through the subcutaneous fat, taking care not to cut across any lymph nodes. Expose the femoral sheath and incise it longitudinally to expose the artery. The femoral vein lies medially and must be protected, but the femoral nerve on the lateral side lies in a deeper plane and is not usually at risk. However, do not be over zealous with positioning of a self-retainer, as the nerve can easily be stretched and a neuropraxia ensues.


5. Dissect a length of the common femoral artery and without undue force pass a Lahey clamp around the back of the artery in order to draw through a plastic sling. Gently lift the artery with the sling and identify its branches and its bifurcation into the superficial and profunda femoral arteries. Isolate these similarly with slings. Take care to avoid damage to the profunda vein, a tributary of which always passes anterior to the main stem of the profunda artery. For a more extensive exposure of the profunda femoris artery divide this vein between ties.


6. If exposure of the greater saphenous vein is required at the same operation make a ‘lazy-S’ incision, commencing vertically over the artery at the inguinal ligament and then deviating medially over the vein in the upper thigh.


7. Transection of the many lymphatics in the femoral triangle may cause a troublesome lymphocele or lymphatic fistula after the operation. There is no sure way of avoiding this, but approach the artery from its lateral rather than its medial side and gently reflect any lymph nodes and visible lymph vessels off the femoral sheath with minimal damage. If there are any obvious lymph leaks at the time of surgery suture the lymphatic channels closed with 6/0 Prolene.



Popliteal artery




1. The popliteal artery can be exposed above and below the knee by medial approaches. Prior to embarking on this surgery decide which part of the artery needs to be accessed and consider how the patient should be positioned on the operating table. The most inaccessible part lies directly behind the joint line and if its exposure at this level is required a posterior approach is essential (see paragraph 4 below).


2. To expose the supragenicular part of the artery the patient is placed supine with adequate support to flex the lower thigh and knee; a longitudinal incision is then made over the medial aspect of the lower thigh (Fig. 23.8). If you intend to perform a bypass with a saphenous vein graft, mark the vein before surgery; otherwise the incision should correspond with the anterior border of the sartorius muscle – the tendency is to place this incision too anteriorly. Deepen the incision to expose the sartorius muscle, which is retracted posteriorly to reveal the neurovascular bundle enveloped by the popliteal fat pad. The artery lies on the bone and the nerve lies some distance away with the vein in between. The popliteal artery is always surrounded by a plexus of veins, which must be carefully separated and divided in order to avoid troublesome bleeding.



3. In order to expose the infrageniculate popliteal artery, make an incision on the medial aspect of the calf along the border of the gastrocnemius muscle (Fig. 23.9). To optimize exposure to this area the tendons of sartorius, semitendinosus and gracilis can be divided. If the greater saphenous vein is to be harvested identify the vein first along an appropriate length before continuing the dissection between the medial head of gastrocnemius and the tibia to reveal the neurovascular bundle. The vein is exposed first and this has to be lifted carefully away to give access to the artery. By dividing the soleus muscle along its attachment to the medial border of the tibia it is possible to expose the origin of the anterior tibial artery and the whole extent of the tibioperoneal trunk through this incision. If necessary, completely divide the medial head of gastrocnemius; this results in little functional disability.



4. If exposure of the whole length of the popliteal artery is required it is better to use a posterior approach. With the patient placed prone, make a ‘lazy-S’ incision (medial proximally to lateral distally) through the popliteal fossa. Deepen the incision through the popliteal fascia and fat pad and define the diamond between the hamstring muscles above and the two heads of gastrocnemius below; then follow the lesser saphenous vein into the neurovascular bundle. In a posterior approach the popliteal artery will be superficial, with the vein and nerve lying deeper.



Tibial arteries




1. The proximal end of the anterior tibial artery is relatively inaccessible, but the remainder of this vessel and its terminal dorsalis pedis branch can be readily exposed through lateral or anterior incisions made directly over the vessels. Retract the tibialis anterior and extensor digitorum longus muscles anteriorly to reveal the artery lying on the interosseous membrane (Fig. 23.10). If exposure of the proximal anterior tibial artery is required this can be achieved very effectively by excision of the upper part of the fibula with disarticulation of the proximal tibiofibular joint. The common peroneal nerve, which winds around the neck of the fibula, must be protected carefully. This approach destroys the lateral ligament of the knee and, while this is well tolerated in elderly, relatively immobile patients, it is best avoided in younger and fitter individuals.



2. The peroneal artery can also be exposed through a lateral incision following removal of a segment of fibula. The peroneal artery lies directly deep to the fibula: it is accompanied only by vein and has no neurovascular bundle. Take care to divide and tie the veins which interdigitate around the artery. Do not be tempted to use diathermy to gain haemostasis. In most cases, however, it is preferable to expose this vessel by a medial approach (see below).


