Treatment of Complications from Prosthetic Infrainguinal Arterial Grafts



Treatment of Complications from Prosthetic Infrainguinal Arterial Grafts


Lloyd M. Taylor Jr.

Gregory J. Landry

Gregory L. Moneta



This chapter describes our treatment of complications that follow use of prosthetic arterial substitutes implanted at and distal to the common femoral artery. For the purposes of this chapter, prosthetic arterial grafts include those made from the polymers polytetrafluoroethylene (PTFE) and polyester (Dacron). We will not discuss complications specific to grafts of biologic origin, such as glutaraldehyde-treated human umbilical vein and cryopreserved homografts, although these share many features with polymer grafts.

The specific complications (and their management) described include occlusion, infection, aneurysm formation, and perigraft seroma. Before considering these complications, a few remarks regarding prevention are in order.


Prevention of Prosthetic Graft Complications


The Decision to Operate

It is axiomatic, but worth emphasizing, that complications cannot occur from an operation that was never performed. In our referral practice, a very large percentage of patients presenting for treatment of prosthetic graft complications were originally operated upon for claudication. For fortunate patients, graft occlusion results in a return to the original symptomatic state. Unfortunately, a disturbingly large number of infrainguinal prosthetic graft occlusions result in ischemia that is more severe than that which was the indication for the original operation. For these patients, and for those who develop prosthetic infections, limb-threatening complications will have resulted from a treatment performed for a disease process that had a very low likelihood of ever threatening their limb. Obviously they (and their surgeons) naturally wish they had never undertaken the surgery in the first place.

The best way to avoid progression to limb-threatening ischemia in a patient with claudication is to not operate for the claudication, especially using a prosthetic graft. Infrainguinal bypass surgery for claudication should be approached very cautiously, and only when fully informed patients clearly understand that the most significant risk to their limb is probably from the treatment, not from the disease.


Prosthetic Versus Vein

The most effective way to prevent postoperative prosthetic graft complications is to construct the bypass conduit from autogenous vein. Intact good-quality greater saphenous vein is the best available conduit, but good-quality lesser saphenous, arm, and deep leg veins are all satisfactory and are all superior to prosthetic, even when multiple segments are anastomosed together to form conduits of adequate length. Two techniques assist in maximizing the number of grafts that can be performed using autogenous vein. The first is the use of duplex scan vein mapping to identify the best conduits. The second is using multiple operative teams to facilitate complex redo bypass surgery. A single operating team of surgeon and assistant (faculty attending and resident, in our practice) can nearly always complete a first-time tibial bypass using intact ipsilateral greater saphenous vein within a reasonable operating time of 3 to 4 hours. When the operation is a redo, with a need to harvest three segments of vein from both arms to create an adequate conduit, the time required may exceed twice that, and that is not an acceptable length operation for an elderly patient with multisystem comorbidities. In this dilemma lies the origin of many a prosthetic graft. On the other hand, two or three operating teams working simultaneously can easily complete such complex operations within the same time required for first-time surgery. The advantages of using autogenous conduit are sufficiently great that surgeons who are unable to muster the necessary manpower for multiple operating teams should seriously consider referral of complex redo cases to medical center services who can.


Confirmation of Technical Success

Adequacy of inflow, conduit, proximal, and distal anastomoses and outflow vessels should be confirmed by objective means, prior to closing wounds/leaving the operating room. At a minimum, improved ankle continuous wave Doppler signals that respond appropriately to temporary graft occlusion and release should be confirmed. Operative completion arteriography is more cumbersome, but it provides more detailed and anatomic information. Abnormalities should be explained, and corrected, before leaving the operating room.


Pharmacologic Management

Patients with atherosclerotic disease should be on antiplatelet therapy with aspirin or clopidogrel. This should be continued perioperatively. The authors add peri-operative
heparin anticoagulation and postoperative warfarin for patients with documented hypercoagulable disorders. The most frequent of these is the presence of anticardiolipin antibodies, which may be found in as many as one third of patients requiring redo bypass surgery. Peri-operative heparin therapy results in an increased incidence of postoperative wound hematomas requiring reoperation for drainage. This is a reasonable exchange for improved graft patency.