3. To expose the posterior tibial artery, make a longitudinal incision on the medial aspect of the calf centred over the junction between gastrocnemius muscle and its Achilles tendon. Incise the deep fascia and develop the plane between the gastrocnemius and soleus muscles to reveal the posterior tibial vessels and nerve lying on the surface of soleus beneath a layer of fascia (Fig. 23.11). Alternatively, the posterior tibial artery and its terminal lateral plantar branch may be exposed by an incision made directly over it, as it lies behind the medial malleolus where it is covered only by deep fascia, and then following it into the foot.



4. To expose the peroneal artery by a medial approach, split the lateral fibres of soleus and flexor hallucis longus muscles. This reveals the artery surrounded by its concomitant veins in the depths of the wound.



Subclavian artery




1. Make a transverse incision 1 cm above the medial third of the clavicle; divide the platysma muscle in the same plane (Fig. 23.12). This exposes the clavicular head of the sternocleidomastoid muscle, which is divided, and also a fat pad containing the scalene lymph nodes. Dissect and retract this fat pad superiorly off the surface of the scalenus anterior muscle. Identify the phrenic nerve, which passes obliquely from lateral to medial across the front of this muscle to lie along the medial border of its tendon and usually separated from it by a few millimetres. Pass the blade of a MacDonald’s dissector behind the tendon of scalenus anterior muscle, in such a way as to protect the phrenic nerve, and divide the tendon by cutting down on to the dissector with a pointed scalpel blade. Retraction of the muscle superiorly exposes the subclavian artery with its vertebral, internal mammary and thyrocervical branches. The first thoracic nerve root and the lower trunk of the brachial plexus cross the first rib above and posterolateral to the artery. The subclavian vein is deep to the clavicle and is not normally seen through this approach. On the left side the thoracic duct enters the confluence of the internal jugular and subclavian veins. If it is damaged, ligate it to prevent the development of a troublesome postoperative chylous fistula.



2. Extensive exposure of the subclavian artery can be obtained by excision of the inner two-thirds of the clavicle, although this is rarely necessary. The two most common operations on the subclavian artery are carotid-subclavian anastomosis or bypass for a proximal occlusion (subclavian steal syndrome) and repair of a subclavian aneurysm (this is usually a misnomer since most so-called subclavian aneurysms involve the first part of the axillary artery). The former is usually completed without difficulty through the approach described above, and the latter is most conveniently accomplished with separate incisions above and below the clavicle to expose the subclavian and axillary arteries (see below).


3. Operations that involve direct exposure of the origin of the subclavian artery have been largely superseded by extrathoracic bypass procedures (carotid-subclavian and subclavian-subclavian bypass). On the rare occasions when direct exposure is considered essential this is best achieved by splitting the manubrium and upper sternum.


Make a right-angled incision with a horizontal component above the medial third of the clavicle and a vertical component in the midline over the manubrium and upper sternum. Complete the supraclavicular exposure of the artery as described above. Deepen the vertical incision through the subcutaneous tissue and periosteum. The periosteum is extremely vascular and diathermy is required to seal the small arteries. Commencing at the suprasternal notch, open a retrosternal plane by finger dissection, and then, with a sternal chisel and hammer or a properly protected reciprocating saw, divide the manubrium and sternum in the midline and spread the edges with a self-retaining retractor. Dissection of the thymus and anterior mediastinal fat is necessary to expose the arch of the aorta and the origins of the supra-aortic vessels. The innominate vein is stretched across the upper part of the incision and must be protected. It is not usually necessary to divide the sternal tendon of the sternocleidomastoid muscle. Close with peristernal wire or strong nylon sutures, taking care to avoid damage to the internal mammary and intercostal arteries when inserting them.


The origin of the left subclavian artery, which arises far back on the aortic arch, can also be exposed through a posterolateral thoracotomy through the bed of the second or third ribs.



AXILLARY AND BRACHIAL ARTERIES




1. Access to the axillary artery is most often required for axillofemoral bypass and occasionally for subclavian aneurysm repair (see above). For an axillofemoral bypass procedure consider placing the arm in abduction to facilitate estimating the length of the graft required. Make a horizontal incision 1 cm below the lateral third of the clavicle, and split the fibres of pectoralis major muscle (Fig. 23.13). This exposes the infraclavicular fat pad, beneath which lies the pectoralis minor muscle. Divide the tendon of this muscle close to its origin at the tip of the acromion process. Some branches of the acromiothoracic vessels may need to be divided. Find the axillary artery surrounded by the cords of the brachial plexus, which must be carefully protected. The axillary artery can be a friable vessel and care should be taken when slings and clamps are applied. Care should also be taken when performing an anastomosis that the back wall of the artery is not inadvertently incorporated in to the suture line.



2. The proximal brachial artery is found in the groove between biceps and brachialis muscles on the inner aspect of the upper arm (Fig. 23.14). At this point it is still enclosed by cords of the brachial plexus joining to form the median nerve, which crosses it obliquely from the lateral to the medial side. These structures must be carefully separated from it.



3. It is more frequently necessary to expose the bifurcation of the brachial artery in order, for example, to perform a brachial embolectomy. To do so, make a ‘lazy-S’ incision (medially proximally and laterally distally) in the antecubital fossa, followed by division of the biceps aponeurosis (Fig. 23.15). Distal extension of this incision permits the radial, ulnar and anterior interosseous arteries to be followed into the forearm.




TYPES OF OPERATION


Details of the techniques used to repair or bypass damaged or diseased arteries will be included within the relevant descriptions of specific arterial operations (see below). However, it is useful at this point to summarize the range of procedures available:



1. Direct repair, interposition grafting and patch grafting for arterial trauma


2. Surgical embolectomy or thrombectomy


3. Thrombolytic therapy, percutaneous suction and mechanical embolectomy


4. Endarterectomy, which, with the exception of carotid endarterectomy, has now been largely supplanted by bypass surgery as the treatment of choice for occlusive disease


5. Bypass grafting


6. Percutaneous and intra-operative (adjunctive) dilatation angioplasty and endovascular stenting for occlusive arterial disease. The basic technique involves the use of a guide-wire and a balloon dilatation catheter.1 Devices exist to assist recanalization of resistant occlusions, including lasers, rotational guide-wires, high-frequency electrocoagulation ablators and various types of atherectomy catheters. None of these has yet found a major role in the routine management of vascular disease, and lasers in particular, despite increasing technological sophistication, have so far proved disappointing. The use of balloon catheters (some with drug elution) has, however, made a major impact in recent years and in vascular centres the majority of patients with occlusive disease are treated by these methods


7. Inlay grafting for aneurysms


8. Endovascular stent-graft repair of aortic and peripheral aneurysms.



QUALITY CONTROL


Success in arterial surgery demands technical perfection and this must always be assured as far as is practically possible by appropriate assessment before the patient leaves the operating room. Omission of this step results in a high incidence of early postoperative occlusion and is therefore unacceptable. It is important to appreciate that the presence of a palpable pulse in a graft gives no indication whatsoever that it is technically satisfactory. There may be no mean forward flow through the graft and yet it will be pulsatile to palpation. Acceptable methods available for assessing vascular reconstructions at operation include the following:



1. Completion angiography. This continues to be the ‘gold-standard’ method. State of the art fluoroscopy is ideal but for infrainguinal reconstructions ‘on-table’ angiography is performed very easily using the simple X-ray equipment available in all standard operating theatres. Angiography allows graft and anastomotic assessment.


Place an X-ray plate wrapped within a sterile Mayo tray cover directly beneath the limb, and take an exposure while injecting 15–20 ml of contrast medium into the proximal end of the graft. Apply a clamp proximal to the injection site during exposure to obviate the necessity for accurate timing of the exposure. Observe proper radiation protection measures during this procedure and further reduce the radiation dose to yourself by interposing a long length of connecting catheter (for example an arterial line) between the syringe and the injection site.


For more proximal reconstructions, special X-ray equipment is required but other methods of quality control may be effective.


2. Intra-operative Doppler flowmetry. Intra-operative Doppler probes give an indication of flow and some can also give a waveform tracing which is helpful in ascertaining stenoses. It is also possible to use a simple hand-held Doppler probe placed in a finger of a sterile surgical glove with gel to assess flow.


3. Angioscopy. Fibreoptic endoscopes of little more than 1 mm in diameter are now available. Inserted at one end, such instruments will allow direct inspection of the interior of a graft and anastomosis. However, such instruments traumatize the flow surface and are expensive and for these reasons have been largely abandoned.


4. A satisfactory arterial reconstruction for occlusive disease restores either normal or improved blood flow to the distal circulation, and confirmation that this has occurred is a minimal requirement. The return of palpable pulses to vessels downstream of the reconstruction, for example in the pedal arteries, is a valuable sign and there are a number of simple and inexpensive devices available to supplement clinical assessment, including strain gauge and photoplethysmographs (digital pulse monitors), toe temperature probes, flat and hand-held Dopplers and pulse oximeters.