Prevention of Infection

By any criterion, infection involving a prosthetic infrainguinal bypass graft is a surgical disaster. Treatment nearly always involves extensive additional surgery and resource intense hospitalization. Limb loss is a frequent result in most series. Obviously these events are best prevented by avoiding the use of prosthetic grafts in the first place. When they must be used, appropriate prophylactic antibiotics and elimination of infected lesions in the same limb prior to, or, when absolutely necessary, simultaneously with bypass grafting are important aspects in prevention. The frequent need for peri-operative anticoagulants in a number of patients requiring infrainguinal grafting means that they have a higher than usual incidence of postoperative hematomas. The authors believe that any postoperative hematoma involving a prosthetic graft should be operatively removed. A draining hematoma resulting in delayed wound healing is a recipe for graft infection.


Treatment of Prosthetic Infrainguinal Graft Occlusions


Acute Postoperative Occlusions

For the purpose of this chapter, acute postoperative graft occlusions are those that occur prior to discharge of the patient from the hospitalization during which the bypass procedure was performed. During this interval, occlusions are usually detected promptly and can be treated immediately, with a reasonable expectation that patency can be restored, and that long-term patency will be acceptable; this is a situation that is almost never true once the patient has been discharged.


Initial Management

Acute postoperative graft occlusions result in return of ankle brachial pressure indices (ABI) to pre-operative levels, or below, and recurrence of pre-operative ischemic symptoms. If the indication for the bypass was claudication, there may be no symptoms in a bed-confined hospital patient. Any decrease in ABI from immediate postoperative values must be explained. In some patients, arteriography may be necessary to determine whether grafts are occluded or patent with another explanation (proximal stenosis, graft stenosis, runoff occlusion, and so on) for the reduced ABI. Once diagnosed, the most appropriate response to acute postoperative graft occlusions is full heparinization followed by an immediate return to the operating room. Of course there may be compelling reasons not to follow this course. Patients and conditions may change markedly postoperatively. Myocardial infarction (MI), pneumonia, or other acute conditions may preclude early reoperation, and other conditions such as gastrointestinal bleeding may preclude anticoagulation. If immediate reoperation is contraindicated, it is extremely unlikely that the original bypass conduit can be salvaged. This may be a reasonable and appropriate price for delay, when dictated by patient condition.


Conduct of the Operation

In addition to the operated extremity, the surgical field should include a source of vein conduit that is sufficient to replace or to extend the original graft. The patient should be placed on an operating table that will accommodate fluoroscopy of the entire extremity arterial tree, from the aortic bifurcation to the toes. Full heparin anticoagulation should be maintained, until the cause of the graft occlusion has been determined and corrected. It is helpful to monitor the dose of heparin intra-operatively using the activated clotting time (ACT).

The first step is to open the incisions over the proximal and distal anastomoses and determine the cause of the occlusion. A normal pulse in the inflow artery/proximal graft rules out inflow obstruction as the cause. Liquid blood in the hood of the distal anastomosis similarly rules out distal obstruction. Hard thrombus in either location points to a cause at the site where it is found.

Catheter thrombectomy of prosthetic grafts is straightforward in the immediate postoperative period. Intra-operative arteriography can then be performed to locate the site of the obstruction that produced the occlusion. Unsuspected or undetected proximal or distal occlusive disease must be repaired or bypassed by graft extension. Technically unsatisfactory anastomoses should never be the cause of graft occlusion; they should have been detected by the measures used to ensure technical success at the time of the first operation. Once the explanation for the thrombosis is found and corrected, the authors prefer to replace the original graft with a new one—thrombectomy is never perfect, and the flow surface has been altered by the thrombosis.

Regardless of the cause of the graft occlusion and the method chosen for its correction, operative completion arteriography should conclude operations performed to correct acute graft occlusions. Once the final reconstruction has been proved to be technically satisfactory, the authors prefer to continue heparin anticoagulation for several days postoperatively, to prevent early rethrombosis.


Rethrombosis

Prosthetic bypass grafts that reocclude, after the operative steps described above have been taken, will not remain patent after another operation in which the thrombus is removed again. If a different operation (different anastomotic sites, new conduit) is possible, it is acceptable to proceed with this, taking patient condition into account. If not, there is little to be gained from repeated and increasingly futile attempts to make a flawed system work.


Treatment of Late Occlusion of Prosthetic Infrainguinal Grafts

Four courses of action are possible in response to graft occlusions that occur following hospital discharge. These include:

Tags:
Jun 16, 2016 | Posted by in CARDIAC SURGERY | Comments Off on Treatment of Complications from Prosthetic Infrainguinal Arterial Grafts

Full access? Get Clinical Tree
Get Clinical Tree app for offline access