ARTERIAL OPERATIONS





REPAIR OF ARTERIAL INJURY



Appraise


Arterial trauma may occur as an isolated event but more often it occurs in association with other injuries, for example fracture of long bones. Under these circumstances there is a danger that the symptoms of ischaemia may be masked and therefore go unrecognized until irreversible tissue damage has occurred. Always assess the distal circulation in cases of fractured long bones or disarticulation injuries, especially those that involve the elbow or knee.



1. Arterial injury is manifest by:



2. Suspicion of arterial injury is an indication for urgent angiography (CT angiography or digital subtraction angiography), except for haemorrhage, in which case proceed directly to surgical exploration unless you are in a centre which can offer radiological options such as embolization.


3. Angiographic discontinuity of a major limb vessel always requires urgent surgical exploration. Occlusion of a single tibial or forearm vessel is usually tolerated without ischaemic damage and does not as a rule require reconstruction.


4. Beware the concept of ‘arterial spasm’. It is true that the smooth muscle of arteries contracts protectively in response to injury so that an important vessel may appear quite small both angiographically and on direct inspection. However, luminal discontinuity is always due to a mechanical fault and demands surgical repair. Never attempt to treat such lesions with vasodilator drugs.


5. In the case of multiple injuries, co-operate closely with colleagues of other specialities in planning surgical treatment. Repair of damaged major arteries always takes precedence over orthopaedic fixation of fractures. However, there is a danger that vascular anastomoses may disrupted during subsequent manipulation of fractures. In these circumstances it may be advisable to restore vascular continuity initially by inserting a temporary intraluminal plastic shunt, and completing the repair once the fractures have been stabilized, when the length of the arterial defect can be accurately measured. Always check for venous disruption as well as arterial damage.


6. Run-in. This is not usually a problem in arterial trauma.


7. Run-off. There is a risk that blood clot may form and occlude vessels distal to the site of injury. The procedure must include measures to deal with this problem (see below), otherwise the run-off vessels are usually normal.


8. Conduit. In the case of limb injuries this is either the original artery repaired directly or an interposition graft of autologous vein. Since only short segments are required, problems are rarely encountered in finding a vein of suitable quality and calibre. If there has been extensive injury to both artery and major veins consider harvesting a segment of vein from the opposite leg or upper limb.


9. For closed injuries to major arteries (e.g. iliac, subclavian) with tearing or rupture of the vessel consider endovascular repair with a covered stent in hospitals with facilities for this type of procedure (see Endovascular repair of aortic and peripheral aneurysms, below).





Assess




1. On entering the haematoma there may be brisk fresh bleeding, in which case apply clamps at the proximal and distal control points already prepared.


2. If there is complete disruption of the artery find the ends and apply soft clamps. It is unlikely that they will be actively bleeding at the time of exploration.


3. The traumatized vessel will be damaged some distance proximally and distally from the principal site of injury, therefore trim each end back a few millimetres at a time until normal undamaged intima is seen.


4. Assess the length of the defect. Attempt direct end-to-end anastomosis only if there will be no tension. In most cases it is more prudent to insert an interposition graft of autologous vein, even if this is only a centimetre in length.


5. If the artery is in continuity there may be bruising of the adventitia at the site of injury and absence of downstream pulsation. These are sure signs of internal disruption. The intima and inner layers of the media split transversely and the edges roll back to form a flap, which obstructs flow, causing secondary thrombosis. It is never sufficient, therefore, to simply inspect the outer surface of such a vessel and it is totally unacceptable to treat such lesions by topical application of vasodilator substances. Excise the damaged segment completely, cutting back each end of the artery as before to find healthy intima.


6. Active arterial bleeding usually signifies incomplete disruption or a lateral wall defect that inhibits protective retraction and constriction of the vessel.



Action




1. Before commencing repair of the artery check for adequate inflow and backflow. If either is inadequate pass a Fogarty catheter distally and proximally to withdraw any propagated clot and then instil heparinized saline.


2. If there are associated orthopaedic injuries consider inserting a temporary intraluminal shunt (see above).


3. The adventitia tends to prolapse over the end of a normal artery that has been cut across. Trim this back to prevent it intruding inside the anastomosis.


4. If direct end-to-end anastomosis is possible, accomplish it by the triangulation technique (see Basic techniques) and in most cases employ interrupted sutures in preference to continuous.


5. If the defect is too great to permit direct repair, harvest a segment of vein of appropriate size. Remember to reverse the vein to avoid obstruction to blood flow by competent valves. Complete the proximal anastomosis first, in end-to-end fashion, using the triangulation technique with interrupted sutures for small or inaccessible vessels or the oblique overlap technique for larger vessels. Apply a clamp to the distal end of the graft and allow arterial pressure to distend it in order to determine the optimum length to avoid both excessive tension and kinking. Finally, complete the distal anastomosis.


6. A small puncture or lateral wall defect, as may result from iatrogenic injury following arterial access for investigation or treatment, may be repaired by direct suture or by closing the arteriotomy with a patch.







SURGICAL EMBOLECTOMY



Appraise




1. Embolic occlusion of a major artery results in acute ischaemia, which, if not relieved quickly, may progress to irreversible tissue damage and limb loss.


2. The differential diagnosis is from acute thrombosis occurring within an already diseased artery. Differentiation between these two conditions may be impossible on clinical grounds alone, especially since embolization is nowadays more commonly associated with ischaemic heart disease than valvular stenosis, and most patients therefore have generalized arteriosclerosis.


3. On examination, if there is an immediate threat to the viability of the limb with loss of power and movement and a neurosensory deficit then immediate surgical exploration is required irrespective of the cause.


4. Revascularization of a limb that is already totally non-viable invariably has fatal consequences due to reperfusion injury and is absolutely contraindicated. Urgent amputation may be life-saving.


5. Under other circumstances urgent angiography is indicated to establish the diagnosis and to permit proper appraisal of the various options for treatment.


6. Surgical embolectomy is indicated for embolic occlusion of:



7. For patients in whom there is no immediate threat to the viability of the limb, more distal emboli, such as those in the popliteal artery, are more appropriately treated by thrombolytic therapy.


8. Surgical embolectomy can be performed under local anaesthesia but general anaesthesia is preferable in the absence of serious anaesthetic risk.


9. Run-in, run-off and conduit usually are not relevant to surgical embolectomy in the absence of associated arterial disease.





Action




1. Make a short longitudinal arteriotomy. In the case of the femoral artery make this directly over the origin of the profunda artery.


2. Select an embolectomy catheter of a size appropriate to the vessel: 3F for axillary and brachial arteries, 4F for the superficial and profunda femoral arteries and 5F for the aortic bifurcation.


3. A number of different makes of embolectomy catheter are available. Choose one with a central irrigating lumen that permits injection of heparinized saline or X-ray contrast medium into the vessels beyond the balloon.


4. Pass the uninflated catheter proximally through the vessel beyond the clot. Inflate the balloon and withdraw the catheter slowly while adjusting the pressure within the balloon to accommodate changes in the diameter of the vessel. Avoid severe friction between the balloon and the arterial wall since this can cause intimal damage to the vessel.


5. Instruct an assistant to control bleeding from the vessel during this process by applying gentle traction to the rubber sling previously placed around it.


6. Repeat the procedure until no more thrombus is retrieved and adequate forward arterial flow is obtained from the vessel. Avoid unnecessary passages of the catheter.


7. Instil heparinized saline into the artery and gently apply a clamp.


8. Repeat the same procedure distally.


9. Fill the vessels with heparinized saline and close the arteriotomy. Directly suture the common femoral artery; consider using a small vein patch for the brachial artery.



DIFFICULTY




1. The catheter will not pass proximally or forceful forward bleeding is not obtained. This can be due to pre-existing arterial disease or to the catheter having been introduced in a subintimal plane. Avoid direct aorto-iliac reconstruction under these circumstances if at all possible and perform either a femoro-femoral crossover or an axillofemoral bypass.


2. The catheter will not pass distally. Obtain an on-table angiogram. This may show embolus impacted at the popliteal bifurcation and in the tibial arteries, or evidence of atherosclerotic occlusion. Instil a small amount of a thrombolytic agent (streptokinase, urokinase or tPA) locally through a small catheter advanced to the site of occlusion.1 Then pass a small Fogarty catheter 15 minutes later; more embolus may be retrieved. Alternatively, expose the infrageniculate popliteal artery to enable Fogarty catheters to be introduced directly into the tibial vessels. This requires the administration of a general anaesthetic. If there is a longstanding atherosclerotic occlusion of the superficial femoral artery, restoration of blood flow to the profunda system alone is likely to be sufficient to save the limb. However, if distal perfusion remains poor, then proceed to femoropopliteal bypass. Where facilities for intra-operative fluoroscopy exist, as an alternative to exposure of the popliteal artery for retrieval of emboli from the tibial arteries, pass the embolectomy catheter over a guide-wire negotiated into each vessel in turn. Assess the result by angiography.





PERCUTANEOUS THROMBOLYTIC THERAPY AND THROMBECTOMY




Prepare



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Mar 28, 2017 | Posted by in GENERAL SURGERY | Comments Off on Arteries

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